Combined Nivolumab and Ipilimumab or Monotherapy in Untreated Melanoma

Practical Approaches to Immunotherapy in the Clinic

The development of immunotherapy using checkpoint blockade has altered the treatment landscape for patients who had but few options only several years ago. Currently, approved anti-checkpoint agents include ipilimumab, the first approved treatment aimed against the cytotoxic T-lymphocyte antigen-4 (CTLA-4) pathway, and pembrolizumab and nivolumab, which inhibit the programmed death-1 (PD-1) pathway. Careful monitoring and early intervention for immune-mediated side effects is important to mitigate toxicity. Immune-mediated response patterns may differ from response associated with conventional therapies, and so it is important to use caution against early abandonment of treatment. Biomarkers as predictive and prognostic markers of efficacy are still under investigation in an attempt to guide treatment selection in patients with advanced melanoma, and additional studies are needed to provide guidance for selection of checkpoint inhibitors to be used in sequence or combination.

Genomic correlates of response to CTLA-4 blockade in metastatic melanoma

Monoclonal antibodies directed against cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), such as ipilimumab, yield considerable clinical benefit for patients with metastatic melanoma by inhibiting immune checkpoint activity, but clinical predictors of response to these therapies remain incompletely characterized. To investigate the roles of tumor-specific neoantigens and alterations in the tumor microenvironment in the response to ipilimumab, we analyzed whole exomes from pretreatment melanoma tumor biopsies and matching germline tissue samples from 110 patients. For 40 of these patients, we also obtained and analyzed transcriptome data from the pretreatment tumor samples. Overall mutational load, neoantigen load, and expression of cytolytic markers in the immune microenvironment were significantly associated with clinical benefit. However, no recurrent neoantigen peptide sequences predicted responder patient populations. Thus, detailed integrated molecular characterization of large patient cohorts may be needed to identify robust determinants of response and resistance to immune checkpoint inhibitors.

Immunological biomarkers predict HIV-1 viral rebound after treatment interruption

Treatment of HIV-1 infection with antiretroviral therapy (ART) in the weeks following transmission may induce a state of 'post-treatment control' (PTC) in some patients, in whom viraemia remains undetectable when ART is stopped. Explaining PTC could help our understanding of the processes that maintain viral persistence. Here we show that immunological biomarkers can predict time to viral rebound after stopping ART by analysing data from a randomized study of primary HIV-1 infection incorporating a treatment interruption (TI) after 48 weeks of ART (the SPARTAC trial). T-cell exhaustion markers PD-1, Tim-3 and Lag-3 measured prior to ART strongly predict time to the return of viraemia. These data indicate that T-cell exhaustion markers may identify those latently infected cells with a higher proclivity to viral transcription. Our results may open new avenues for understanding the mechanisms underlying PTC, and eventually HIV-1 eradication.

Genomic correlates of response to CTLA-4 blockade in metastatic melanoma

Monoclonal antibodies directed against cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), such as ipilimumab, yield considerable clinical benefit for patients with metastatic melanoma by inhibiting immune checkpoint activity, but clinical predictors of response to these therapies remain incompletely characterized. To investigate the roles of tumor-specific neoantigens and alterations in the tumor microenvironment in the response to ipilimumab, we analyzed whole exomes from pretreatment melanoma tumor biopsies and matching germline tissue samples from 110 patients. For 40 of these patients, we also obtained and analyzed transcriptome data from the pretreatment tumor samples. Overall mutational load, neoantigen load, and expression of cytolytic markers in the immune microenvironment were significantly associated with clinical benefit. However, no recurrent neoantigen peptide sequences predicted responder patient populations. Thus, detailed integrated molecular characterization of large patient cohorts may be needed to identify robust determinants of response and resistance to immune checkpoint inhibitors.

Nivolumab in Resected and Unresectable Metastatic Melanoma: Characteristics of Immune-Related Adverse Events and Association with Outcomes

PURPOSE

Retrospective analysis of irAEs in melanoma patients treated with nivolumab.

EXPERIMENTAL DESIGN

Data were pooled from 148 patients (33 resected, 115 unresectable) treated with nivolumab plus peptide vaccine or nivolumab alone every 2 weeks for 12 weeks. Patients with stable disease or regression received an additional 12-week cycle, then nivolumab alone every 12 weeks for up to 2 additional years. Frequency, grade, and characteristics of immune-related adverse events (irAE) were analyzed. A 12-week landmark survival analysis using a multivariate time-dependent Cox proportional hazard model assessed difference in overall survival (OS) in the presence or absence of irAEs.

