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Angiogenesis and the Tumor Vasculature as Antitumor Immune Modulators: The Role of Vascular Endothelial Growth Factor and Endothelin
Abstract
Cancer immunotherapies have yielded promising results in recent years, but new approaches must be utilized if more patients are to experience the benefits of these therapies. Angiogenesis and the tumor endothelium confer unique immune privilege to a growing tumor, with significant effects on diverse immunological processes such as hematopoietic cell maturation, antigen presentation, effector T cell differentiation, cytokine production, adhesion, and T cell homing and extravasation. Here, we review the role of angiogenesis and the tumor endothelium on regulation of the antitumor immune response. We place particular emphasis on the role of vascular endothelial growth factor (VEGF) in the suppression of numerous immunological processes that control tumor progression. Further, we describe the unique crosstalk between the VEGF and endothelin systems, and how their interactions may shape the antitumor immune response. These insights establish new targets for combinatorial approaches to modify existing cancer immunotherapies.
... 7 Evidence suggests that peripheral immune tolerance and angiogenesis are closely connected and cooperate to sustain tumour growth. 8,9 Thus, inhibition of both angiogenesis and immuno suppression might result in improved and more durable clinical benefit. In the KEYNOTE-826 trial, pembrolizumab was combined with a chemotherapy-alone backbone with optional bevacizumab; 5 thus, the role of immunotherapy with standard antiangiogenic therapy was inferred only from subgroup analyses. ...
... Median treatment duration was 12·7 months (IQR 7·6-24·8) in the experimental group versus 8·5 months (5·1-13·9) in the standard group. Median duration of chemotherapy was six cycles (IQR 6-8) in both groups, whereas median bevacizumab duration was longer in the experimental group (14 cycles [IQR 7-25]) than the standard group (ten cycles [6][7][8][9][10][11][12][13][14][15][16][17][18]). Median atezolizumab duration was 16 cycles (IQR 8-32). ...
... Preclinical studies showed the potential synergistic efficacy of ICIs with TKIs and antiangiogenic drugs. Immunosuppressive properties of vascular endothelial growth factor (VEGF) have been demonstrated in preclinical models via inhibition of T-cell infiltration due to diminished permeability of tumor vessels (34,35). Additionally, VEGF inhibits T-cell development and causes the upregulation of PD-1 and CTLA-4 expression on immune cells (36,37). ...
... Additionally, VEGF inhibits T-cell development and causes the upregulation of PD-1 and CTLA-4 expression on immune cells (36,37). Although the clinical activity as single agent is modest, it has been shown that anti-angiogenic drugs could normalize the tumor vasculature and increase T cell infiltration by inducing the upregulation of the leukocyte adhesion molecules such as ICAM-1 and VCAM-1 on tumor endothelial cells (34). It was previously shown that VEGF inhibitor could synergize with ICIs in metastatic melanoma and there is an increase interest in combining anti-angiogenic treatments with ICIs to turn "cold' tumors into "hot" tumors (38). ...
The prevalence of primary liver cancer is rapidly rising all around the world. Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Unfortunately, the traditional treatment methods to cure HCC showed poor efficacy in patients who are not candidates for liver transplantation. Until recently, tyrosine kinase inhibitors (TKIs) were the front-line treatment for unresectable liver cancer. However, rapidly emerging new data has drastically changed the landscape of HCC treatment. The combination treatment of atezolizumab plus bevacizumab (immunotherapy plus anti-VEGF) was shown to provide superior outcomes and has become the new standard first-line treatment for unresectable or metastatic HCC. Currently, ongoing clinical trials with immune checkpoint blockade (ICB) have focused on assessing the benefit of antibodies against programmed cell death 1 (PD-1), programmed cell death-ligand 1 (PD-L1), and cytotoxic T-lymphocyte- associated antigen 4 (CTLA-4) as monotherapies or combination therapies in patients with HCC. In this review, we briefly discuss the mechanisms underlying various novel immune checkpoint blockade therapies and combination modalities along with recent/ongoing clinical trials which may generate innovative new treatment approaches with potential new FDA approvals for HCC treatment in the near future.
... Activation of these receptors stimulated endothelium NO synthase-mediated NO production by ECs as well as prostacyclin synthesis [86]. ET-1 has been shown to directly promote tumor angiogenesis by inducing EC survival, proliferation, and invasion in an ETBR-dependent manner [87]. In this context, monocytes\macrophages, due to the production of MVs with ET, can act as regulators of physiological and pathological angiogenesis [87]. ...
... ET-1 has been shown to directly promote tumor angiogenesis by inducing EC survival, proliferation, and invasion in an ETBR-dependent manner [87]. In this context, monocytes\macrophages, due to the production of MVs with ET, can act as regulators of physiological and pathological angiogenesis [87]. ...
Monocytes\macrophages regulate angiogenesis via cytokine production and contact interactions with endothelial cells (ECs). The biological effects of macrophage-derived microvesicles (MVs) are studied using cell lines, such as monocytic leukemia THP-1 cell line. The effect of MVs produced by THP-1 cells on EC phenotype and functions remain understudied. In this research, we studied the effect of MVs produced by THP-1 cells on the phenotype, proliferation, migration, and vascular formation of EA.Hy926 ECs. MVs produced by THP-1 cells express CD54, CD18, CD11a, CD11b, CD29, CD120a, CD120b, VEGFR1, VEGFR2, CD105, CD119, TGFR2 on the surface and contain ERK1/2, pERK1/2 Akt, FGF10, endothelin-2. The transfer of an intracellular protein labeled with a fluorescent dye from MVs produced by THP-1 cells to EA.Hy926 ECs was established. It was found that MVs derived from THP-1 cells inhibit EC proliferation. In high concentrations, MVs reduce EC migration, increase the length but decrease the number of vessels formed by ECs, promoting the development of non-branching angiogenesis. On the contrary, in low concentrations, MVs increase EC migration, reduce the length, and increase the number of vessels formed by ECs, promoting the development of branching angiogenesis. Thus, the fundamental possibility of the influence of MVs produced by THP-1 cells on the processes of angiogenesis has been established. Proteins found in the MVs composition may be responsible for the observed effects of MVs on ECs. 136 AIMS Allergy and Immunology Volume 5, Issue 3, 135-159.
... Suzuki et al. showed for the first time that VEGFR2 is selectively expressed by FOXP3 high but not FOXP3 low Tregs (55). Neuropilins acted as co-receptors, increasing the binding affinity of VEGF for VEGFRs (56,57). Promoted VEGF signaling through conjunction with neuropilin-1 may enhance Treg activation and create a tolerogenic environment (57). ...
... Neuropilins acted as co-receptors, increasing the binding affinity of VEGF for VEGFRs (56,57). Promoted VEGF signaling through conjunction with neuropilin-1 may enhance Treg activation and create a tolerogenic environment (57). It is therefore reasonable that targeting VEGFA/VEGFR can modulate antitumor immunity by interfering with inhibitory Tregs. ...
In addition to the crucial role in promoting the growth of tumor vessels, vascular endothelial growth factor (VEGF) is also immunosuppressive. VEGF can inhibit the function of T cells, increase the recruitment of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs), and hinder the differentiation and activation of dendritic cells (DCs). Recent studies have investigated the role of antiangiogenic agents in antitumor immunity, especially in recent 3 years. Therefore, it is necessary to update the role of targeting VEGF/VEGFR in antitumor immunity. In this review, we focus on the latest clinical and preclinical findings on the modulatory role of antiangiogenic agents targeting VEGF/VEGFR in immune cells, including effector T cells, Tregs, MDSCs, DCs, tumor-associated macrophages, and mast cells. Our review will be potentially helpful for the development of combinations of angiogenesis inhibitors with immunological modulators.
... Suzuki et al. showed for the first time that VEGFR2 is selectively expressed by FOXP3 high but not FOXP3 low Tregs (55). Neuropilins acted as co-receptors, increasing the binding affinity of VEGF for VEGFRs (56,57). Promoted VEGF signaling through conjunction with neuropilin-1 may enhance Treg activation and create a tolerogenic environment (57). ...
... Neuropilins acted as co-receptors, increasing the binding affinity of VEGF for VEGFRs (56,57). Promoted VEGF signaling through conjunction with neuropilin-1 may enhance Treg activation and create a tolerogenic environment (57). It is therefore reasonable that targeting VEGFA/VEGFR can modulate antitumor immunity by interfering with inhibitory Tregs. ...
... Furthermore, the CD10+GPR77+CAF subset has been found in human cancer tissue samples to contribute to tumor stem cell proliferation by secreting IL-6 and IL-8, hence contributing to tumor growth and resistance to chemotherapy (Freeman and Mielgo, 2020;Dhandapani et al., 2023). VEGF and its downstream signaling pathways can promote angiogenic conversion (Fukumura et al., 2018), and may be a significant contributor to immune resistance (Shojaei et al., 2007;Kandalaft et al., 2010;Hack et al., 2020). ...
Among all malignant tumors, lung cancer has the highest mortality and morbidity rates. The non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) are the most common histological subtypes. Although there are a number of internationally recognized lung cancer therapy regimens, their therapeutic effects remain inadequate. The outlook for individuals with lung carcinoma has ameliorated partly thanks to the intensive study of the tumor microenvironment and immune checkpoint inhibitors. Numerous cancers have been effectively treated with immunotherapy, which has had positive therapeutic results. Global clinical trials have validated that PD-1/PD-L1 inhibitors are effective and safe for treating lung cancer either independently or in combination, and they are gradually being recommended as systemic treatment medications by numerous guidelines. However, the immunotherapy resistance restricts the immunotherapy efficacy due to the formation of tumor immunosuppressive microenvironment and tumor mutations, and immunotherapy is only effective for a small percentage of lung cancer patients. To summarize, while tumor immunotherapy is benefiting an increasing number of lung cancer patients, most of them still develop natural or acquired resistance during immunotherapy. Consequently, a crucial and urgent topic is understanding and tackling drug resistance triggered by immunotherapy in lung cancer treatment. This review will outline the presently recognized mechanisms of immunotherapy resistance and reversal strategies in lung cancer.
... In patients with NSCLC and LM combination of VEGF blockade, chemotherapy, and ICI significantly prolonged PFS compared to chemotherapy and ICI alone (222). VEGF signaling has been implicated in diminished antitumoral immunity by several mechanisms, including reducing cytotoxic activity of peripheral CD8 + T cells (223), enhancing Treg cell activation (224)(225)(226), and inducing immunosuppressive effects of MDSCs (68). VEGF-A also directly induces FASL expression leading to apoptosis of CD8 + T cells (227). ...
The liver is a functionally unique organ with an immunosuppressive microenvironment. The liver is the sixth most common site of primary cancer in humans and is a frequent site of metastasis from other solid tumors. The development of effective therapies for primary and metastatic liver cancer has been challenging due to the complex metabolic and immune microenvironment of the liver. The liver tumor microenvironment (TME) in primary and secondary (metastatic) liver cancers is heterogenous and consists of unique immune and stromal cell populations. Crosstalk between these cell populations and tumor cells creates an immunosuppressive microenvironment within the liver which potentiates cancer progression. Immune checkpoint inhibitors (ICIs) are now clinically approved for the management of primary and secondary liver cancer and can partially overcome liver immune tolerance, but their efficacy is limited. In this review, we describe the liver microenvironment and the use of immunotherapy in primary and secondary liver cancer. We discuss emerging combination strategies utilizing locoregional and systemic therapy approaches which may enhance efficacy of immunotherapy in primary and secondary liver cancer. A deeper understanding of the immunosuppressive microenvironment of the liver will inform novel therapies and therapeutic combinations in order to improve outcomes of patients with primary and secondary liver cancer.
... been demonstrated in solid malignancies including HCC and renal cell carcinoma 13, 28-30 . VEGF pathway signaling has been implicated to diminish anti-tumoral immunity by several mechanisms, including reducing the cytotoxic activity of peripheral T cells, 31 enhancing T regulatory cell activation [32][33][34] , and inducing myeloid derived suppressor cells, which in turn elicit immunosuppressive effects by lymphocyte depletion, generation of oxidative stress, interfering with lymphocyte trafficking and activation of T regulatory cells 35 . VEGF-A also directly induces FASL expression leading to apoptosis of CD8 + T cells 36 . ...
Liver cancer remains a challenge of global health, being the 4th leading cause of cancer death worldwide. Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, and is usually precipitated by chronic viral infections (hepatitis B and C), non-alcoholic steatohepatitis, heavy alcohol use, and other factors which may lead to chronic inflammation and cirrhosis of the liver. There have been significant advances in the systemic treatment options for HCC over the past decades, with several approvals of both immune checkpoint inhibitors and tyrosine kinase inhibitors in patients with preserved liver function. These advances have led to improvement in survival outcomes, with expected survival of greater than 18 months, in those with sensitive tumors, adequate liver function, and those functionally fit to receive sequential therapies. Several ongoing and promising trials are now evaluating combinational strategies with novel systemic agents and combinations of systemic therapy with locoregional therapy. In view of these trials, further advances in the treatment of HCC are foreseen in the near future.
... Resected RCC tumors exhibit T-cell infiltration, indicating immune recognition of tumors but with ineffective tumor cell killing [5]. Von Hippel-Lindau (VHL) gene mutation is the most common mutation in ccRCCs, associated with immunosuppressive and anti-angiogenic effects [6]. Cytotoxic T lymphocyte associated protein-4 (CTLA-4) is a component of the regulatory feedback cycle known to reduce T-cell response. ...
Renal cell carcinoma (RCC) is the most common kidney cancer in adults (approximately 90%), and clear cell RCC (ccRCC) is the most frequent histologic subtype (approximately 75%). We reviewed the safety and efficacy of checkpoint inhibitors (CPIs) in ccRCC, identifying 5927 articles in PubMed, Embase, Cochrane, and Web of Science. Ten randomized control (N = 7765) and 10 non-randomized (N = 572) studies were included. Overall, 4819 patients treated with CPI combinations were compared with everolimus, sunitinib, or placebo. Overall response rates (ORR) were 9-25% with nivolumab (niv), 42% with niv + ipilimumab (ipi), 55.7% with niv + cabozantinib, 56% with niv + tivozanib vs. 5% with everolimus. ORR was 51.5-58% with avelumab + axitinib vs. 25.5% with sunitinib. ORR was 59.3-73% with pembrolizumab + tyrosine kinase inhibitor vs. 25.7% with sunitinib. ORR was 32-36% with atezolizumab + bevacizumab vs. 29-33% with sunitinib. In patients with PD-L1+ve and -ve ccRCC, niv, atezolizumab, ipi, and pembrolizumab were safe and effective alone and when combined with cabozantinib, tivozanib, axitinib, levantinib, and pegilodecakin. Atezolizumab + bevacizumab was safe and effective in ccRCC with high PD-L1 expression. Pembrolizumab was safe and effective in preventing recurrence in ccRCC patients with nephrectomy. Additional randomized, double-blind, multicenter clinical trials are needed to confirm these results.
... Therefore, the unique characteristics of ccRCC made it an attractive disease for the treatment with ICI [24]. The absence of VHL in most ccRCC led to the increase of VEGF, which promotes immunosuppression as well as angiogenesis [25]. An important area underway was to adapt ICI to these tumor-specific immune characteristics [26,27]. ...
