Nivolumab in a patient with refractory Hodgkin's lymphoma after allogeneic stem cell transplantation

The influence of immune checkpoint blockade on the outcomes of allogeneic hematopoietic stem cell transplantation

The principle of immune checkpoint blockade therapy is based on the activation of T cells. Immune checkpoint inhibitors (ICIs), such as anti-PD-1/PD-L1 and anti-CTLA-4 antibodies, have demonstrated effectiveness in treating solid tumors by reinvigorating the immune system to recognize and eliminate malignant cells. In recent years, ICIs have shown promise in certain patients with relapsed or refractory lymphoma and myeloid malignancies. Allogeneic hematopoietic stem cell transplant (allo-HCT) currently remains the only curative immunotherapy option for eligible patients with these hematologic malignancies. An increasing number of patients with indications for allo-HCT have received treatment with ICIs either before the procedure or as a therapy for relapse after allo-HCT. Nevertheless, initial reports suggest that patients exposed to immune checkpoint inhibitors either before or after allo-HCT are at an increased risk of developing severe graft-versus-host disease and other immune-related adverse events, likely due to the persistent effects of immune checkpoint blocking. Maximizing therapeutic benefits while minimizing side effects of the combination of checkpoint blockade immunotherapy and allo-HCT is an active area of research aimed at improving the prognosis of relapsed or refractory hematologic malignancies. However, there is still a lack of rational design strategies to optimize the combined use of these two different types of immunotherapies. In this review, we addressed the scientific rationale behind ICIs for treating lymphoma and myeloid malignancies. We also summarized the evidence supporting the use of ICIs as salvage therapy before and after allo-HCT. Additionally, we offered insights into current approaches for preventing and treating graft-versus-host disease and other immune-related adverse events during the procedure.

Safety and efficacy of immune checkpoint inhibitors after allogeneic hematopoietic cell transplantation

The immune system plays a major role in preventing infections and cancers. Impairment in immunity may facilitate the development of neoplasia owing to defective immune surveillance, among other mechanisms. Immune evasion plays a significant role in relapse after allogeneic hematopoietic cell transplantation (alloHCT); one purported mechanism is through immune checkpoint signaling pathways. Checkpoint inhibitors (CPIs) are FDA approved for relapsed classical Hodgkin's Lymphoma (cHL), primary mediastinal large B cell Lymphoma (PMBCL) and other solid tumors. Retrospective studies evaluating the outcomes of alloHCT after prior exposure to CPIs showed favorable survival outcomes but high rates of graft-versus-host disease (GVHD); the risk appears to be lower when using post-transplant cyclophosphamide as GVHD prophylaxis. CPIs have increasingly been used to prevent or treat post-alloHCT relapse. Available data, albeit limited, supports the clinical activity of CPIs in post-alloHCT relapse; however, serious and even fatal cases of GVHD have been reported. The optimal timing, schedule, dosing, and patients likely to benefit from this strategy are yet to be identified. In this review, we highlight the immune system's role in cancer surveillance and relapse prevention and discuss the current clinical evidence of CPIs use in post-alloHCT relapse.

Successful restoration of checkpoint inhibitors efficacy after allogeneic hematopoietic cell transplant for classic Hodgkin lymphoma patients

BACKGROUND

Classic Hodgkin lymphoma (cHL) is a highly-curable disease. However, relapses after bone marrow transplant are challenging especially relapses after allogeneic transplant.

METHODS

A retrospective chart review of the institution transplant database to summarize the safety and efficacy of checkpoint inhibitors (CPIs) use for cHL relapses postallo-HCT in patients who already failed to derive sustained benefit from CPIs received prior to allo-HCT.

RESULTS

Six cases were identified and reviewed. All patients received and failed to derive sustained benefit from CPIs and brentuximab vedotin preallo-HCT. The median age at the time of allo-HCT was 28.6 years (IQR 23.6-34.2), the median number of lines received prior to allo-HCT was 6.5 (range 5-9). The median duration of CPI therapy prior to allo-HCT was 8.1 months (IQR 6.7-12.9). The median time between the discontinuation of CPI and allo-HCT was 5.78 months (IQR 3.15-15.8). The median time to progression postallo-HCT was 5.75 months (IQR 2.6-11.7). The median time between allo-HCT and re-challenge with a CPI was 7.6 months (IQR 3.2-28.6). The median time of follow up after starting postallo-HCT CPIs was 16 months (IQR 7.25-25.75). Five out six patients responded and two patients developed GvHD.

CONCLUSION

Our report shows preserved efficacy without any new safety signals by using CPIs postallo-HCT despite using and having failed to derive sustained benefit from CPIs preallo-HCT.

Considerations for immunotherapy in patients with cancer and comorbid immune dysfunction

Immune checkpoint inhibitors have been widely incorporated for cancer treatment in a variety of solid and hematologic malignancies. Multiple clinical trials have demonstrated the efficacy of PD-1/PD-L1 and CTLA-4 axis inhibition in the metastatic and adjuvant settings. Due to the risks of autoimmune toxicity with these agents, stringent inclusion/exclusion criteria were employed in those initial clinical trials. These criteria led to exclusion or underrepresentation of a variety of patient populations with underlying immune dysfunction. These populations included patients with preexisting autoimmune diseases, solid organ or bone marrow transplant recipients, patients with HIV or viral hepatitis infections, patients receiving concurrent chronic steroid therapy, as well as patients who were elderly, pregnant, or had poor performance status. Thus, established guidelines on the use of immune checkpoint inhibitors in these patients are lacking, and evidence to support efficacy or toxicity are overall limited to retrospective studies and case series. Fortunately, ongoing clinical trials are now including these patients and are shedding light on whether these underrepresented populations can also safely benefit from immune checkpoint inhibitor therapies. In this review, we summarize the most clinically relevant available data on the use of checkpoint inhibitors in immunocompromised patient groups with a primary focus on safety.

