Gene Therapy for Pediatric Cancer: State of the Art and Future Perspectives

While modern treatments have led to a dramatic improvement in survival for pediatric malignancy, toxicities are high and a significant proportion of patients remain resistant. Gene transfer offers the prospect of highly specific therapies for childhood cancer. “Corrective” genes may be transferred to overcome the genetic abnormalities present in the precancerous cell. Alternatively, genes can be introduced to render the malignant cell sensitive to therapeutic drugs. The tumor can also be attacked by decreasing its blood supply with genes that inhibit vascular growth. Another possible approach is to modify normal tissues with genes that make them more resistant to conventional drugs and/or radiation, thereby increasing the therapeutic index. Finally, it may be possible to attack the tumor indirectly by using genes that modify the behavior of the immune system, either by making the tumor more immunogenic, or by rendering host effector cells more efficient. Several gene therapy applications have already been reported for pediatric cancer patients in preliminary Phase 1 studies. Although no major clinical success has yet been achieved, improvements in gene delivery technologies and a better understanding of mechanisms of tumor progression and immune escape have opened new perspectives for the cure of pediatric cancer by combining gene therapy with standard therapeutic available treatments

Virus-specific T cells for the immunocompromised patient

While progress has been made in the treatment of both hematologic cancers and solid tumors, chemorefractory or relapsed disease often portends a dismal prognosis, and salvage chemotherapy or radiation expose patients to intolerable toxicities and may not be effective. Hematopoietic stem cell transplant offers the promise of cure for many patients, and while mismatched, unrelated or haploidentical donors are increasingly available, the recipients are at higher risk of severe immunosuppression and immune dysregulation due to graft versus host disease. Viral infections remain a primary cause of severe morbidity and mortality in this patient population. Again, many therapeutic options for viral disease are toxic, may be ineffective or generate resistance, or fail to convey long-term protection. Adoptive cell therapy with virus-specific T cells (VSTs) is a targeted therapy that is efficacious and has minimal toxicity in immunocompromised patients with CMV and EBV infections in particular. Products have since been generated specific for multiple viral antigens (multi-VST), which are not only effective but also confer protection in 70-90% of recipients when used as prophylaxis. Notably, these products can be generated from either virus-naive or virus-experienced autologous or allogeneic sources, including partially matched HLA-matched third-party donors. Obstacles to effective VST treatment are donor availability and product generation time. Banking of third-party VST is an attractive way to overcome these constraints and provide products on an as-needed basis. Other developments include epitope discovery to broaden the number of viral antigens targets in a single product, the optimization of VST generation from naive donor sources, and the modification of VSTs to enhance persistence and efficacy in vivo. © 2017 Houghtelin and Bollard

Children's Oncology Group's 2013 blueprint for research: Non‐Hodgkin lymphoma

Non‐Hodgkin lymphomas account for approximately 7% of cancers diagnosed in patients less than 20 years of age, with approximately 800 cases diagnosed annually at COG institutions. With current therapies, cure rates range from 70% to over 90%, even for children with disseminated disease. However, two major challenges need to be overcome: (i) to optimize upfront treatment to prevent relapse since prognosis for patients with relapsed disease remains poor and (ii) minimize long‐term side effects in survivors. Hence, the future initiatives for the treatment of pediatric NHL are to utilize novel targeted therapies to not only improve outcomes but to decrease bystander organ toxicities and late effects. Pediatr Blood Cancer 2013; 60: 979–984. © 2012 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97477/1/24416_ftp.pd

Immunotherapy for Epstein-Barr Virus-Related Lymphomas

Latent EBV infection is associated with several malignancies, including EBV post-transplant lymphoproliferative disorders (LPD), Hodgkin and non-Hodgkin lymphomas, nasopharyngeal carcinoma and Burkitt lymphoma. The range of expression of latent EBV antigens varies in these tumors, which influences how susceptible the tumors are to immunotherapeutic approaches. Tumors expressing type III latency, such as in LPD, express the widest array of EBV antigens making them the most susceptible to immunotherapy. Treatment strategies for EBV-related tumors include restoring normal cellular immunity by adoptive immunotherapy with EBV-specific T cells and targeting the malignant B cells with monoclonal antibodies. We review the current immunotherapies and future studies aimed at targeting EBV antigen expression in these tumors

