Lamprey immune protein-1 (LIP-1) from Lampetra japonica induces cell cycle arrest and cell death in HeLa cells

The lamprey (Lampetra japonica), a representative of the jawless vertebrates, is the oldest extant species in the world. LIP-1, which has a jacalin-like domain and an aerolysin pore-forming domain, has previously been identified in Lampetra japonica. However, the structure and function of the LIP-1 protein have not been described. In this study, the LIP-1 gene was overexpressed in HeLa cells and H293T cells. The results showed that the overexpression of LIP-1 in HeLa cells significantly elevated LDH release (P < 0.05), phosphatidylserine exposure and ROS accumulation. The overexpression of LIP-1 also had remarkable effects on the organelles in HeLa cells, while it had no effect on H293T cell organelles. Array data indicated that overexpression of LIP-1 primarily upregulated P53 signaling pathways in HeLa cells. Cell cycle assay results confirmed that LIP-1 caused arrest in the G₂/M phase of the cell cycle in HeLa cells. In summary, our findings provide insights into the function and characterization of LIP-1 genes in vertebrates and establish the foundation for further research into the biological function of LIP-1. Our observations suggest that this lamprey protein has the potential for use in new applications in the medical field.

Primary mediastinal B-cell lymphoma: biology and evolving therapeutic strategies

Primary mediastinal B-cell lymphoma (PMBCL) is recognized as a distinct clinicopathologic entity that predominantly affects adolescents and young adults and is more common in female subjects. Although PMBCL is considered to be a subtype of diffuse large B-cell lymphoma, its clinical, morphologic, and biological characteristics overlap significantly with those of nodular sclerosing Hodgkin lymphoma (NSHL). Over the past few years, the shared biology of these 2 entities has been highlighted in several studies, and mediastinal gray zone lymphoma, with features intermediate between PMBCL and NSHL, has been recognized as a unique molecular entity. Although there is a lack of consensus about the optimal therapeutic strategy for adolescent and young adult patients newly diagnosed with PMCBL, highly curative strategies that obviate the need for mediastinal radiation are favored by most. Progress in understanding the biology of PMBCL and its close relationship to NSHL have helped pave the way for the investigation of novel approaches such as immune checkpoint inhibition. Other strategies such as adoptive T-cell therapy and targeting CD30 are also being studied.

Harnessing the power of the immune system in non-Hodgkin lymphoma: immunomodulators, checkpoint inhibitors, and beyond

Non-Hodgkin lymphoma is a malignancy of B lymphocytes that typically infiltrate sites of disease, including the lymph nodes, spleen, and bone marrow. Beyond the presence of malignant cells, many immune cells are also present within the tumor microenvironment. Although these immune cells have the potential to regulate the growth of malignant B cells, intratumoral immune cells are unable to eradicate lymphoma cells and most patients with lymphoma have clinical evidence of disease progression. Recent data have identified some of the mechanisms that account for the suppressed antitumor immune response and have created opportunities for treatment to overcome the deficiencies. Two general categories of immunological therapies are available. The first approach is to use agents that prevent inhibitory signals via immune checkpoint receptors that downregulate immune cell function. Blockade of suppressive programmed cell death 1 (PD-1) or CTLA-4 signaling has resulted in significant clinical activity by allowing intratumoral T cells to remain activated and target malignant cells. A second approach is to additionally activate T cells that are suboptimally active or suppressed, by providing signals through costimulatory molecules including CD27 or CD40 or by adding immunostimulatory cytokines. There has been significant heterogeneity in the responses to these treatment approaches. Clinical responses are seen in many diseases, but the most promising responses have been with PD-1 blockade in Hodgkin lymphoma. In other lymphomas, responses are seen but only in a subset of patients. Further research is needed to identify the mechanisms that account for response and to identify patients most likely to benefit from immune modulation.

A new frontier in treatment of advanced melanoma: Redefining clinical management in the era of immune checkpoint inhibitors

Immune checkpoint inhibitors have revolutionized treatment of advanced cutaneous melanoma. This group of novel therapeutic agents differs from other systemic treatments and has necessitated a new approach for several fundamental aspects of clinical practice in oncology. Marked differences in outcomes associated with immune checkpoint inhibitors compared with other systemic therapies has required a new paradigm for prognostication in the setting of advanced melanoma. Distinct patterns of tumor response have required new norms for disease monitoring. A unique spectrum of toxicity is associated with use of immune checkpoint inhibitors which can be severe and refractory. Patients and clinicians must be informed regarding immune-related adverse events, yet in the published literature, there is substantial variability in reporting. As immune checkpoint inhibitors gain a prominent role in cancer treatment, standardization of adverse event reporting will be vital to ensure validity of evidence and to promote safe clinical practice.