Accumulating pieces of evidence suggested that immunotypes may indicate the overall immune landscape in the tumor microenvironment, which were closely related to therapeutic response. The purpose of this study was to classify and define the immune subtypes of clear cell renal cell carcinoma (ccRCC), so as to authenticate the potential immune subtypes that respond to immunotherapy. Transcriptome expression profile and mutation profile data of ccRCC, as well as clinical characteristics used in this study were obtained from TCGA database. There were significant differences in the infiltration of immune cells, immune checkpoints, and antigens between ccRCC and para-cancerous tissues. According to immune components, patients with ccRCC were divided into three immune subtypes, with different clinical and molecular characteristics. Compared with other subtypes, IS2 showed cold immune phenotype, and was associated with better survival. IS1 represented complex immune populations and was associated with poor overall survival (OS) and progression free survival (PFS). Further analysis indicated that expression of immune checkpoints also differed among the three subtypes, and was abnormally up-regulated in IS3. Pathway enrichment analysis indicated that the mTOR signaling pathway was abnormally enriched in IS3, while the TGF_BETA, ANGIOGENESIS and receptor tyrosine kinase signaling pathways were abnormally enriched in IS2. Furthermore, there was an abnormal enrichment of the epithelial-to-mesenchymal transition (EMT) signaling pathway in IS1, which may be associated with a higher rate of metastasis. Finally, SCG2 was screened as a specific antigen of ccRCC, which was not only related to poor prognosis, but also significantly associated with immune cells and immune checkpoints. In conclusion, the immune subtypes of ccRCC may provide new insights into the tumor biology and the precise clinical management of this disease.
... Hence, there is no risk of oncogene activation as the RNA cannot integrate into the host genome [33]. RNA can be readily amplified with polymerase chain reaction to a large amount from limited tumor biopsies or tumor stroma [36]. As RNA is less stable than DNA, careful handling of the initial biopsy excision is required [33,37]. ...
Due to the intrinsic genetic instability of tumor cells, aberrant and novel tumor antigens can be expressed and serve as potential targets for cancer immunotherapy. This intrinsic feature can be exploited by cancer immunotherapy, particularly with cancer vaccination. Personalized cancer vaccination strategy can be a potent approach to trigger a broad-based antitumor response that is both beneficial and relevant to individual cancer patients. Also, cancer vaccination strategy can be designed to help elicit immunological memory for long-lasting tumor control. In this review, we describe the different types of personalized cancer vaccines and summarize the completed and ongoing cancer vaccination clinical trials in the last 10 years (database from www.clinicaltrials.gov). We also discuss the pros and cons of using different tumor animal models, i.e. syngeneic models, patient-derived xenografts models and genetically engineered mouse models, as tools for investigating cancer vaccination strategies. Finally, we describe preclinical studies that seek to test new emerging vaccination strategies as well as improving existing methods.
... Angiogenesis pathways interact with both DNA repair mechanisms and immune activity. Tumor hypoxia causes downregulation of genes involved in DNA repair, e.g., RAD51 and BRCA1, leading to further DNA damage, genomic instability, and cell death [293,294] . Thus, combining inhibition of DNA repair and angiogenesis pathways may modulate the immune response by increasing DNA damage and tumor mutational burden and attenuating immunosuppressive microenvironments. ...
Triple-negative breast cancer (TNBC) represents the subtype of breast cancer with the most aggressive biological behavior and the worst prognosis compared to other breast cancers. Metastatic TNBC is characterized by a high proliferative index, rapid progression with metastases to the viscera and central nervous system, and generally an unfavorable prognosis with a survival of about one year. It is, therefore, necessary to identify specific targets and more effective treatments for patients with TNBC. Evidence of the effect of the tumor immune microenvironment on clinical outcomes is considered a significant issue in breast cancer therapeutics. Compared to other subtypes of breast cancer, TNBC is characterized by a higher mutational burden and is recognized as the most immunogenic among them. Based on these findings, immune checkpoint inhibition was evaluated in TNBC with encouraging results. Indeed, enhancing antitumor immunity in TNBC by blocking the cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) axis or the programmed cell death-1 (PD-1) receptor/programmed death-ligand 1 (PD-L1) pathway is a promising treatment option. In this review, we examine the role of monoclonal antibodies targeting CTLA-4 and PD-1/PD-L1 in this breast cancer subtype and discuss combination approaches for early and advanced disease.
... RNA therapy allows the exposure of tumor cells to a variety of tumor antigens TAAs and TSAAs [149]. The latter advantage is important in the context of the relationship between the tumor stroma and tumor cells in the anti-neoplastic response [143,150]. However, the efficacy of the anti-cancer genetic vaccine has not been demonstrated in clinical trials [151,152]. ...
Biological therapies have changed the face of oncology by targeting cancerous cells while reducing the effect on normal tissue. This publication focuses mainly on new therapies that have contributed to the advances in treatment of certain malignancies. Immunotherapy, which has repeatedly proven to be a breakthrough therapy in melanoma, as well as B-ALL therapy with CAR T cells, are of great merit in this progress. These therapies are currently being developed by modifying bispecific antibodies and CAR T cells to improve their efficiency and bioavailability. Work on improving the therapy with oncolytic viruses is also progressing, and efforts are being made to improve the immunogenicity and stability of cancer vaccines. Combining various biological therapies, immunotherapy with oncolytic viruses or cancer vaccines is gaining importance in cancer therapy. New therapeutic targets are intensively sought among neoantigens, which are not immunocompromised, or antigens associated with tumor stroma cells. An example is fibroblast activation protein α (FAPα), the overexpression of which is observed in the case of tumor progression. Universal therapeutic targets are also sought, such as the neurotrophic receptor tyrosine kinase (NTRK) gene fusion, a key genetic driver present in many types of cancer. This review also raises the problem of the tumor microenvironment. Stromal cells can protect tumor cells from chemotherapy and contribute to relapse and progression. This publication also addresses the problem of cancer stem cells resistance to treatment and presents attempts to avoid this phenomenon. This review focuses on the most important strategies used to improve the selectivity of biological therapies.
... Consistent with this finding, higher expression of VEGFR2 was found in Tregs compared to other CD4 + T cells (59,60), suggesting a preferential role of VEGF signaling in Tregs. Interestingly, neuropilin-1, an co-receptor increasing the binding affinity of VEGF for VEGFRs, is also highly expressed in Tregs (61), which mediates the activation of Tregs and thus enhances their suppressive function (62). VEGF can directly bind to Neuropilin 1 (Nrp-1) on Tregs and guide their migration into a tumor (63). ...
Immune checkpoint blockade (ICB) has become a standard treatment for non-small cell lung cancer (NSCLC). However, most patients with NSCLC do not benefit from these treatments. Abnormal vasculature is a hallmark of solid tumors and is involved in tumor immune escape. These abnormalities stem from the increase in the expression of pro-angiogenic factors, which is involved in the regulation of the function and migration of immune cells. Anti-angiogenic agents can normalize blood vessels, and thus transforming the tumor microenvironment from immunosuppressive to immune-supportive by increasing the infiltration and activation of immune cells. Therefore, the combination of immunotherapy with anti-angiogenesis is a promising strategy for cancer treatment. Here, we outline the current understanding of the mechanisms of vascular endothelial growth factor/vascular endothelial growth factor receptor (VEGF/VEGFR) signaling in tumor immune escape and progression, and summarize the preclinical studies and current clinical data of the combination of ICB and anti-angiogenic drugs in the treatment of advanced NSCLC.
... A number of drugs with direct or indirect antiangiogenic properties have already been approved by the FDA, such as bevacizumab, nintedanib, ramucirumab, axitinib, cabozantinib, lenvatinib, sunitinib, sorafenib and pazopanib. Used in a range of solid tumors, these agents disrupt the vascular supply, starve the tumor of nutrients and oxygen and induce the upregulation of leukocyte adhesion molecules (ICAM-1 and VCAM-1) on tumor endothelial cells [153,154]. The latter mechanism leads to increased T-cell infiltration, which can be harnessed to target tumors with the immune-excluded phenotype [155]. ...
Immune checkpoint inhibitors have revolutionized the treatment landscape for a number of cancers over the last few decades. Nevertheless, a majority of patients still do not benefit from these treatments. Such patient-specific lack of response can be predicted, in part, from the immune phenotypes present in the tumor microenvironment. We provide a perspective on options to reprogram the tumors and their microenvironment to increase the therapeutic efficacy of immunotherapies and expand their efficacy against cold tumors. Additionally, we review data from current preclinical and clinical trials aimed at testing the different therapeutic options in monotherapy or preferably in combination with checkpoint inhibitors.
... Through this study, we investigated the tumor development induced by melanoma cells B16F10 and the anticarcinogenic properties of baccarin and p-coumaric acid, isolated compounds from green propolis, in mice treated orally for 26 days. Previous in vitro studies demonstrated the cytotoxic effects of propolis extracts as well as of isolated specific compounds in cell lines derived from different cancer types, such as breast [23,24], colon [25], uterine, cervix, and lung [26]. Accordingly, we aimed to obtain an in vivo proof of concept about the action of baccarin and p-coumaric acid on certain fundamental factors related to the development and progression of tumors. ...
Background: Cutaneous melanoma is the most aggressive form of skin cancer, with the worst prognosis, and it affects a younger population than most cancers. The high metastatic index, in more advanced stages, and the high aggressiveness decrease the effectiveness of currently used therapies, such as surgical removal, radiotherapy, cryotherapy, and chemotherapy, used alone or in combination. Based on these disadvantages, research focused on alternative medicine offers great potential for therapeutic innovation. Medicinal plants represent a remarkable source of compounds for the treatment of various diseases. Methods: In this study, we investigated the tumoral behavior of melanoma under treatment with the compounds baccarin and p-coumaric acid, extracted from green propolis, in mice inoculated with B16F10 cells for 26 days. Results: A significant modulation in the number of inflammatory cells recruited to the tumor region and blood in the groups treated with the compounds was observed. In addition, a significant reduction in the amount of blood vessels and mitosis in the neoplastic area was noticed. Conclusions: Through our research, we confirmed that baccarin and coumaric acid, isolated substances from Brazilian green propolis, have a promising anticarcinogenic potential to be explored for the development of new antitumor agents, adhering to the trend of drugs with greater tolerance and biological effectiveness.
... The immune system is a critical and complex regulator of tumor evolution. Tumor angiogenesis not only supplies nutrients and oxygen to cancer tissues but also actively modulates antitumor immune activity (Kandalaft et al. 2011). The angiogenic vasculature of the Yu Zhang, Fei Wang and Hao-ran Sun authors contributed equally to this work. ...
Purpose
Apatinib, an antiangiogenic drug, has shown beneficial effects only in a fraction of advanced gastric cancer (GC) patients. Given the recent success of immunotherapies, combination of apatinib with immune checkpoint inhibitor may provide sustained and potent antitumor responses.
Methods
Immunocompetent mice with subcutaneous MFC tumors grown were given a combination of apatinib and anti-PD-L1 antibody therapy. GC tissues from patients undergoing curative resection in China were collected, and the density of HEVs, MSI status and tumor-infiltrated lymphocytes were analyzed by immunohistochemical staining.
Results
Combined apatinib and PD-L1 blockade therapy synergistically delayed tumor growth and increased survival in MFC-bearing immunocompetent mice. The combination therapy promoted antitumor immunity by increasing the ratio of CD8⁺ cytotoxic T cells to Foxp3⁺ Treg cells, the accumulation of CD20⁺ B cells and the Th1/Th2 cytokine ratio (IFN-γ/IL-10). The combination therapy induced the formation of HEVs through activation of LTβR signaling, thus promoting CD8⁺ cytotoxic T cell and CD20⁺ B cell infiltration in tumors. In clinical GC samples, the density of HEVs positively correlated with the intratumoral infiltration of CD8⁺ cytotoxic T cells and CD20⁺ B cells. MSI-high GC showed a higher density of HEVs, CD8⁺ cytotoxic T cells and CD20⁺ B cells than MSS/MSI-low GC. GC patients with high densities of HEVs, CD8⁺ cytotoxic T cells and CD20⁺ B cells had an improved prognosis with superior overall survival.
Conclusion
Combining apatinib with PD-L1 blockade treatment synergistically enhances antitumor immune responses and promotes HEV formation in GC.
... The immune system is a critical and complex regulator of tumor evolution. Tumor angiogenesis not only supplies nutrients and oxygen to cancer tissues but also actively modulates antitumor immune activity (Kandalaft et al. 2011). The angiogenic vasculature of the tumor provides a barrier to prevent effective leukocytes priming for tumor control, which presents a signi cant challenge to the success of immunotherapy (Ramjiawan et al. 2017). ...
Purpose
Apatinib, an antiangiogenic drug, has showed beneficial effects only in a fraction of advanced gastric cancer (GC) patients. Given the recent success of immunotherapies, combination of apatinib with immune checkpoint inhibitor may provide sustained and potent antitumor responses.
Methods
Immunocompetent mice with subcutaneous MFC tumors grown were given combination of apatinib and anti-PD-L1 antibody therapy. GC tissues from patients undergoing curative resection in China were collected, and the density of HEVs, MSI status and tumor-infiltrated lymphocytes were analyzed by immunohistochemical staining.
Results
Combined apatinib and PD-L1 blockade therapy synergistically delayed tumor growth and increased survival in MFC-bearing immunocompetent mice. The combination therapy promoted antitumor immunity by increasing the ratio of CD8⁺ cytotoxic T cells to Foxp3⁺ Treg cells, the accumulation of CD20⁺ B cells and the Th1/Th2 cytokine ratio (IFN-γ/IL-10). The combination therapy induced the formation of HEVs through activation of LTβR signaling, thus promoting CD8⁺ cytotoxic T cell and CD20⁺ B cell infiltration in tumors. In clinical GC samples, the density of HEVs positively correlated with the intratumoral infiltration of CD8⁺ cytotoxic T cells and CD20⁺ B cells. MSI-high GC showed a higher density of HEVs, CD8⁺ cytotoxic T cells and CD20⁺ B cells than MSS/MSI-low GC. GC patients with high densities of HEVs, CD8⁺ cytotoxic T cells and CD20⁺ B cells had an improved prognosis with superior overall survival.
Conclusion
Combining apatinib with PD-L1 blockade treatment synergistically enhances antitumor immune responses and promotes HEV formation in GC.
... • Being able to trigger the receptor-mediated interaction with the tumor cell to elicit the killing response [83,84]. ...
Radiation therapy (RT) in some cases results in a systemic anticancer response known as the abscopal effect. Multiple hypotheses support the role of immune activation initiated by RT-induced DNA damage. Optimal radiation dose is necessary to promote the cGAS-STING pathway in response to radiation and initiate an IFN-1 signaling cascade that promotes the maturation and migration of dendritic cells to facilitate antigen presentation and stimulation of cytotoxic T cells. T cells then exert a targeted response throughout the body at areas not subjected to RT. These effects are further augmented through the use of immunotherapeutic drugs resulting in increased T-cell activity. Tumor infiltrating lymphocyte presence and TREX1, KPNA2 and p53 signal expression are being explored as prognostic biomarkers.
... However, only a small proportion of patients responded to ICI monotherapy, and the improvement in overall survival (OS) as a result of ICIs is largely attributed to the long-term survival in a minority of patients (7). Additionally, several studies have shown that vascular endothelial growth factor (VEGF) inhibitors promoted T cell infiltration and reversed the inhibitory effect on antigen-presenting cells (APCs) (8)(9)(10). These findings provided the theoretical foundations for combination therapy involving anti-angiogenic drugs and ICIs. ...
Immune checkpoint inhibitors (ICIs) are currently a first-line treatment option for clear cell renal cell carcinoma (ccRCC). However, recent clinical studies have shown that a large number of patients do not respond to ICIs. Moreover, only a few patients achieve a stable and durable response even with combination therapy based on ICIs. Available studies have concluded that the response to immunotherapy and targeted therapy in patients with ccRCC is affected by the tumor immune microenvironment (TIME), which can be manipulated by targeted therapy and tumor genomic characteristics. Therefore, an in-depth understanding of the dynamic nature of the TIME is important for improving the efficacy of immunotherapy or combination therapy in patients with advanced ccRCC. Here, we explore the possible mechanisms by which the TIME affects the efficacy of immunotherapy and targeted therapy, as well as the factors that drive dynamic changes in the TIME in ccRCC, including the immunomodulatory effect of targeted therapy and genomic changes. We also describe the progress on novel therapeutic modalities for advanced ccRCC based on the TIME. Overall, this review provides valuable information on the optimization of combination therapy and development of individualized therapy for advanced ccRCC.
