[Show abstract][Hide abstract] ABSTRACT: During the past decades, anticancer immunotherapy has evolved from a promising therapeutic option to a robust clinical reality. Many immunotherapeutic regimens are now approved by the US Food and Drug Administration and the European Medicines Agency for use in cancer patients, and many others are being investigated as standalone therapeutic interventions or combined with conventional treatments in clinical studies. Immunotherapies may be subdivided into "passive" and "active" based on their ability to engage the host immune system against cancer. Since the anticancer activity of most passive immunotherapeutics (including tumor-targeting monoclonal antibodies) also relies on the host immune system, this classification does not properly reflect the complexity of the drug-host-tumor interaction. Alternatively, anticancer immunotherapeutics can be classified according to their antigen specificity. While some immunotherapies specifically target one (or a few) defined tumor-associated antigen(s), others operate in a relatively non-specific manner and boost natural or therapy-elicited anticancer immune responses of unknown and often broad specificity. Here, we propose a critical, integrated classification of anticancer immunotherapies and discuss the clinical relevance of these approaches.
[Show abstract][Hide abstract] ABSTRACT: Metastatic melanomas are frequently refractory to most adjuvant therapies such as chemotherapies and radiotherapies. Recently, immunotherapies have shown good results in the treatment of some metastatic melanoma. Immune cell infiltration in the tumor has been associated with successful immunotherapy. More generally, tumor infiltrating lymphocytes (TILs) in primary tumor and in metastases of melanoma patients have been demonstrated to correlate positively with favorable clinical outcomes. Altogether, these findings suggest the importance of being able to identify, quantify and characterize immune infiltration at the tumor site for a better diagnostic and treatment choice. In this paper, we used Fourier Transform Infrared (FTIR) imaging to identify and quantify different subpopulations of T cells: the cytotoxic T cells (CD8+), the helper T cells (CD4+) and the regulatory T cells (T reg). As a proof of concept, we investigated pure populations isolated from human peripheral blood from 6 healthy donors. These subpopulations were isolated from blood samples by magnetic labeling and purities were assessed by Fluorescence Activated Cell Sorting (FACS). Results presented here show that Fourier Transform Infrared (FTIR) imaging followed by supervised Partial Least Square Discriminant Analysis (PLS-DA) allows an accurate identification of CD4+ T cells and CD8+ T cells (> 86%). We then developed a PLS regression allowing the quantification of T reg in different mix of immune cells (e.g. Peripheral Blood Mononuclear Cells (PBMC)). Altogether, these results demonstrate the sensitivity of infrared imaging to detect low biological variability observed in T cell subpopulations.
[Show abstract][Hide abstract] ABSTRACT: Autoimmune side effects are frequent in cancer patients treated with "immune checkpoint" targeting antibodies, but are rare with cancer vaccines. Here we report on a metastatic melanoma patient who developed pulmonary sarcoid-like granulomatosis following repetitive vaccinations with peptides and CpG. Despite multiple metastases, including the brain, the patient is alive and well more than 13 years after diagnosis of metastatic disease. The strongly activated tumor specific CD8+ T cells showed robust and long-term memory and effector functions. Possibly, long-term survival and adverse autoimmune events may become more common for vaccines inducing robust anticancer immune responses as in this patient.
[Show abstract][Hide abstract] ABSTRACT: Chronic viral infections and malignant tumours induce T cells that have a reduced ability to secrete effector cytokines and have upregulated expression of the inhibitory receptor PD1 (programmed cell death protein 1). These features have so far been considered to mark terminally differentiated 'exhausted' T cells. However, several recent clinical and experimental observations indicate that phenotypically exhausted T cells can still mediate a crucial level of pathogen or tumour control. In this Opinion article, we propose that the exhausted phenotype results from a differentiation process in which T cells stably adjust their effector capacity to the needs of chronic infection. We argue that this phenotype is optimized to cause minimal tissue damage while still mediating a critical level of pathogen control. In contrast to the presently held view of functional exhaustion, this new concept better reflects the pathophysiology and clinical manifestations of persisting infections, and it provides a rationale for emerging therapies that enhance T cell activity in chronic infection and cancer by blocking inhibitory receptors.
