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ABSTRACT: Human soluble interleukin-7 receptor (sIL7R)α circulates in high molar excess compared with IL-7, but its biology remains unclear. We demonstrate that sIL7Rα has moderate affinity for IL-7 but does not bind thymic stromal lymphopoietin. Functionally, sIL7Rα competes with cell-associated IL-7 receptor to diminish excessive IL-7 consumption and, thus, enhances the bioactivity of IL-7 when the cytokine is limited, as it is presumed to be in vivo. IL-7 signaling in the presence of sIL7Rα also diminishes expression of CD95 and suppressor of cytokine signaling 1, both regulatory molecules. Murine models confirm diminished consumption of IL-7 in the presence of sIL7Rα and also demonstrate a potentiating effect of sIL7Rα on IL-7-mediated homeostatic expansion and experimental autoimmune encephalomyelitis exacerbation. In multiple sclerosis and several other autoimmune diseases, IL7R genotype influences susceptibility. We measured increased sIL7Rα levels, as well as increased IL-7 levels, in multiple sclerosis patients with the predisposing IL7R genotype, consistent with diminished IL-7 consumption in vivo. This work demonstrates that sIL7Rα potentiates IL-7 bioactivity and provides a basis to explain the increased risk of autoimmunity observed in individuals with genotype-induced elevations of sIL7Rα.
Proceedings of the National Academy of Sciences 04/2013; · 9.68 Impact Factor
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Waleed Haso,
Damiel W Lee,
Nirali N Shah,
Maryalice Stetler-Stevenson,
Constance M Yuan,
Ira H Pastan,
Dimiter S Dimitrov,
Richard A Morgan,
David J Fitzgerald,
David M Barrett,
Alan S Wayne, Crystal L Mackall,
Rimas J Orentas
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ABSTRACT: Immune targeting of B cell malignancies using chimeric antigen receptors (CARs) is a promising new approach, but critical factors impacting CAR efficacy remain unclear. To test the suitability of targeting CD22 on precursor B cell acute lymphoblastic leukemia (BCP-ALL), lymphoblasts from 111 patients with BCP-ALL were assayed for CD22 expression and all were found to be CD22 positive, with median CD22 expression levels of 3,500 sites/cell. Three distinct binding domains targeting CD22 were fused to various TCR signaling domains ± an IgG heavy chain constant domain (CH2CH3) to create a series of vector constructs suitable to delineate optimal CAR configuration. CARs derived from the m971 anti-CD22 moAb, which targets a proximal CD22 epitope demonstrated superior anti-leukemic activity compared to those incorporating other binding domains, and addition of a 4-1BB signaling domain to CD28.CD3ζ constructs diminished potency, whereas increasing affinity of the anti-CD22 binding motif, and extending the CD22 binding domain away from the membrane via CH2CH3 had no effect. We conclude that 2nd generation m971 derived anti-CD22-CARs are promising novel therapeutics that should be tested in BCP-ALL.
Blood 12/2012; · 9.90 Impact Factor
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Melinda S Merchant,
James I Geller,
Kristin Baird,
Alexander J Chou,
Susana Galli,
Ava Charles,
Martha Amaoko,
Eunice H Rhee,
Anita Price,
Leonard H Wexler,
Paul A Meyers,
Brigitte C Widemann,
Maria Tsokos, Crystal L Mackall
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ABSTRACT: PURPOSELexatumumab is an agonistic, fully human monoclonal antibody against tumor necrosis factor-related apoptosis-inducing ligand receptor 2 with preclinical evidence of activity in pediatric solid tumors. PATIENTS AND METHODS
This phase I dose-escalation study examined the safety, tolerability, pharmacokinetics, and immunogenicity of lexatumumab at doses up to, but not exceeding, the adult maximum-tolerated dose (3, 5, 8, and 10 mg/kg), administered once every 2 weeks to patients age ≤ 21 years with recurrent or progressive solid tumors.ResultsTwenty-four patients received a total of 56 cycles of lexatumumab over all four planned dose levels. One patient had grade 2 pericarditis consistent with radiation recall, and one patient developed grade 3 pneumonia with hypoxia during the second cycle. Five patients experienced stable disease for three to 24 cycles. No patients experienced complete or partial response, but several showed evidence of antitumor activity, including one patient with recurrent progressive osteosarcoma who experienced resolution of clinical symptoms and positron emission tomography activity, ongoing more than 1 year off therapy. One patient with hepatoblastoma showed a dramatic biomarker response. CONCLUSION
Pediatric patients tolerate 10 mg/kg of lexatumumab administered once every 14 days, the maximum-tolerated dose identified in adults. The drug seems to mediate some clinical activity in pediatric solid tumors and may work with radiation to enhance antitumor effects.