Combinatorial immunotherapy and nanoparticle mediated hyperthermia

Immune checkpoint therapy has become the first widely adopted immunotherapy for patients with late stage malignant melanoma, with potential for a wide range of cancers. While some patients can experience long term disease remission, this is limited only to a subset of patients and tumor types. The path forward to expand this therapy to more patients and tumor types is currently thought to be combinatorial treatments, the combination of immunotherapy with other treatments. In this review, the combinatorial approach of immune checkpoint therapy combined with nanoparticle-assisted localized hyperthermia is discussed, starting with an overview of the different nanoparticle hyperthermia approaches in development, an overview of the state of immune checkpoint therapy, recent reports of immune checkpoint therapy and nanoparticle-assisted hyperthermia in a combinatorial approach, and finally a discussion of future research topics and areas to be explored in this new combinatorial approach to cancer treatment.

Progress and opportunities for enhancing the delivery and efficacy of checkpoint inhibitors for cancer immunotherapy

Despite the advent of immune checkpoint blockade for effective treatment of advanced malignancies, only a minority of patients responds to therapy and significant immune-related adverse events remain to be minimized. Innovations in engineered drug delivery systems and controlled release strategies can improve drug accumulation at and retention within target cells and tissues in order to enhance therapeutic efficacy while simultaneously reducing drug exposure in off target tissues to minimize the potential for treatment-associated toxicities. This review will outline basic principles of the immune physiology of checkpoint signaling, the existing knowledge of dose-efficacy relationships in checkpoint inhibition, the influence of administration route on treatment efficacy, as well as the resulting checkpoint inhibitor antibody biodistribution profiles amongst target versus systemic tissues. It will also highlight recent successes in the application of drug delivery principles and technologies towards augmenting checkpoint blockade therapy in cancer. Delivery strategies that have been developed for other therapeutic and immunotherapy applications with as-of-yet underexplored potential in checkpoint inhibition therapy will also be discussed.

[Brain tumor immunotherapy: Illusion or hope?]

Immunotherapy has proven efficient for many tumors and is now part of standard of care in many indications. What is the picture for brain tumors? The recent development of anti-CTLA-4 and PD1 immune checkpoint inhibitors, which have the ability to restore T lymphocytes activity, has gathered enthusiasm and is now paving the way towards more complex models of immune system manipulation. These models include, among others, vaccination and adoptive T cell transfer technologies. Complementary to those strategies, molecules capable of reshaping the immune tumor microenvironment are currently being investigated in early phase trials. Indeed, the tumor bed is hostile to anti-tumor immune responses due to many escape mechanisms, and this is particularly true in the context of brain tumors, a master in eliciting immunosuppressive cells and molecules. The goal of this review is to describe the hopes and challenges of brain tumors immunotherapy and to propose an inventory of the current clinical research with specific focus on the therapies targeting the tumor microenvironment.

Evolution of Neoantigen Landscape during Immune Checkpoint Blockade in Non-Small Cell Lung Cancer

Immune checkpoint inhibitors have shown significant therapeutic responses against tumors containing increased mutation-associated neoantigen load. We have examined the evolving landscape of tumor neoantigens during the emergence of acquired resistance in patients with non-small cell lung cancer after initial response to immune checkpoint blockade with anti-PD-1 or anti-PD-1/anti-CTLA-4 antibodies. Analyses of matched pretreatment and resistant tumors identified genomic changes resulting in loss of 7 to 18 putative mutation-associated neoantigens in resistant clones. Peptides generated from the eliminated neoantigens elicited clonal T-cell expansion in autologous T-cell cultures, suggesting that they generated functional immune responses. Neoantigen loss occurred through elimination of tumor subclones or through deletion of chromosomal regions containing truncal alterations, and was associated with changes in T-cell receptor clonality. These analyses provide insight into the dynamics of mutational landscapes during immune checkpoint blockade and have implications for the development of immune therapies that target tumor neoantigens.Significance: Acquired resistance to immune checkpoint therapy is being recognized more commonly. This work demonstrates for the first time that acquired resistance to immune checkpoint blockade can arise in association with the evolving landscape of mutations, some of which encode tumor neoantigens recognizable by T cells. These observations imply that widening the breadth of neoantigen reactivity may mitigate the development of acquired resistance. Cancer Discov; 7(3); 264-76. ©2017 AACR.See related commentary by Yang, p. 250This article is highlighted in the In This Issue feature, p. 235.