[Show abstract][Hide abstract] ABSTRACT: Anti-CTLA-4 treatment improves the survival of patients with advanced-stage melanoma. However, although the anti-CTLA-4 antibody ipilimumab is now an approved treatment for patients with metastatic disease, it remains unknown by which mechanism it boosts tumor-specific T cell activity. In particular, it is unclear whether treatment amplifies previously induced T cell responses or whether it induces new tumor-specific T cell reactivities. Using a combination ultraviolet (UV)-induced peptide exchange and peptide-major histocompatibility complex (pMHC) combinatorial coding, we monitored immune reactivity against a panel of 145 melanoma-associated epitopes in a cohort of patients receiving anti-CTLA-4 treatment. Comparison of pre- and posttreatment T cell reactivities in peripheral blood mononuclear cell samples of 40 melanoma patients demonstrated that anti-CTLA-4 treatment induces a significant increase in the number of detectable melanoma-specific CD8 T cell responses (P = 0.0009). In striking contrast, the magnitude of both virus-specific and melanoma-specific T cell responses that were already detected before start of therapy remained unaltered by treatment (P = 0.74). The observation that anti-CTLA-4 treatment induces a significant number of newly detected T cell responses-but only infrequently boosts preexisting immune responses-provides strong evidence for anti-CTLA-4 therapy-enhanced T cell priming as a component of the clinical mode of action.
Science translational medicine 09/2014; 6(254):254ra128. · 14.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The Melan-A/MART-126-35 antigenic peptide is one of the best studied human tumor-associated antigens. It is expressed in healthy melanocytes and malignant melanoma and is recognized by CD8+ T cells in the context of the MHC class I molecule HLA-A*0201. While an unusually large repertoire of CD8+ T cells specific for this antigen has been documented, the reasons for its generation have remained elusive. In this issue of the European Journal of Immunology, Pinto et al. [Eur. J. Immunol. 2014. 44: XXXX-XXXX] uncover one important mechanism by comparing the thymic expression of the Melan-A gene to that in the melanocyte lineage. This study shows that medullary thymic epithelial cells (mTECs) dominantly express a truncated Melan-A transcript, the product of mis-initiation of transcription. Consequently, the protein product in mTECs lacks the immunodominant epitope spanning residues 26-35, thus precluding central tolerance to this antigen. In contrast, melanocytes and melanoma tumor cells express almost exclusively the full-length Melan-A transcript, thus providing the target antigen for efficient recognition by HLA-A2-restricted CD8+ T cells. The frequency of these alternative gene transcription modes may be more common than previously appreciated and may represent an important factor modulating the efficiency of central tolerance induction in the thymus.This article is protected by copyright. All rights reserved
European Journal of Immunology 08/2014; · 4.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Immunotherapy offers a promising novel approach for the treatment of cancer and both adoptive T-cell transfer and immune modulation lead to regression of advanced melanoma. However, the potential synergy between these two strategies remains unclear.
We investigated in 12 patients with advanced stage IV melanoma the effect of multiple MART-1 analog peptide vaccinations with (n = 6) or without (n = 6) IMP321 (LAG-3Ig fusion protein) as an adjuvant in combination with lymphodepleting chemotherapy and adoptive transfer of autologous PBMCs at day (D) 0 (Trial registration No: NCT00324623). All patients were selected on the basis of ex vivo detectable MART-1-specific CD8 T-cell responses and immunized at D0, 8, 15, 22, 28, 52, and 74 post-reinfusion.
After immunization, a significant expansion of MART-1-specific CD8 T cells was measured in 83% (n = 5/6) and 17% (n = 1/6) of patients from the IMP321 and control groups, respectively (P < 0.02). Compared to the control group, the mean fold increase of MART-1-specific CD8 T cells in the IMP321 group was respectively >2-, >4- and >6-fold higher at D15, D30 and D60 (P < 0.02). Long-lasting MART-1-specific CD8 T-cell responses were significantly associated with IMP321 (P < 0.02). At the peak of the response, MART-1-specific CD8 T cells contained higher proportions of effector (CCR7- CD45RA+/-) cells in the IMP321 group (P < 0.02) and showed no sign of exhaustion (i.e. were mostly PD1-CD160-TIM3-LAG3-2B4+/-). Moreover, IMP321 was associated with a significantly reduced expansion of regulatory T cells (P < 0.04); consistently, we observed a negative correlation between the relative expansion of MART-1-specific CD8 T cells and of regulatory T cells. Finally, although there were no confirmed responses as per RECIST criteria, a transient, 30-day partial response was observed in a patient from the IMP321 group.