Journal of Clinical Oncology 10/2012; · 18.37 Impact Factor
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ABSTRACT: IL-7 plays many essential roles in human health and disease. Congenital deficiencies in IL-7 signaling result in profound immunodeficiency, polymorphisms in IL7Rα modulate susceptibility to autoimmune disease, and acquired somatic activating mutations in IL7Rα contribute to neoplastic transformation in B cell and T cell leukemia. In response to lymphopenia, IL-7 accumulates to supranormal levels, which alters T cell homeostasis by augmenting T cell reactivity toward self and cognate antigens. This physiologic response is now routinely exploited to improve the efficacy of adoptive cell therapies for cancer. Clinical trials of recombinant IL-7 have demonstrated safety and potent immunorestorative effects, and current studies are investigating whether rhIL-7 therapy can improve outcomes in chronic viral infection and in the context of cancer immunotherapies. Building upon the large fund of knowledge regarding the basic biology of IL-7, this review will discuss the many and varied roles of IL-7 in human health and disease.
Seminars in Immunology 03/2012; 24(3):218-24. · 6.39 Impact Factor
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ABSTRACT: Technological advances now allow us to rapidly produce CARs and other antibody-derived therapeutics targeting cell surface receptors. To maximize the potential of these new technologies, relevant extracellular targets must be identified. The Pediatric Oncology Branch of the NCI curates a freely accessible database of gene expression data for both pediatric cancers and normal tissues, through which we have defined discrete sets of over-expressed transcripts in 12 pediatric cancer subtypes as compared to normal tissues. We coupled gene expression profiles to current annotation databases (i.e., Affymetrix, Gene Ontology, Entrez Gene), in order to categorize transcripts by their sub-cellular location. In this manner we generated a list of potential immune targets expressed on the cell surface, ranked by their difference from normal tissue. Global differences from normal between each of the pediatric tumor types studied varied, indicating that some malignancies expressed transcript sets that were more highly diverged from normal tissues than others. The validity of our approach is seen by our findings for pre-B cell ALL, where targets currently in clinical trials were top-ranked hits (CD19, CD22). For some cancers, reagents already in development could potentially be applied to a new disease class, as exemplified by CD30 expression on sarcomas. Moreover, several potential new targets shared among several pediatric solid tumors are herein identified, such as MCAM (MUC18), metadherin (MTDH), and glypican-2 (GPC2). These targets have been identified at the mRNA level and are yet to be validated at the protein level. The safety of targeting these antigens has yet to be demonstrated and therefore the identified transcripts should be considered preliminary candidates for new CAR and therapeutic antibody targets. Prospective candidate targets will be evaluated by proteomic analysis including Westerns and immunohistochemistry of normal and tumor tissues.
Frontiers in oncology. 01/2012; 2:194.
