Adoptive T-cell therapy for cancer: The era of engineered T cells

Is the use of unrelated donor transplantation leveling off in Europe? The 2016 European Society for Blood and Marrow Transplant activity survey report

Hematopoietic cell transplantation (HCT) is an established procedure for acquired and congenital disorders of the hematopoietic system. In 2016, there was a tendency for continued activity in this field with 43,636 HCT in 39,313 patients [16,507 allogeneic (42%), 22,806 autologous (58%)] reported by 679 centers in 49 countries in 2016. The main indications were myeloid malignancies 9547 (24%; 96% allogeneic), lymphoid malignancies 25,618 (65%; 20% allogeneic), solid tumors 1516 (4%; 2% allogeneic), and non-malignant disorders 2459 (6%; 85% allogeneic). There was a remarkable leveling off in the use of unrelated donor HCT being replaced by haploidentical HCT. Continued growth in allogeneic HCT for marrow failure, AML, and MPN was seen, whereas MDS appears stable. Allogeneic HCT for lymphoid malignancies vary in trend with increases for NHL and decreases for Hodgkin lymphoma and myeloma. Trends in CLL are not clear, with recent increases after a decrease in activity. In autologous HCT, the use in myeloma continues to expand but is stable in Hodgkin lymphoma. There is a notable increase in autologous HCT for autoimmune disease. These data reflect the most recent advances in the field, in which some trends and changes are likely to be related to development of non-transplant technologies.

Cancer immunotherapy using tumor antigen-reactive T cells

Studies over the last 30 years have shown the promise of cancer immunotherapy using T cells. In particular, since the report by Rosenberg and colleagues in 2002 that adoptive T-cell therapy (ACT) under lymphopenic conditions substantially increased response rates in melanoma patients, ACT has become a promising immunotherapeutic route to cancer treatment. Here we provide a brief history of ACT and review the characteristics of T-cell therapeutics that are specific to this approach. Since every T-cell treatment has its own unique properties in terms of number and type of target antigens, and number of epitopes and type of T cells, we review the main strategies for designing ACT: how Ag specificity is determined, how is it standardized and the need for lymphodepletion to induce epitope spreading. We also briefly consider the next generation of ACT.

Future of anti-PD-1/PD-L1 applications: Combinations with other therapeutic regimens

Programmed cell death 1 (PD-1)/programmed cell death 1 ligand (PD-L1) blockade has shown promising effects in cancer immunotherapy. Removing the so-called " brakes" on T cell immune responses by blocking the PD-1/PD-L1 check point should boost anti-tumor immunity and provide durable tumor regression for cancer patients. However, 30%-60% of patients show no response to PD-1/PD-L1 blockade. Thus, it is urgent to explore the underlying resistance mechanisms to improve sensitivity to anti-PD-1/PD-L1 therapy. We propose that the mechanisms promoting resistance mainly include T cell exclusion or exhaustion at the tumor site, immunosuppressive factors in the tumor microenvironment (TME), and a range of tumor-intrinsic factors. This review highlights the power of studying the cellular and molecular mechanisms of resistance to improve the rational design of combination therapeutic strategies that can be translated to the clinic. Here, we briefly discuss the development of PD-1/PD-L1 blockade agents and focus on the current issues and future prospects for potential combinatorial therapeutic strategies that include anti-PD-1/PD-L1 therapy, based upon the available preclinical and clinical data.

Liver immunotolerance and hepatocellular carcinoma: Patho-physiological mechanisms and therapeutic perspectives

At the moment of the diagnosis of hepatocellular carcinoma (HCC), 70% of patients have only access to palliative treatments, with very few therapeutic options. Liver immunology is very specific, and liver immunotolerance is particularly developed because of the constant and massive influx of antigens. Deregulation of hepatic immunotolerance is implicated in chronic liver diseases development and particularly in liver carcinogenesis. For these reasons, HCC may be an excellent candidate for anticancer immunotherapies such as immune checkpoint inhibitors targeting CTLA-4 and PD-L1/PD-1. Nonetheless, because of the specific immune environment of the liver and the frequent association of HCC with hepatocellular insufficiency, the safety and the efficacy of these new treatments have to be properly studied in this situation. Thus, multiple phase II and III studies are in progress studying immune checkpoint inhibitor monotherapies, combination of different immunotherapies or local strategies such as transarterial chemoembolization combined with immune checkpoint inhibitors. Currently, only the final results of the tremelimumab phase II and the Nivolumab phase I/II study (CheckMate-040) are available. The latter is promising but need to be confirmed by the ongoing phase III studies to confirm the place of immunotherapy in the treatment of HCC. With many new molecular targets and therapeutic combination, immunotherapy represents a new hope in treating HCC patients although serious evaluation is still needed to confirm its interest.