Les inhibiteurs des points de contrôle immunitaire dans le cancer bronchique non à petites cellules de stade avancé

IMMUNE CHECKPOINT INHIBITORS IN ADVANCED NON-SMALL CELL LUNG CANCER: T-cell-directed strategies represent currently a major advance in the treatment of advanced non-small-cell lung cancer, regarding their efficacy and tolerance. Nivolumab and pembrolizumab, two monoclonal antibodies targeting programmed cell death protein 1 (PD-1) have shown their efficacy in phase III studies. Several other drugs are developed and the benefit of association is being evaluated. In this article, we propose to summarize the clinical development of immune checkpoint inhibitors in patients with advanced non-small cell lung cancer.

A case of pembrolizumab-induced type-1 diabetes mellitus and discussion of immune checkpoint inhibitor-induced type 1 diabetes

Immune checkpoint inhibitors such as pembrolizumab, ipilimumab, and nivolumab, now FDA-approved for use in treating several types of cancer, have been associated with immune-related adverse effects. Specifically, the antibodies targeting the programmed-cell death-1 immune checkpoint, pembrolizumab and nivolumab, have been rarely reported to induce the development of type 1 diabetes mellitus. Here we describe a case of a patient who developed antibody-positive type 1 diabetes mellitus following treatment with pembrolizumab in combination with systemic chemotherapy for metastatic adenocarcinoma of the lung. We will also provide a brief literature review of other rarely reported cases of type 1 diabetes presenting after treatment with pembrolizumab and nivolumab, as well as discussion regarding potential mechanisms of this adverse effect and its importance as these drugs continue to become even more widespread.

Checkpoint inhibition in myeloma

Historically, attempts at cancer immunotherapy have emphasized strategies designed to stimulate or augment the immune system into action. In the past decade, a complementary approach has developed, that of releasing immune cells from inhibitory restraint. Discoveries in the fundamental biology of how immunity is regulated, how the immune system interfaces with malignancy, and how cancer cells may exploit these processes to evade detection have all been translated into the rapidly growing field of therapeutic immune checkpoint inhibition for cancer. Myeloma is a malignancy associated with significant immune dysfunction imparted both by the disease itself as well as by many of the immunosuppressive therapies that have been used in the past. The growing body of preclinical data regarding immunoregulatory mechanisms that appear active in myeloma has begun to be translated to clinical trials targeting these signaling axes. This review will attempt to summarize the current understanding of the basic biology of several immune checkpoint pathways that may be important in myeloma and provide an up-to-date overview of recent and ongoing clinical trials of immune checkpoint inhibitors in myeloma. Finally, several current challenges and possible future directions of immune checkpoint blockade in myeloma will be reviewed.

Decreased somatic hypermutation induces an impaired peripheral B cell tolerance checkpoint

Patients with mutations in AICDA, which encodes activation-induced cytidine deaminase (AID), display an impaired peripheral B cell tolerance. AID mediates class-switch recombination (CSR) and somatic hypermutation (SHM) in B cells, but the mechanism by which AID prevents the accumulation of autoreactive B cells in blood is unclear. Here, we analyzed B cell tolerance in AID-deficient patients, patients with autosomal dominant AID mutations (AD-AID), asymptomatic AICDA heterozygotes (AID+/-), and patients with uracil N-glycosylase (UNG) deficiency, which impairs CSR but not SHM. The low frequency of autoreactive mature naive B cells in UNG-deficient patients resembled that of healthy subjects, revealing that impaired CSR does not interfere with the peripheral B cell tolerance checkpoint. In contrast, we observed decreased frequencies of SHM in memory B cells from AD-AID patients and AID+/- subjects, who were unable to prevent the accumulation of autoreactive mature naive B cells. In addition, the individuals with AICDA mutations, but not UNG-deficient patients, displayed Tregs with defective suppressive capacity that correlated with increases in circulating T follicular helper cells and enhanced cytokine production. We conclude that SHM, but not CSR, regulates peripheral B cell tolerance through the production of mutated antibodies that clear antigens and prevent sustained interleukin secretions that interfere with Treg function.