Adenoviral Infections in Hematopoietic Stem Cell Transplantation

AbstractAdenoviruses are lytic DNA viruses that are ubiquitous in human communities. In total, 51 different serotypes with varying tissue tropisms have been identified. Adenovirus infections, although frequent, are rarely fatal in immunocompetent individuals who have potent innate and adaptive immunity. But in immunosuppressed individuals, adenoviruses are a significant cause of morbidity and mortality, with limited treatment options. In particular, pediatric recipients of allogeneic hematopoietic stem cell transplantation frequently develop infections early in the posttransplantation period. Because the endogenous recovery of adenovirus-specific T cells has proven important in controlling infection, we explore the potential of adoptive T-cell immunotherapy as a therapeutic strategy. We discuss the advantages and limitations of T-cell therapy for the prophylaxis and treatment of adenovirus infection posttransplantation

A single exercise bout enhances the manufacture of viral-specific T-cells from healthy donors: implications for allogeneic adoptive transfer immunotherapy

Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections remain a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). The adoptive transfer of donor-derived viral-specific cytotoxic T-cells (VSTs) is an effective treatment for controlling CMV and EBV infections after HSCT; however, new practical methods are required to augment the ex vivo manufacture of multi-VSTs from healthy donors. This study investigated the effects of a single exercise bout on the ex vivo manufacture of multi-VSTs. PBMCs isolated from healthy CMV/EBV seropositive participants before (PRE) and immediately after (POST) 30-minutes of cycling exercise were stimulated with CMV (pp65 and IE1) and EBV (LMP2A and BMLF1) peptides and expanded over 8 days. The number (fold difference from PRE) of T-cells specific for CMV pp65 (2.6), EBV LMP2A (2.5), and EBV BMLF1 (4.4) was greater among the VSTs expanded POST. VSTs expanded PRE and POST had similar phenotype characteristics and were equally capable of MHC-restricted killing of autologous target cells. We conclude that a single exercise bout enhances the manufacture of multi-VSTs from healthy donors without altering their phenotype or function and may serve as a simple and economical adjuvant to boost the production of multi-VSTs for allogeneic adoptive transfer immunotherapy

Acute exercise enhances the expansion of cytotoxic T-cells specific to leukemia and melanoma antigens: implications for adoptive transfer immunotherapy?

INTRODUCTION: The ex vivo expansion of tumor-associated-antigen (TAA)-specific cytotoxic T-cells from healthy donors for adoptive transfer in cancer patients has been used successfully to prevent relapse after hematopoietic stem cell transplantation (HSCT). However, this therapy is limited by the difficulty in priming and expanding sufficient numbers of functional TAA-specific T-cells, as T-cells recognizing TAA are usually low in frequency and avidity in healthy donors. Furthermore, monocyte-derived dendritic cells (Mo-DC) are used for TAA-presentation, but their manufacture is limited by low blood monocyte numbers. Therefore, large and impractical numbers of blood cells are required to successfully expand TAA-specific T-cells. Acute exercise is well-known to transiently activate and increase the numbers of T-cells and monocytes in peripheral blood. We therefore hypothesized that the immune-enhancing effects of exercise could be harnessed to enhance the ex vivo expansion of TAA-specific T-cells for adoptive transfer immunotherapy. AIMS: To examine the effects of acute exercise on (1) the number and function of TAA-specific T-cells expanded ex vivo, and 2) the generation and function of mo-DC. METHODS: 12 healthy adults (mean ± SD: Age 27±2.6yrs) completed an acute bout of stair-running exercise (time: 104±17sec). Mo-DC generated from pre and post exercise blood samples were pulsed with the melanoma-associated-antigens MAGE-A4 and PRAME, the common tumor-antigen survivin, and the leukemia-associated-antigen WT-1. Autologous DC were used to expand TAA-specific T-cells obtained before and after exercise over 14-days. T-cells were enumerated and phenotyped by flow cytometry and function was assessed by ELISPOT and antigen-specific cytotoxicity. RESULTS: A greater number of mo-DC were generated from post-exercise blood samples (pre: 2.0±1.0 X106cells, post: 5.2±2.6 X106cells). This was due to the 1.7 fold increase in blood monocytes post-exercise, as the number of mo-DC generated per input CD14+cell did not differ (pre: 0.40±0.25, post: 0.59±0.36). Total T-cell expansion was increased post-exercise (fold-increase: pre: 2.48±0.75, post: 2.90±0.74). ELISPOT revealed that the majority of donors had enrichment in TAA-specific T-cells post-exercise, as T-cell lines expanded from post-exercise samples exhibited an increased interferon-gamma response to TAA compared to T-cell lines expanded from pre-exercise samples. Exercise had no effect on T-cell phenotype or antigen-specific cytotoxicity in the expanded cells. CONCLUSION: These data indicate that a single bout of exercise enhances mo-DC generation and the expansion of TAA-specific T-cells ex vivo. Exercise may therefore serve as an adjuvant to enhance the expansion of TAA-specific T-cells in healthy donors and improve the efficacy of adoptive transfer therapy in cancer patients