Safety and Efficacy of Immune Checkpoint Inhibitors in Children and Young Adults with Haematological Malignancies: Review and Future Perspectives

Despite the marked improvement in overall survival rates of paediatric patients with haematological malignancies that has been achieved during the last decades, there is still a pressing need for novel therapeutic approaches for the subset of patients with relapsed or refractory disease. Immune checkpoint inhibitors aim to induce potent anti-tumour immune responses by targeted blockade of inhibitory receptors and have shown great promise in preclinical models and studies in the adult population. However, paediatric malignancies present unique features and so far, experience with these agents remains limited. In the current review we present an overview of efficacy and safety data from case reports, case series and clinical trials employing the use of immune checkpoint inhibitors in children, adolescents and young adults with haematological malignancies. We also discuss new possibilities involving novel targets and combination treatments and provide a summary of the currently registered clinical trials.

Case Report: Combination Therapy With PD-1 Blockade for Acute Myeloid Leukemia After Allogeneic Hematopoietic Stem Cell Transplantation Resulted in Fatal GVHD

Background: Azacitidine is commonly used in the treatment of relapsed acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) after allogeneic hematopoietic stem cell transplantation (allo-HSCT), but the effectiveness of this monotherapy is still very low. A possible mechanism of resistance to hypomethylating agents (HMAs) is the upregulation of the expression of inhibitory checkpoint receptors and their ligands, making the combination of HMAs and immune checkpoint blockade therapy a rational approach. Although the safety of anti-programmed cell death protein (PD)-1 antibodies for patients with post-allo-HSCT remains a complicated issue, the preliminary clinical result of combining azacitidine with anti-PD-1 antibodies is encouraging; however, the safety and efficacy of this approach need further investigation. Case Presentation: We reported a case of treated secondary (ts)-AML in a patient who received tislelizumab (an anti-PD-1 antibody) in combination with azacitidine. The patient relapsed after allo-HSCT and was previously exposed to HMAs-based therapy. The patient received tislelizumab for compassionate use. After the combination treatment, the patient achieved complete remission with incomplete hematologic recovery, negative minimal residual disease (MRD) by flow cytometry (FCM), and negative Wilms' tumor protein 1 (WT1). However, the patient successively developed serious immune-related adverse events (irAEs) and graft vs. host disease (GVHD) and eventually died from complications of GVHD. Conclusion: To our knowledge, this is the first case to report the combined use of tislelizumab and azacitidine to treat relapsed AML posttransplantation. This report highlights the safety concerns of using an anti-PD-1 antibody in combination with azacitidine after allo-HSCT, especially the risk of GVHD, and provides a basis for future studies.

Use of checkpoint inhibitors in patients with lymphoid malignancies receiving allogeneic cell transplantation: a review

Monoclonal antibodies against checkpoint receptors or its ligands have demonstrated high response rates and durable remissions in patients with relapsed Hodgkin lymphoma (HL) and other lymphoid malignancies. However, most patients will eventually progress on therapy and may benefit from further treatments including allogenic hematopoietic cell transplantation (allo-HCT). Furthermore, the use of checkpoint inhibitors (CPI) has emerged as a treatment option for patients relapsing after allo-HCT. The immune effects of the checkpoint blockade leading to a T-cell activation have raised some concerns on the safety of these therapies used either before or after allo-HCT, due to the potential risk of graft-versus-host disease (GVHD). Furthermore, CPI might also induce other immune toxicities, that can affect almost any organ, as a result of the dysregulation on the immune system balance. This review aims to focus on the evidence behind the use of CPI in patients with lymphoma who undergo allo-HCT. We summarize the clinical data generated to date about the use of CPI in HL and other lymphoid malignancies, the mechanisms of checkpoint inhibition in the context of allo-HCT as well as the clinical and biological observations of different GVHD prophylaxis in this setting. Furthermore, we discuss the evidence from retrospective series and early clinical trials on the feasibility and safety of the use of CPI in patients who relapsed after allo-HCT.

The Role of Immune Checkpoint Molecules for Relapse After Allogeneic Hematopoietic Cell Transplantation

Immune checkpoint molecules represent physiological brakes of the immune system that are essential for the maintenance of immune homeostasis and prevention of autoimmunity. By inhibiting these negative regulators of the immune response, immune checkpoint blockade can increase anti-tumor immunity, but has been primarily successful in solid cancer therapy and Hodgkin lymphoma so far. Allogeneic hematopoietic cell transplantation (allo-HCT) is a well-established cellular immunotherapy option with the potential to cure hematological cancers, but relapse remains a major obstacle. Relapse after allo-HCT is mainly thought to be attributable to loss of the graft-versus-leukemia (GVL) effect and hence escape of tumor cells from the allogeneic immune response. One potential mechanism of immune escape from the GVL effect is the inhibition of allogeneic T cells via engagement of inhibitory receptors on their surface including PD-1, CTLA-4, TIM3, and others. This review provides an overview of current evidence for a role of immune checkpoint molecules for relapse and its treatment after allo-HCT, as well as discussion of the immune mediated side effect graft-vs.-host disease. We discuss the expression of different immune checkpoint molecules on leukemia cells and T cells in patients undergoing allo-HCT. Furthermore, we review mechanistic insights gained from preclinical studies and summarize clinical trials assessing immune checkpoint blockade for relapse after allo-HCT.

Successful Use of Nivolumab in a Patient with Head and Neck Cancer After Allogeneic Bone Marrow Transplantation

Recently, programmed cell death 1(PD-1) inhibitors have shown a significant curative effect in the treatment of most solid cancers and some hematological malignancies. The effects of PD-1 inhibitors in recurrent head and neck squamous cell carcinoma (HNSCC) have also been confirmed. However, there is a lack of reliable clinical evidence to confirm the safety and efficacy of PD-1 inhibitors in patients after allogeneic hematopoietic stem cell transplantation, especially when the patient has a second primary cancer. Generally, graft-versus-host disease (GVHD) is unpredictable among these patients. Here we report the case of a patient who successfully used nivolumab without any GVHD or other immune-related adverse events for HNSCC after allogeneic bone marrow transplantation because of the Philadelphia chromosome-positive T cell acute lymphoblastic leukemia.