Perspectives for immunotherapy in endocrine cancer

The fight against cancer has seen major breakthroughs in recent years. More than a decade ago, tyrosine kinase inhibitors targeting constitutively activated signaling cascades within the tumor inaugurated a new era of oncological therapy. Recently, immunotherapy with immune checkpoint inhibitors has started to revolutionize the treatment of several malignancies, most notably malignant melanoma, leading to the renaissance and the long-awaited breakthrough of immunooncology. This review provides an overview of the basis of immunotherapy from its initial concepts of anti-tumor immunity and cell-based therapy to the development of immune checkpoint inhibitors and discusses published studies and the perspectives of immunooncology for the treatment of endocrine malignancies.

Immune checkpoint inhibitor-related hypophysitis and endocrine dysfunction: clinical review

Immune checkpoint inhibitors are a new and effective class of cancer therapy, with ipilimumab being the most established drug in this category. The drugs' mechanism of action includes promoting the effector T cell response to tumours and therefore increased autoimmunity is a predictable side effect. The endocrine effects of these drugs include hypophysitis and thyroid dysfunction, with rare reports of adrenalitis. The overall incidence of hypophysitis with these medications is up to 9%. Primary thyroid dysfunction occurs in up to 15% of patients, with adrenalitis reported in approximately 1%. The mean onset of endocrine side effects is 9 weeks after initiation (range 5-36 weeks). Investigation and/or screening for hypophysitis requires biochemical and radiological assessment. Hypopituitarism is treated with replacement doses of deficient hormones. Since the endocrine effects of immune checkpoint inhibitors are classed as toxic adverse events, most authors recommend both discontinuation of the immune checkpoint inhibiting medication and 'high-dose' glucocorticoid treatment. However, this has been challenged by some authors, particularly if the endocrine effects can be managed (e.g. pituitary hormone deficiency), and the therapy is proving effective as an anticancer agent. This review describes the mechanism of action of immune checkpoint inhibitors and details the key clinical endocrine-related consequences of this novel class of immunotherapies.

Immune checkpoint blockade with concurrent electrochemotherapy in advanced melanoma: a retrospective multicenter analysis

Growing evidence suggests that concurrent loco-regional and systemic treatment modalities may lead to synergistic anti-tumor effects in advanced melanoma. In this retrospective multicenter study, we evaluate the use of electrochemotherapy (ECT) combined with ipilimumab or PD-1 inhibition. We investigated patients with unresectable or metastatic melanoma who received the combination of ECT and immune checkpoint blockade for distant or cutaneous metastases within 4 weeks. Clinical and laboratory data were collected and analyzed with respect to safety and efficacy. A total of 33 patients from 13 centers were identified with a median follow-up time of 9 months. Twenty-eight patients received ipilimumab, while five patients were treated with a PD-1 inhibitor (pembrolizumab n = 3, nivolumab n = 2). The local overall response rate (ORR) was 66.7 %. The systemic ORR was 19.2 and 40.0 % in the ipilimumab and PD-1 cohort, respectively. The median duration of response was not reached in either group. The median time to disease progression was 2.5 months for the entire population with 2 months for ipilimumab and 5 months for PD-1 blockade. The median overall survival was not reached in patients with ipilimumab and 15 months in the PD-1 group. Severe systemic adverse events were detected in 25.0 % in the ipilimumab group. No treatment-related deaths were observed. This is the first reported evaluation of ECT and simultaneous PD-1 inhibition and the largest published dataset on ECT with concurrent ipilimumab. The local response was lower than reported for ECT only. Ipilimumab combined with ECT was feasible, tolerable and showed a high systemic response rate.

Adverse Events Associated with Immune Checkpoint Blockade in Patients with Cancer: A Systematic Review of Case Reports

Background

Three checkpoint inhibitor drugs have been approved by the US Food and Drug Administration for use in specific types of cancers. While the results are promising, severe immunotherapy-related adverse events (irAEs) have been reported.

Objectives

To conduct a systematic review of case reports describing the occurrence of irAEs in patients with cancer following checkpoint blockade therapy, primarily to identify potentially unrecognized or unusual clinical findings and toxicity.

Data Sources

We searched Medline, EMBASE, Web of Science, PubMed ePubs, and Cochrane CENTRAL with no restriction through August 2015.

Study Selection

Studies reporting cases of cancer develop irAEs following treatment with anti CTLA-4 (ipilimumab) or anti PD-1 (nivolumab or pembrolizumab) antibodies were included.

Data Extraction

We extracted data on patient characteristics, irAEs characteristics, how irAEs were managed, and their outcomes.