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Kristin Baird,
Terry J Fry,
Seth M Steinberg,
Michael R Bishop,
Daniel H Fowler,
Cynthia P Delbrook,
Jennifer L Humphrey,
Alison Rager,
Kelly Richards,
Alan S Wayne, Crystal L Mackall
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ABSTRACT: Some subsets of pediatric sarcoma patients have very poor survival rates. We sought to determine the feasibility and efficacy of allogeneic hematopoietic stem cell transplantation (alloHSCT) in pediatric sarcoma populations with <25% predicted overall survival (OS). Patients with ultrahigh-risk Ewing's sarcoma family of tumors (ESFT), alveolar rhabdomyosarcoma, or desmoplastic small round cell tumors received EPOCH-fludarabine induction, a cyclophosphamide/fludarabine/melphalan preparative regimen, and HLA matched related peripheral blood stem cells. Thirty patients enrolled; 7 did not undergo alloHSCT because of progressive disease with diminishing performance status during induction. All 23 alloHSCT recipients experienced rapid full-donor engraftment, with no peritransplantation mortality. Five of 23 alloHSCT recipients (22%) remain alive (OS of 30% by Kaplan-Meier analysis at 3 years), including 3 of 7 (42%) transplanted without overt disease (median survival 14.5 versus 29.0 months from alloHSCT for patients transplanted with versus without overt disease, respectively). Among the 28 patients who progressed on the study, the median survival from date of progression was 1.9 months for the 7 who did not receive a transplant compared with 11.4 months for the 21 transplanted (P = .0003). We found prolonged survival after posttransplantation progression with several patients exhibiting indolent tumor growth. We also saw several patients with enhanced antitumor effects from posttransplantation chemotherapy (objective response to pretransplantation EPOCH-F was 24% versus 67% to posttransplantation EOCH); however, this was associated with increased toxicity. This largest reported series of alloHSCT in sarcomas demonstrates that alloHSCT is safe in this population, and that patients undergoing alloHSCT without overt disease show higher survival rates than reported using standard therapies. Enhanced chemo- and radiosensitivity of tumors and normal tissues was observed posttransplantation.
Biology of blood and marrow transplantation: journal of the American Society for Blood and Marrow Transplantation 09/2011; 18(5):698-707. · 3.15 Impact Factor
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ABSTRACT: The Second International Conference on Immunotherapy in Pediatric Oncology was held in Houston, Texas, USA, October 11-12, 2010, to discuss the progress and challenges that have occurred in cutting edge immunotherapeutic strategies currently being developed for pediatric oncology. Major topics included immune targeting of acute lymphoblastic leukemia and pediatric solid tumors, chimeric antigen receptors (CARs) for hematologic malignancies and solid tumors, enhancing graft-versus-leukemia for pediatric cancers, overcoming hurdles of immunotherapy, strategies to active the innate immune system, and moving immunotherapy beyond phase I studies. Significant progress has been made in the last 2 years both in the development of novel immunobiologics such as CARs, and in establishing survival benefits of an anti-GD2 monoclonal antibody in randomized studies. Although there is much excitement going forward, a great deal of laboratory and regulatory challenges lie ahead in improving the efficacy of each of these modalities as well as getting them to patients in a timely and cost-effective fashion. The resulting discussions will hopefully lead to new collaborations and insight for further translational and clinical studies.
Pediatric Hematology and Oncology 09/2011; 28(6):459-60. · 0.89 Impact Factor
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ABSTRACT: Interleukin-7 (IL-7) is required for T cell development and for maintaining and restoring homeostasis of mature T cells. IL-7 is a limiting resource under normal conditions, but it accumulates during lymphopaenia, leading to increased T cell proliferation. The administration of recombinant human IL-7 to normal or lymphopenic mice, non-human primates and humans results in widespread T cell proliferation, increased T cell numbers, modulation of peripheral T cell subsets and increased T cell receptor repertoire diversity. These effects raise the prospect that IL-7 could mediate therapeutic benefits in several clinical settings. This Review summarizes the biology of IL-7 and the results of its clinical use that are available so far to provide a perspective on the opportunities for clinical application of this cytokine.
Nature Reviews Immunology 05/2011; 11(5):330-42. · 32.25 Impact Factor
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ABSTRACT: Immunotherapies targeting cellular immunity are currently approved for treatment of melanoma, renal cell carcinoma, and prostate cancer. Studies on the immunogenicity and immune responsiveness of pediatric tumors are limited, therefore, it remains unclear to what extent T-cell-based immunotherapy holds promise for pediatric solid tumors.