RESULTS

IrAEs of any grade were observed in 68.2% of patients (101 of 148). Grade III/IV irAEs were infrequent: 3 (2%) had grade III rash, 2 (1.35%) had asymptomatic grade III elevation in amylase/lipase, and 2 (1.35%) had grade III colitis. A statistically significant OS difference was noted among patients with any grade of irAE versus those without (P ≤ 0.001), and OS benefit was noted in patients who reported three or more irAE events (P ≤ 0.001). Subset analyses showed statistically significant OS differences with rash [P = 0.001; HR, 0.423; 95% confidence interval (CI), 0.243-0.735] and vitiligo (P = 0.012; HR, 0.184; 95% CI, 0.036-0.94). Rash and vitiligo also correlated with statistically significant OS differences in patients with metastatic disease (P = 0.004 and P = 0.028, respectively). No significant survival differences were seen with other irAEs (endocrinopathies, colitis, or pneumonitis).

CONCLUSIONS

Cutaneous irAEs are associated with improved survival in melanoma patients treated with nivolumab, and clinical benefit should be validated in larger prospective analyses.

Emerging targets for combination therapy in melanomas

Cutaneous melanomas are often difficult to treat when diagnosed in advanced stages. Melanoma cells adapt to survive in extreme environmental conditions and are among the tumors with larger genomic instability. Here we discuss some intrinsic and extrinsic mechanisms of resistance of melanoma cells to both conventional and target therapies, such as autophagy, adaptation to endoplasmic reticulum stress, metabolic reprogramming, mechanisms of tumor repopulation and the role of extracellular vesicles in this later phenomenon. These biological processes are potentially targetable and thus provide a platform for research and discovery of new drugs for combination therapy to manage melanoma patient treatment.

Novel Therapies for Metastatic Melanoma: An Update on Their Use in Older Patients

Cutaneous melanoma is the most aggressive form of skin cancer. With age as a risk factor, melanoma is projected to become a substantial healthcare burden. The clinical course of melanoma in older patients is different from that in middle-aged and younger patients: melanomas are thicker, have higher mitotic rates and are more likely to be ulcerated. Older patients also have a higher mortality rate, yet, paradoxically, have a lower rate of lymph node metastases. After decades of no significant progress in the treatment of this devastating disease, novel insights into the mechanisms underlying the pathophysiology of metastatic melanoma have led to new and remarkably efficient therapeutic opportunities. The discovery that about half of all melanomas carry BRAF mutations led to the introduction of targeted therapy with significant improvements in clinical outcomes. Although these drugs appear to be equally effective in older patients, specific considerations regarding adverse events are required. Besides targeted therapy, immunotherapy has emerged as an alternative therapeutic option. Antibodies that block cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed cell death protein 1 (PD-1) can induce responses with high durability. Despite an aging immune system, older patients seem to benefit to the same degree from these treatments, apparently without increased toxicity. In this review, we focus on the epidemiology, clinicopathological features, and recent developments of systemic treatment in cutaneous melanoma with regard to older patients.

Phase II study of ipilimumab monotherapy in Japanese patients with advanced melanoma

PURPOSE

Ipilimumab is designed to block cytotoxic T-lymphocyte antigen-4 to augment antitumor T cell responses. In studies of predominantly Caucasian patients with advanced melanoma, ipilimumab was associated with durable response, long-term survival benefit, and a manageable safety profile. This phase II study assessed the safety of ipilimumab in Japanese patients with unresectable stage III or IV melanoma.

METHODS

Patients received ipilimumab 3 mg/kg every 3 weeks for four doses. The database lock for the original analysis was in August 2014. Overall survival, progression-free survival, and data on deaths were based on an updated, follow-up analysis (database lock April 2015).

RESULTS

Data are reported from 20 patients. Fifteen patients (75 %) received all four doses of ipilimumab during induction. Twelve patients (60 %) had at least one drug-related adverse event (AE), and no patients discontinued due to a drug-related AE. There were no deaths related to study drug. The most common drug-related AEs were rash (n = 7), pyrexia (n = 3), increased aspartate aminotransferase (AST; n = 3), and increased alanine aminotransferase (ALT; n = 3). Twelve patients (60 %) reported immune-related AEs (irAEs); most frequent were skin (n = 9) and liver (n = 3) disorders. Grade 3 irAEs were ALT and AST elevation (n = 2) and diabetes mellitus (n = 1). Two patients had a partial response and two had stable disease, yielding a 20 % disease control rate. Median overall survival and progression-free survival were 8.71 and 2.74 months, respectively.