Data Synthesis

191 publications met inclusion criteria, reporting on 251 cases. Most patients had metastatic melanoma (95.6%), and the majority were treated with ipilimumab (93.2%). Autoimmune colitis, hepatitis, endocrinopathies, and cutaneous irAEs were the most frequently reported irAEs in ipilimumab treated patients. A broad spectrum of toxicities were reported for almost every body system. Moreover, well-defined diseases such as sarcoidosis, polyarthritis, polymyalgia rheumatica/arteritis, lupus, celiac disease, dermatomyositis, and Vogt-Koyanagi-like syndrome were reported. The most frequent irAEs reported with anti-PD1 agents were dermatitis for pembrolizumab, and thyroid disease and pneumonitis for nivolumab. Complete resolution of adverse events occurred in most cases. However, persistent irAEs and death were reported, mainly in patients treated with ipilimumab.

Limitations

Our study is limited by information available in the original reports.

Conclusions

Evidence from case reports shows that cancer patients develop irAEs following checkpoint blockade therapy, and can occasionally develop clearly defined autoimmune systemic diseases. While discontinuation of therapy and/or treatment can result in resolution of irAEs, long-term sequelae and death have been reported.

Checkpoint inhibitors and other novel immunotherapies for advanced renal cell carcinoma

The management of advanced renal cell carcinoma (RCC) has dramatically changed over the past decade. Therapies that target the vascular endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) pathways have considerably expanded treatment options; however, most patients with advanced RCC still have limited overall survival. Increased understanding of the mechanisms of T cell-antigen recognition and function has led to the development of novel immunotherapies to treat cancer, chief among them inhibitors of checkpoint receptors - molecules whose function is to restrain the host immune response. In 2015, the FDA approved the first checkpoint inhibitor nivolumab for patients with advanced RCC following treatment with antiangiogenic therapy based on improved overall survival compared with the standard of care. Ongoing phase III trials are comparing checkpoint-inhibitor-based combination regimens with antiangiogenesis agents in the first-line setting. The field is evolving rapidly, with many clinical trials already testing several checkpoint inhibitors alone, in combination, or with other targeted therapies. In addition, different novel immune therapies are being investigated including vaccines, T-cell agonists, and chimeric antigen receptor T cells. Determining which patients will benefit from these therapies and which combination approaches will result in better response will be important as this field evolves.

Clonal neoantigens elicit T cell immunoreactivity and sensitivity to immune checkpoint blockade

As tumors grow, they acquire mutations, some of which create neoantigens that influence the response of patients to immune checkpoint inhibitors. We explored the impact of neoantigen intratumor heterogeneity (ITH) on antitumor immunity. Through integrated analysis of ITH and neoantigen burden, we demonstrate a relationship between clonal neoantigen burden and overall survival in primary lung adenocarcinomas. CD8(+)tumor-infiltrating lymphocytes reactive to clonal neoantigens were identified in early-stage non-small cell lung cancer and expressed high levels of PD-1. Sensitivity to PD-1 and CTLA-4 blockade in patients with advanced NSCLC and melanoma was enhanced in tumors enriched for clonal neoantigens. T cells recognizing clonal neoantigens were detectable in patients with durable clinical benefit. Cytotoxic chemotherapy-induced subclonal neoantigens, contributing to an increased mutational load, were enriched in certain poor responders. These data suggest that neoantigen heterogeneity may influence immune surveillance and support therapeutic developments targeting clonal neoantigens.

PD-1 Pathway Inhibitors: Immuno-Oncology Agents for Restoring Antitumor Immune Responses

Immune checkpoint inhibitors are designed to restore a patient's own antitumor immune response that has been suppressed during tumor development. The first monoclonal antibodies against the immune checkpoint programmed death 1 (PD-1) receptor, nivolumab and pembrolizumab, are now approved for clinical use. Both agents are indicated for the treatment of advanced melanoma, as well as for the treatment of metastatic non-small cell lung cancer (NSCLC). Nivolumab is also approved for the treatment of advanced renal cell carcinoma. In patients with melanoma, these agents result in objective response rates of ~25-40%, with durable responses lasting more than 2 years in some cases. Results from phase III trials have shown improved survival with nivolumab versus standard-of-care chemotherapy in both patients with advanced melanoma and those with advanced NSCLC. In patients with advanced melanoma, both PD-1 inhibitors (nivolumab and pembrolizumab) have shown improved survival versus ipilimumab. PD-1 inhibitors are associated with adverse events that have immune etiologies, with grade greater than 3 adverse events typically reported in 16% or less of patients. However, most immune-mediated adverse events (including grade 3-4 adverse events) can be managed by using published management algorithms without permanent discontinuation of the agent. As nivolumab and pembrolizumab enter the clinic, and with more PD-1 pathway agents in development for a range of tumor types, this review aims to provide pharmacists with a basic understanding of the role of PD-1 in modulating the immune system and their use in the cancer treatment. The most recent clinical efficacy and safety data are discussed, highlighting the response characteristics distinctive to immune checkpoint inhibitors, along with pharmacokinetic and pharmacodynamic data and cost considerations.