Ex Vivo Expanded Multi-Specific Cytotoxic T Lymphocytes Derived from HIV+ Patients and HIV Negative Donors Using GMP Compliant Methodologies Recognize Multiple HIV Antigens and Suppress HIV Replication

Coderch de Sentmenat, José Antoni

CMV-specific T-cells Mobilized with Exercise have Broad Epitope Specificity and a High-Differentiated Effector Memory Phenotype.

Introduction: Dynamic exercise evokes a rapid redeployment of cytotoxic T-cell subsets with high surface expression of b2 adrenergic receptors, presumably to enhance immunosurveillance during acute stress. As this response is affected by age and infection history, the main aim of this study was to examine latent CMV infection as a potential confounder to age-related differences in blood CD8+ T-cell responses to exercise. The second aim of this study was to examine the impact of acute exercise on the mobilization of CMV-specific T-cells in the peripheral blood compartment. Methods: Healthy young (n=16) and older (n=16) humans counterbalanced by CMV IgG serostatus (positive or negative) exercised for 30-minutes at ~80% peak cycling power. Isolated blood lymphocytes phenotypes were assessed by flow cytometry and Enzyme-linked immunospot (ELISPOT) analysis was used to determine the frequency and function of T-cells secreting IFN-g in response to CMV antigens. Maximum likelihood linear mixed models (LMM) were used to determine main effects of exercise (pre, post and 1h post-exercise), age (young or old) and CMV status (positive or negative) on total numbers of blood lymphocytes and their subsets. Results: Those with CMV redeployed ~2 times more CD8+ T-cells and ~6-times more KLRG1+/CD28- and CD45RA+/CCR7- CD8+ subsets than non-infected exercisers. Seronegative older exercisers had an impaired redeployment of total CD8+ T-cells, CD45RA+/CCR7+ and (KLRG1-/CD28+) CD8+ subsets. Redeployed CD8+ T-cell numbers were similar between infected young and old. CMVpp65 specific CD8+ cells in HLA/A2* subjects increased ~2.7 fold after exercise, a response that was driven by the KLRG1+/CD28-/CD8+ subset. Stimulating PBMCs before and after exercise with CMVpp65 and CMV IE-1 antigens and overlapping peptide pools revealed a 2.1 and 4.4 fold increases in CMVpp65 and CMV IE-1 IFN-g secreting cells respectively. The breadth of the T cell response was maintained after exercise with the magnitude of the response being amplified across the entire epitope repertoire. Conclusion: We conclude that latent CMV infection overrides age-related impairments in CD8+ T-cell redeployment with exercise. We also show for the first time that many T-cells redeployed with exercise are specific to CMVpp65 and CMV IE-1 antigens, have broad epitope specificity, and are mostly of a high-differentiated effector memory phenotype. We anticipate that these findings may have clinical implications, with acute exercise serving as a simple strategy to increase numbers of available antigen-specific cells in blood that can be harvested for expansion and adoptive T-cell transfer in HSCT recipients