Combined Nivolumab and Ipilimumab or Monotherapy in Untreated Melanoma

Clinical outcomes of melanoma brain metastases treated with stereotactic radiation and anti-PD-1 therapy

BACKGROUND

The anti-programmed death-1 (anti-PD-1) therapy nivolumab has significant clinical activity in patients with metastatic melanoma. However, little is known about the safety and outcomes in patients receiving anti-PD-1 therapy and stereotactic radiation for the treatment of brain metastases (BMs).

PATIENTS AND METHODS

Data were analyzed retrospectively from two prospective nivolumab protocols enrolling 160 patients with advanced resected and unresectable melanoma at a single institution. Patients were included if BMs were diagnosed and treated with stereotactic radiation within 6 months of receiving nivolumab. The primary end point of this study was neurotoxicity; secondary end points included BM control and survival.

RESULTS

Twenty-six patients with a total of 73 BMs treated over 30 sessions were identified. Radiation was administered before, during and after nivolumab in 33 lesions (45%), 5 lesions (7%), and 35 lesions (48%), respectively. All BMs were treated with stereotactic radiosurgery (SRS) in a single session except 12 BMs treated with fractionated stereotactic radiation therapy, nine of which were in the postoperative setting. One patient experienced grade 2 headaches following SRS with symptomatic relief with steroid treatment. No other treatment-related neurologic toxicities or scalp reactions were reported. Eight (11%) local BM failures with a ≥20% increase in volume were noted. Of these lesions, hemorrhage was noted in 4, and edema was noted in 7. Kaplan-Meier estimates for local BM control following radiation at 6 and 12 months were 91% and 85%, respectively. Median overall survival (OS) from the date of stereotactic radiation and nivolumab initiation was 11.8 and 12.0 months, respectively, in patients receiving nivolumab for unresected disease (median OS was not reached in patients treated in the resected setting).

CONCLUSIONS

In our series, stereotactic radiation to melanoma BMs is well tolerated in patients who received nivolumab. BM control and OS appear prolonged compared with standard current treatment. Prospective evaluation is warranted.

Prognostic and predictive biomarkers in melanoma: an update

Malignant melanoma is one of the most aggressive cancers. Several new therapeutic strategies that focus on immuno- and/or targeted therapy have been developed, which have entered clinical trials or already been approved. This review provides an update on prognostic and predictive biomarkers in melanoma that may be used to improve the clinical management of patients. Prognostic markers include conventional histopathological characteristics, chromosomal aberrations, gene expression patterns and miRNA profiles. There is a trend towards multi-marker assays and whole-genome molecular screening methods to determine the prognosis of individual patients. Predictive biomarkers, including targeted components of signal transduction, developmental or transcriptional pathways, can be used to determine patient response towards a particular treatment or combination thereof. The rapid evolution of sequencing technologies and multi-marker screening will change the spectrum of patients who become candidates for therapeutic agents, and in addition create new ethical and regulatory challenges.

Survival of patients with advanced metastatic melanoma: The impact of novel therapies

The survival of advanced metastatic melanoma has been greatly improved within the past few years. New therapeutic strategies like kinase inhibitors for BRAF-mutant melanoma and immune checkpoint blockers proved to prolong survival times within clinical trials, and many of them have already entered routine clinical use. However, these different treatment modalities have not yet been tested against each other, which complicate therapy decisions. We performed an explorative analysis of survival data from recent clinical trials. Thirty-five Kaplan-Meier survival curves from 17 trials were digitised, re-grouped by matching inclusion criteria and treatment line, and averaged by therapy strategy. Notably, the survival curves grouped by therapy strategy revealed a very high concordance, even if different agents were used. The greatest survival improvement was observed with the combination of BRAF plus MEK inhibitors as well as with Programmed-death-1 (PD1) blockers with or without cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) blockers, respectively, with these two treatment strategies showing similar survival outcomes. For first-line therapy, averaged survival proportions of patients alive at 12 months were 74.5% with BRAF plus MEK inhibitor treatment versus 71.9% with PD-1 blockade. This explorative comparison shows the kinase inhibitors as similarly effective as immune checkpoint blockers with regard to survival. However, to confirm these first trends for implementation into an individualised treatment of melanoma patients, data from prospective clinical trials comparing the different treatment strategies head-to-head have to be awaited.

Nutrient Competition: A New Axis of Tumor Immunosuppression

It is thought that cancer cells engage in Warburg metabolism to meet intrinsic biosynthetic requirements of cell growth and proliferation. Papers by Chang et al. and Ho et al. show that Warburg metabolism enables tumor cells to restrict glucose availability to T cells, suppressing anti-tumor immunity.