Targeted breast cancer therapy by harnessing the inherent blood group antigen immune system

Cancer gene therapy has attracted increasing attention for its advantages over conventional therapy in specific killing of tumor cells. Here, we attempt to prove a novel therapeutic approach that targets tumors by harnessing the blood antigen immune response system, which is inherently present in patients with breast cancers. Breast cancer MDA-MB-231 cells expressed blood group H antigen precursor. After ectopic expression of blood group A glycosyltransferase, we found that the H precursor was converted into the group A antigen, appearing on the surface of tumor cells. Incubation with group B plasma from breast cancer patients activated the antigen-antibody-complement cascade and triggered tumor cell killing. Interestingly, expression of blood A antigen also reduced tumorigenesis in breast cancer cells by inhibiting cell proliferation, migration, and tumor sphere formation. Cell cycle analysis revealed that cancer cells were paused at S phase due to the activation of cell cycle regulatory genes. Furthermore, pro-apoptotic genes were unregulated by the A antigen, including BAX, P21, and P53, while the anti-apoptotic BCL2 was down regulated. Importantly, we showed that extracellular HMGB1 and ATP, two critical components of the immunogenic cell death pathway, were significantly increased in the blood A antigen-expressing tumor cells. Collectively, these data suggest that blood antigen therapy induces specific cancer cell killing by activating the apoptosis and immunogenic cell death pathways. Further translational studies are thereby warranted to apply this approach in cancer immuno-gene therapy.

Prostate cancer immunotherapy, particularly in combination with androgen deprivation or radiation treatment. Customized pharmacogenomic approaches to overcome immunotherapy cancer resistance

Conventional therapeutic approaches for advanced prostate cancer - such as androgen deprivation, chemotherapy, radiation - come up often against lack of effectiveness because of possible arising of correlative cancer cell resistance and/or inadequate anti-tumor immune conditions. Whence the timeliness of resorting to immune-based treatment strategies including either therapeutic vaccination-based active immunotherapy or anti-tumor monoclonal antibody-mediated passive immunotherapy. Particularly attractive, as for research studies and clinical applications, results to be the cytotoxic T-lymphocyte check point blockade by the use of anti-CTLA-4 and PD-1 monoclonal antibodies, particularly when combined with androgen deprivation therapy or radiation. Unlike afore said immune check point inhibitors, both cell-based (by the use of prostate specific antigen carriers autologous dendritic cells or even whole cancer cells) and recombinant viral vector vaccines are able to induce immune-mediated focused killing of specific antigen-presenting prostate cancer cells. Such vaccines, either used alone or concurrently/sequentially combined with above-mentioned conventional therapies, led to generally reach, in the field of various clinical trials, reasonable results particularly as regards the patient's overall survival. Adoptive trasferred T-cells, as adoptive T-cell passive immunotherapy, and monoclonal antibodies against specific antigen-endowed prostate cancer cells can improve immune micro-environmental conditions. On the basis of a preliminary survey about various immunotherapy strategies, are here also outlined their effects when combined with androgen deprivation therapy or radiation. What's more, as regard the immune-based treatment effectiveness, it has to be pointed out that suitable personalized epigenetic/gene profile-achieved pharmacogenomic approaches to target identified gene aberrations, may lead to overcome - as well as for conventional therapies - possible prostate cancer resistance to immunotherapy.

Cellular immunotherapies for cancer

Lessons learned over decades on the use of gene and cell therapies have found clinical applicability in the field of cancer immunotherapy. On December 16^th, 2016 a symposium was held in Pamplona (Spain) to analyze and discuss the critical points for the clinical success of adoptive cell transfer strategies in cancer immunotherapy. Cellular immunotherapy is being currently exploited for the development of new cancer vaccines using ex vivo manipulated dendritic cells or to enhance the number of effector cells, transferring reinvigorated NK cells or T cells. In this meeting report, we summarize the main topics covered and provide an overview of the field of cellular immunotherapy.

Use of haploidentical stem cell transplantation continues to increase: the 2015 European Society for Blood and Marrow Transplant activity survey report

Hematopoietic stem cell transplantation (HSCT) is an established procedure for many acquired and congenital disorders of the hematopoietic system. A record number of 42 171 HSCT in 37 626 patients (16 030 allogeneic (43%), 21 596 autologous (57%)) were reported by 655 centers in 48 countries in 2015. Trends include continued growth in transplant activity over the last decade, with the highest percentage increase seen in middle-income countries but the highest absolute growth in the very-high-income countries in Europe. Main indications for HSCT were myeloid malignancies 9413 (25% 96% allogeneic), lymphoid malignancies 24 304 (67% 20% allogeneic), solid tumors 1516 (4% 3% allogeneic) and non-malignant disorders 2208 (6% 90% allogeneic). Remarkable is the decreasing use of allogeneic HSCT for CLL from 504 patients in 2011 to 255 in 2015, most likely to be due to new drugs. Use of haploidentical donors for allogeneic HSCT continues to grow: 2012 in 2015, a 291% increase since 2005. Growth is seen for all diseases. In AML, haploidentical HSCT increases similarly for patients with advanced disease and for those in CR1. Both marrow and peripheral blood are used as the stem cell source for haploidentical HSCT with higher numbers reported for the latter.