Vaccination with IMP321 as an adjuvant in combination with lymphodepleting chemotherapy and adoptive transfer of autologous PBMCs induced more robust and durable cellular antitumor immune responses, supporting further development of IMP321 as an adjuvant for future immunotherapeutic strategies.
Journal of Translational Medicine 04/2014; 12(1):97. · 3.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The clinical success of adoptive immunotherapy of cancer relies on the selection of target antigens that are highly expressed in tumor cells but absent in essential normal tissues. A group of genes that encode the cancer/testis or cancer germline antigens have been proposed as ideal targets for immunotherapy due to their high expression in multiple cancer types and their restricted expression in immunoprivileged normal tissues. In the present work we report the isolation and characterization of human T cell receptors (TCRs) with specificity for synovial sarcoma X breakpoint 2 (SSX2), a cancer/testis antigen expressed in melanoma, prostate cancer, lymphoma, multiple myeloma and pancreatic cancer, among other tumors. We isolated seven HLA-A2 restricted T cell receptors from natural T cell clones derived from tumor-infiltrated lymph nodes of two SSX2-seropositive melanoma patients, and selected four TCRs for cloning into retroviral vectors. Peripheral blood lymphocytes (PBL) transduced with three of four SSX2 TCRs showed SSX241-49 (KASEKIFYV) peptide specific reactivity, tumor cell recognition and tetramer binding. One of these, TCR-5, exhibited tetramer binding in both CD4 and CD8 cells and was selected for further studies. Antigen-specific and HLA-A*0201-restricted interferon-γ release, cell lysis and lymphocyte proliferation was observed following culture of TCR engineered human PBL with relevant tumor cell lines. Codon optimization was found to increase TCR-5 expression in transduced T cells, and this construct has been selected for development of clinical grade viral vector producing cells. The tumor-specific pattern of expression of SSX2, along with the potent and selective activity of TCR-5, makes this TCR an attractive candidate for potential TCR gene therapy to treat multiple cancer histologies.
PLoS ONE 03/2014; 9(3):e93321. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: CD8(+) T-cell functions are critical for preventing chronic viral infections by eliminating infected cells. For healthy immune responses, beneficial destruction of infected cells must be balanced against immunopathology resulting from collateral damage to tissues. These processes are regulated by factors controlling CD8(+) T-cell function, which are still incompletely understood. Here, we show that the interferon regulatory factor 4 (IRF4) and its cooperating binding partner B-cell-activating transcription factor (BATF) are necessary for sustained CD8(+) T-cell effector function. Although Irf4(-/-) CD8(+) T cells were initially capable of proliferation, IRF4 deficiency resulted in limited CD8(+) T-cell responses after infection with the lymphocytic choriomeningitis virus. Consequently, Irf4(-/-) mice established chronic infections, but were protected from fatal immunopathology. Absence of BATF also resulted in reduced CD8(+) T-cell function, limited immunopathology, and promotion of viral persistence. These data identify the transcription factors IRF4 and BATF as major regulators of antiviral cytotoxic T-cell immunity.Cell Death and Differentiation advance online publication, 14 February 2014; doi:10.1038/cdd.2014.19.