A new rhabdomyosarcoma cell line (M3-9-M) was derived from an embryonal rhabdomyosarcoma (ERMS) occurring in a C57BL/6 mouse transgenic for hepatocyte growth factor and heterozygous for mutated p53. Primary tumors and metastases derived from M3-9-M were studied for similarities to human ERMS, and for immunogenicity and immune responsiveness.
Primary and metastatic tumors develop after orthotopic injection of M3-9-M into immunocompetent C57BL/6 mice, which mirror human ERMS with regard to histology, gene expression, and metastatic behavior. Whole cell vaccination using irradiated M3-9-M cells or M3-9-M-pulsed dendritic cells (DC)-induced tumor-specific T-cell responses that prevent tumor growth following low-dose tumor injection, and slow tumor growth following higher doses. Administration of anti-CD25 moAbs to deplete CD4(+)CD25(+)FOXP3(+) regulatory T cells prior to tumor vaccination enhanced the potency of the ERMS tumor vaccine. Adoptive immunotherapy with M3-9-M primed T cells plus DC-based vaccination resulted in complete eradication of day 10 M3-9-M derived tumors.
M3-9-M derived murine ERMS is immunogenic and immunoresponsive; regulatory T cells contribute to immune evasion by murine rhabdomyosarcoma. Adoptive immunotherapy with DC vaccination can eradicate low tumor burdens. Future work will seek to identify the tumor-associated antigens that mediate protective and therapeutic immunity in this model.
Pediatric Blood & Cancer 04/2011; 57(6):921-9. · 1.89 Impact Factor
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ABSTRACT: Natural killer (NK) cells can mediate potent antitumor effects, but factors regulating the efficiency of tumor lysis remain unclear. Studies in allogeneic stem cell transplantation highlight an important role for killer cell immunoglobulin-like receptor (KIR) mismatch in overcoming human leukocyte antigen-mediated inhibitory signals. However, other activating and inhibitory signals also modulate tumor lysis by NK cells. We used rhIL15 and artificial antigen presenting cells expressing CD137L and IL15Rα to activate and expand peripheral blood NK cells (CD137L/IL15 NK) up to 1000-fold in 3 weeks. Compared with resting NK cells, CD137L/IL15 NK cells show modest increases in KIR expression and substantial increases in NKG2D, tumor necrosis factor-related apoptosis-inducing ligand, and natural cytotoxicity receptors (NCRs: NKp30, NKp44, NKp46). Compared with resting NK cells, CD137L/IL15 NK cells mediate enhanced cytotoxicity against allogeneic and autologous tumors and KIR signaling did not substantially inhibit cytotoxicity. Rather, tumor lysis by CD137L/IL15 activated NK cells was predominantly driven by NCR signaling as blockade of NCRs dramatically diminished the lysis of a wide array of tumor targets. Furthermore, tumor lysis by CD137L/IL15 NK cells was tightly linked to NCR expression levels that peaked on day 8 to 10 after NK activation, and cytotoxicity diminished on subsequent days as NCR expression declined. We conclude that KIR mismatch is not a prerequisite for tumor killing by CD137L/IL15 NK cells and that NCR expression provides a biomarker for predicting potency of CD137L/IL15 NK cells in studies of NK cell-based immunotherapy.
Journal of immunotherapy (Hagerstown, Md.: 1997) 03/2011; 34(2):187-95. · 3.20 Impact Factor
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Paul F Robbins,
Richard A Morgan,
Steven A Feldman,
James C Yang,
Richard M Sherry,
Mark E Dudley,
John R Wunderlich,
Azam V Nahvi,
Lee J Helman, Crystal L Mackall, [......],
Marybeth S Hughes,
Nicholas P Restifo,
Mark Raffeld,
Chyi-Chia Richard Lee,
Catherine L Levy,
Yong F Li,
Mona El-Gamil,
Susan L Schwarz,
Carolyn Laurencot,
Steven A Rosenberg
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ABSTRACT: Adoptive immunotherapy using tumor-infiltrating lymphocytes represents an effective cancer treatment for patients with metastatic melanoma. The NY-ESO-1 cancer/testis antigen, which is expressed in 80% of patients with synovial cell sarcoma and approximately 25% of patients with melanoma and common epithelial tumors, represents an attractive target for immune-based therapies. The current trial was carried out to evaluate the ability of adoptively transferred autologous T cells transduced with a T-cell receptor (TCR) directed against NY-ESO-1 to mediate tumor regression in patients with metastatic melanoma and synovial cell sarcoma.