The Safety of available immunotherapy for the treatment of glioblastoma

INTRODUCTION

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults. Current standard of care involves maximal surgical resection combined with adjuvant chemoradiation. Growing support exists for a role of immunotherapy in treating these tumors with the goal of targeted cytotoxicity. Here we review data on the safety for current immunotherapies being tested in GBM. Areas covered: Safety data from published clinical trials, including ongoing clinical trials were reviewed. Immunotherapeutic classes currently under investigation in GBM include various vaccination strategies, adoptive T cell immunotherapy, immune checkpoint blockade, monoclonal antibodies, and cytokine therapies. Trials include children, adolescents, and adults with either primary or recurrent GBM. Expert opinion: Based on the reviewed clinical trials, the current immunotherapies targeting GBM are safe and well-tolerated with minimal toxicities which should be noted. However, the gains in patient survival have been modest. A safe and well-tolerated combinatory immunotherapeutic approach may be essential for optimal efficacy towards GBM.

T Cells Redirected to a Minor Histocompatibility Antigen Instruct Intratumoral TNFα Expression and Empower Adoptive Cell Therapy for Solid Tumors

Donor-derived allogeneic T cells evoke potent graft versus tumor (GVT) effects likely due to the simultaneous recognition of tumor-specific and host-restricted minor histocompatibility (H) antigens. Here we investigated whether such effects could be reproduced in autologous settings by TCR gene-engineered lymphocytes. We report that T cells redirected either to a broadly expressed Y-encoded minor H antigen or to a tumor-associated antigen, although poorly effective if individually transferred, when simultaneously administered enabled acute autochthonous tumor debulking and resulted in durable clinical remission. Y-redirected T cells proved hyporesponsive in peripheral lymphoid organs, whereas they retained effector function at the tumor site, where in synergy with tumor-redirected lymphocytes, they instructed TNFα expression, endothelial cell activation, and intratumoral T-cell infiltration. While neutralizing TNFα hindered GVT effects by the combined T-cell infusion, a single injection of picogram amounts of NGR-TNF, a tumor vessel-targeted TNFα derivative currently in phase III clinical trials, substituted for Y-redirected cells and enabled tumor debulking by tumor-redirected lymphocytes. Together, our results provide new mechanistic insights into allogeneic GVT, validate the importance of targeting the tumor and its associated stroma, and prove the potency of a novel combined approach suitable for immediate clinical implementation. Cancer Res; 77(3); 658-71. ©2016 AACR.

A Perspective of Immunotherapy for Prostate Cancer

In cancer patients, the immune system is often altered with an excess of inhibitory factors, such as immunosuppressive cytokines, produced by regulatory T cells (Treg) or myeloid-derived suppressor cells (MDSC). The manipulation of the immune system has emerged as one of new promising therapies for cancer treatment, and also represents an attractive strategy to control prostate cancer (PCa). Therapeutic cancer vaccines and immune checkpoint inhibitors have been the most investigated in clinical trials. Many trials are ongoing to define the effects of immune therapy with established treatments: androgen deprivation therapy (ADT) and chemotherapy (CT) or radiotherapy (RT). This article discusses some of these approaches in the context of future treatments for PCa.

How antigen specificity directs regulatory T-cell function: self, foreign and engineered specificity

Regulatory T cells (Tregs) are a suppressive subset of T cells that have important roles in maintaining self-tolerance and preventing immunopathology. The T-cell receptor (TCR) and its antigen specificity play a dominant role in the differentiation of cells to a Treg fate, either in the thymus or in the periphery. This review focuses on the effects of the TCR and its antigen specificity on Treg biology. The role of Tregs with specificity for self-antigen has primarily been studied in the context of autoimmune disease, although recent studies have focused on their role in steady-state conditions. The role of Tregs that are specific for pathogens, dietary antigens and allergens is much less studied, although recent data suggest a significant and previously underappreciated role for Tregs during memory responses to a wide range of foreign antigens. The development of TCR- or chimeric antigen receptor (CAR)-transduced T cells means we are now able to engineer Tregs with disease-relevant antigen specificities, paving the way for ensuring specificity with Treg-based therapies. Understanding the role that antigens play in driving the generation and function of Tregs is critical for defining the pathophysiology of many immune-mediated diseases, and developing new therapeutic interventions.

Marrow-Infiltrating Lymphocytes - Role in Biology and Cancer Therapy

The past several years have witnessed the acceptance of immunotherapy into the mainstream of therapies for patients with cancer. This has been driven by the clinical successes of antibodies to the checkpoint inhibitors, CTLA-4 and PD-1, capable of imparting long-term remissions in several solid tumors as well as Hodgkin’s lymphoma (1) and the therapeutic successes of adoptive T-cell transfer with chimeric antigen receptors (2) or modified T-cell receptors (3) that have mostly utilized peripheral T-cells. One emerging area of therapeutic T cell intervention has been the utilization of marrow-infiltrating lymphocytes (MILs) – a novel form of adoptive T-cell therapy. This approach was initially developed to increase the likelihood of a precursor T-cell population with an enhanced tumor specificity in bone marrow (BM)-derived malignancies. However, the unique attributes of BM T-cells and their interaction with their microenvironment provide significant rationale to utilize these cells therapeutically in diseases that extend beyond hematologic malignancies.