Cell death and differentiation 02/2014; · 8.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Metastatic melanoma has a poor prognosis with high resistance to chemotherapy and radiation. Recently, the anti-CTLA-4 antibody ipilimumab has demonstrated clinical efficacy, being the first agent to significantly prolong the overall survival of inoperable stage III/IV melanoma patients. A major aim of patient immune monitoring is the identification of biomarkers that predict clinical outcome. We studied circulating myeloid-derived suppressor cells (MDSC) in ipilimumab-treated patients to detect alterations in the myeloid cell compartment and possible correlations with clinical outcome. Lin(-) CD14(+) HLA-DR(-) monocytic MDSC were enriched in peripheral blood of melanoma patients compared to healthy donors (HD). Tumor resection did not significantly alter MDSC frequencies. During ipilimumab treatment, MDSC frequencies did not change significantly compared to baseline levels. We observed high inter-patient differences. MDSC frequencies in ipilimumab-treated patients were independent of baseline serum lactate dehydrogenase levels but tended to increase in patients with severe metastatic disease (M1c) compared to patients with metastases in skin or lymph nodes only (M1a), who had frequencies comparable to HD. Interestingly, clinical responders to ipilimumab therapy showed significantly less lin(-) CD14(+) HLA-DR(-) cells as compared to non-responders. The data suggest that the frequency of monocytic MDSC may be used as predictive marker of response, as low frequencies identify patients more likely benefitting from ipilimumab treatment. Prospective clinical trials assessing MDSC frequencies as potential biomarkers are warranted to validate these observations.
Cancer Immunology and Immunotherapy 12/2013; · 3.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Persistent viruses are kept in check by specific lymphocytes. The clonal T cell receptor (TCR) repertoire against Epstein-Barr virus (EBV), once established following primary infection, exhibits a robust stability over time. However, the determinants contributing to this long-term persistence are still poorly characterized. Taking advantage of an in vivo clinical setting where lymphocyte homeostasis was transiently perturbed, we studied EBV antigen-specific CD8 T cells before and after non-myeloablative lympho-depleting chemotherapy of melanoma patients. Despite more advanced T cell differentiation, patients T cells showed clonal composition comparable to healthy individuals, sharing a preference for TRBV20 and TRBV29 gene segment usage and several co-dominant public TCR clonotypes. Moreover, our data revealed the presence of relatively few dominant EBV antigen-specific T cell clonotypes, which mostly persisted following transient lympho-depletion (TLD) and lymphocyte recovery, likely related to absence of EBV reactivation and de novo T cell priming in these patients. Interestingly, persisting clonotypes frequently co-expressed memory/homing-associated genes (CD27, IL7R, EOMES, CD62L/SELL and CCR5) supporting the notion that they are particularly important for long-lasting CD8 T cell responses. Nevertheless, the clonal composition of EBV-specific CD8 T cells was preserved over time with the presence of the same dominant clonotypes after non-myeloablative chemotherapy. The observed clonotype persistence demonstrates high robustness of CD8 T cell homeostasis and reconstitution.
PLoS ONE 10/2013; 8(10):e78686. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Immunotherapy is a promising means to fight cancer, prompting a steady increase in clinical trials and correlative laboratory studies in this field. As antitumor T cells play central roles in immunity against malignant diseases, most immunotherapeutic protocols aim to induce and/or strengthen their function. Various treatment strategies have elicited encouraging clinical responses; however, major challenges have been uncovered that should be addressed in order to fully exploit the potential of immunotherapy. Here, we outline pitfalls for the mobilization of antitumor T cells and offer solutions to improve their therapeutic efficacy. We provide a critical perspective on the main methodologies used to characterize T-cell responses to cancer therapies, with a focus on discrepancies between T-cell attributes measured in vitro and protective responses in vivo. This review altogether provides recommendations to optimize the design of future clinical trials and highlights important considerations for the proficient analysis of clinical specimens available for research.
Expert Review of Vaccines 10/2013; · 4.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To investigate the mechanism(s) of resistance to the RAF-inhibitor vemurafenib, we performed a comprehensive analysis of the genetic alterations occurring in metastatic lesions from a patient with a BRAFV600E-mutant cutaneous melanoma who, after a first response, underwent subsequent rechallenge with this drug.
We obtained blood and tissue samples from a patient diagnosed with a BRAFV600E-mutant cutaneous melanoma that was treated with vemurafenib and achieved a near-complete response. At progression, he received additional lines of chemo/immunotherapy and was successfully re-challenged with vemurafenib. Exome and RNA sequencing were performed on a pre-treatment tumor and two subcutaneous resistant metastases, one that was present at baseline and previously responded to vemurafenib (PV1), and one that appeared de novo after reintroduction of the drug (PV2). A culture established from PV1 was also analyzed.