RAG-mediated DNA double-strand breaks activate a cell type-specific checkpoint to inhibit pre-B cell receptor signals

DNA double-strand breaks (DSBs) activate a canonical DNA damage response, including highly conserved cell cycle checkpoint pathways that prevent cells with DSBs from progressing through the cell cycle. In developing B cells, pre-B cell receptor (pre-BCR) signals initiate immunoglobulin light (Igl) chain gene assembly, leading to RAG-mediated DNA DSBs. The pre-BCR also promotes cell cycle entry, which could cause aberrant DSB repair and genome instability in pre-B cells. Here, we show that RAG DSBs inhibit pre-BCR signals through the ATM- and NF-κB2-dependent induction of SPIC, a hematopoietic-specific transcriptional repressor. SPIC inhibits expression of the SYK tyrosine kinase and BLNK adaptor, resulting in suppression of pre-BCR signaling. This regulatory circuit prevents the pre-BCR from inducing additional Igl chain gene rearrangements and driving pre-B cells with RAG DSBs into cycle. We propose that pre-B cells toggle between pre-BCR signals and a RAG DSB-dependent checkpoint to maintain genome stability while iteratively assembling Igl chain genes.

Immune Checkpoint Inhibitors in Brain Metastases: From Biology to Treatment

Cancer immunotherapy has been a subject of intense research over the last several years, leading to new approaches for modulation of the immune system to treat malignancies. Immune checkpoint inhibitors (anti-CLTA-4 antibodies and anti-PD-1/PD-L1 antibodies) potentiate the host's own antitumor immune response. These immune checkpoint inhibitors have shown impressive clinical efficacy in advanced melanoma, metastatic kidney cancer, and metastatic non-small cell lung cancer (NSCLC)-all malignancies that frequently cause brain metastases. The immune response in the brain is highly regulated, challenging the treatment of brain metastases with immune-modulatory therapies. The immune microenvironment in brain metastases is active with a high density of tumor-infiltrating lymphocytes in certain patients and, therefore, may serve as a potential treatment target. However, clinical data of the efficacy of immune checkpoint inhibitors in brain metastases compared with extracranial metastases are limited, as most clinical trials with these new agents excluded patients with active brain metastases. In this article, we review the current scientific evidence of brain metastases biology with specific emphasis on inflammatory tumor microenvironment and the evolving state of clinical application of immune checkpoint inhibitors for patients with brain metastases.

Basic Overview of Current Immunotherapy Approaches in Cancer

Recent success of immunotherapy strategies such as immune checkpoint blockade in several malignancies has established the role of immunotherapy in the treatment of cancer. Cancers use multiple mechanisms to co-opt the host-tumor immune interactions, leading to immune evasion. Our understanding of the host-tumor interactions has evolved over the past few years and led to various promising new therapeutic strategies. This article will focus on the basic principles of immunotherapy, novel pathways/agents, and combinatorial immunotherapies.

Programmed death 1 immune checkpoint inhibitors

Programmed death 1 (PD-1) is an immune checkpoint that provides inhibitory signals to the immune system in order to modulate the activity of T cells in peripheral tissues and maintain self-tolerance in the setting of infection and inflammation. In cancer, the immune checkpoints are exploited so that the tumor cells are able to evade the immune system. Immune checkpoint inhibitors are a type of cancer immunotherapy that targets pathways such as PD-1 in order to reinvigorate and enhance the immune response against tumor cells. The US Food and Drug Administration (FDA) has approved 2 PD-1 inhibitors, nivolumab and pembrolizumab, and several others are under investigation. Although PD-1 inhibitors have demonstrated activity in many different types of malignancies, FDA approval has been granted only in melanoma and in non-small cell lung cancer (NSCLC). Identifying biomarkers that can predict response to PD-1 inhibitors is critical to maximizing the benefit of these agents. Future directions for PD-1 inhibitors include investigation of combination therapies, use in malignancies other than melanoma and NSCLC, and refinement of biomarkers.

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.