A clinical trial was performed in patients with metastatic melanoma or metastatic synovial cell sarcoma refractory to all standard treatments. Patients with NY-ESO-1-positive tumors were treated with autologous TCR-transduced T cells plus 720,000 iU/kg of interleukin-2 to tolerance after preparative chemotherapy. Objective clinical responses were evaluated using Response Evaluation Criteria in Solid Tumors (RECIST).
Objective clinical responses were observed in four of six patients with synovial cell sarcoma and five of 11 patients with melanoma bearing tumors expressing NY-ESO-1. Two of 11 patients with melanoma demonstrated complete regressions that persisted after 1 year. A partial response lasting 18 months was observed in one patient with synovial cell sarcoma.
These observations indicate that TCR-based gene therapies directed against NY-ESO-1 represent a new and effective therapeutic approach for patients with melanoma and synovial cell sarcoma. To our knowledge, this represents the first demonstration of the successful treatment of a nonmelanoma tumor using TCR-transduced T cells.
Journal of Clinical Oncology 01/2011; 29(7):917-24. · 18.37 Impact Factor
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ABSTRACT: Essential survival signals within hematopoietic stem cell (HSC) and thymic niches are mediated by receptor tyrosine kinases, which can be reversibly inhibited using clinically available drugs. We studied whether sunitinib, a multityrosine kinase inhibitor that inhibits KIT, enhances engraftment after bone marrow transplantation (BMT) in mice. Sunitinib diminished hematopoietic progenitor cell numbers, and sunitinib enhanced marrow, peripheral myeloid, and lymphoid engraftment after BMT in Rag1(-/-) mice. Sunitinib augmented HSC engraftment because recipients displayed increased myeloid and lymphoid engraftment and because sunitinib-treated recipients of purified HSCs showed enhanced engraftment of secondary hosts. However, sunitinib preferentially augmented T-cell engraftment with lesser effects on myeloid and HSC engraftment. Consistent with this, sunitinib preferentially depleted the early thymic progenitor subset in the thymus. Sunitinib did not increase engraftment in mice with deficient KIT signaling, and the pattern of more potent effects on T cell compared with HSC engraftment observed in sunitinib-treated hosts was also observed after BMT into KIT(W/Wv) mice. These results implicate KIT as a critical modulator of thymic niches. We conclude that transient, pharmacologic inhibition of KIT enhances accessibility of marrow and thymic niches, and provides a novel, noncytotoxic approach to accomplish engraftment after stem cell transplantation.
Blood 03/2010; 115(20):4120-9. · 9.90 Impact Factor
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Pediatric Clinics of North America 02/2010; 57(1):xvii-xix. · 2.24 Impact Factor
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Martin Guimond,
Aharon G Freud,
Hsiaoyin C Mao,
Jianhua Yu,
Bradley W Blaser,
Jeffrey W Leong,
Jeffrey B Vandeusen,
Adrienne Dorrance,
Jianying Zhang, Crystal L Mackall,
Michael A Caligiuri
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ABSTRACT: IL-15 is required for NK cell development and homeostasis in vivo. Because IL-15 is presented in trans via its high-affinity IL-15Ralpha-chain to cells expressing the IL-15Rbetagamma complex, we postulated that certain IL-15-bearing cells must be required for NK cell homeostasis. Using IL-15(WT/WT) and IL-15(-/-) mice, bone marrow chimeras with normal cellularity, and a selective depletion of CD11c(hi) dendritic cells (DCs), we demonstrate that ablation of the resting CD11c(hi) DC population results in a highly significant decrease in the absolute number of mature NK cells. In contrast, administration of Flt3 ligand increases the CD11c(hi) DC population, which, when expressing IL-15, significantly expands mature NK cells via enhanced survival and proliferation. In summary, a CD11c(hi) DC population expressing IL-15 is required to maintain NK cell homeostasis under conditions of normal cellularity and also is required to mediate Flt3 ligand-induced NK cell expansion in vivo.