... These changes result in increased T-cell infiltration and eventually convert an immunosuppressive microenvironment into one, which is immunosupportive. [191][192][193] Therefore, a number of scientists have suggested that the use of ICBs during the window of "vascular normalization" may result in superior clinical outcomes. In a preclinical breast cancer model, targeting the tumor vasculature resulted in a more homogeneous distribution of functional tumor vessels. ...
Despite great success in cancer immunotherapy, immune checkpoint-targeting drugs are not the most popular weapon in the armory of cancer therapy. Accumulating evidence suggests that the tumor immune microenvironment plays a critical role in anti-cancer immunity, which may result in immune checkpoint blockade therapy being ineffective, in addition to other novel immunotherapies in cancer patients. In the present review, we discuss the deficiencies of current cancer immunotherapies. More importantly, we highlight the critical role of tumor immune microenvironment regulators in tumor immune surveillance, immunological evasion, and the potential for their further translation into clinical practice. Based on their general targetability in clinical therapy, we believe that tumor immune microenvironment regulators are promising cancer immunotherapeutic targets. Targeting the tumor immune microenvironment, alone or in combination with immune checkpoint-targeting drugs, might benefit cancer patients in the future.
... An ongoing phase II trial (NCT02336165) using bevacizumab in combination with the immune checkpoint inhibitor, durvalumab (an anti-PD-L1 antibody), was designed to assess the potential synergy between these antibodies in GBM patients (55). Even though the impact of bevacizumab on glioma tumor immunity remains unclear at this stage, studies in other tumor types suggest that bevacizumab may have immune-stimulating effects and could provide synergistic therapy when combined with immune-checkpoint inhibitors in non-small-cell lung cancer (NSCLC) patients (56)(57)(58). Studies have also been performed in order to test the efficacy of bevacizumab when combined with chemotherapeutic drugs. ...
Glioblastoma multiforme (GBM) is the most aggressive type of malignant brain tumor. Current FDA-approved treatments include surgical resection, radiation, and chemotherapy, while hyperthermia, immunotherapy, and most relevantly, nanoparticle (NP)-mediated delivery systems or combinations thereof have shown promise in preclinical studies. Drug-carrying NPs are a promising approach to brain delivery as a result of their potential to facilitate the crossing of the blood–brain barrier (BBB) via two main types of transcytosis mechanisms: adsorptive-mediated transcytosis (AMT) and receptor-mediated transcytosis (RMT). Their ability to accumulate in the brain can thus provide local sustained release of tumoricidal drugs at or near the site of GBM tumors. NP-based drug delivery has the potential to significantly reduce drug-related toxicity, increase specificity, and consequently improve the lifespan and quality of life of patients with GBM. Due to significant advances in the understanding of the molecular etiology and pathology of GBM, the efficacy of drugs loaded into vectors targeting this disease has increased in both preclinical and clinical settings. Multitargeting NPs, such as those incorporating multiple specific targeting ligands, are an innovative technology that can lead to decreased off-target effects while simultaneously having increased accumulation and action specifically at the tumor site. Targeting ligands can include antibodies, or fragments thereof, and peptides or small molecules, which can result in a more controlled drug delivery system compared to conventional drug treatments. This review focuses on GBM treatment strategies, summarizing current options and providing a detailed account of preclinical findings with prospective NP-based approaches aimed at improving tumor targeting and enhancing therapeutic outcomes for GBM patients.
... VEGF, initially described as vascular permeability factor [206,207], stimulates vascular permeability through disruption of endothelial cell-cell junctions and induce hyperpermeability and degradation of endothelial membrane with leakage of macromolecules from the intravascular compartment to the peritoneal space. VEGF along with other angiogenic factors including basic fibroblast growth factor (bFGF), angiogenin, transforming growth factors (TGFα and β), IL-6 and IL-8 stimulate endothelial cell proliferation and migration in the peritoneal TME leading to neovascularization and angiogenesis [208][209][210]. ...
Platinum resistance in epithelial ovarian cancer (OvCa) is rising at an alarming rate, with recurrence of chemo-resistant high grade serous OvCa (HGSC) in roughly 75% of all patients. Additionally, HGSC has an abysmal five-year survival rate, standing at 39% and 17% for FIGO stages III and IV, respectively. Herein we review the crucial cellular interactions between HGSC cells and the cellular and non-cellular components of the unique peritoneal tumor microenvironment (TME). We highlight the role of the extracellular matrix (ECM), ascitic fluid as well as the mesothelial cells, tumor associated macrophages, neutrophils, adipocytes and fibroblasts in platinum-resistance. Moreover, we underscore the importance of other immune-cell players in conferring resistance, including natural killer cells, myeloid-derived suppressive cells (MDSCs) and T-regulatory cells. We show the clinical relevance of the key platinum-resistant markers and their correlation with the major pathways perturbed in OvCa. In parallel, we discuss the effect of immunotherapies in re-sensitizing platinum-resistant patients to platinum-based drugs. Through detailed analysis of platinum-resistance in HGSC, we hope to advance the development of more effective therapy options for this aggressive disease.
... As a pro-angiogenic regulator secreted by several solid tumours, VEGF plays an important role in immunosuppression by inhibiting various immune cells that exist in the tumour microenvironment [29]. Additionally, VEGF can negatively regulate dendritic cell (DC) maturation, induce CD8 + T cell apoptosis and activate antigen-specific regulatory T cells [30,31]. The functional importance of VEGF in tumour angiogenesis and immunosuppression has therefore provided a convincing rationale for the development of inhibitors such as endostar that target the VEGF signalling pathway [32]. ...
Background:
Immunotherapy has been shown to be effective as a first-line treatment option for non-small cell lung cancer (NSCLC) patients. Unfortunately, it has failed to acquire an anticipant anti-tumour effect for relatively lower clinical benefit rates. It is therefore important to identify novel strategies for improving immunotherapy. Endostar is a novel recombinant human endostatin that exerts its anti-angiogenic effects via vascular endothelial growth factor (VEGF)-related signalling pathways. Anti-programmed death receptor 1 (PD-1) antibody is an immune checkpoint inhibitor that was developed to stimulate the immune system. In this study, the synergy of PD-1 blockade and endostar was assessed in a lung carcinoma mouse model.
Methods:
Lewis lung carcinoma (LLC)-bearing mice were randomly assigned into three groups: controls, anti-PD-1 and anti-PD-1+endostar. The levels of cytokines such as interleukin (IL)-17, transforming growth factor-β1 (TGF-β1) and interferon-γ (IFN-γ) were measured with enzyme-linked immune sorbent assay (ELISA). The expression of VEGF, CD34 and CD31 was assessed with immunohistochemistry (IHC). The proportion of mature dendritic cells (mDC) and myeloid-derived suppressor cells (MDSC) was analysed with flow cytometry. The major proteins in PI3K/AKT/mTOR and autophagy were quantified with Western blot.
Results:
Anti-PD-1 combined with endostar dramatically suppressed tumour growth in LLC mouse models. This synergistic effect resulted in decreased pro-inflammatory cytokine IL-17 and immunosuppressive factor TGF-β1 levels, increased IFN-γ secretion, reduced myeloid-derived suppressor cell (MDSC) accumulation, and reversed CD8 + T cell suppression. The expression of VEGF, CD34 and CD31 was significantly down-regulated, while tumour cell apoptosis and PI3K/AKT/mTOR-mediated autophagy was up-regulated.
Conclusion:
The combination of anti-PD-1 and endostar has a remarkably synergic effect on LLC tumour growth by means of improving the tumour microenvironment and activating autophagy.
... Stimulation of the host's immune system with immune checkpoint inhibitors showed robust anti-tumor effects and hold promise for the treatment of malignant tumors [15,16]. Considering the facts that tumor immune microenvironment is bound up with tumor angiogenic vasculature, effort has been made to investigate the relationship between anti-angiogenic therapy and tumor immunotherapy [17][18][19]. It was reported that anti-tumor effect of VEGF/VEGFR inhibitors was dependent on their abilities to elicit an immuneactivated milieu in breast and pancreatic tumors. ...
Background:
Inhibitors targeting VEGF and VEGFR are commonly used in the clinic, but only a subset of patients could benefit from these inhibitors and the efficacy was limited by multiple relapse mechanisms. In this work, we aimed to investigate the role of innate immune response in anti-angiogenic therapy and explore efficient therapeutic strategies to enhance efficacy of anti-angiogenic therapy against non-small cell lung cancer (NSCLC).
Methods:
Three NSCLC tumor models with responses to VEGF inhibitors were designed to determine innate immune-related underpinnings of resistance to anti-angiogenic therapy. Immunofluorescence staining, fluorescence-activated cell sorting and immunoblot analysis were employed to reveal the expression of immune checkpoint regulator CD47 in refractory NSCLC. Metastatic xenograft models and VEGFR1-SIRPα fusion protein were applied to evaluate the therapeutic effect of simultaneous disruption of angiogenetic axis and CD47-SIRPα axis.
Results:
Up-regulation of an innate immunosuppressive pathway, CD47, the ligand of the negative immune checkpoint regulator SIRPα (signal regulatory protein alpha), was observed in NSCLC tumors during anti-angiogenic therapy. Further studies revealed that CD47 upregulation in refractory lung tumor models was mediated by TNF-α/NF-κB1 signal pathway. Targeting CD47 could trigger macrophage-mediated elimination of the relapsed NSCLC cells, eliciting synergistic anti-tumor effect. Moreover, simultaneously targeting VEGF and CD47 by VEGFR1-SIRPα fusion protein induced macrophages infiltration and sensitized NSCLC to angiogenesis inhibitors and CD47 blockade.
Conclusions:
Our research provided evidence that CD47 blockade could sensitize NSCLC to anti-angiogenic therapy and potentiate its anti-tumor effects by enhancing macrophage infiltration and tumor cell destruction, providing novel therapeutics for NSCLC by disrupting CD47/SIRPα interaction and angiogenetic axis.
... Tumor hypoxia induces downregulation of genes involved in DNA repair, e.g., RAD51 and BRCA1, leading to further DNA damages, genomic instability, and cell death [6]. VEGF suppresses lymphocyte trafficking across endothelia into tumor deposits and sites of inflammation to promote vessel growth [7]. Combining inhibition of DNA repair and angiogenesis pathways therefore may modulate the immune response by increasing DNA damage and TMB and by attenuating immunosuppressive microenvironments. ...
Background:
Strategies to improve activity of immune checkpoint inhibitors are needed. We hypothesized enhanced DNA damage by olaparib, a PARP inhibitor, and reduced VEGF signaling by cediranib, a VEGFR1-3 inhibitor, would complement anti-tumor activity of durvalumab, a PD-L1 inhibitor, and the 3-drug combination would be tolerable.
Methods:
This phase 1 study tested the 3-drug combination in a 3 + 3 dose escalation. Cediranib was taken intermittently (5 days on/2 days off) at 15 or 20 mg (dose levels 1 and 2, respectively) with durvalumab 1500 mg IV every 4 weeks, and olaparib tablets 300 mg twice daily. The primary end point was the recommended phase 2 dose (RP2D). Response rate, pharmacokinetic (PK), and correlative analyses were secondary endpoints.
Results:
Nine patients (7 ovarian/1 endometrial/1 triple negative breast cancers, median 3 prior therapies [2-6]) were treated. Grade 3/4 adverse events include hypertension (1/9), anemia (1/9) and lymphopenia (3/9). No patients experienced dose limiting toxicities. The RP2D is cediranib, 20 mg (5 days on/2 days off) with full doses of durvalumab and olaparib. Four patients had partial responses (44%) and 3 had stable disease lasting ≥6 months, yielding a 67% clinical benefit rate. No significant effects on olaparib or cediranib PK parameters from the presence of durvalumab, or the co-administration of cediranib or olaparib were identified. Tumoral PD-L1 expression correlated with clinical benefit but cytokines and peripheral immune subsets did not.
Conclusions:
The RP2D is tolerable and has preliminary activity in recurrent women's cancers. A phase 2 expansion study is now enrolling for recurrent ovarian cancer patients.
Trial registration:
ClinicalTrials.gov identifier: NCT02484404. Registered June 29, 2015.
... The clinical activity of anti-angiogenic drugs is modest when used as single agent. However, it has been shown that anti-angiogenic drugs normalize the tumor vasculature and induce the upregulation of the leukocyte adhesion molecules ICAM-1 and VCAM-1 on tumor endothelial cells (83), leading to increased T cell infiltration (84). These therapies may thus represent a treatment of choice for tumors characterized by T cells blocked in the periphery of the tumor in order to enhance intratumoral penetration of T cells. ...
Therapeutic monoclonal antibodies targeting immune checkpoints (ICPs) have changed the treatment landscape of many tumors. However, response rate remains relatively low in most cases. A major factor involved in initial resistance to ICP inhibitors is the lack or paucity of tumor T cell infiltration, characterizing the so-called “cold tumors.” In this review, we describe the main mechanisms involved in the absence of T cell infiltration, including lack of tumor antigens, defect in antigen presentation, absence of T cell activation and deficit of homing into the tumor bed. We discuss then the different therapeutic approaches that could turn cold into hot tumors. In this way, specific therapies are proposed according to their mechanism of action. In addition, ‘‘supra-physiological’’ therapies, such as T cell recruiting bispecific antibodies and Chimeric Antigen Receptor (CAR) T cells, may be active regardless of the mechanism involved, especially in MHC class I negative tumors. The determination of the main factors implicated in the lack of preexisting tumor T cell infiltration is crucial for the development of adapted algorithms of treatments for cold tumors.
... One of the most well studied cytokines known to have important functions in the tumor microenvironment is vascular endothelial growth factor (VEGF). Angiogenesis driven by VEGF signaling is believed to play a role in solid tumor progression and anti-angiogenic therapies are now being considered also as anti-tumor immune modulators [57]. VEGF modifies the anti-tumor immune response at several levels including the prevention of TIL trafficking and promotion of immunosuppressive Treg and MDSC subsets [58]. ...
Immune checkpoint blockade therapy is a powerful treatment strategy for many cancer types. Many patients will have limited responses to monotherapy targeted to a single immune checkpoint. Both inhibitory and stimulatory immune checkpoints continue to be discovered. Additionally, many receptors previously identified to play a role in tumor formation and progression are being found to have immunomodulatory components. The success of immunotherapy depends on maximizing pro-anti-tumor immunity while minimizing immunosuppressive signaling. Combining immune checkpoint targeted approaches with each other or with other receptor targets is a promising schema for future therapeutic regimen designs.
... Antiangiogenic agents such as tyrosine kinase inhibitors are being studied in combination with ICIs in renal cell carcinoma (RCC), based on the rationale that VEGF inhibition has an effect on tumor growth, reduces immunosuppression in the TME, and promotes T cell trafficking to the tumor. 91,92 JAVELIN Renal 100 (NCT02493751) is an ongoing openlabel, multicenter (U.S., U.K., and Japan), dose-finding and dose-expansion, phase Ib study of avelumab plus axitinib as first-line therapy in patients with advanced clear-cell RCC following primary tumor resection. 93 Patients enrolled in the dose-finding phase received 5 mg of axitinib p.o. twice daily for 7 days, followed by combination therapy with avelumab plus continuation of axitinib. ...