The Role of Immune Checkpoints after Cellular Therapy

Cellular therapies utilize the powerful force of the human immune system to target malignant cells. Allogeneic hematopoietic stem cell transplantation (allo-HCT) is the most established cellular therapy, but chimeric antigen receptor (CAR) T cell therapies have gained attention in recent years. While in allo-HCT an entirely novel allogeneic immune system facilitates a so-called Graft-versus-tumor, respectively, Graft-versus-leukemia (GvT/GvL) effect against high-risk hematologic malignancies, in CAR T cell therapies genetically modified autologous T cells specifically attack target molecules on malignant cells. These therapies have achieved high success rates, offering potential cures in otherwise detrimental diseases. However, relapse after cellular therapy remains a serious clinical obstacle. Checkpoint Inhibition (CI), which was recently designated as breakthrough in cancer treatment and consequently awarded with the Nobel prize in 2018, is a different way to increase anti-tumor immunity. Here, inhibitory immune checkpoints are blocked on immune cells in order to restore the immunological force against malignant diseases. Disease relapse after CAR T cell therapy or allo-HCT has been linked to up-regulation of immune checkpoints that render cancer cells resistant to the cell-mediated anti-cancer immune effects. Thus, enhancing immune cell function after cellular therapies using CI is an important treatment option that might re-activate the anti-cancer effect upon cell therapy. In this review, we will summarize current data on this topic with the focus on immune checkpoints after cellular therapy for malignant diseases and balance efficacy versus potential side effects.

Systematic Review of the Safety of Immune Checkpoint Inhibitors Among Kidney Transplant Patients

INTRODUCTION

Kidney transplant (Ktx) recipients are excluded from clinical trials of immune checkpoint inhibitors. The aim of this systematic review was to assess the safety of immune checkpoint inhibitors among Ktx patients.

METHODS

A literature search was conducted using MEDLINE, EMBASE, and Cochrane Database from inception through April 2019. We included studies that reported outcomes of Ktx recipients who received immune checkpoint inhibitors for cancer treatment. Outcomes of interest were allograft rejection and/or allograft failure.

RESULTS

Twenty-seven articles with a total of 44 Ktx patients treated with immune checkpoint inhibitor were identified. Of 44 Ktx patients, 18 were reported to have acute rejection. Median time from immune checkpoint inhibitors to acute rejection diagnosis was 24 (interquartile range, 10-60) days. Reported types of acute allograft rejection were cellular rejection (33%), mixed cellular and antibody-mediated rejection (17%), and unspecified type (50%). Fifteen (83%) had allograft failure and 8 (44%) died. Three patients had a partial remission (17%), 1 patient achieved cancer response (6%), and 5 patients had stable disease (28%).

CONCLUSION

The findings of our study raise awareness of the increased risk for acute allograft rejection/failure following immune checkpoint inhibitors for cancer treatment among Ktx patients, in particular with programmed cell death 1 (PD-1) inhibitors. Future large-scale clinical studies are required to appraise the pathogenesis and plan optimal balanced therapy that helps sustain graft tolerance.

Italian expert panel consensus statement on the optimal use of PD-1 blockade therapy in classical Hodgkin lymphoma

Programmed death 1 (PD-1) blocking antibodies now represent a major advance in the treatment of patients with classical Hodgkin lymphoma (cHL) who relapse after autologous stem cell transplantation (ASCT) and pre- and/or post-ASCT brentuximab vedotin or after at least three lines of therapy. However, uncertainties still remain on the optimal use of these agents in refractory Hodgkin disease. A panel of experts was convened to produce a consensus document aimed at providing practice recommendations for the optimal use of PD-1 blocking antibodies in cHL, especially on pretreatment selection and evaluation of cHL patients' response and treatment length, management of PD-1 blockade therapy-treated patients, evaluation and management of toxicity. Our hope is that these recommendations might help hematologists to improve optimal management of patients with pretreated cHL.

Multi-organ failure induced by Nivolumab in the context of allo-stem cell transplantation

Background

Immune checkpoint inhibitors have radically changed the landscape of anti-tumor therapies in several malignancies. However the adverse events associated with immune checkpoint blockade in combination with other treatments remains to be thoroughly documented. Here we report the case of a 33-year-old male with classical Hodgkin lymphoma who was successfully treated for lymphoma but experienced serious and eventually fatal multisystem organ failure following nivolumab administration and allogeneic stem cell transplantation.

Case presentation

The patient was diagnosed with stage IIIa nodular sclerosing Hodgkin lymphoma. Originally treated by chemotherapy and autologous stem cell transplantation, he subsequently received two allogeneic stem cell transplants from matched and haplo-identical siblings upon successive disease recurrences. Nivolumab treatment was administered prior to the second allograft, after which complete remission of lymphoma was achieved (year 10), as evidenced by clinical and radiographic examination. However within the next 3 months, the patient went on to develop a constellation of symptoms affecting multiple organs, including acute pneumonia with no evidence of bacterial infection, widespread cutaneous eruptions on trunk and lower limbs, mucosal ulcerations, myositis, diarrhea and colitis. Further complications included hepatic cytolysis, acute renal failure, pancreatitis, as well as complete heart block. Some of these injuries being suggestive of graft-versus-host disease, the patient was administered immunosuppressive therapy (mycophenolate, steroids and polyvalent immunoglobulins), but died shortly afterwards. Tissue biopsies revealed extensive lymphocytic infiltration (mostly CD3 + T cells) in skin, liver, and most peculiarly in muscles, including the myocardium. Massive lymphoid-histiocytic infiltration of muscle fibers was accompanied by acute necrotizing myositis and endomysial inflammation.