The Journal of Immunology 02/2010; 184(6):2769-75. · 5.79 Impact Factor
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Claude Sportès,
Rebecca R Babb,
Michael C Krumlauf,
Frances T Hakim,
Seth M Steinberg,
Catherine K Chow,
Margaret R Brown,
Thomas A Fleisher,
Pierre Noel,
Irina Maric,
Maryalice Stetler-Stevenson,
Julie Engel,
Renaud Buffet,
Michel Morre,
Robert J Amato,
Andrew Pecora, Crystal L Mackall,
Ronald E Gress
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ABSTRACT: Interleukin-7 (IL-7) has critical and nonredundant roles in T-cell development, hematopoiesis, and postdevelopmental immune functions as a prototypic homeostatic cytokine. Based on a large body of preclinical evidence, it may have multiple therapeutic applications in immunodeficiency states, either physiologic (immunosenescence), pathologic (HIV), or iatrogenic (postchemotherapy and posthematopoietic stem cell transplant), and may have roles in immune reconstitution or enhancement of immunotherapy. We report here on the toxicity and biological activity of recombinant human IL-7 (rhIL-7) in humans.
Subjects with incurable malignancy received rhIL-7 subcutaneously every other day for 2 weeks in a phase I interpatient dose escalation study (3, 10, 30, and 60 microg/kg/dose). The objectives were safety and dose-limiting toxicity determination, identification of a range of biologically active doses, and characterization of biological and, possibly, antitumor effects.
Mild to moderate constitutional symptoms, reversible spleen and lymph node enlargement, and marked increase in peripheral CD3(+), CD4(+), and CD8(+) lymphocytes were seen in a dose-dependent and age-independent manner in all subjects receiving >or=10 microg/kg/dose, resulting in a rejuvenated circulating T-cell profile, resembling that seen earlier in life. In some subjects, rhIL-7 induced in the bone marrow a marked, transient polyclonal proliferation of pre-B cells showing a spectrum of maturation as well as an increase in circulating transitional B cells.
This study shows the potent biological activity of rhIL-7 in humans over a well-tolerated dose range and allows further exploration of its possible therapeutic applications.
Clinical Cancer Research 01/2010; 16(2):727-35. · 7.74 Impact Factor
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ABSTRACT: Interleukin-7 has critical and nonredundant roles in T cell development, hematopoiesis, and postdevelopmental immune functions as a prototypic homeostatic cytokine. Based on a large body of preclinical evidence, it may have multiple therapeutic applications in immunodeficiency states, either physiologic (immuno-senescence), pathologic (HIV) or iatrogenic (postchemotherapy and posthematopoietic stem cell transplant) and may have roles in immune reconstitution or enhancement of immunotherapy. Early clinical development trials in humans show that, within a short time, rhIL-7 administration results in a marked preferential expansion of both naive and memory CD4 and CD8 T cell pools with a tendency toward enhanced CD8 expansion. As a result, lymphopenic or normal older hosts develop an expanded circulating T cell pool with a profile that resembles that seen earlier in life with increased T cell repertoire diversity. These results, along with a favorable toxicity profile, open a wide perspective of potential future clinical applications.
Annals of the New York Academy of Sciences 12/2009; 1182:28-38. · 3.15 Impact Factor
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ABSTRACT: Although most children with cancer are cured, there remain significant limitations of standard treatment, most notably chemotherapy resistance and non-specific toxicities. Novel immune-based therapies that target pediatric malignancies offer attractive adjuncts and/or alternatives to commonly employed cytotoxic regimens of chemotherapy or radiotherapy. Elucidation of the principles of tumor biology and the development of novel laboratory technologies over the last decade have led to substantial progress in bringing immunotherapies to the bedside.
Current immunotherapeutic clinical trials in pediatric oncology and the science behind their development are reviewed.