Although immunotherapies have been employed for many decades, immune checkpoint inhibitors have only recently entered the oncologic landscape. Avelumab is a fully human monoclonal antibody that blocks the interaction between PD-L1 on tumor cells and PD-1 on T cells, thereby inhibiting immunosuppression in the tumor microenvironment and reducing tumor growth. Most early clinical trials of avelumab as monotherapy and in combination regimens were part of the international JAVELIN clinical trial program, which included more than 7000 patients in more than 30 trials with at least 15 tumor types. Avelumab has been approved by the U.S. FDA for the treatment of metastatic Merkel cell carcinoma and metastatic urothelial carcinoma that has progressed during or following treatment with a platinum-based regimen. Its acceptable safety profile and ability to induce durable responses in otherwise deadly tumors provide the rationale for its use in other tumor types and in combination with other therapies.
... The blockade of VEGFR and PD-L1 pathways induces high endothelial venules that promote lymphocyte infiltration and activity through activation of lymphotoxin receptor [14,15]. VEGF could also inhibit dendritic cell maturation and leukocyte-endothelial interaction by reducing ICAM-1 and VCAM-1 adhesion molecules [16]. The combination between axitinib (a VEGFR 1,2,3 inhibitor) and pembrolizumab (a PD-1 inhibitor) has been tested in a Phase IB trial showing a very promising ORR (73%) with a tolerable safety profile [17,18]. ...
... BRAF mutation status was recently reported to describe populations with differing overall survival after immune checkpoint inhibitors [20]. BRAF V600E is proangiogenic in several human tumour models [21,22], while VEGF has wider regulatory function beyond angiogenesis, including on immune cells [23][24][25] . ...
Background
Bevacizumab is a recombinant humanised monoclonal antibody to vascular endothelial growth factor (VEGF) shown to improve survival in advanced solid cancers. We evaluated the role of adjuvant bevacizumab in melanoma patients at high risk of recurrence.
Patients and Methods
Patients with resected AJCC stage IIB, IIC and III cutaneous melanoma were randomised to receive either adjuvant bevacizumab (7.5 mg/kg IV 3 weekly for 1 year) or standard observation. The primary endpoint was detection of an 8% difference in 5 year overall survival (OS) rate; secondary endpoints included disease-free interval (DFI) and distant metastasis-free interval (DMFI). Tumour and blood were analysed for prognostic and predictive markers.
Results
1343 patients recruited between 2007 and 2012 were predominantly stage III (73%), with median age 56 years (range 18-88 years). With 6.4 years median follow-up, 515 (38%) patients had died (254 [38%] bevacizumab; 261 [39%] observation); 707 (53%) patients had disease recurrence (336 [50%] bevacizumab, 371 [55%] observation). OS at 5 years was 64% for both groups (Hazard ratio [HR] 0.98; 95% confidence interval [CI] 0.82-1.16, p=0.78). At 5 years, 51% were disease-free on bevacizumab versus 45% on observation (HR 0.85; 95% CI 0.74-0.99, p=0.03), 58% were distant metastasis-free on bevacizumab versus 54% on observation (HR 0.91; 95% CI 0.78-1.07, p=0.25). 44% of 682 melanomas assessed had a BRAFV600 mutation. In the observation arm, BRAF mutant patients had a trend towards poorer OS compared with BRAF wild type patients (p=0.06). BRAF mutation positivity trended towards better OS with bevacizumab (p=0.21).
Conclusions
Adjuvant bevacizumab after resection of high risk melanoma improves DFI, but not OS. BRAF mutation status may predict for poorer OS untreated and potential benefit from bevacizumab.
... Vascular endothelial growth factor (VEGF) has a wellestablished role in angiogenesis and is increasingly being recognized as a modulator of the immune response. Increased VEGF produced by malignant cells can directly expand the Treg population, stall the maturation of tumor antigenpresenting dendritic cells, and affect lymphocyte trafficking across the endothelium as well as indirectly inhibit the tumordirected T cell response through expansion of myeloidderived suppressor cells, which act through a variety of mechanisms including increased IDO production [41][42][43][44]. In preclinical mouse models of melanoma, the addition of anti-VEGF therapy to adoptive T cell transfer or a GM-CSF secreting tumor cell vaccine led to increased T cell recruitment and prolonged survival [45,46]. ...
Purpose of review:
Checkpoint blockade has changed the treatment landscape in non-small cell lung cancer (NSCLC), but single-agent approaches are effective for only a select subset of patients. Here, we will review the evidence for combination immunotherapies in NSCLC and the clinical data evaluating the efficacy of this approach.
Recent findings:
Clinical trials evaluating combination PD-1 and CTLA-4 blockade as well as PD-1 in combination with agents targeting IDO1, B7-H3, VEGF, and EGFR show promising results. Additional studies targeting other immune pathways like TIGIT, LAG-3, and cellular therapies are ongoing. Combination immunotherapy has the potential to improve outcomes in NSCLC. Data from early clinical trials is promising and reveals that these agents can be administered together safely without a significant increase in toxicity. Further studies are needed to evaluate their long-term safety and efficacy and to determine appropriate patient selection.
... Moreover, tumor irregular blood vessels with altered perfusion hinder homing of immune cells leading tumor escape, acting like a gate to circulating lymphocytes [44]. ...
Introduction: Breast cancer (BC) is the most common cancer diagnosed among women. The development of new personalized therapeutic strategies has reshaped the landscape in this field. However, BC is still the first cause of death among women. Interestingly, several preclinical studies and some clinical evidences are focused their attention on the role of immune system and immunotherapy on cancer control, also in BC.
Areas covered: Usually, BC has been considered a not immunogenic tumor for its low mutational load. However, recent studies have evidenced that some subtypes, triple negative and HER-2 positive BC, are “hot” tumors, thus more immunogenic. Moreover, the presence of immune infiltrate is positively associated with favorable prognosis. Therefore, the use of immune-checkpoint inhibitors seems to be an encouraging treatment option also in BC. Among these drugs, atezolizumab is an anti-PD-L1 monoclonal antibody with a particular structure that reduce antibody-dependent cellular cytotoxicity against T cells, increasing quantitatively and qualitatively the effective response.
Expert opinion: The use of immunotherapy is a promising option for BC. However, at the same time it still raises many doubts. Surely, the research and the validation of immune biomarkers can permit to identify patients who more benefit from these drugs. Moreover, additional studies should evaluate as to induce immunogenicity in cold tumors. Then again, the understanding of mechanism of primary and acquired resistance can help the development of novel strategies to enhance effector response, overcoming these resistances.
... VEGF has also been shown to exert immune-suppressive effects through support of tissue remodeling and fibrosis and prevention of immune infiltration into tumors. Thus, VEGF inhibition has also emerged as a potential strategy to facilitate the antitumor immune response (88,89). An early trial exploring the combination of the VEGF receptor (VEGFR) tyrosine kinase inhibitor (TKI) sunitinib with tremelimumab in patients with melanoma was unfortunately met with unexpected dose-limiting toxicity in the form of acute kidney injury (90). ...
Immune checkpoint inhibitors enhance the activation and antitumor activity of the immune system, resulting in durable response rates in a select group of patients. Cytotoxic T lymphocyte antigen 4 (CTLA4) inhibitors target the inhibitory interaction between CTLA4 and CD80 or CD86. Programmed death 1 (PD1) inhibitors target the interaction between PD1 receptors on T-cells and PD-ligand 1 (PD-L1) and PD-ligand 2, blocking the inhibitory signaling and resulting in activation of T-cell effector function. These therapeutic drugs were originally evaluated in patients with metastatic melanoma before expansion to all tumor types, including non-small cell lung cancer (NSCLC) with promising results. The PD1 inhibitors such as pembrolizumab have now received FDA approval in the first-line setting for patients with positive PD-L1 expression tumor types; however, only a portion of patients have shown objective and sustainable responses. To expand the number of patients with observed response to immunotherapeutic agents including patients with negative PD-L1 expression tumors, clinical trials are ongoing to assess the safety and efficacy of combination immune checkpoint inhibitors and combination immune checkpoint inhibitors with targeted therapy. Immune checkpoint inhibitors have been found to be a promising therapeutic drug class with sustainable response rates and a tolerable safety profile, and efforts continue to improve these drugs in patients with NSCLC.
Poor prognosis is a distinctive feature of triple-negative breast cancer (TNBC). Chemotherapy has long represented the main and unique treatment for patients with TNBC. Recently, immune checkpoint inhibitors (ICIs) were investigated in several clinical trials and were approved for clinical use in TNBC patients that express programmed cell death protein-1 (PD-1) in combination with chemotherapy in the first-line setting. ICIs are also being investigated in the neoadjuvant and adjuvant settings for TNBC. This chapter aims to discuss different ICIs used to treat all TNBC stages to date.
In cancer pathogenesis, soluble mediators are responsible for a type of inflammation that favors the progression of tumors. The mechanisms chiefly involve changes in the cellular composition of the tumor tissue stroma and in the functional modulation of myeloid and lymphoid leukocytes. Active immunosuppression, pro-angiogenesis, changes in leukocyte traffic, extracellular-matrix remodeling and alterations in tumor-antigen presentation are the main mechanisms linked to the inflammation that fosters tumor growth and metastasis. Soluble inflammatory mediators and their receptors are amenable to various types of inhibitors that can be combined with other immunotherapy approaches. The main pro-inflammatory targets which can be interfered with at present and which are under preclinical and clinical development are IL-1b, IL-6, the CXCR1/2 chemokine axis, TNFa, VEGF, LIF, CCL2, IL-35 and prostaglandins. In many instances, the corresponding neutralizing agents are already clinically available and can be repurposed as a result of their use in other areas of medicine such as autoimmune diseases and chronic inflammatory conditions.
There is an increasing interest in combining immune checkpoint inhibitors (ICIs) with anti-angiogenic drugs to enhance their anti-tumor effects. In this study, three anti-angiogenic agents, DC101 (acting on VEGFR2), SAR131675 (acting on VEGFR3), and fruquintinib (a small-molecule inhibitor acting on multiple targets) were administered to B16F1-OVA-loaded C57BL/6 mice. Immune cells infiltration in the tumor tissues, vascular normalization, and high-endothelial venule (HEV) formation were assessed to provide evidence for drug combination. Both DC101 and fruquintinib significantly slowed the melanoma growth and increased the proportion of CD3+ and CD8+ T cells infiltration compared with SAR131675, of note, the effect of DC101 was more pronounced. Moreover, DC101 and fruquintinib increased the interferon-γ and perforin levels, meanwhile, DC101 increased the granzyme B levels, whereas fruquintinib and SAR131675 did not. Only the fruquintinib-treated group showed decreased regulatory T cells infiltration. We found upregulation of PD-L1 expression in tumor cells and CD45+ immune cells in DC101-treated group as well as upregulation of PD-1 expression on CD3+ T cells. However, fruquintinib only increased PD-L1 expression in tumors. Both DC101 and fruquintinib reduced the proportion of CD31+ vessels, while DC101 increased the ratio of α-SMA +/CD31+ cells and reduced the expression of HIF-1α more than fruquintinib. Moreover, DC101 enhanced the infiltration of dendritic cells and B cells, and local HEV formation. In conclusion, our data indicate that DC101 may be a better choice for the combined clinical application of ICIs and anti-angiogenic agents.
Investigation of the role of progranulin/GP88 on the proliferation and survival of a wide variety of cells has been steadily increasing. Several human diseases stem from progranulin dysregulation either through its overexpression in cancer or its absence as in the case of null mutations in some form of frontotemporal dementia. The present review focuses on the role of progranulin/GP88 in cancer development, progression, and drug resistance. Various aspects of progranulin identification, biology, and signaling pathways will be described. Information will be provided about its direct role as an autocrine growth and survival factor and its paracrine effect as a systemic factor as well as via interaction with extracellular matrix proteins and with components of the tumor microenvironment to influence drug resistance, migration, angiogenesis, inflammation, and immune modulation. This chapter will also describe studies examining progranulin/GP88 tumor tissue expression as well as circulating level as a prognostic factor for several cancers. Due to the wealth of publications in progranulin, this review does not attempt to be exhaustive but rather provide a thread to lead the readers toward more in-depth exploration of this fascinating and unique protein.
There has been unprecedented progress in the development of systemic therapies for patients with metastatic melanoma over the last decade. There is now tremendous potential and momentum to further and markedly reduce the impact of this disease. However, developing more effective treatments for metastases to the CNS remains a critical challenge for patients with melanoma. Melanoma patients with active CNS metastases have largely been excluded from both early-phase and registration trials for all currently approved targeted and immune therapies for this disease. While this exclusion has generally been justified in clinical research due to concerns about poor prognosis, lack of CNS penetration of agents, and/or risk of toxicities, recent post-approval trials have shown the feasibility, safety, and clinical benefit of clinical investigation in these patients. These trials have also identified key areas for which more effective strategies are needed. In parallel, recent translational and preclinical research has provided insights into novel immune, molecular and metabolic features of melanoma brain metastases that may mediate the aggressive biology and therapeutic resistance of these tumors. Together, these advances suggest the need for new paradigms for therapeutic development for melanoma patients with CNS metastasis.
Regulatory T cells (T regs ) are key immunosuppressive cells that promote tumor growth by hindering the effector immune response. T regs utilize multiple suppressive mechanisms to inhibit pro-inflammatory responses within the tumor microenvironment (TME) by inhibition of effector function and immune cell migration, secretion of inhibitory cytokines, metabolic disruption and promotion of metastasis. In turn, T regs are being targeted in the clinic either alone or in combination with other immunotherapies, in efforts to overcome the immunosuppressive TME and increase anti-tumor effects. However, it is now appreciated that T regs not only suppress cells intratumorally via direct engagement, but also serve as key interactors in the peritumor, stroma, vasculature and lymphatics to limit anti-tumor immune responses prior to tumor infiltration. We will review the suppressive mechanisms that T regs utilize to alter immune and non-immune cells outside and within the TME and discuss how these mechanisms collectively allow T regs to create and promote a physical and biological barrier, resulting in an immune-excluded or limited tumor microenvironment.
Introduction:
We have experienced several paradigm shifts and substantial changes in the treatment of metastatic renal cell carcinoma (mRCC) over the last two decades. Combination therapy with immune checkpoint inhibitors (ICI) as a dual combination (ICI-ICI) or with VEGFR-tyrosine kinase inhibitors (VEGF-TKI) has shown remarkable efficacy in mRCC patients and has become the standard of care in first-line therapy.
Areas covered:
In this review, we will discuss the background as well as the benefits of combining ICI with TKI compared to ICI-ICI combination therapy for mRCC treatment and will also briefly highlight biomarkers for patient selection on therapies to improve patient outcomes and limit toxicities.
Expert opinion:
Due to the mediated additional anti-tumor effects, there is a strong rationale to combine ICIs and TKIs for mRCC therapy. When comparing first-line therapy options, the exceptionally higher ORR and PFS for the ICI-TKI combinations should be highlighted, whereas, nevertheless, the complete response rate is slightly higher for the ICI-ICI combination. In terms of an individualized therapeutic approach, biomarkers predicting the success or failure of an anti-VEGF-based regimen or ICI therapy as a corresponding mono- or combination therapy are lacking so far, however, gene expression signatures can be a landmark in this field.
Introduction
To date, there is no validated predictive biomarker available that guides treatment selection between an immune-based or an anti-VEGF-based regimen in patients with metastatic renal cell carcinoma (mRCC). Here, valid biomarkers could increase the benefit of therapy and thereby safe unnecessary toxicity. Recently, phase II and III clinical trials have shown a correlation between molecular clusters and responses to targeted therapy with tyrosine kinase inhibitors (TKIs), immune checkpoint inhibitors (ICIs) or as combination of both in patients with clear-cell mRCC.
Areas covered
This review discusses recent advances in the discovery of predictive biomarkers, highlighting the growing role of genetic analysis for treatment selection and its potential impact on precision medicine in mRCC. In this context, we extensively analyzed the available literature from Pubmed’s archives on this topic.