Conclusions

Multi-organ failure represents a rare but potentially fatal outcome of immune checkpoint blockade in patients receiving allogeneic stem cell grafts. Nivolumab may induce atypical immune-mediated tissue inflammation and damage, such as the extensive muscular polymyositis described here in a patient with Hodgkin lymphoma. Nivolumab might also worsen GVHD symptoms in the context of allogeneic stem cell transplantation. Irrespective of the actual pathological mechanisms, clinicians should be alerted to these fatal drug-related toxicities.

Immune checkpoint blockade for Merkel cell carcinoma: actual findings and unanswered questions

PURPOSE

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine carcinoma arising from the skin. We aimed to review and deal with some of the most relevant controversial topics on the correct use of immunotherapy for the treatment of MCC.

METHODS

The primary search was carried out via PubMed, EMBASE, and the Cochrane Library (until 31st May, 2018), while other articles and guidelines were retrieved from related papers or those referenced in these papers. Additionally, we performed an extensive search on ClinicalTrials.gov to gather information on the ongoing clinical trials related to this specific topic.

RESULTS

We performed an up-to-date critical review taking into account the results of both retrospective and prospective published studies evaluating these issues: Are there any predictive criteria of response to immunotherapy? What is the correct place of immunotherapy in the treatment algorithm of MCC? What is the best choice after immunotherapy failure? What to do with patients for whom immunotherapy is not been feasible or contraindicated? How long should immunotherapy be prolonged, and what follow-up should be offered after complete response?

CONCLUSION

The therapeutic landscape of MCC is rapidly evolving: many open issues will probably be resolved, and many other questions are likely to arise in the next few years. The results of ongoing prospective clinical trials and of several other studies on these issues are eagerly awaited.

Immune checkpoint inhibitors in the management of malignancies in transplant recipients

Cancer immunotherapy, an area of active research, has thus far yielded several exciting breakthroughs in cancer treatment strategies. So far, immune checkpoint inhibitors have been the most promising method of cancer immunotherapy. CTLA-4, PD-1 and PD-L1 are the immune checkpoint molecules against which monoclonal antibodies act against and revolutionised the treatment of several malignancies. However, it is still unclear whether using these monoclonal antibodies in patients with malignancy and a history of transplant is as beneficial as in patients without a history of transplantation. The reason being, with the therapeutic benefit, also comes the inherent disadvantage of transplant rejection because of the activation of T-cells against donor antigens. So, transplant-related complications limit the usage of the checkpoint blockade therapy to treat malignancies. Here, we review the data published in this context and suggest optimal approaches to using the currently available repertoire of immunotherapies.

Significant Risk of Graft-versus-Host Disease with Exposure to Checkpoint Inhibitors before and after Allogeneic Transplantation

Investigators are using checkpoint inhibitors (CPIs) to treat aggressive hematologic malignancies in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) and in some patients with relapsed disease after allo-HSCT. CTLA-4 inhibitors and PD-1 inhibitors are 2 main types of CPIs, which work through activation of the immune system. On one hand, CPIs can achieve graft-versus-tumor effect, and on the other hand, there is a risk of graft-versus-host disease (GVHD). After a comprehensive literature review, we included data (n = 283) from 24 studies (11 original manuscripts and 13 case reports or case series) and evaluated the results to assess the safety and efficacy of CPI use in conjunction with allo-HSCT. Among the 283 patients, 107 received CPI before allo-HSCT, and 176 received CPI after allo-HSCT. The most common indication for CPI use was for Hodgkin lymphoma. The CPIs used in various studies included ipilimumab, nivolumab, and pembrolizumab. Among the patients exposed to CPI before allo-HSCT, 56% developed acute GVHD and 29% developed chronic GVHD. Investigators reported 20 deaths, 60% of which were GVHD-related. The overall mortality risk with GVHD is 11%. In this group, investigators noted an objective response rate (ORR) in 68% of patients, with complete remission (CR) in 47%, partial remission (PR) in 21%, and stable disease in 11%. Among the patients who received a CPI after allo-HSCT for disease relapse, 14% developed acute GVHD and 9% developed chronic GVHD. Investigators reported 40 deaths, 28% of which were GVHD-related. The mortality risk with GVHD is approximately 7%. Investigators reported ORR in 54% of patients, with CR in 33%, PR in 21%, and disease stabilization in 5%. After careful evaluation of collective data, we found that CPI use both before and after allo-HSCT can be highly effective, but exposure can lead to a significantly increased risk of GVHD-related morbidity and mortality in this patient population. Despite limited availability of data, there is need for extreme caution while making decisions regarding the use of CPIs. Detailed discussions and prospective well-designed clinical trials are needed to explore this issue further.

Immune-checkpoint inhibitors to treat cancers in specific immunocompromised populations: a critical review

INTRODUCTION

Because of their efficacy against numerous cancers, immune-checkpoint inhibitors (ICIs), anti-cytotoxic T-lymphocyte antigen-4, and anti-programmed cell death monoclonal antibodies are being used ever more often in oncology. However, some patients were excluded from clinical trials because of their comorbidities despite their potentially higher cancer frequencies, as is the case for immunocompromised patients. Areas covered: We analyzed reported preclinical and clinical information and evaluated the risk/benefit ratio for four immunocompromised populations: people living with human immunodeficiency virus (PLHs), solid-organ transplant recipients, recipients of hematopoietic stem-cell allografts, and patients with autoimmune diseases. Expert commentary: Information available in the literature is fragmentary and scarce, making it difficult to evaluate the risk/benefit ratio. It can, nonetheless, be noted that ICI use in PLHs seems possible. For solid-organ transplant recipients, the risk for the graft seems elevated. For the other two populations, it is difficult to conclude at this time.