Most of the immune-based therapies studied to date have been well tolerated, and some have shown promise in the setting of refractory or high-risk malignancies, demonstrating that immunotherapy has the potential to overcome resistance to conventional chemotherapy.
Some immune-based therapies, such as ch14.18 and MTP-PE, have already been proven effective in phase III randomized trials. Further studies are needed to optimize and integrate other therapies into standard regimens, and to test them in randomized trials for patients with childhood cancer.
Expert opinion on biological therapy 12/2009; 10(2):163-78. · 3.22 Impact Factor
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ABSTRACT: The development of a new soft tissue lesion in an otherwise healthy child, adolescent, or young adult can present many challenges for pediatric or medical oncology teams. Although uncommon, the diagnosis of a soft tissue malignancy should always be considered in the differential diagnosis of persistent pain, even if no mass is palpable. The definitive diagnosis and treatment of a soft tissue mass is aided by timely scans, appropriate biopsy for anatomic and molecular pathology, and a treatment approach guided by the specific diagnosis. Because pediatric soft tissue sarcomas are rare, cooperative groups play a crucial role in defining the standard of care through retrospective series and well-designed prospective clinical trials. Enrollment of newly diagnosed patients in clinical studies should be encouraged in order to continue to improve outcomes and understanding of these rare tumors. This review focuses on the current recommendations for management of sarcomas that typically occur in the soft tissues of pediatric and young adult patients.
The Oncologist 11/2009; 14(11):1139-53. · 3.91 Impact Factor
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ABSTRACT: Lymphopenia enhances the effectiveness of adoptive immunotherapy by facilitating expansion of transferred T cells but also limits the T-cell repertoire available to mediate immune responses and, in humans, is associated with chronic immune dysfunction. Previous studies concluded that lymphopenia augments adoptive immunotherapy by diminishing Tregs and increasing homeostatic cytokines. We sought to determine whether targeted therapies that replicate the physiology of lymphopenia in lymphoreplete hosts could provide a similarly supportive milieu. Pmel-1 T cells were transferred to B16-bearing lymphopenic versus lymphoreplete mice receiving alphaCD25 and/or recombinant human interleukin-7. Although CD25-based Treg depletion was inefficient because of peripheral expansion of CD4+CD25-FOXP3+ cells, outcomes were better in alphaCD25-treated lymphoreplete hosts than in lymphopenic hosts, and adoptive immunotherapy was most effective in lymphoreplete hosts receiving alphaCD25 plus recombinant human interleukin-7. Lymphopenic hosts supported increased proliferation of adoptively transferred antigen-specific T cells, but cells transferred to lymphoreplete recipients receiving targeted therapies showed superior function. Further, determinant spreading was substantial in lymphoreplete hosts but absent in lymphopenic hosts. These results demonstrate that targeted therapies delivered to mimic the "physiology of lymphopenia" enhance the efficacy of adoptive immunotherapy in lymphoreplete hosts and provide a potentially superior alternative to the induction of lymphopenia.
Blood 09/2009; 114(18):3831-40. · 9.90 Impact Factor
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ABSTRACT: The first annual conference on immunotherapy in pediatric oncology was held in Bethesda, MD, from September 9 to 10, 2008 to discuss the state-of-the-art of immunotherapeutic strategies currently being explored in pediatric oncology. Major topics included targeting cell surface receptors, understanding and improving T-cell-based therapies, augmenting innate immune strategies, and enhancing graft-versus-leukemia for pediatric malignancies. As can be seen in the summaries of the individual presentations, significant progress has been made in developing preclinical models of pediatric tumors and a variety of novel immunobiologic therapies are approaching, or already in, the clinic. Although there is much excitement about the potential utility of these agents, a great deal of challenges lie ahead in improving the efficacy of each of these modalities and getting them to patients in a timely fashion. The resulting discussions will hopefully lead to new collaborations and insight for further translational and clinical studies.
Journal of Pediatric Hematology/Oncology 05/2009; 31(4):227-44. · 1.16 Impact Factor