Expert opinion
Molecular subclassification which predicts responses to TKI, or ICI therapy is an exciting step toward personalized medicine in mRCC, but this still requires validation. However, intratumoral heterogeneity in relationship to the predictive power of molecular analysis of the primary tumor and circulating tumor DNA is challenging and requires further analysis.
Background: Apatinib, an antiangiogenic drug, has showed beneficial effects only in a fraction of advanced gastric cancer (GC) patients. Given the recent success of immunotherapies, combination of apatinib with immune checkpoint inhibitor may provide sustained and potent antitumor responses.
Methods: Immunocompetent mice with subcutaneous MFC tumors grown were given combination of apatinib and anti-PD-L1 antibody therapy. GC tissues from patients undergoing curative resection in China were collected, and the density of HEVs, MSI status and tumor-infiltrated lymphocytes were analyzed by immunohistochemical staining.
Results: Combined apatinib and PD-L1 blockade therapy synergistically delayed tumor growth and increased survival in MFC-bearing immunocompetent mice. The combination therapy promoted antitumor immunity by increasing the ratio of CD8⁺ cytotoxic T cells to Foxp3⁺ Treg cells, the accumulation of CD20⁺ B cells and the Th1/Th2 cytokine ratio (IFN-γ/IL-10). The combination therapy induced the formation of HEVs through activation of LTβR signaling mediated by DCs, thus promoting CD8⁺ cytotoxic T cell and CD20⁺ B cell infiltration in tumors. In clinical GC samples, the density of HEVs positively correlated with the intratumoral infiltration of CD8⁺ cytotoxic T cells and CD20⁺ B cells. MSI-high GC showed a higher density of HEVs, CD8⁺ cytotoxic T cells and CD20⁺ B cells than MSS/MSI-low GC. GC patients with high densities of HEVs, CD8⁺ cytotoxic T cells and CD20⁺ B cells had an improved prognosis with superior overall survival.
Conclusions: Combining apatinib with PD-L1 blockade treatment synergistically enhances antitumor immune responses and promotes HEV formation in GC.
Although immunotherapy has led to durable responses in diverse cancers, unfortunately, there has been limited efficacy and clinical response rates due to primary or acquired resistance to immunotherapy. To maximize the potential of immunotherapy, combination therapy with antiangiogenic drugs seems to be promising. Some phase III trials showed superiority for survival with the combination of immunotherapy and antiangiogenic therapy. In this study, we describe a synergistic mechanism of immunotherapy and antiangiogenic therapy and summarize current clinical trials of these combinations.
Introduction: The immune checkpoint inhibitors (ICI) programmed cell death protein and ligands 1 (PD1- and PD-L1) as well as cytotoxic T-lymphocyte-associated protein 4 have demonstrated clinical efficacy in genitourinary cancer. While different ICI exist, focus of the current study work was to evaluate the PD-L1 antibody avelumab within this framework of ICI.
Areas covered: The manuscript reviews the pharmacological characteristics and preclinical and clinical data of avelumab in the treatment for advanced or metastatic genitourinary cancers. It highlights its respective clinical relevance and special features in the context of the other available ICI.
Expert opinion: Avelumab has shown promising antitumor activity and a manageable safety profile in patients with mRCC and mUC as mono- and combination therapy. The approach of an avelumab maintenance therapy in mUC is promising and could become part of future clinical practice. Results of ICI used in the neoadjuvant or adjuvant setting are eagerly awaited. Avelumab’s uniqueness is its capacity to enhance antibody-dependent cell-mediated cytotoxicity. Because of this, currently ongoing clinical trials investigate the combination of avelumab with other immune modulating agents like IL-12 and IL-15. Thereby, it can be assumed that avelumab will have an ongoing role in the treatment of patients with genitourinary tumors.
Kidney cancer has unique features that make this malignancy attractive for therapeutic approaches that target components of the immune system. Immune checkpoint inhibition is a well-established part of kidney cancer treatment, and rapid advances continue to be made in this field. Initial preclinical studies that elucidated the biology of the programmed cell death 1 (PD-1), programmed cell death 1 ligand 1 (PD-L1) and cytotoxic T lymphocyte antigen 4 (CTLA-4) immune checkpoints led to a series of clinical trials that resulted in regulatory approval of nivolumab and the combination of ipilimumab plus nivolumab for the treatment of advanced renal cell carcinoma. Subsequent data led to approvals of combination strategies of immune checkpoint inhibition plus agents that target the vascular endothelial growth factor receptor and a shift in the current standard of renal cell carcinoma care. However, controversies remain regarding the optimal therapy selection and treatment strategy for individual patients, which might be eventually overcome by current intensive efforts in biomarker research. That work includes evaluation of tumour cell PD-L1 expression, gene expression signatures, CD8⁺ T cell density and others. In the future, further advances in the understanding of immune checkpoint biology might reveal new therapeutic targets beyond PD-1, PD-L1 and CTLA-4, as well as new combination approaches.
Since 2015, immunotherapies, especially immune checkpoint inhibitors (ICIs), have made great breakthroughs in non-small-cell lung cancer (NSCLC). Among them, nivolumab, pembrolizumab and atezolizumab have been granted US Food and Drug Administration approval for NSCLC. It is imperative to combine ICIs with chemotherapy, radiotherapy, antivascular therapy and targeted therapy. But in the bright future, there are two problems. One is how to use biomarkers to select the beneficiaries. The other is how to achieve a balance between drug effectiveness and safety. There are now seven drugs targeting the programmed death-1/programmed death ligand-1 (PD-1/PD-L1) and cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) pathways that have been or are expected to enter clinical treatment. This review focuses on these drugs and summarizes clinical trials that have been reported or that ongoing ones have already entered the recruiting state.
A new peptide family (endothelin (ET] consisting of three members in mammals appears to be present in mice according to genomic Southern blot analysis. Two ET-related genes were identified by cloning and sequence analysis of a mouse genome. One encoded a peptide identical to porcine and human vasoconstrictor peptide ET, and the other encoded a novel peptide differing from ET in 3 amino acid residues, with 4 cysteines in the same positions as in ET. This novel peptide was synthesized and confirmed to have in vivo pressor activity similar to that of ET. Northern blot analysis, however, indicated the gene of this novel peptide to be expressed only in the intestine, and not in other tissues or cell lines, or endothelial cells. Furthermore, the peptide evoked a strong contractile response in the guinea pig ileum. This peptide may thus be reasonably classified as a gastrointestinal peptide, vasoactive intestinal contractor.
Vascular endothelial growth factor (VEGF) is a homodimeric peptide growth factor which binds to two structurally related tyrosine kinase receptors denoted Flt1 and KDR. In order to compare the signal transduction via these two receptors, the human Flt1 and KDR proteins were stably expressed in porcine aortic endothelial cells. Binding analyses using 125I-VEGF revealed Kd values of 16 pM for Flt1 and 760 pM for KDR. Cultured human umbilical vein endothelial (HUVE) cells were found to express two distinct populations of binding sites with affinities similar to those for Flt1 and KDR, respectively. The KDR expressing cells showed striking changes in cell morphology, actin reorganization and membrane ruffling, chemotaxis and mitogenicity upon VEGF stimulation, whereas Flt1 expressing cells lacked such responses. KDR was found to undergo ligand-induced autophosphorylation in intact cells, and both Flt1 and KDR were phosphorylated in vitro in response to VEGF, however, KDR much more efficiently than Flt1. Neither the receptor-associated activity of phosphatidylinositol 3'-kinase nor tyrosine phosphorylation of phospholipase C-gamma were affected by stimulation of Flt1 or KDR expressing cells, and phosphorylation of GTPase activating protein was only slightly increased. Members of the Src family such as Fyn and Yes showed an increased level of phosphorylation upon VEGF stimulation of cells expressing Flt1 but not in cells expressing KDR. The maximal responses in KDR expressing porcine aortic endothelial cells were obtained at higher VEGF concentrations as compared to HUVE cells, i.e. in the presence of Flt1. This difference could possibly be explained by the formation of heterodimeric complexes between KDR and Flt1, or other molecules, in HUVE cells.
We have analyzed the presence of immature and mature dendritic cells (DCs) within adenocarcinoma of the breast using immunohistochemistry. Immature DCs were defined by expression of CD1a-, Langerin-, and intracellular major histocompatibility complex class II–rich vesicles. Mature DCs were defined by expression of CD83 and DC-Lamp. Breast carcinoma cells were defined by morphology and/or cytokeratin expression. We demonstrate two levels of heterogeneity of DCs infiltrating breast carcinoma tissue: (a) immature CD1a+ DCs, mostly of the Langerhans cell type (Langerin+), were retained within the tumor bed in 32/32 samples and (b) mature DCs, CD83+DC-Lamp+, present in 20/32 samples, are confined to peritumoral areas. The high numbers of immature DCs found in the tumor may be best explained by high levels of macrophage inflammatory protein 3α expression by virtually all tumor cells. Confirming the immature/mature DC compartmentalization pattern, in vitro–generated immature DCs adhere to the tumor cells, whereas mature DCs adhere selectively to peritumoral areas. In some cases, T cells are clustering around the mature DCs in peritumoral areas, thus resembling the DC–T cell clusters of secondary lymphoid organs, which are characteristic of ongoing immune reactions.
Vascular endothelial growth factor (VEGF), produced by almost all tumor cells, affects the ability of hemopoietic progenitor cells (HPC) to differentiate into functional dendritic cells (DC) during the early stages of their maturation. In this study we demonstrate specific binding of VEGF to HPC. This binding was efficiently competed by placenta growth factor (PlGF), a ligand reportedly specific for the Flt-1 receptor. The number of binding sites for VEGF decreased during DC maturation in vitro associated with decreased levels of mRNA for Flt-1. VEGF significantly inhibited nuclear factor-kB (NF-kB)-dependent activation of reporter gene transcription during the first 24 h in culture. The presence of VEGF significantly decreased the specific DNA binding of NF-kB as early as 30 min after induction with TNF-a. This was followed on days 7 to 10 by decreases in the mRNA for RelB and c-Rel, two subunits of NF-kB. Blockade of NF-kB activity in HPC at early stages of differentiation with an adenovirus expressing a dominant IkB inhibitor of NF-kB reproduced the pattern of effects observed with VEGF. Thus, NF-kB plays an important role in maturation of HPCs to DC, and VEGF activation of the Flt-1 receptor is able to block the activation of NF-kB in this system. Blockade of NF-kB activation in HPCs by tumor-derived factors may therefore be a mechanism by which tumor cells can directly down-modulate the ability of the immune system to generate effective antitumor immune responses. The Journal of Immunology, 1998, 160: 1224 -1232.
The cytokine FLT3 ligand (FL) enhances dendritic cell (DC) generation and has therefore been proposed as a means to boost antitumor immunity. Vascular endothelial growth factor (VEGF) is produced by a large percentage of tumors and is required for development of tumor neovasculature. We previously showed that VEGF decreases DC production and function in vivo. In this study, we tested the hypothesis that VEGF regulates FL effects on DC generation. In seven experiments, four groups of mice were treated with PBS, VEGF alone (100 ng/h), FL alone (10 mg/day), or with the combination of FL and VEGF. VEGF and PBS were administered continuously for 14 days via s.c. pumps. FL was given s.c. daily for 9 days, beginning on day 4. Tissues were collected and the number, phenotype, and function of lymph node, splenic, and thymic DCs were analyzed on day 14. As expected, treatment with FL resulted in a marked increase in the number of lymph node and spleen DCs and a smaller increase in thymic DC. Pretreatment of mice with VEGF inhibited these FL effects in lymph nodes and thymus by about 50%, whereas spleen DC numbers were undiminished by VEGF. VEGF treatment in vivo also inhibited the ability of FL to increase the number of hemopoietic precursor cells and the level of maturity exhibited by DC derived from these hemopoietic precursor cells in vitro. VEGF inhibited FL-inducible activation of transcription factor NF-kB. These data suggest that VEGF interferes with the ability of FL to promote dendritic cell differentiation from bone marrow progenitor cells in mice and therefore may decrease the therapeutic efficacy of FL in settings where increased numbers of DCs might provide clinical benefits. The Journal of Immu- nology, 1999, 163: 3260 -3268.
The 4-1BB receptor is an inducible type I membrane protein and member of the tumor necrosis factor receptor (TNFR) superfamily
that is rapidly expressed on the surface of CD4+ and CD8+ T cells after antigen- or mitogen-induced activation. Cross-linking of 4-1BB and the T cell receptor (TCR) on activated
T cells has been shown to deliver a costimulatory signal to T cells. Here, we expand upon previously published studies by
demonstrating that CD8+ T cells when compared with CD4+ T cells are preferentially responsive to both early activation events and proliferative signals provided via the TCR and
4-1BB. In comparison, CD28-mediated costimulatory signals appear to function in a reciprocal manner to those induced through
4-1BB costimulation. In vivo examination of the effects of anti-4-1BB monoclonal antibodies (mAbs) on antigen-induced T
cell activation have shown that the administration of epitope-specific anti-4-1BB mAbs amplified the generation of H-2d–specific cytotoxic T cells in a murine model of acute graft versus host disease (GVHD) and enhanced the rapidity of cardiac
allograft or skin transplant rejection in mice. Cytokine analysis of in vitro activated CD4+ and CD8+ T cells revealed that anti-4-1BB costimulation markedly enhanced interferon-γ production by CD8+ T cells and that anti-4-1BB mediated proliferation of CD8+ T cells appears to be IL-2 independent. The results of these studies suggest that regulatory signals delivered by the 4-1BB
receptor play an important role in the regulation of cytotoxic T cells in cellular immune responses to antigen.
Memory CD8 T cells can be divided into two subsets, central (T(CM)) and effector (T(EM)), but their lineage relationships and their ability to persist and confer protective immunity are not well understood. Our results show that T(CM) have a greater capacity than T(EM) to persist in vivo and are more efficient in mediating protective immunity because of their increased proliferative potential. We also demonstrate that, following antigen clearance, T(EM) convert to T(CM) and that the duration of this differentiation is programmed within the first week after immunization. We propose that T(CM) and T(EM) do not necessarily represent distinct subsets, but are part of a continuum in a linear naive --> effector --> T(EM) --> T(CM) differentiation pathway.
The T cell antigen receptor (TCR)-CD3 complex is unique in having ten cytoplasmic immunoreceptor tyrosine-based activation motifs (ITAMs). The physiological importance of this high TCR ITAM number is unclear. Here we generated 25 groups of mice expressing various combinations of wild-type and mutant ITAMs in TCR-CD3 complexes. Mice with fewer than seven wild-type CD3 ITAMs developed a lethal, multiorgan autoimmune disease caused by a breakdown in central rather than peripheral tolerance. Although there was a linear correlation between the number of wild-type CD3 ITAMs and T cell proliferation, cytokine production was unaffected by ITAM number. Thus, high ITAM number provides scalable signaling that can modulate proliferation yet ensure effective negative selection and prevention of autoimmunity.
Cell adhesion molecules (CAMs) are cell surface glycoproteins that mediate the physical interactions between adjacent cells and between cells and the surrounding extracellular matrix. CAMs belong to different protein families, depending on their structural and functional properties. Furthermore, the expression of certain CAMs under physiological conditions is restricted to specific cell types. Besides playing a key homeostatic role in maintaining the architecture of quiescent tissues, CAMs have also to adapt to the microenvironmental changes that occur during certain physiological and pathological processes. This is best exemplified by cancer vascularization, where the expression and function of vascular CAMs are dynamically regulated in response to tissue alterations induced by tumor growth as well as by changes in the surrounding stroma. This enables endothelial cells (ECs) to leave the quiescent state and re-enter the angiogenic cascade. The latter is a multistep process carried out by different types of specialized ECs. This review describes the actual or supposed function of the various CAM subsets in the sequential series of events that underlie vascular changes during tumor angiogenesis. Notably, elucidating the mechanism of action of endothelial CAMs in cancer vasculature is expected to open new therapeutic avenues aimed at interfering with tumor growth and dissemination.