CONCLUSION

Ipilimumab 3 mg/kg had a manageable AE profile in this Japanese patient population with clinical outcomes similar to that in Caucasian patients. CLINICALTRIALS.

GOV IDENTIFIER

NCT01990859.

Histone Modifications, Modifiers and Readers in Melanoma Resistance to Targeted and Immune Therapy

The treatment of melanoma has been revolutionized by new therapies targeting MAPK signaling or the immune system. Unfortunately these therapies are hindered by either primary resistance or the development of acquired resistance. Resistance mechanisms involving somatic mutations in genes associated with resistance have been identified in some cases of melanoma, however, the cause of resistance remains largely unexplained in other cases. The importance of epigenetic factors targeting histones and histone modifiers in driving the behavior of melanoma is only starting to be unraveled and provides significant opportunity to combat the problems of therapy resistance. There is also an increasing ability to target these epigenetic changes with new drugs that inhibit these modifications to either prevent or overcome resistance to both MAPK inhibitors and immunotherapy. This review focuses on changes in histones, histone reader proteins and histone positioning, which can mediate resistance to new therapeutics and that can be targeted for future therapies.

Inhibition of Immune Checkpoints and Vascular Endothelial Growth Factor as Combination Therapy for Metastatic Melanoma: An Overview of Rationale, Preclinical Evidence, and Initial Clinical Data

The role of angiogenesis as a mediator of immune regulation in the tumor microenvironment has recently come into focus. Furthermore, emerging evidence indicates that immunotherapy can lead to immune-mediated vasculopathy in the tumor, suggesting that the tumor vasculature may be an important interface between the tumor-directed immune response and the cancer itself. The advent of immune checkpoint inhibition as an effective immunotherapeutic strategy for many cancers has led to a better understanding of this interface. While the inhibition of angiogenesis through targeting of vascular endothelial growth factor (VEGF) has been used successfully for the treatment of cancer for many years, the mechanisms of its anti-tumor activity remain poorly understood. Initial studies of the complex relationship between angiogenesis, VEGF signaling and the immune system suggest that the combination of immune checkpoint blockade with angiogenesis inhibition has potential. While the majority of this work has been performed in metastatic melanoma, immunotherapy is rapidly showing promise in a broad range of malignancies and efforts to enhance immunotherapy will broadly impact the future of oncology. Here, we review the preclinical rationale and clinical investigations of combined angiogenesis inhibition and immunotherapy/immune checkpoint inhibition as a potentially promising combinatorial approach for cancer treatment.

Resection Followed by Involved-Field Fractionated Radiotherapy in the Management of Single Brain Metastasis

Introduction

We expanded upon our previous experience using involved-field fractionated radiotherapy (IFRT) as an alternative to whole brain radiotherapy or stereotactic radiosurgery for patients with surgically resected brain metastases (BM).

Materials and methods

All patients with single BM who underwent surgical resection followed by IFRT at our institution from 2006 to 2013 were evaluated. Local recurrence (LR)-free survival, distant failure (DF)-free survival, and overall survival (OS) were determined. Analyses were performed associating clinical variables with LR and DF. Salvage approaches and toxicity of treatment for each patient were also assessed.

Results

Median follow-up was 19.1 months. Fifty-six patients were treated with a median dose of 40.05 Gy/15 fractions with IFRT to the resection cavity. LR-free survival was 91.4%, DF-free survival was 68.4%, and OS was 77.7% at 12 months. No variables were associated with increased LR; however, melanoma histopathology and infratentorial location were associated with DF on multivariate analysis. LRs were salvaged in 5/8 patients, and DFs were salvaged in 24/29 patients. Two patients developed radionecrosis.

Conclusion

Adjuvant IFRT is feasible and safe for well-selected patients with surgically resected single BM. Acceptable rates of local control and salvage of distal intracranial recurrences continue to be achieved with continued follow-up.