We identified two NRAS activating somatic mutations, Q61R and Q61K, affecting two main subpopulations in the metastasis PV1, and a BRAF alternative splicing, involving exons 4-10, in the metastasis PV2. These alterations, known to confer resistance to RAF inhibitors, were tumor-specific, mutually exclusive, and were not detected in pre-treatment tumor samples. In addition, the oncogenic PIK3CAH1047R mutation was detected in a subpopulation of PV1, but this mutation did not appear to play a major role in vemurafenib resistance in this metastasis.
This work describes the co-existence within the same patient of different molecular mechanisms of resistance to vemurafenib affecting different metastatic sites. These findings have direct implications for the clinical management of BRAF-mutant melanoma.
Clinical Cancer Research 08/2013; · 8.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent studies of cancer patients revealed high diversity in oncogenic mechanisms, leading to increased treatment individualization for subgroups of patients with frequent cancers. A similar development may not be possible for patients with rare cancers, such as Merkel cell carcinoma (MCC). Finding shared disease mechanisms may open new options to understanding and treating such tumors. Tumor-infiltrating CD8+ T cells are frequently associated with favorable clinical outcome in a remarkably large spectrum of cancers. In this issue, Afanasiev et al. suggest a mechanism that may hinder the tumor homing of CD8+ T cells in MCC patients. It is possible that therapeutic mobilization of anti-cancer T cells may be useful in patients who share this specific immune biological feature.
Journal of Investigative Dermatology 08/2013; 133(8):1929-32. · 6.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Over the past few decades, Fourier transform infrared (FTIR) spectroscopy coupled to microscopy has been recognized as an emerging and potentially powerful tool in cancer research and diagnosis. For this purpose, histological analyses performed by pathologists are mostly carried out on biopsied tissue that undergoes the formalin-fixation and paraffin-embedding (FFPE) procedure. This processing method ensures an optimal and permanent preservation of the samples, making FFPE-archived tissue an extremely valuable source for retrospective studies. Nevertheless, as highlighted by previous studies, this fixation procedure significantly changes the principal constituents of cells, resulting in important effects on their infrared (IR) spectrum. Despite the chemical and spectral influence of FFPE processing, some studies demonstrate that FTIR imaging allows precise identification of the different cell types present in biopsied tissue, indicating that the FFPE process preserves spectral differences between distinct cell types. In this study, we investigated whether this is also the case for closely related cell lines. We analyzed spectra from 8 cancerous epithelial cell lines: 4 breast cancer cell lines and 4 melanoma cell lines. For each cell line, we harvested cells at subconfluence and divided them into two sets. We first tested the "original" capability of FTIR imaging to identify these closely related cell lines on cells just dried on BaF2 slides. We then repeated the test after submitting the cells to the FFPE procedure. Our results show that the IR spectra of FFPE processed cancerous cell lines undergo small but significant changes due to the treatment. The spectral modifications were interpreted as a potential decrease in the phospholipid content and protein denaturation, in line with the scientific literature on the topic. Nevertheless, unsupervised analyses showed that spectral proximities and distances between closely related cell lines were mostly, but not entirely, conserved after FFPE processing. Finally, PLS-DA statistical analyses highlighted that closely related cell lines are still successfully identified and efficiently distinguished by FTIR spectroscopy after FFPE treatment. This last result paves the way towards identification and characterization of cellular subtypes on FFPE tissue sections by FTIR imaging, indicating that this analysis technique could become a potential useful tool in cancer research.
[Show abstract][Hide abstract] ABSTRACT: During chronic infection, pathogen-specific CD8(+) T cells upregulate expression of molecules such as the inhibitory surface receptor PD-1, have diminished cytokine production and are thought to undergo terminal differentiation into exhausted cells. Here we found that T cells with memory-like properties were generated during chronic infection. After transfer into naive mice, these cells robustly proliferated and controlled a viral infection. The reexpanded T cell populations continued to have the exhausted phenotype they acquired during the chronic infection. Thus, the cells underwent a form of differentiation that was stably transmitted to daughter cells. We therefore propose that during persistent infection, effector T cells stably differentiate into a state that is optimized to limit viral replication without causing overwhelming immunological pathology.