Endothelin (ET) receptors are widely expressed within the human body with one of their major functions being regulation of
the vascular tone. Pulmonary arterial hypertension and other complications associated with SSc are related to the function
and or dysregulation of these receptors. As ET receptors also play a crucial role in SSc, this review will discuss the expression
and physiological functions of ET receptors in the human organism, their signalling pathways, the complications of diseases
they are associated with and their importance as a therapeutic target in SSc.
The programmed death-1 ligand/programmed death-1 (PD-L/PD-1) pathway has been recently suggested to play a pivotal role in the immune evasion of tumors from host immune system. In this study, we tried to reveal the clinical importance and therapeutic potential of the PD-L/PD-1 pathway in pancreatic cancer, which is one of the most aggressive and intractable malignant tumors.
We used immunohistochemistry to investigate PD-L expression in 51 patients with pancreatic cancer who underwent surgery and explored the therapeutic efficacy of blocking the PD-L1/PD-1 pathway in murine pancreatic cancer in vivo.
PD-L1-positive patients had a significantly poorer prognosis than the PD-L1-negative patients, whereas there was no significant correlation of tumor PD-L2 expression with patient survival. PD-L1 expression was inversely correlated with tumor-infiltrating T lymphocytes, particularly CD8(+) T cells. These clinical data have suggested that the PD-L1/PD-1 pathway may be a critical regulator in human pancreatic cancer. Monoclonal antibodies against PD-L1 or PD-1 induced a substantial antitumor effect on murine pancreatic cancer in vivo. PD-L1 blockade promoted CD8(+) T-cell infiltration into the tumor and induced local immune activation. Furthermore, the combination of anti-PD-L1 monoclonal antibody and gemcitabine exhibited a significant synergistic effect on murine pancreatic cancer and resulted in complete response without overt toxicity.
Our data suggest for the first time that PD-L1 status may be a new predictor of prognosis for patients with pancreatic cancer and provide the rationale for developing a novel therapy of targeting the PD-L/PD-1 pathway against this fatal disease.
To determine how self-tolerance can alter the ability of the immune system to respond against tumor-associated Ags that are also expressed by normal tissue, we designed experiments in which the same protein was expressed both as a tumor Ag and as a transgene product. Unlike conventional BALB/c mice that rejected renal carcinoma cells transfected with the influenza virus hemagglutinin (Renca-HA), transgenic mice that are tolerant of HA due to its expression as a self-Ag on pancreatic islet beta cells, (Ins-HA mice) supported progressive growth of these tumor cells. However, when Ins-HA mice were immunized with a recombinant strain of vaccinia virus expressing the dominant H-2Kd peptide epitope of HA before receiving Renca-HA cells, they too were able to reject the tumor cells. Rejection of Renca-HA cells by immunized Ins-HA mice was found to be associated with the generation of CTL having much lower avidity for target cells presenting the KdHA epitope than CTL from immunized conventional BALB/c mice. Significantly, we show that self-tolerance to the HA Ag is quantitative rather then absolute, and that vaccination of Ins-HA mice can activate low avidity KdHA-specific CD8+ T cells that are able to reject tumor cells expressing high levels of HA, yet these mice remain tolerant of pancreatic islet beta cells expressing HA.
mt is a cross-disciplinary biomedical journal devoted to publishing the most exciting advances in pharmacology and therapeutics, as they pertain to advances in translational and clinical medicine. It is recognized as one of the most prestigious journals in the field. With an impact factor of 6.825*, mt ranks in the top 4.2% of scientific journals in the latest Science Citation Index. Published monthly online and in print.
Although cancer vaccines with defined antigens are commonly used, the use of whole tumor cell preparations in tumor immunotherapy is a very promising approach and can obviate some important limitations in vaccine development. Whole tumor cells are a good source of TAAs and can induce simultaneous CTLs and CD4(+) T helper cell activation. We review current approaches to prepare whole tumor cell vaccines, including traditional methods of freeze-thaw lysates, tumor cells treated with ultraviolet irradiation, and RNA electroporation, along with more recent methods to increase tumor cell immunogenicity with HOCl oxidation or infection with replication-incompetent herpes simplex virus.
Therapeutic prostate-specific antigen (PSA) -targeted poxviral vaccines for prostate cancer have been well tolerated. PROSTVAC-VF treatment was evaluated for safety and for prolongation of progression-free survival (PFS) and overall survival (OS) in a randomized, controlled, and blinded phase II study.
In total, 125 patients were randomly assigned in a multicenter trial of vaccination series. Eligible patients had minimally symptomatic castration-resistant metastatic prostate cancer (mCRPC). PROSTVAC-VF comprises two recombinant viral vectors, each encoding transgenes for PSA, and three immune costimulatory molecules (B7.1, ICAM-1, and LFA-3). Vaccinia-based vector was used for priming followed by six planned fowlpox-based vector boosts. Patients were allocated (2:1) to PROSTVAC-VF plus granulocyte-macrophage colony-stimulating factor or to control empty vectors plus saline injections.
Eighty-two patients received PROSTVAC-VF and 40 received control vectors. Patient characteristics were similar in both groups. The primary end point was PFS, which was similar in the two groups (P = .6). However, at 3 years post study, PROSTVAC-VF patients had a better OS with 25 (30%) of 82 alive versus 7 (17%) of 40 controls, longer median survival by 8.5 months (25.1 v 16.6 months for controls), an estimated hazard ratio of 0.56 (95% CI, 0.37 to 0.85), and stratified log-rank P = .0061.
PROSTVAC-VF immunotherapy was well tolerated and associated with a 44% reduction in the death rate and an 8.5-month improvement in median OS in men with mCRPC. These provocative data provide preliminary evidence of clinically meaningful benefit but need to be confirmed in a larger phase III study.
Immune homeostasis is dependent on tight control over the size of a population of regulatory T (T(reg)) cells capable of suppressing over-exuberant immune responses. The T(reg) cell subset is comprised of cells that commit to the T(reg) lineage by upregulating the transcription factor Foxp3 either in the thymus (tT(reg)) or in the periphery (iT(reg)). Considering a central role for Foxp3 in T(reg) cell differentiation and function, we proposed that conserved non-coding DNA sequence (CNS) elements at the Foxp3 locus encode information defining the size, composition and stability of the T(reg) cell population. Here we describe the function of three Foxp3 CNS elements (CNS1-3) in T(reg) cell fate determination in mice. The pioneer element CNS3, which acts to potently increase the frequency of T(reg) cells generated in the thymus and the periphery, binds c-Rel in in vitro assays. In contrast, CNS1, which contains a TGF-beta-NFAT response element, is superfluous for tT(reg) cell differentiation, but has a prominent role in iT(reg) cell generation in gut-associated lymphoid tissues. CNS2, although dispensable for Foxp3 induction, is required for Foxp3 expression in the progeny of dividing T(reg) cells. Foxp3 binds to CNS2 in a Cbf-beta-Runx1 and CpG DNA demethylation-dependent manner, suggesting that Foxp3 recruitment to this 'cellular memory module' facilitates the heritable maintenance of the active state of the Foxp3 locus and, therefore, T(reg) lineage stability. Together, our studies demonstrate that the composition, size and maintenance of the T(reg) cell population are controlled by Foxp3 CNS elements engaged in response to distinct cell-extrinsic or -intrinsic cues.
In this study, we find that CD45RO+ memory populations of CD4+ T lymphocytes express the vascular endothelial growth factor (VEGF) receptors KDR and Flt-1 at both the mRNA and protein levels. Furthermore, by Western blot analysis, we find that VEGF increases the phosphorylation and activation of ERK and Akt within CD4+CD45RO+ T cells. These VEGF-mediated signaling responses were inhibited by a KDR-specific small interfering RNA in a VEGF receptor-expressing Jurkat T cell line and by SU5416, a pharmacological KDR inhibitor, in CD4+CD45RO+ T cells. We also find that VEGF augments mitogen-induced production of IFN-gamma in a dose-dependent manner (p < 0.001) and significantly (p < 0.05) increases directed chemotaxis of this T cell subset. Collectively, our results for the first time define a novel function for VEGF and KDR in CD45RO+ memory T cell responses that are likely of great pathophysiological importance in immunity.
Mucosal vaccination via the respiratory tract can elicit protective immunity in animal infection models, but the underlying mechanisms are still poorly understood. We show that a single intranasal application of the replication-deficient modified vaccinia virus Ankara, which is widely used as a recombinant vaccination vector, results in prominent induction of bronchus-associated lymphoid tissue (BALT). Although initial peribronchiolar infiltrations, characterized by the presence of dendritic cells (DCs) and few lymphocytes, can be found 4 d after virus application, organized lymphoid structures with segregated B and T cell zones are first observed at day 8. After intratracheal application, in vitro-differentiated, antigen-loaded DCs rapidly migrate into preformed BALT and efficiently activate antigen-specific T cells, as revealed by two-photon microscopy. Furthermore, the lung-specific depletion of DCs in mice that express the diphtheria toxin receptor under the control of the CD11c promoter interferes with BALT maintenance. Collectively, these data identify BALT as tertiary lymphoid structures supporting the efficient priming of T cell responses directed against unrelated airborne antigens while crucially requiring DCs for its sustained presence.
The effect of blocking VEGF activity in solid tumors extends beyond inhibition of angiogenesis. However, no studies have compared the effectiveness of mechanistically different anti-VEGF inhibitors with respect to changes in tumor growth and alterations in the tumor microenvironment. In this study we use three distinct breast cancer models, a MDA-MB-231 xenograft model, a 4T1 syngenic model, and a transgenic model using MMTV-PyMT mice, to explore the effects of various anti-VEGF therapies on tumor vasculature, immune cell infiltration, and cytokine levels. Tumor vasculature and immune cell infiltration were evaluated using immunohistochemistry. Cytokine levels were evaluated using ELISA and electrochemiluminescence. We found that blocking the activation of VEGF receptor resulted in changes in intra-tumoral cytokine levels, specifically IL-1beta, IL-6 and CXCL1. Modulation of the level these cytokines is important for controlling immune cell infiltration and ultimately tumor growth. Furthermore, we demonstrate that selective inhibition of VEGF binding to VEGFR2 with r84 is more effective at controlling tumor growth and inhibiting the infiltration of suppressive immune cells (MDSC, Treg, macrophages) while increasing the mature dendritic cell fraction than other anti-VEGF strategies. In addition, we found that changes in serum IL-1beta and IL-6 levels correlated with response to therapy, identifying two possible biomarkers for assessing the effectiveness of anti-VEGF therapy in breast cancer patients.
Transforming growth factor-beta (TGF-beta) is an immunosuppressive cytokine, having direct suppressive activity against conventional CD4(+) and CD8(+)T cells and natural killer cells, thereby inhibiting tumor immunosurveillance. Here, we investigated possible synergy between anti-TGF-beta (1D11) and a peptide vaccine on induction of antitumor immunity, and the mechanisms accounting for synergistic efficacy.
The effect of combination treatment with a peptide vaccine and anti-TGF-beta was examined in a subcutaneous TC1 tumor model, as well as the mechanisms of protection induced by this treatment.
Anti-TGF-beta significantly and synergistically improved vaccine efficacy as measured by reduction in primary tumor growth, although anti-TGF-beta alone had no impact. The number of tumor antigen-specific CTL with high functional avidity as measured by IFN-gamma production and lytic activity was significantly increased in vaccinated mice by TGF-beta neutralization. Although TGF-beta is known to play a critical role in CD4(+)Foxp3(+) Treg cells, Treg depletion/suppression by an anti-CD25 monoclonal antibody (PC61) before tumor challenge did not enhance vaccine efficacy, and adding anti-TGF-beta did not affect Treg numbers in lymph nodes or tumors or their function. Also, TGF-beta neutralization had no effect on interleukin-17-producing T cells, which are induced by TGF-beta and interleukin-6. Absence of type II NKT cells, which induce myeloid cells to produce TGF-beta, was not sufficient to eliminate all sources of suppressive TGF-beta. Finally, the synergistic protection induced by anti-TGF-beta vaccine augmentation was mediated by CD8(+) T cells since anti-CD8 treatment completely abrogated the effect.
These results suggest that TGF-beta blockade may be useful for enhancing cancer vaccine efficacy.
Many patients who present with early-stage colorectal cancer (International Union Against Cancer TNM stages I and II) are nevertheless at high risk of relapse. We hypothesized that intratumoral immune reaction could influence their prognosis.
The intratumoral immune reaction was investigated in 29 tumors by large-scale real-time polymerase chain reaction. Cytotoxic (CD8) and memory (CD45RO) T cells were quantified by immunohistochemical analyses of tissue microarrays from the center (CT) and the invasive margin (IM) of the 602 tumors from two independent cohorts. The results were correlated with tumor recurrence and patient survival.
Patients with a strong infiltration of CD45RO(+) cells in the tumor exhibited an increased expression of T-helper 1 and cytotoxicity-related genes. Densities of CD45RO(+) and CD8(+) cells in tumor regions (CT/IM) classified the patients into four distinct prognostic groups based on the presence of high density of each marker in each tumor region. The four groups were associated with dramatic differences in disease-free, disease-specific, and overall survival (all P < .0001). Five years after diagnosis, only 4.8% (95% CI, 0.6% to 8.8%) of patients with high densities of CD8(+) plus CD45RO(+) cells had tumor recurrence, and 86.2% (CI, 79.4% to 93.6%) survived. In contrast, the tumor recurred in 75% (95% CI, 17% to 92.5%) of patients with low densities of these cells, and only 27.5% (95% CI, 10.5% to 72%) survived (all P < .0001). Multivariate analyses showed that the immune criteria had independent effects on the rates of complete remission and survival.
The combined analysis of CD8(+) plus CD45RO(+) cells in specific tumor regions could provide a useful criterion for the prediction of tumor recurrence and survival in patients with early-stage colorectal cancer.
The engagement of CD28 with its ligand B7.1/CD80 results in potent costimulation of T-cell activation initiated through the CD3/T-cell receptor complex. The biochemical basis of CD28 costimulatory function is poorly understood. The signalling pathways used by CD28 are unlike those used by the CD3/T-cell receptor in that they are resistant to cyclosporin A and independent of changes in cyclic AMP concentrations. These differences suggest that each pathway provides unique biochemical information which is required for T-cell activation. We report here that CD28 becomes tyrosine-phosphorylated following interaction with B7.1/CD80, which induces formation of a complex with phosphatidylinositol-3-OH kinase, mediated by the SH2 domains of the p85 subunit of the kinase. Phosphatidylinositol-3-OH kinase is a heterodimer of this 85K regulatory subunit and a 110K catalytic subunit, and is a common substrate for most receptor tyrosine kinases and some cytokine receptors, binding through its SH2 domain to phosphotyrosine in the motif Tyr-X-X-Met in the CD28 sequence, which is highly conserved between human, mouse and rat and lies in the intracellular domain. We show that CD28 mutants that have their kinase-binding site deleted or the tyrosine at position 173 substituted by phenylalanine do not associate with the kinase after CD28 stimulation and cannot stimulate production of interleukin-2. Our results suggest that phosphatidylinositol-3-OH kinase is critical for signalling by CD28.
The growth of non-Hodgkin lymphomas can be influenced by tumor-immune system interactions. Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a negative regulator of T-cell activation that serves to dampen antitumor immune responses. Blocking anti-CTLA-4 monoclonal antibodies improves host resistance to immunogenic tumors, and the anti-CTLA-4 antibody ipilimumab (MDX-010) has clinical activity against melanoma, prostate, and ovarian cancers.