PD-1 and PD-L1 blockade in gastrointestinal malignancies

Immunotherapy represents a major breakthrough in cancer therapy in recent years. Immune-checkpoint blockade using PD-1 and PD-L1 antibodies appears to be one of the most promising immunotherapy approaches. Immunotherapy differs from conventional cancer treatment because of its ability to produce durable responses in some patients. In this review article, we explore the available evidence and summarise current clinical trials for PD-1 and PD-L1 blockade in gastrointestinal malignancies. The challenge now is to develop strategies to increase the efficacy of PD-1 and PD-L1 blockade in gastrointestinal cancer patients, such as combination therapy with chemotherapy, radiotherapy or other immunotherapy, along with validating biomarkers to select patients and personalise treatment.

The Rapid Emergence of Novel Therapeutics in Advanced Malignant Melanoma

For decades, no cancer therapy had been shown to improve average survival in metastatic melanoma. Two critical events have occurred, the discovery of melanoma driver mutation subsets and the discovery of immune checkpoint inhibitors, which have allowed for the development of modern, effective therapies. These findings have facilitated a rapid emergence of novel therapeutics for the disease with multiple FDA approvals in the last several years. The drugs vemurafenib, trametinib, and dabrafenib, which inhibit the commonly mutated BRAF pathway, have been approved based on improvements in survival outcomes. Agents that block immune checkpoints on lymphocytes allowing for immune cell activity against melanoma have also been approved based on improved survival outcomes such as ipilimumab and nivolumab. Pembrolizumab, another immune checkpoint inhibitor, has also been approved based on the response rate and duration of response in a phase 1 trial. Further agents and combinations of approved agents are positioned to possibly further increase this tally of approved drugs. This review will discuss recently approved novel agents and select drugs in development in advanced melanoma.

Releasing the Brake on Oncolytic Viral Therapy

Oncolytic virus that selectively targets and eradicates tumor cells and immune checkpoint blockade that unleashes host antitumor immune responses show synergistic effects against cancer. This combination holds great promise for future treatment of a broad range of cancers in patients. Clin Cancer Res; 21(24); 5417-9. ©2015 AACR.See related article by Rojas et al., p. 5543.

Advances in immunotherapy for treatment of lung cancer

Different approaches for treating lung cancer have been developed over time, including chemotherapy, radiotherapy and targeted therapies against activating mutations. Lately, better understanding of the role of the immunological system in tumor control has opened multiple doors to implement different strategies to enhance immune response against cancer cells. It is known that tumor cells elude immune response by several mechanisms. The development of monoclonal antibodies against the checkpoint inhibitor programmed cell death protein 1 (PD-1) and its ligand (PD-L1), on T cells, has led to high activity in cancer patients with long lasting responses. Nivolumab, an anti PD-1 inhibitor, has been recently approved for the treatment of squamous cell lung cancer patients, given the survival advantage demonstrated in a phase III trial. Pembrolizumab, another anti PD-1 antibody, has received FDA breakthrough therapy designation for treatment of non-small cell lung cancer (NSCLC), supported by data from a phase I trial. Clinical trials with anti PD-1/PD-L1 antibodies in NSCLC have demonstrated very good tolerability and activity, with response rates around 20% and a median duration of response of 18 months.

Immune checkpoint targeting as anti-cancer immunotherapy: promises, questions, challenges and the need for predictive biomarkers at ASCO 2015

Immunotherapy targeting "immune checkpoints" first made the headlines at the ASCO (American Society of Clinical Oncology) Annual Meeting in 2013, took centre stage at 2014 and consolidated its position as a potentially curative first-line therapy as reflected by the presentations at ASCO 2015. For the first time, previously refractory cancers are proving amenable to treatment, but still only a fraction, usually a minority, of patients respond. The hunt for factors predicting responses and for biomarkers to monitor treatment was a major theme of this year's meeting, as briefly discussed in this Editorial.

Beyond CTLA-4 and PD-1, the Generation Z of Negative Checkpoint Regulators

In the last two years, clinical trials with blocking antibodies to the negative checkpoint regulators CTLA-4 and PD-1 have rekindled the hope for cancer immunotherapy. Multiple negative checkpoint regulators protect the host against autoimmune reactions but also restrict the ability of T cells to effectively attack tumors. Releasing these brakes has emerged as an exciting strategy for cancer treatment. Conversely, these pathways can be manipulated to achieve durable tolerance for treatment of autoimmune diseases and transplantation. In the future, treatment may involve combination therapy to target multiple cell types and stages of the adaptive immune responses. In this review, we describe the current knowledge on the recently discovered negative checkpoint regulators, future targets for immunotherapy.