Recommendations for managing PD-1 blockade in the context of allogeneic HCT in Hodgkin lymphoma: taming a necessary evil

PD-1 blockade is an effective therapy in relapsed/refractory (R/R) classical Hodgkin Lymphoma (cHL) who have relapsed after or are ineligible for autologous hematopoietic cell transplantation (HCT). Although single-agent anti-PD-1 monoclonal antibodies (mAb’s) are associated with high response rates and durable remissions, available results to date suggest that a large majority of patients will eventually progress on therapy. Many of these patients are potential candidates for allogeneic HCT (allo-HCT) after receiving anti-PD-1 mAb’s, and allo-HCT remains for now the only treatment with demonstrated curative potential in this setting. However, initial reports suggested that allo-HCT in this setting may be associated with increased risk of early transplant-related toxicity, likely driven by lingering effects of PD-1 blockade. Furthermore, many patients with R/R cHL who undergo allo-HCT will relapse after transplantation, most often with limited treatment options. Here again, PD-1 blockade appears to yield high response rates, but with an increased risk of attendant immune toxicity. Many questions remain regarding the use of PD-1 blockade before or after allo-HCT, especially in relation to the feasibility, outcome, optimal timing, and method of allo-HCT after PD-1 blockade. Despite the scarcity of prospective data, these questions are unavoidable and must be tackled by clinicians in the routine care of patients with advanced cHL. We provide consensus recommendations of a working group based on available data and experience, in an effort to help guide treatment decisions until more definitive data are obtained.

Dynamics of Lymphocyte Reconstitution After Hematopoietic Transplantation During Chronic Lymphocytic Choriomeningitis Virus Infection

Bone marrow transplantation is a treatment for various cancers and genetic diseases, and the only case of a cured HIV infection involved the use of this clinical procedure, highlighting the potential use of this therapy for curing many chronic diseases. However, little is known about how chronic viral infection influences lymphocyte reconstitution after bone marrow transplantation. To address this, we infected mice with chronic lymphocytic choriomeningitis virus, and performed bone marrow transplantation to assess lymphocyte reconstitution. Interestingly, we observed that adoptively transferred marrow cells exhibited preferential B cell differentiation in chronically infected mice. Moreover, donor marrow cells that were adoptively transferred into chronically infected mice differentiated into virus-specific CD8 T cells that were able to expand after PD-L1 blockade. Taken together, our data show that chronic viral infection induces a biased differentiation of bone marrow stem cells into B cells, and that exhausted virus-specific CD8 T cells generated de novo in this setting are rescuable by PD-1 blockade. These data contribute to the understanding of how chronic viral infection impacts lymphocyte reconstitution, and may provide valuable information to improve current hematopoietic transplantation regimens in chronically infected hosts.

Immunotherapy for the Treatment of Hodgkin Lymphoma: An Evolving Paradigm

Classical Hodgkin lymphoma (cHL) is one of the most common lymphomas in the Western world. Although most patients are cured with standard first-line therapy, up to 20% of patients will have relapsed or refractory disease. Although the conventional approach to treatment has consisted of chemotherapy, radiation, and for those who relapse, autologous or allogeneic transplantation, newer approaches have become available in recent years, including immunoconjugates and checkpoint inhibitors. These approaches have shown significant efficacy in clinical trials and might be associated with fewer long-term toxicities compared with conventional therapies. In this review we discuss the biology of cHL as it pertains to the immunosuppressive tumor microenvironment and then review the existing clinical trial results of several emerging immunotherapies in this context, including immune checkpoint inhibitors and adoptive cellular therapy. Finally, several clinical practice issues pertaining to the use of immunotherapies are discussed.

Increased Coexpression of PD-1, TIGIT, and KLRG-1 on Tumor-Reactive CD8+ T Cells During Relapse after Allogeneic Stem Cell Transplantation

Allogeneic stem cell transplantation (allo-SCT) can be a curative treatment for patients with a hematologic malignancy due to alloreactive T cell responses recognizing minor histocompatibility antigens (MiHA). Yet tumor immune escape mechanisms can cause failure of T cell immunity, leading to relapse. Tumor cells display low expression of costimulatory molecules and can up-regulate coinhibitory molecules that inhibit T cell functionality on ligation with their counter-receptors on the tumor-reactive T cells. The aim of this explorative study was to evaluate immune checkpoint expression profiles on T cell subsets and on cytomegalovirus (CMV)- and/or MiHA-reactive CD8⁺ T cells of allo-SCT recipients using a 13-color flow cytometry panel, and to correlate these expression patterns to clinical outcomes. MiHA-reactive CD8⁺ T cells exhibited an early differentiated CD27⁺⁺/CD28⁺⁺ phenotype with low KLRG-1 and CD57 expression. These T cells also displayed increased expression of PD-1, TIM-3, and TIGIT compared with total effector memory T cells and CMV-specific CD8⁺ T cells in healthy donors and allo-SCT recipients. Remarkably, high coexpression of PD-1, TIGIT, and KLRG-1 on MiHA-reactive CD8⁺ T cells was associated with relapse after allo-SCT. Taken together, these findings indicate that MiHA-specific CD8⁺ T cells of relapsed patients have a distinctive coinhibitory expression signature compared with patients who stay in remission. This phenotype may serve as a potential monitoring tool in patients. Moreover, these findings suggest that PD-1 and TIGIT play important roles in regulating T cell-mediated tumor control, providing a rationale for immunotherapy with blocking antibodies to treat relapse after allo-SCT.