We did a phase I trial of ipilimumab in patients with relapsed/refractory B-cell lymphoma to evaluate safety, immunologic activity, and potential clinical efficacy. Treatment consisted of ipilimumab at 3 mg/kg and then monthly at 1 mg/kg x 3 months (dose level 1), with subsequent escalation to 3 mg/kg monthly x 4 months (dose level 2).
Eighteen patients were treated, 12 at the lower dose level and 6 at the higher dose level. Ipilimumab was generally well tolerated, with common adverse events attributed to it, including diarrhea, headache, abdominal pain, anorexia, fatigue, neutropenia, and thrombocytopenia. Two patients had clinical responses; one patient with diffuse large B-cell lymphoma had an ongoing complete response (>31 months), and one with follicular lymphoma had a partial response lasting 19 months. In 5 of 16 cases tested (31%), T-cell proliferation to recall antigens was significantly increased (>2-fold) after ipilimumab therapy.
Blockade of CTLA-4 signaling with the use of ipilimumab is well tolerated at the doses used and has antitumor activity in patients with B-cell lymphoma. Further evaluation of ipilimumab alone or in combination with other agents in B-cell lymphoma patients is therefore warranted.
We report that OX40 stimulation drives all lineages of CD4 T cell development, including regulatory T cells (Tregs), and the plasticity of the response is dependant on local cytokines. In TGF-beta1-treated cultures, an OX40 agonist increased IFN-gamma and IL-4 production and diverted T cells from the Treg lineage. However, cytokine blockade in the context of OX40 stimulation promoted enhanced Treg accumulation. This observation was evident in naive mice, as OX40 engagement enhanced Treg proliferation and accumulation in vivo. Lastly, OX40 agonist administration influenced experimental autoimmune encephalomyelitis disease severity in opposing directions, depending on the timing of administration. Given during Ag priming, the OX40 agonist drove Treg expansion and inhibited disease, whereas given later it enhanced T cell effector cytokine production in the CNS and exacerbated disease. Hence, OX40 signaling can augment the accumulation of all CD4 T cell lineages; however, its accentuation of immune responses may have vastly different biologic outcomes depending upon the local cytokine milieu.
The vascular endothelial growth factor family has recently been expanded by the isolation of two new VEGF-related factors, VEGF-B and VEGF-C. The physiological functions of these factors are largely unknown. Here we report the cloning and characterization of mouse VEGF-C, which is produced as a disulfide-linked dimer of 415 amino acid residue polypeptides, sharing an 85% identity with the human VEGF-C amino acid sequence. The recombinant mouse VEGF-C protein was secreted from transfected cells as VEGFR-3 (Flt4) binding polypeptides of 30–32x10(3) Mr and 22–23x10(3) Mr which preferentially stimulated the autophosphorylation of VEGFR-3 in comparison with VEGFR-2 (KDR). In in situ hybridization, mouse VEGF-C mRNA expression was detected in mesenchymal cells of postimplantation mouse embryos, particularly in the regions where the lymphatic vessels undergo sprouting from embryonic veins, such as the perimetanephric, axillary and jugular regions. In addition, the developing mesenterium, which is rich in lymphatic vessels, showed strong VEGF-C expression. VEGF-C was also highly expressed in adult mouse lung, heart and kidney, where VEGFR-3 was also prominent. The pattern of expression of VEGF-C in relation to its major receptor VEGFR-3 during the sprouting of the lymphatic endothelium in embryos suggests a paracrine mode of action and that one of the functions of VEGF-C may be in the regulation of angiogenesis of the lymphatic vasculature.
Dendritic cells (DC) are critically involved in the initiation of primary immune processes, including tumor rejection. In our study, we investigated the effect of interleukin-10 (IL-10)–treated human DC on the properties of CD8+ T cells that are known to be essential for the destruction of tumor cells. We show that IL-10–pretreatment of DC not only reduces their allostimulatory capacity, but also induces a state of alloantigen-specific anergy in both primed and naive (CD45RA+) CD8+ T cells. To investigate the influence of IL-10–treated DC on melanoma-associated antigen-specific T cells, we generated a tyrosinase-specific CD8+ T-cell line by several rounds of stimulation with the specific antigen. After coculture with IL-10–treated DC, restimulation of the T-cell line with untreated, antigen-pulsed DC demonstrated peptide-specific anergy in the tyrosinase-specific T cells. Addition of IL-2 to the anergic T cells reversed the state of both alloantigen- or peptide-specific anergy. In contrast to optimally stimulated CD8+ T cells, anergic tyrosinase-specific CD8+ T cells, after coculture with peptide-pulsed IL-10–treated DC, failed to lyse an HLA-A2–positive and tyrosinase-expressing melanoma cell line. Thus, our data demonstrate that IL-10–treated DC induce an antigen-specific anergy in cytotoxic CD8+ T cells, a process that might be a mechanism of tumors to inhibit immune surveillance by converting DC into tolerogenic antigen-presenting cells.
Defective function of dendritic cells (DC) in cancer has been recently described and may represent one of the mechanisms of tumor evasion from immune system control. We have previously shown in vitro that vascular endothelial growth factor (VEGF), produced by almost all tumors, is one of the tumor-derived factors responsible for the defective function of these cells. In this study, we investigated whether in vivo infusion of recombinant VEGF could reproduce the observed DC dysfunction. Continuous VEGF infusion, at rates as low as 50 ng/h (resulting in serum VEGF concentrations of 120 to 160 pg/mL), resulted in a dramatic inhibition of dendritic cell development, associated with an increase in the production of B cells and immature Gr-1+ myeloid cells. Infusion of VEGF was associated with inhibition of the activity of the transcription factor NF-κB in bone marrow progenitor cells. Experiments in vitro showed that VEGF itself, and not factors released by VEGF-activated endothelial cells, affected polypotent stem cells resulting in the observed abnormal hematopoiesis. These data suggest that VEGF, at pathologically relevant concentrations in vivo, may exert effects on pluripotent stem cells that result in blocked DC development as well as affect many other hematopoietic lineages.
We studied the correlation between expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and their receptors with vascularity, metastasis, and proliferative index of human colon cancers. Immunohistochemical analyses using antibodies against VEGF, bFGF, their receptors (KDR,flt-1, bek, and fig), factor VIII, and proliferating cell nuclear antigen were carried out on archival specimens of 52 human colon carcinomas and 10 adenomas. Vessels were quantitated by light microscopy (×200), and the intensity of staining for VEGF and bFGF was assessed on a scale of 0–3+. The presence or absence of immunostaining for KDR,/Zr-7, bek, and fig was evaluated in endothelial cells, and proliferation was determined by counting the number of proliferating cell nuclear antigen-positive cells per 500 tumor cells. Expression of VEGF and KDR was higher in metastatic than in nonmetastatic neoplasms and directly correlated with the extent of neovascularization and the degree of proliferation, whereas expression of bFGF, flt-1, bek, and fig did not differ among tumor types. Vessel counts were greater in metastatic tumors than in nonmetastatic tumors. These findings support the hypothesis that VEGF is an important angiogenic factor in primary and metastatic human colon cancer. VEGF expression and vessel counts may aid in predicting patients at risk for metastasis from colon cancer. © 1995, American Association for Cancer Research. All rights reserved.
Activation of the endothelin receptor B (ETRB) in cultured melanocyte precursors promotes cell proliferation while inhibiting differentiation, two hallmarks of malignant transformation. We therefore tested whether ETRB has a similar role in malignant transformation of melanoma. When tested in culture, we find that the selective ETRB antagonist BQ788 can inhibit the growth of seven human melanoma cell lines, but not a human kidney cell line. This inhibition often is associated with increases in pigmentation and in the dendritic shape that is characteristic of mature melanocytes. In three cell lines we also observe a major increase in cell death. In contrast, the endothelin receptor A (ETRA) antagonist BQ123 does not have these effects, although all the cell lines express both ETRA and ETRB mRNA. Extending these studies in vivo, we find that administration of BQ788 significantly slows human melanoma tumor growth in nude mice, including a complete growth arrest in half of the mice treated systemically. Histological examination of tumor sections suggests that BQ788 also enhances melanoma cell death in vivo. Thus, ETRB inhibitors may be beneficial for the treatment of melanoma.
Co-signaling molecules in the B7-CD28 family have been intensively studied over the past decade and have brought much excitement to the field of immune regulation. The discovery of new functions for the classical pathways CD80/CD86/CD28/CTLA-4 and the identification of novel pathways of the family, including B7-H1/B7-DC/PD-1, B7-H2/ICOS, B7-H3, B7-H4 and BTLA, are greatly broadening our understanding of the control of T cell-mediated immune responses and tolerance.
The involvement of immune mechanisms in tumor angiogenesis is unclear. Here we describe a new mechanism of tumor vasculogenesis mediated by dendritic cell (DC) precursors through the cooperation of β-defensins and vascular endothelial growth factor-A (Vegf-A). Expression of mouse β-defensin-29 recruited DC precursors to tumors and enhanced tumor vascularization and growth in the presence of increased Vegf-A expression. A new leukocyte population expressing DC and endothelial markers was uncovered in mouse and human ovarian carcinomas coexpressing Vegf-A and β-defensins. Tumor-infiltrating DCs migrated to tumor vessels and independently assembled neovasculature in vivo. Bone marrow–derived DCs underwent endothelial-like differentiation ex vivo, migrated to blood vessels and promoted the growth of tumors expressing high levels of Vegf-A. We show that β-defensins and Vegf-A cooperate to promote tumor vasculogenesis by carrying out distinct tasks: β-defensins chemoattract DC precursors through CCR6, whereas Vegf-A primarily induces their endothelial-like specialization and migration to vessels, which is mediated by Vegf receptor-2.
Induction of Fas-mediated activation-induced cell death in antitumor T cells has been hypothesized to permit tumor escape from immune destruction. Several laboratories have proposed that expression of Fas ligand (L) by tumor is the basis for this form of T cell tolerance. In this study, we characterized murine tumor-infiltrating lymphocytes (TIL) for activation status, cell cycle status, level of apoptosis, cytokine secretion, and proliferative capacity. TILs express multiple activation markers (circa CD69, CD95L, CD122, and LFA-1) and contain IL-2 and IFN-g mRNAs, but are neither cycling nor apoptotic in situ. In addition, TIL are dramatically suppressed in proliferative response and do not secrete IL-2 and IFN-g. However, upon purification and activation in vitro, TIL secrete high levels of IL-2 and IFN-g, enter S phase, and then die by Fas-mediated apoptosis. Activation by injection of anti-TCR Ab or IL-2 into tumor-bearing mice induced TIL entrance into S phase preceding apoptosis, showing that TIL have functional TCR-mediated signal transduction in situ. Our data demonstrate that TIL, not tumor, express both Fas and FasL, are arrested in G1, do not secrete cytokine in situ, and, upon activation in vitro and in vivo, rapidly die by activation-induced cell death. The Journal of Immunology, 2001, 166: 6074 - 6083.
Purpose: Endothelin-1 (ET-1) and its receptors (ETAR and ETBR), referred to as the endothelin (ET) axis, are overexpressed in breast carcinomas, and influence tumorigenesis and tumor progression by various mechanisms, including angiogenesis. The objective of the study was to clarify if expression of the ET axis participates in angiogenesis of breast carcinoma
Experimental Design: We analyzed expression of ET-1, ETAR, ETBR, and vascular endothelial growth factor (VEGF) immunohistochemically in 600 tissue array specimens from 200 paraffin-embedded breast carcinomas performing tissue microarray technology. Microvessel density (MVD) was determined by counting microvessels (identified by factor VIII) in each core specimen.
Results: Moderate or strong immunostaining was observed for ET-1 in 25.4%, for ETAR in 43.7%, and for ETBR in 22.2% of breast carcinomas. Of all cases, 44.7% showed significant expression of VEGF. MVD varied between different tumor specimens (range, 0–80; median, 17). We observed a statistically significant correlation between MVD and ET expression status with higher MVD in ET-positive tumors. Moreover, expression of VEGF was found more frequently in tumors with overexpression of the ET axis (each P < 0.001). Staining of VEGF was correlated positively with MVD
Conclusions: These results indicate that increased ET-1, ETAR, and ETBR expression is associated with increased VEGF expression and higher vascularity of breast carcinomas and, thus, could be involved in the regulation of angiogenesis in breast cancer. Our findings provide evidence that the expression pattern of the ET-axis and in particular of ETAR may have clinical relevance in future antiangiogenic targeted therapies for breast cancer.
Cytokines and growth factors are powerful modulators of the immune response. Their aberrant expression either by the tumor cells or by the tumor infiltrating lymphocytes confers a selective advantage to the tumor to grow and suppress the cytotoxic activity of the infiltrating lymphocytes. Therefore, analysis of these soluble factors in the tumor microenvironment can provide an insight into the understanding of the tumor behavior and may be used as a prognostic factor. In the present study the nature of the tumor infiltrating lymphocytes (TILs) and cytokine profile was examined in 36 and 19 mammary carcinoma tissues, respectively, by immunohistochemistry and PCR.Phenotypic differences in the number of cytotoxic T lymphocytes (CD8+) and lymphokine activated killer cells (CD16) was observed among TILs when patients with either early disease stage (39% and 46.6%, respectively) or those alive with no residual disease (31% and 52%, respectively) were compared with late stage (9.7% and 22.8%, respectively) or those dead of disease (14.6% and 15.6%, respectively). Furthermore, analysis of the 19 tumor samples for cytokine mRNA expression by RT-PCR revealed the presence of TNF-α, IL-10, TGF-β1, and IL-2. However, semi-quantitative PCR analysis demonstrated TGF- β1 expression to be significantly higher in patients with a favorable outcome (1.0246 attomoles/μmoles) as compared to patients with a poor prognosis (0.1157 attomoles/μmoles).Our results demonstrate the potential biological significance of certain host factors, particularly TILs and TGF β1 expression, on the outcome of breast cancer. Int. J. Cancer 74:492–501, 1997. © 1997 Wiley-Liss, Inc.
Background:
Many studies have shown that angiogenesis plays an important role in the growth, progression, and metastasis of solid tumors. Recently, several angiogenic factors have been identified. Vascular endothelial growth factor (VEGF) is thought to be one such angiogenic factor and is also thought to be a selective mitogen for endothelial cells. We investigated the correlation between the expression of VEGF and the progression of gastric carcinoma.
Methods:
One hundred twenty-nine specimens resected from patients with gastric carcinoma were investigated by staining with a polyclonal antibody against VEGF. Correlations between the expression of VEGF, microvessel density, and various clincopathologic factors were studied.
Results:
Microvessel density, determined by immunostaining for Factor VIII related antigen, was significantly higher in VEGF-positive tumors than in VEGF-negative tumors. VEGF positivity was correlated with vessel involvement, lymph node metastasis, and liver metastasis. Moreover, patients with VEGF-positive tumors had a significantly poorer prognosis than those with VEGF-negative tumors. Multivariate analysis indicated that the expression of VEGF is an independent prognostic factor in patients with gastric cancer. According to the mode of recurrence, the frequency of hepatic metastases was significantly increased among patients with VEGF-positive tumors.
Conclusions:
The expression of VEGF may be a good prognostic indicator for patients with gastric carcinoma and may also be useful as a predictor of the mode of recurrence in patients with gastric carcinoma.