The role of thioredoxin reductase 1 in melanoma metabolism and metastasis

Although significant progress has been made in targeted and immunologic therapeutics for melanoma, many tumors fail to respond, and most eventually progress when treated with the most efficacious targeted combination therapies thus far identified. Therefore, alternative approaches that exploit distinct melanoma phenotypes are necessary to develop new approaches for therapeutic intervention. Tissue microarrays containing human nevi and melanomas were used to evaluate levels of the antioxidant protein thioredoxin reductase 1 (TR1), which was found to increase as a function of disease progression. Melanoma cell lines revealed metabolic differences that correlated with TR1 levels. We used this new insight to design a model treatment strategy that creates a synthetic lethal interaction wherein targeting TR1 sensitizes melanoma to inhibition of glycolytic metabolism, resulting in a decrease in metastases in vivo. This approach holds the promise of a new clinical therapeutic strategy, distinct from oncoprotein inhibition.

Adaptive Immune Resistance: How Cancer Protects from Immune Attack

Adaptive immune resistance is a process in which the cancer changes its phenotype in response to a cytotoxic or proinflammatory immune response, thereby evading it. This adaptive process is triggered by the specific recognition of cancer cells by T cells, which leads to the production of immune-activating cytokines. Cancers then hijack mechanisms developed to limit inflammatory and immune responses and protect themselves from the T-cell attack. Inhibiting adaptive immune resistance is the mechanistic basis of responses to PD-1 or PD-L1-blocking antibodies, and may be of relevance for the development of other cancer immunotherapy strategies.

SIGNIFICANCE

Several new immunotherapy strategies to treat cancer are based on inhibiting processes through which cancer adapts and evades from an immune response. Recognizing the specific adaptive resistance mechanisms in each case is likely to allow the personalized development of immunotherapies tailored to block how a particular cancer protects itself from the immune system.

Prospects of immune checkpoint modulators in the treatment of glioblastoma

Glioblastoma is the most common primary brain tumour in adults. Prognosis is poor: even with the current gold-standard first-line treatment—maximal safe resection and combination of radiotherapy with temozolomide chemotherapy—the median overall survival time is only approximately 15-17 months, because the tumour recurs in virtually all patients, and no commonly accepted standard treatment for recurrent disease exists. Several targeted agents have failed to improve patient outcomes in glioblastoma. Immunotherapy with immune checkpoint inhibitors such as ipilimumab, nivolumab, and pembrolizumab has provided relevant clinical improvements in other advanced tumours for which conventional therapies have had limited success, making immunotherapy an appealing strategy in glioblastoma. This Review summarizes current knowledge on immune checkpoint modulators and evaluates their potential role in glioblastoma on the basis of preclinical studies and emerging clinical data. Furthermore, we discuss challenges that need to be considered in the clinical development of drugs that target immune checkpoint pathways in glioblastoma, such as specific properties of the immune system in the CNS, issues with radiological response assessment, and potential interactions with established and emerging treatment strategies.

A broad-spectrum integrative design for cancer prevention and therapy: The challenge ahead

Despite exciting advances in targeted therapies, high drug costs, marginal therapeutic benefits and notable toxicities are concerning aspects of today's cancer treatments. This special issue of Seminars in Cancer Biology proposes a broad-spectrum, integrative therapeutic model to complement targeted therapies. Based on extensive reviews of the cancer hallmarks, this model selects multiple high-priority targets for each hallmark, to be approached with combinations of low-toxicity, low-cost therapeutics, including phytochemicals, adapted to the well-known complexity and heterogeneity of malignancy. A global consortium of researchers has been assembled to advance this concept, which is especially relevant in an era of rapidly expanding capacity for genomic tumor analyses, alongside alarming growth in cancer morbidity and mortality in low- and middle-income nations.

AFM13: a first-in-class tetravalent bispecific anti-CD30/CD16A antibody for NK cell-mediated immunotherapy

Monoclonal antibodies against CD20 molecule have been leading the revolution of lymphoma treatment. In addition to monoclonal antibodies against CD20 and CD30, novel agents of immunotherapeutics in clinical development are being developed and are rapidly migrating to clinical application. One area of active development is NK cell activators, such as AFM13. This review will highlight the latest development of AFM13 as the first-in-class tetravalent bispecific anti-CD30/CD16A antibody for NK cell-mediated immunotherapy.