Nivolumab for the Treatment of Classical Hodgkin Lymphoma

Objective: To review nivolumab for the treatment of classical Hodgkin lymphoma (cHL). Data Sources: Literature searches were conducted in Medline (1946 to May week 3 2017), EMBASE (1974 to 2017 week 22), and Google Scholar using the terms Hodgkin lymphoma AND nivolumab. Study Selection and Data Extraction: Two clinical trials (phase I and phase II) were identified. Data Synthesis: Nivolumab inhibits programmed death receptor-1 allowing for increased T-cell mediated immune surveillance of tumors. Nivolumab was evaluated in cHL patients after failure of autologous stem cell transplantation and brentuximab vedotin consolidation. Patients received nivolumab 3 mg/kg every 2 weeks. In the phase I trial, the objective response rate was 87% (95% confidence interval [CI] = 66-97) and the rate of progression-free survival (PFS) at 24 weeks was 86% (95% CI = 62-95). The most common adverse events (AE) included rash (22%) and decreased platelet count (17%). Following extended follow-up at a median of 86 weeks, 50% of the initial responders maintained a durable response. In the phase II clinical trial, 53 patients (66.3%, 95% CI = 54.8-76.4) achieved an objective response and PFS at 6 months was 76.9% (95% CI = 64.9-85.3). The common AE were fatigue (25%), infusion-related reactions (20%), and rash (16%). After further follow-up at a median of 15.4 months, 12-month overall survival was 94.9% (median overall survival not reached). Conclusions: Nivolumab is an effective option in treating patients with relapsed/refractory cHL with an acceptable safety profile. Further studies are needed to investigate the role of nivolumab for the treatment of cHL.

[Preventative and therapeutic relapse strategies after allogeneic hematopoietic stem cell transplantation: Guidelines from the Francophone society of bone marrow transplantation and cellular therapy (SFGM-TC)]

Disease relapse remains the first cause of mortality of hematological malignancies after allogeneic hematopoietic stem cell transplantation (allo-HCT). The risk of recurrence is elevated in patients with high-risk cytogenetic or molecular abnormalities, as well as when allo-HCT is performed in patients with refractory disease or with persistent molecular or radiological (PET-CT scan) residual disease. Within the frame of the 7th annual workshops of the francophone society for bone marrow transplantation and cellular therapy, the working group reviewed the literature in order to elaborate unified guidelines for the prevention and treatment of relapse after allo-HCT. For high risk AML and MDS, a post transplant maintenance strategy is possible, using hypomethylating agents or TKI anti-FLT3 when the target is present. For Philadelphia positive ALL, there was a consensus for the use of post-transplant TKI maintenance. For lymphomas, there are no strong data on the use of post-transplant maintenance, and hence a preemptive strategy is recommended based on modulation of immunosuppression, close follow-up of donor chimerism, and donor lymphocytes infusion. For multiple myeloma, even though the indication of allo-HCT is controversial, our recommendation is post transplant maintenance using bortezomib, due to its a good toxicity profile without increasing the risk of GVHD.

Immune Checkpoint Blockade and Hematopoietic Stem Cell Transplant

Allogeneic hematopoietic stem cell transplant (HSCT) relies primarily upon graft-versus-tumor activity for cancer eradication. Relapse remains the principal cause of treatment failure after HSCT, implying frequent immune escape, which in at least some cases, appears to be mediated by increased expression of inhibitory immune checkpoints. In an attempt to restore anti-tumor immunity, checkpoint blockade therapy (CBT) targeting PD-1 and CLTA-4 has been used in conjunction with both allogeneic and autologous HSCT. Clinical experience in this setting is limited to several small clinical trials and case series, but together they suggest that treatment with CBT can effectively amplify anti-tumor immune responses. However, intrinsic to its mechanism is also the risk that CBT in the HSCT setting may also cause significant immune toxicity. Fatal immune-related adverse events and graft-versus-host disease have been observed, but in most cases, immune side effects appear to be reversible with steroids and CBT discontinuation. As clinical investigation continues, improved understanding of immune checkpoint biology will be critical to optimize safe and efficacious treatment strategies.

Immune checkpoint inhibitors in challenging populations

Immune checkpoint inhibitors, including those targeting the programmed cell death 1/programmed cell death ligand 1 and cytotoxic T lymphocyte antigen 4 pathways, are revolutionizing cancer therapeutics. Both activity and toxicities largely stem from unleashing tumor- or host-specific cytotoxic T cells. Many patients seen in routine clinical practice have not qualified for or have been seriously underrepresented in immune checkpoint inhibitor clinical trials. Thus, a major gap in knowledge regarding the safety and efficacy of these agents persists in many populations, even after regulatory approval. To address this challenge, this review aggregates and synthesizes the available preclinical and clinical data surrounding immune checkpoint inhibitor therapy in challenging clinical populations to assist both academic and community oncologists in treatment decision making. Specifically, this review focuses on the safety and activity of immune checkpoint inhibitors in patients with autoimmune disorders, organ transplant patients, patients with chronic viral infections, patients with ongoing immunosuppressant use, patients with organ dysfunction, pregnant patients, patients with brain metastases, patients at extremes of age, and patients with an impaired functional status. Cancer 2017;123:1904-1911. © 2017 American Cancer Society.

Emerging treatment options for the management of Hodgkin's lymphoma: clinical utility of nivolumab

Classical Hodgkin's lymphoma (cHL) is a B-cell malignancy comprised of pathologic Reed Sternberg cells with a surrounding immune-tolerant inflammatory milieu. RS cells evade immune recognition in part through programmed death ligand 1 (PD-L1) overexpression, which is genetically programmed through copy number alterations, polysomy, and amplification of the 9p24.1 locus encoding PD-L1. By engaging with PD-1+ T-cells, PD-L1 delivers a potent immune suppressive signal promoting immunologic escape of the tumor cell. Enhancing antitumor immune response by targeting PD-1 with the monoclonal antibody nivolumab has proved to be effective in multiple solid tumors, but the highest response rates to date have been reported in patients with cHL, with over 65% of treated patients achieving an objective clinical response. In this review, we will summarize the published evidence regarding the activity of nivolumab in cHL as well as its current place in therapy. We will review the pharmacology, mechanism of action, and side effects of nivolumab as well as the emerging data indicating possible increased risk of graft versus host disease in patients treated with PD-1 inhibitors either pre- or post-allogeneic stem cell transplant. Given the remarkable single-agent activity and safety profile of PD-1 inhibitors in heavily pretreated patients with cHL, the possibility of employing nivolumab in combination with other active agents and earlier in therapy is a promising area of active investigation, and we will briefly summarize current clinical trials.