Decreased immune function in cancer patients is well-characterized (I), and tumor cells have developed a variety of mechanisms, to avoid anti-tumor immune responses (2–8). One mechanism for inhibition of immune cell function by tumors in the production of soluble factors, such as IL-10, TNF,
TGF-β, and Vascular Endothelial Growth Factor (VEGF). The effects of these factors appear, to be twofold: To inhibit effect
or function and to impair the development of immune cells by acting on earlier stages of immunopoiesis. Immune suppression
by tumors is accomplished by a variety of cellular and molecular mechanisms, and virtually all branches of the immune system
can be affected. VEGF and its receptors have profound effects on the early development and differentiation of both vascular
endothelial and hematopoetic progenitors (9). It induces proliferation of mature endothelial cells and is an important component in the formation of tumor neovasculature
(10). VEGF is abundantly expressed by a large percentage of solid tumors and this over-expression is closely associated with
a poor prognosis (11, 12). Some of the earliest hematopoetic progenitors express receptors for VEGF (13), and we have demonstrated that VEGF causes a defect in the functional maturation of dendritic cells (DC) from progenitors.
This developmental defect is associated with impaired activation of NF-κB (14–17). This review describes research demonstrating that VEGF is not only important for tumor vascularization, but is also a key
factor produced by solid tumors to inhibit recognition and destruction of tumor cells by the immune system.
Induction of specific antitumor cytotoxic T cell responses was studied in BALB/c mice bearing tumors transfected with a mutant human p53 minigene. We observed that mice were resistant to the induction of peptide-specific CTL as early as 5 days after challenge with a minimal lethal dose of tumor cells, and the cell types responsible for this effect were further characterized. The contribution of CD4+and CD8+T cells in this response was studied after peptide-pulsed dendritic cell (DC) immunization.In vitrodepletion of CD4+cells during peptide restimulation reduced the level of specific lysis in control mice, and depletion of CD8+T cells completely abrogated it. Substitution of CD8+cells from immunized control mice during restimulation of cells from immunized tumor-bearing mice did not change the level of specific lysis. Substitution of the CD4+from tumor-bearing mice by CD4+cells from control mice improved CTL response, although this response did not reach control values. Peptide-pulsed dendritic cells isolated from tumor-bearing mice showed a significantly reduced ability to induce specific CTL in control animals and reduced ability to restimulate immune T cells from control micein vitro.DC from tumor-bearing mice also had a reduced ability to stimulate control allogeneic T cells. Restimulation of T cells from immunized tumor-bearing mice with DC from control animals, but not from tumor-bearing mice, dramatically increased specific CTL responses to control levels. Macrophages at the same concentration were not able to improve CTL function. Thus, defective antigen presentation by DC appears to be a major determinant for CTL nonresponsiveness to peptide antigens in tumor-bearing mice, and addition of control DC can restore specific lysis. These data provide a basis for new approaches to peptide-based cancer immunotherapy.
The mediators and cellular effectors of inflammation are important constituents of the local environment of tumours. In some types of cancer, inflammatory conditions are present before a malignant change occurs. Conversely, in other types of cancer, an oncogenic change induces an inflammatory microenvironment that promotes the development of tumours. Regardless of its origin, 'smouldering' inflammation in the tumour microenvironment has many tumour-promoting effects. It aids in the proliferation and survival of malignant cells, promotes angiogenesis and metastasis, subverts adaptive immune responses, and alters responses to hormones and chemotherapeutic agents. The molecular pathways of this cancer-related inflammation are now being unravelled, resulting in the identification of new target molecules that could lead to improved diagnosis and treatment.
The mammalian immune system discriminates between modes of cell death; necrosis often results in inflammation and adaptive immunity, whereas apoptosis tends to be anti-inflammatory and promote immune tolerance. We have examined apoptosis for the features responsible for tolerance; specifically, we looked at the roles of caspases and mitochondria. Our results show that caspase activation targeted the mitochondria to produce reactive oxygen species (ROS), which were critical to tolerance induction by apoptotic cells. ROS oxidized the potential danger signal high-mobility group box-1 protein (HMGB1) released from dying cells and thereby neutralized its stimulatory activity. Apoptotic cells failed to induce tolerance and instead stimulated immune responses by scavenging or by mutating a mitochondrial caspase target protein when ROS activity was prohibited. Similarly, blocking sites of oxidation in HMGB1 prevented tolerance induction by apoptotic cells. These results suggest that caspase-orchestrated mitochondrial events determine the impact of apoptotic cells on the immune response.
An accurate assessment of the cervical lymph node metastasis status in oral cavity cancer not only helps predict the prognosis of patients, but also helps surgeons to perform the appropriate treatment. We investigated the utilization of microarray technology focusing on the differences in gene expression profiles between primary tumors of oral squamous cell carcinoma that had metastasized to cervical lymph nodes and those that had not metastasized in the hope of finding new biomarkers to serve for diagnosis and treatment of oral cavity cancer. To design this experiment, we prepared two groups: the learning case group with 30 patients and the test case group with 13 patients. All tissue samples were performed using laser captured microdissection to yield cancer cells, and RNA was isolated from purified cancer cells. To identify a predictive gene expression signature, the different gene expressions between the two groups with and without metastasis in the learning case (n = 30) were analyzed, and the 85 genes expressed differentially were selected. Subsequently, to construct a more accurate prediction model, we further selected the genes with a high power for prediction from the 85 genes using the AdaBoost algorithm. The eight candidate genes, DCTD, IL-15, THBD, GSDML, SH3GL3, PTHLH, RP5-1022P6 and C9orf46, were selected to achieve the minimum error rate. Quantitative reverse transcription-polymerase chain reaction was carried out to validate the selected genes. From these statistical methods, the prediction model was constructed including the eight genes and this model was evaluated by using the test case group. The results in 12 of 13 cases ( approximately 92.3%) were predicted correctly.
We have explored the role of an activation-induced T cell molecule, 4-1BB (CDw137), in the amplification of tumor immunity by retrovirus-mediated transduction of the 4-1BB ligand (4-1BBL) into tumor cells. Mice inoculated with P815 tumor cells expressing 4-1BBL developed a strong cytotoxic T lymphocyte (CTL) response and long-term immunity against wild-type tumor. The optimal effect of 4-1BBL in CTL stimulation required B7-CD28 interaction since blockade of this interaction by antibodies down-regulated the expression of 4-1BB on T cells and decreased CTL activity. Furthermore, co-expression of 4-1BBL and B7-1 in the poorly immunogenic AG104A sarcoma enhanced the induction of effector CTL and the rejection of the wild-type tumor while neither 4-1BBL nor B7-1 single transfectants were effective, suggesting a synergistic effect between the 4-1BB and the CD28 co-stimulatory pathways. Our results underscore the importance of the 4-1BB T cell stimulation pathway in the amplification of an antitumor immune response.
The monoclonal immunoglobulin (Ig) (M-component) secreted by the tumour plasma cells in multiple myeloma (MM) has specific antigenic determinants (idiotypes; id) that can serve as tumour-specific antigens. The intact Ig molecule is a weak antigen, and small fragments of id protein might be more immunogenic for the induction of id-specific immunity. Dendritic cells (DC) have attracted attention as the most efficient antigen-presenting cells and promising adjuvants for immunotherapy in tumours. In this study the in vitro T-cell response against F(ab')2 and Fab fragments, heavy and light chains of the M-component was examined in five patients with MM clinical stage I. All fragments were able to stimulate T cells but F(ab')2 or Fab fragments and heavy chains induced a stronger response than light chains. DC induced a significantly stronger id-specific immune response than monocytes. Moreover, with DC as antigen-presenting cells, a predominant interferon (IFN)-gamma (type-1 T-cell) response was seen in all patients. Both IFN-gamma and interleukin (IL)-4 (type-1 and type-2 T-cell) responses were noted when monocytes were used. Our study suggests that DC pulsed with idiotypic fragments such as F(ab')2 fragment and heavy chain can be used for the induction of type-1 anti-idiotypic T-cell response for immunotherapy in MM.
Vascular endothelial growth factor (VEGF), a major regulator of angiogenesis, binds to two receptor tyrosine kinases, KDR/Flk-1 and Flt-1. We now describe the purification and the expression cloning from tumor cells of a third VEGF receptor, one that binds VEGF165 but not VEGF121. This isoform-specific VEGF receptor (VEGF165R) is identical to human neuropilin-1, a receptor for the collapsin/semaphorin family that mediates neuronal cell guidance. When coexpressed in cells with KDR, neuropilin-1 enhances the binding of VEGF165 to KDR and VEGF165-mediated chemotaxis. Conversely, inhibition of VEGF165 binding to neuropilin-1 inhibits its binding to KDR and its mitogenic activity for endothelial cells. We propose that neuropilin-1 is a novel VEGF receptor that modulates VEGF binding to KDR and subsequent bioactivity and therefore may regulate VEGF-induced angiogenesis.
This phase II study assessed the antitumor activity of tremelimumab, a fully human, anti-CTL-associated antigen 4 monoclonal antibody, in patients with melanoma.
Patients with refractory/relapsed melanoma received 15 mg/kg tremelimumab every 90 days. After 4 doses, patients with tumor response or stable disease were eligible to receive < or =4 additional doses. Primary endpoint was best overall tumor response assessed by an independent endpoint review committee, and secondary endpoints included duration of response, overall survival, progression-free survival, and safety.
Of 251 patients enrolled, 246 (241 response-evaluable) received tremelimumab. Objective response rate was 6.6% (16 partial responses); duration of response was 8.9 to 29.8 months. Eight (50%) objective responses occurred in patients with stage IV M(1c) disease, and 11 (69%) were ongoing at last tumor assessment. Eight (3.3%) patients achieved responses in target lesions (Response Evaluation Criteria in Solid Tumors) despite progressive disease within the first cycle. All 8 survived for >20 months; 5 (63%) remained alive. Clinical benefit rate (overall response + stable disease) was 21% (16 partial responses and 35 stable disease), and median overall survival was 10.0 months. Progression-free survival at 6 months was 15%, and survival was 40.3% at 12 months and 22% at 24 months. Common treatment-related adverse events were generally mild to moderate, and grade 3/4 adverse events included diarrhea (n = 28, 11%), fatigue (n = 6, 2%), and colitis (n = 9, 4%). There were 2 (0.8%) treatment-related deaths.
Tremelimumab showed an objective response rate of 6.6%, with all responses being durable > or =170 days since enrollment, suggesting a potential role for tremelimumab in melanoma.
Ipilimumab is a human monoclonal antibody that blocks cytotoxic T-lymphocyte antigen 4 and has shown promising activity in advanced melanoma. We aimed to ascertain the antitumour efficacy of ipilimumab in patients with advanced melanoma.
We undertook a randomised, double-blind, phase 2 trial in 66 centres from 12 countries. 217 patients with previously treated stage III (unresectable) or stage IV melanoma were randomly assigned a fixed dose of ipilimumab of either 10 mg/kg (n=73), 3 mg/kg (n=72), or 0.3 mg/kg (n=72) every 3 weeks for four cycles (induction) followed by maintenance therapy every 3 months. Randomisation was done with a permuted block procedure, stratified on the basis of type of previous treatment. The primary endpoint was best overall response rate (the proportion of patients with a complete or partial response, according to modified WHO criteria). Efficacy analyses were done by intention to treat, whereas safety analyses included patients who received at least one dose of ipilimumab. This study is registered with ClinicalTrials.gov, number NCT00289640.
The best overall response rate was 11.1% (95% CI 4.9-20.7) for 10 mg/kg, 4.2% (0.9-11.7) for 3 mg/kg, and 0% (0.0-4.9) for 0.3 mg/kg (p=0.0015; trend test). Immune-related adverse events of any grade arose in 50 of 71, 46 of 71, and 19 of 72 patients at doses of 10 mg/kg, 3 mg/kg, and 0.3 mg/kg, respectively; the most common grade 3-4 adverse events were gastrointestinal immune-related events (11 in the 10 mg/kg group, two in the 3 mg/kg group, none in the 0.3 mg/kg group) and diarrhoea (ten in the 10 mg/kg group, one in the 3 mg/kg group, none in the 0.3 mg/kg group).
Ipilimumab elicited a dose-dependent effect on efficacy and safety measures in pretreated patients with advanced melanoma, lending support to further studies at a dose of 10 mg/kg.
Bristol-Myers Squibb.
Immunotherapeutic agents produce antitumor effects by inducing cancer-specific immune responses or by modifying native immune processes. Resulting clinical response patterns extend beyond those of cytotoxic agents and can manifest after an initial increase in tumor burden or the appearance of new lesions (progressive disease). Response Evaluation Criteria in Solid Tumors or WHO criteria, designed to detect early effects of cytotoxic agents, may not provide a complete assessment of immunotherapeutic agents. Novel criteria for the evaluation of antitumor responses with immunotherapeutic agents are required.
The phase II clinical trial program with ipilimumab, an antibody that blocks CTL antigen-4, represents the most comprehensive data set available to date for an immunotherapeutic agent. Novel immune therapy response criteria proposed, based on the shared experience from community workshops and several investigators, were evaluated using data from ipilimumab phase II clinical trials in patients with advanced melanoma.
Ipilimumab monotherapy resulted in four distinct response patterns: (a) shrinkage in baseline lesions, without new lesions; (b) durable stable disease (in some patients followed by a slow, steady decline in total tumor burden); (c) response after an increase in total tumor burden; and (d) response in the presence of new lesions. All patterns were associated with favorable survival.
Systematic criteria, designated immune-related response criteria, were defined in an attempt to capture additional response patterns observed with immune therapy in advanced melanoma beyond those described by Response Evaluation Criteria in Solid Tumors or WHO criteria. Further prospective evaluations of the immune-related response criteria, particularly their association with overall survival, are warranted.
Immune homeostasis is regulated by a finely tuned network of positive-negative regulatory mechanisms that guarantees proper surveillance avoiding hyperactivity that would lead to autoimmunity and inflammatory diseases. Immune responses involve the activation of immunoreceptors that contain tyrosine-based activation motifs (ITAMs). One arm of control involves immunoreceptor tyrosine-based inhibitory motif (ITIM)-bearing receptors, which upon co-aggregation initiate an inhibitory signal through recruitment of signal-aborting phosphatases. Recently, a new immunoregulatory function has been ascribed to ITAMs, which represent in fact dual function modules that, under specific configurations termed inhibitory ITAM (ITAMi), can propagate inhibitory signals. One paradigm is the immunoglobulin A (IgA) Fc receptor (FcalphaRI), which, upon interaction with IgA monomers in the absence of antigen, initiates a powerful inhibitory signal involving Src homology 2 domain-containing phosphatase 1 (SHP-1) recruitment that suppresses cell activation launched by a whole variety of heterologous receptors without co-aggregation. This explains the long known function of IgA as an anti-inflammatory isotype. The importance of this control mechanism in immune homeostasis is underlined by the high incidence of autoimmune and allergic diseases in IgA-deficient patients. ITAMi is now described for an increasing number of immunoreceptors with multiple roles in immunity. ITAMi signaling is also exploited by Escherichia coli to achieve immune evasion during sepsis. Here, we review our current understanding of ITAMi regulatory mechanisms in immune responses and discuss its role in immune homeostasis.
Commensurate with their roles in regulating cytokine-dependent inflammation and immunity, signal transducer and activator of transcription (STAT) proteins are central in determining whether immune responses in the tumour microenvironment promote or inhibit cancer. Persistently activated STAT3 and, to some extent, STAT5 increase tumour cell proliferation, survival and invasion while suppressing anti-tumour immunity. The persistent activation of STAT3 also mediates tumour-promoting inflammation. STAT3 has this dual role in tumour inflammation and immunity by promoting pro-oncogenic inflammatory pathways, including nuclear factor-kappaB (NF-kappaB) and interleukin-6 (IL-6)-GP130-Janus kinase (JAK) pathways, and by opposing STAT1- and NF-kappaB-mediated T helper 1 anti-tumour immune responses. Consequently, STAT3 is a promising target to redirect inflammation for cancer therapy.