Nivolumab and pembrolizumab as immune-modulating monoclonal antibodies targeting the PD-1 receptor to treat melanoma

Malignant melanoma is an important issue in oncology due to its high incidence, high mortality, and resistance to systemic therapy; however, targeted immunotherapy has noticeably improved the survival rates of melanoma patients. Promising targeted immunotherapies for malignant melanoma include the blockade of immune checkpoints with antibodies targeting cytotoxic T lymphocyte-associated antigen 4 and the programmed cell death protein 1 pathway. The US FDA-approved antibody ipilimumab targets cytotoxic T lymphocyte-associated antigen 4; however, it was limited by toxicity and a low response. Nivolumab and pembrolizumab (formerly lambrolizumab), the two FDA-approved anti-programmed death-1 monoclonal antibodies, show highly durable response rates and long-term safety, validating the importance of the programmed cell death protein 1 pathway blockade for treatment of malignant melanoma.

What's new in melanoma? Combination!

Melanoma was again a focus of attention at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting, in particular the use of combination treatment strategies involving immunotherapies and/or targeted agents. New data on targeted therapies confirmed previous findings, with combined BRAF inhibitor (vemurafenib) plus MEK inhibitor (cobimetinib) improving progression-free survival (PFS) compared to vemurafenib monotherapy in patients with BRAFV600 mutation-positive tumors (CoBRIM trial). Positive results were also seen with combined dabrafenib and trametinib in patients with BRAF V600E/K metastatic melanoma and encorafenib plus binimetinib in BRAFV600-mutant cutaneous melanoma. Even more interesting news centered on the use of combination immunotherapy, in particular the randomized, double-blind CheckMate 067 study in which median PFS with nivolumab plus ipilimumab was 11.5 months, compared to 2.9 months with ipilimumab alone (HR 0.42) and 6.9 months with nivolumab alone (HR 0.57). Of interest, in patients with ≥5% PD-L1 expression, median PFS was 14 months with the combination or with nivolumab alone compared with 3.9 months in the ipilimumab group, while in the PD-L1 negative cohort, the combination remained superior to both monotherapies. Given that combination therapy was accompanied by a high occurrence of side-effects, this raises the suggestion that combination therapy might be reserved for PD-L1 negative patients only, with PD-L1 positive patients achieving the same benefit from nivolumab monotherapy. However, overall survival data are awaited and the equivalence of single agent to the combination remains unconvincing. Interesting data were also reported on the combination of T-VEC (talimogene laherparepvec) with ipilimumab, and the anti-PD-1 agent MEDI4736 (durvolumab) combined with dabrafenib plus trametinib. Emerging data also suggested that predictive markers based on immunoprofiling and mismatch repair deficiency may be of clinical use. In conclusion, the use of combination approaches to treat patients with melanoma, as well as other cancers, is no longer a just a wish for the future but is today a clinical reality with a rapidly growing evidence-base. Moreover, the most exciting consideration is that this is far from the end of the story, but rather a fantastic introduction.

Fcγ-receptor tag team boosts anti-tumor immunity

Anti-tumor monoclonal antibodies eliminate tumor cells through different mechanisms including antibody-mediated cell cytotoxicity and generation of long-term anti-tumor T cell responses. In a recent publication, DiLillo and Ravetch demonstrate how this vaccinal effect is mediated by engagement of Fcγ receptors expressed on antigen-presenting cells.

Immunotherapy and radiation therapy for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a particularly aggressive thoracic malignancy with limited survival following combination chemotherapy. As a result, there has been increased interested in immunotherapy for mesothelioma, both in the first-line and salvage settings. Early investigations of interleukin-2 (IL-2) and interferon alfa-2a/b have been limited by modest response rates and toxicity, whereas cytokine gene therapy is currently being investigated and shows early promise. The most prominent class of immunotherapies to be trialed with mesothelioma in the past half-decade has been immune checkpoint inhibitors (CPI). Early results are encouraging, particularly for agents targeting the PD-1/PD-L1 pathways. With the increasing recognition of the immune potential of mesothelioma, interest in the immunomodulatory properties of radiation therapy has emerged. The combination of immunotherapy and radiation therapy may allow for complimentary immunologic effects that can enhance antitumor response. This article reviews the existing literature on the efficacy of immunotherapy for MPM, describes the rationale for combining immunotherapy with radiation therapy, and discusses early literature on this treatment combination.