[Show abstract][Hide abstract] ABSTRACT: Anti-self/tumor T cell function can be improved by increasing TCR-peptide MHC (pMHC) affinity within physiological limits, but paradoxically further increases (Kd < 1 μM) lead to drastic functional declines. Using human CD8+ T cells engineered with TCRs of incremental affinity for the tumor antigen HLA-A2/NY-ESO-1, we investigated the molecular mechanisms underlying this high-affinity-associated loss of function. As compared with cells expressing TCR affinities generating optimal function (Kd = 5 to 1 μM), those with supraphysiological affinity (Kd = 1 μM to 15 nM) showed impaired gene expression, signaling, and surface expression of activatory/costimulatory receptors. Preferential expression of the inhibitory receptor programmed cell death-1 (PD-1) was limited to T cells with the highest TCR affinity, correlating with full functional recovery upon PD-1 ligand 1 (PD-L1) blockade. In contrast, upregulation of the Src homology 2 domain-containing phosphatase 1 (SHP-1/PTPN6) was broad, with gradually enhanced expression in CD8+ T cells with increasing TCR affinities. Consequently, pharmacological inhibition of SHP-1 with sodium stibogluconate augmented the function of all engineered T cells, and this correlated with the TCR affinity-dependent levels of SHP-1. These data highlight an unexpected and global role of SHP-1 in regulating CD8+ T cell activation and responsiveness and support the development of therapies inhibiting protein tyrosine phosphatases to enhance T cell-mediated immunity.
The Journal of clinical investigation 02/2013; · 15.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: EMD 521873 (Selectikine or NHS-IL2LT) is a fusion protein consisting of modified human IL-2 which binds specifically to the high-affinity IL-2 receptor, and an antibody specific for both single- and double-stranded DNA, designed to facilitate the enrichment of IL-2 in tumor tissue. METHODS: An extensive analysis of pharmacodynamic (PD) markers associated with target modulation was assessed during a first-in-human phase I dose-escalation trial of Selectikine. RESULTS: Thirty-nine patients with metastatic or locally advanced tumors refractory to standard treatments were treated with increasing doses of Selectikine, and nine further patients received additional cyclophosphamide. PD analysis, assessed during the first two treatment cycles, revealed strong activation of both CD4+ and CD8+ T-cells and only weak NK cell activation. No dose response was observed. As expected, Treg cells responded actively to Selectikine but remained at lower frequency than effector CD4+ T-cells. Interestingly, patient survival correlated positively with both high lymphocyte counts and low levels of activated CD8+ T-cells at baseline, the latter of which was associated with enhanced T-cell responses to the treatment. CONCLUSIONS: The results confirm the selectivity of Selectikine with predominant T-cell and low NK cell activation, supporting follow-up studies assessing the clinical efficacy of Selectikine for cancer patients.
Journal of Translational Medicine 01/2013; 11(1):5. · 3.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cytotoxic CD8 T cells mediate immunity to pathogens and they are able to eliminate malignant cells. Immunity to viruses and bacteria primarily involves CD8 T cells bearing high affinity T cell receptors (TCRs), which are specific to pathogen-derived (non-self) antigens. Given the thorough elimination of high affinity self/tumor-antigen reactive T cells by central and peripheral tolerance mechanisms, anti-cancer immunity mostly depends on TCRs with intermediate-to-low affinity for self-antigens. Because of this, a promising novel therapeutic approach to increase the efficacy of tumor-reactive T cells is to engineer their TCRs, with the aim to enhance their binding kinetics to pMHC complexes, or to directly manipulate the TCR-signaling cascades. Such manipulations require a detailed knowledge on how pMHC-TCR and co-receptors binding kinetics impact the T cell response. In this review, we present the current knowledge in this field. We discuss future challenges in identifying and targeting the molecular mechanisms to enhance the function of natural or TCR-affinity optimized T cells, and we provide perspectives for the development of protective anti-tumor T cell responses.