PD-1 blockade for relapsed lymphoma post-allogeneic hematopoietic cell transplant: high response rate but frequent GVHD

Given the limited treatment options for relapsed lymphoma post-allogeneic hematopoietic cell transplantation (post-allo-HCT) and the success of programmed death 1 (PD-1) blockade in classical Hodgkin lymphoma (cHL) patients, anti-PD-1 monoclonal antibodies (mAbs) are increasingly being used off-label after allo-HCT. To characterize the safety and efficacy of PD-1 blockade in this setting, we conducted a multicenter retrospective analysis of 31 lymphoma patients receiving anti-PD-1 mAbs for relapse post-allo-HCT. Twenty-nine (94%) patients had cHL and 27 had ≥1 salvage therapy post-allo-HCT and prior to anti-PD-1 treatment. Median follow-up was 428 days (range, 133-833) after the first dose of anti-PD-1. Overall response rate was 77% (15 complete responses and 8 partial responses) in 30 evaluable patients. At last follow-up, 11 of 31 patients progressed and 21 of 31 (68%) remain alive, with 8 (26%) deaths related to new-onset graft-versus-host disease (GVHD) after anti-PD-1. Seventeen (55%) patients developed treatment-emergent GVHD after initiation of anti-PD-1 (6 acute, 4 overlap, and 7 chronic), with onset after a median of 1, 2, and 2 doses, respectively. GVHD severity was grade III-IV acute or severe chronic in 9 patients. Only 2 of these 17 patients achieved complete response to GVHD treatment, and 14 of 17 required ≥2 systemic therapies. In conclusion, PD-1 blockade in relapsed cHL allo-HCT patients appears to be highly efficacious but frequently complicated by rapid onset of severe and treatment-refractory GVHD. PD-1 blockade post-allo-HCT should be studied further but cannot be recommended for routine use outside of a clinical trial.

Efficacy and tolerability of nivolumab after allogeneic transplantation for relapsed Hodgkin lymphoma

Allogeneic hematopoietic cell transplantation (allo-HCT) is indicated for patients with relapsed or refractory Hodgkin lymphoma (HL). Although long-term disease control can be achieved, relapse is still frequent. The programmed cell death protein 1 (PD-1) pathway-blocking antibody nivolumab has shown substantial therapeutic activity and an acceptable safety profile in patients with relapsed or refractory HL who did not receive allo-HCT. However, PD-1 blocking strategy can increase the risk of graft-versus-host disease (GVHD) in murine models. We retrospectively assessed the efficacy and toxicity of nivolumab as a single agent in 20 HL patients relapsing after allo-HCT. GVHD occurred in 6 patients (30%) after nivolumab initiation. All 6 patients had prior history of acute GVHD. The patients with nivolumab-induced GVHD were managed by standard treatment for acute GVHD. Two patients died as a result of GVHD, 1 of progressive disease and 1 of complications related to a second allo-HCT. Overall response rate was 95%. At a median follow-up of 370 days, the 1-year progression-free survival rate was 58.2% (95% CI, 33.1%-76.7%) and the overall survival rate was 78.7% (95% CI, 52.4%-91.5%). Among 13 patients still in response, 6 received a single dose of nivolumab and 7 remain on nivolumab. Compared with standard options for this indication, our results show that nivolumab is effective with an acceptable safety profile.

Tolerance and effectiveness of nivolumab after pediatric T-cell replete, haploidentical, bone marrow transplantation: A case report

To date, there has been a lack of pediatric experience regarding the efficacy and tolerability of immune checkpoint inhibitors after haploidentical hematopoietic stem cell transplant (HSCT). We present the case of a 22-year-old female with multiple-relapsed Hodgkin lymphoma (HL) who presented with a new relapse after haploidentical (post-haplo) HSCT. Anti-PD-1 therapy with nivolumab resulted in significant objective disease response and clinical improvement without notable side effects, including the absence of a graft-versus-host disease (GVHD). This case report suggests that immune checkpoint inhibition may be safely tolerated even in the setting of haploidentical HSCT, without triggering overt GVHD.

PD-1 blockade induces remissions in relapsed classical Hodgkin lymphoma following allogeneic hematopoietic stem cell transplantation

Background

Allogeneic hematopoietic stem cell transplantation and checkpoint blockade therapy are immune-based therapies that have activity in selected refractory hematologic malignancies. Interest has developed in combining these treatments for high-risk hematologic diseases. However, there is concern that checkpoint blockade could augment graft-versus-host disease, and very few studies have evaluated the safety of checkpoint blockade in the post-allogeneic setting. Here, we report the outcomes of three patients with relapsed classical Hodgkin’s lymphoma following allogeneic transplant that were treated with the anti-PD-1 antibody, nivolumab.

Case presentations

Three patients with Hodgkin’s lymphoma relapsed following allogeneic transplant received nivolumab therapy at our institution. All patients were free of graft-versus-host disease and were off of all systemic immunosuppressive medications at the time of nivolumab treatment. Nivolumab was well-tolerated in two of the patients. However, nivolumab had to be discontinued in one patient due to development of immune-related polyarthritis requiring treatment with systemic corticosteroids and methotrexate. Objective responses were observed in all three patients.

Conclusions

Our case series demonstrates that anti-PD-1 therapy with nivolumab can be highly effective following allogeneic transplant for Hodgkin’s lymphoma, but serious immune-related adverse events can occur, requiring very close monitoring and interruption of therapy.

Fatal graft-versus-host disease after allogeneic stem cell transplantation in a patient recently exposed to nivolumab

Allogeneic hematopoietic stem cell transplantation and checkpoint blockade therapy are immune-based salvage therapies for Hodgkin's lymphoma; however, the use of programmed death 1 blocking agents in the allogeneic stem cell transplantation setting could augment the incidence of steroid refractory graft-versus-host disease. Few studies suggest that that nivolumab is safe in patients previously treated with an allogeneic stem cell transplantation. Likewise, there are very limited data on the use of nivolumab before allogeneic stem cell transplantation. Here, we report a case of fatal graft-versus-host disease in a patient who underwent allogeneic stem cell transplantation 26 days after the last administration of nivolumab. Careful monitoring and close clinical assessment of atypical presentation for graft-versus-host disease in these patients, interval of time from nivolumab administration to allogeneic stem cell transplantation, drug dosage adjustments or more effective allo prophilaxys should been evaluated in prospective clinical trial.

Nivolumab in the Treatment of Hodgkin Lymphoma

Despite an extensive immune infiltrate that is recruited to the tumor by malignant Reed-Sternberg cells in Hodgkin lymphoma, the antitumor immune response is ineffective and unable to eradicate the malignant cells. The ineffective immune response is in part due to PD-1 signaling that renders intratumoral immune cells anergic. Reed-Sternberg cells have been shown to upregulate expression of the PD-1 ligands, PD-L1 and PD-L2, due to either genetic alterations at chromosome 9p24.1 or Epstein-Barr virus infection, and these ligands suppress the function of PD-1⁺ intratumoral T cells. Blockade of PD-1 signaling has proven to be a highly successful therapeutic approach, and the use of the anti-PD-1 mAb nivolumab recently received accelerated approval by the FDA for patients with classical Hodgkin lymphoma that has relapsed or progressed after autologous stem cell transplant and posttransplantation brentuximab vedotin. Initial clinical trials using nivolumab in this patient population resulted in high response rates that were durable. Adverse events associated with nivolumab included immune-mediated adverse reactions and infusion reactions, but these were well tolerated, allowing for continued nivolumab administration. Clinical trials are now in progress to test the use of nivolumab in combination with standard chemotherapy or with novel agents with a goal of improving the outcome of patients with Hodgkin lymphoma. Clin Cancer Res; 23(7); 1623-6. ©2016 AACR.

Targeting Immune Checkpoints in Hematologic Malignancies

The use of antibodies that target immune checkpoint molecules on the surface of T-lymphocytes and/or tumor cells has revolutionized our approach to cancer therapy. Cytotoxic-T-lymphocyte antigen (CTLA-4) and programmed cell death protein 1 (PD-1) are the two most commonly targeted immune checkpoint molecules. Although the role of antibodies that target CTLA-4 and PD-1 has been established in solid tumor malignancies and Food and Drug Administration approved for melanoma and non-small cell lung cancer, there remains a desperate need to incorporate immune checkpoint inhibition in hematologic malignancies. Unlike solid tumors, a number of considerations must be addressed to appropriately employ immune checkpoint inhibition in hematologic malignancies. For example, hematologic malignancies frequently obliterate the bone marrow and lymph nodes, which are critical immune organs that must be restored for appropriate response to immune checkpoint inhibition. On the other hand, hematologic malignancies are the quintessential immune responsive tumor type, as proven by the success of allogeneic stem cell transplantation (allo-SCT) in hematologic malignancies. Also, sharing an immune cell lineage, malignant hematologic cells often express immune checkpoint molecules that are absent in solid tumor cells, thereby offering direct targets for immune checkpoint inhibition. A number of clinical trials have demonstrated the potential for immune checkpoint inhibition in hematologic malignancies before and after allo-SCT. The ongoing clinical studies and complimentary immune correlatives are providing a growing body of knowledge regarding the role of immune checkpoint inhibition in hematologic malignancies, which will likely become part of the standard of care for hematologic malignancies.

Recent advances in the management of Hodgkin lymphoma

Hodgkin lymphoma (HL) is a rare cancer of the immune system that typically affects lymph nodes and sometimes other organs. Although the majority of patients can be potentially cured with the use of multi-agent chemotherapy and radiotherapy, a proportion of them will relapse or develop resistant disease for which treatment options are limited. In recent years, new agents have been developed and tested in HL with encouraging results. Two classes of drugs stand out as highly active in advanced HL based on recent study results: antibody-drug conjugates and programmed death 1 inhibitors. Clinical trials in HL with these agents have been completed in the past several years and the results have recently become available. In this review, we discuss the recent advances in the management of HL with a focus on strategies to decrease toxicity and a review of the two drug classes that have the potential to change the landscape of treatment of this disease.

Targeting the PD-1 pathway in patients with relapsed classic Hodgkin lymphoma following allogeneic stem cell transplant is safe and effective

Patients with classic Hodgkin lymphoma (cHL) that has relapsed after autologous or allogeneic transplant have limited treatment options and a poor prognosis. Immunotherapy with agents that target the PROGRAMMED DEATH 1 (PD-1) receptor have demonstrated clinical activity with durable responses in early-phase clinical trials in this patient population; however, patients with a history of allogeneic stem cell transplantation (SCT) were intentionally excluded from participation in those studies due to concerns for reactivation of graft-versus-host disease (GVHD). We describe the clinical course of two patients with advanced cHL and prior treatment with allogeneic stem cell transplantation (SCT) that were treated with the PD-1 inhibitor pembrolizumab. Both patients had no active graft-versus-host disease (GVHD) at the time initiation of therapy and were maintained on low-dose prednisone. Treatment with pembrolizumab was well tolerated and not associated with reactivation of GVHD. Both patients responded (1 partial, 1 complete) and remain on therapy as of November 30, 2015. This report indicates that immunotherapy targeting the PD-1 pathway can be safely administered to patients with cHL and a history of allogeneic SCT and produce tumor responses. Further studies in this patient population are needed.