Molecular Pathways: Targeting IDO1 and Other Tryptophan Dioxygenases for Cancer Immunotherapy

Indoleamine 2, 3-dioxygenase 1 (IDO1), IDO2, and tryptophan 2, 3-dioxygenase (TDO) comprise a family of enzymes that catalyze the first- and rate-limiting step associated with the catabolic conversion of tryptophan (Trp) into kynurenine (Kyn). Through subsequent enzymatic and spontaneous reactions, Kyn is further converted into the energetic substrates, NAD(+) and ATP, to fuel cellular metabolic functions. Coincidently, the depletion of Trp and accumulation of Kyn has been demonstrated to induce effector T-cell apoptosis/dysfunction and immunosuppressive regulatory T-cell induction, respectively. Similar to other immune checkpoints, IDO1 and TDO are suggested to be important targets for immunotherapeutic intervention. This is represented by the recent growth of efforts to inhibit the Trp-to-Kyn pathway as a means to control immunosuppression. Inhibitors currently in clinical trials, INCB024360, GDC-0919, indoximod, and an IDO1 peptide-based vaccine, are being evaluated for their efficacy against a wide range of cancers including melanoma, glioblastoma, non-small cell lung, pancreatic, and/or breast cancer, as well as metastatic disease. Despite the rapid development of potent clinical grade inhibitors, strategic questions remain. Here, we review the state of the literature with respect to current therapeutic inhibitors of tryptophan catabolism, evaluation of those efforts preclinically and clinically, compensatory changes that occur with therapeutic targeting, as well as newly recognized signaling features that raise critical questions to the field. Given the rapidly evolving interest in determining how IDO1/TDO, and to an unknown extent, IDO2, can be targeted for increasing cancer immunotherapeutic efficacy, we present a brief but comprehensive analysis that addresses critical questions, while highlighting the mechanics that remain to be explored.

Mismatch repair deficiency associated with complete remission to combination programmed cell death ligand immune therapy in a patient with sporadic urothelial carcinoma: immunotheranostic considerations

Background

Mismatch repair deficiency (MMRD) is a common pathway of malignant transformation accounting for approximately 15–20 % of human carcinogensis. It has been postulated that MMRD increases tumor antigenicity and highlights a role for immunotherapeutic approach MMR-deficient cancers. This strategy was pursued in a patient with upper tract urothelial carcinoma, and the results are reported here.

Case Presentation

Molecular profiling was performed using next generation DNA sequencing and (IHC) testing for MMR and PD-L1. A patient with sporadic, high grade urothelial carcinoma of the renal pelvis was found to have a hypermutator genotype with 73 mutations occurring amidst 62 known drivers of malignancy, and 340 VUS alterations. MMR deficiency phenotype was confirmed by the absence of MSH2 and MSH6 as well as deleterious mutations in these genes. IHC staining for programmed cell death ligand-1 [PD-L1] revealed 2+ staining in 80 % of cells. The patient gained access to combination immunotherapy trial utilizing MEDI4736 and MEDI0680 through a clinical trial. The patient achieved a prolonged, complete remission within two months and had no severe ill effects from the treatment.

Conclusion

Given their ability to generate neo-antigens, MMR-deficient cancers may be uniquely susceptible to immune checkpoint inhibitor strategies, including urothelial tract cancers. Screening for MMR deficient cancers has the potential to become a routine strategy for evaluating the role of PD-L1 inhibitors for patient with advanced disease. (Trial registration: Clinicaltrials.gov NCT00938834. Registered 13 July 2009)

Clinical relevance of host immunity in breast cancer: from TILs to the clinic

The clinical relevance of the host immune system in breast cancer has long been unexplored. Studies developed over the past decade have highlighted the biological heterogeneity of breast cancer, prompting researchers to investigate whether the role of the immune system in this malignancy is similar across different molecular subtypes of the disease. The presence of high levels of lymphocytic infiltration has been consistently associated with a more-favourable prognosis in patients with early stage triple-negative and HER2-positive breast cancer. These infiltrates seem to reflect favourable host antitumour immune responses, suggesting that immune activation is important for improving survival outcomes. In this Review, we discuss the composition of the immune infiltrates observed in breast cancers, as well as data supporting the clinical relevance of host antitumour immunity, as represented by lymphocytic infiltration, and how this biomarker could be used in the clinical setting. We also discuss the rationale for enhancing immunity in breast cancer, including early data on the efficacy of T-cell checkpoint inhibition in this setting.

Loss of PTEN Promotes Resistance to T Cell-Mediated Immunotherapy

T cell-mediated immunotherapies are promising cancer treatments. However, most patients still fail to respond to these therapies. The molecular determinants of immune resistance are poorly understood. We show that loss of PTEN in tumor cells in preclinical models of melanoma inhibits T cell-mediated tumor killing and decreases T-cell trafficking into tumors. In patients, PTEN loss correlates with decreased T-cell infiltration at tumor sites, reduced likelihood of successful T-cell expansion from resected tumors, and inferior outcomes with PD-1 inhibitor therapy. PTEN loss in tumor cells increased the expression of immunosuppressive cytokines, resulting in decreased T-cell infiltration in tumors, and inhibited autophagy, which decreased T cell-mediated cell death. Treatment with a selective PI3Kβ inhibitor improved the efficacy of both anti-PD-1 and anti-CTLA-4 antibodies in murine models. Together, these findings demonstrate that PTEN loss promotes immune resistance and support the rationale to explore combinations of immunotherapies and PI3K-AKT pathway inhibitors.

SIGNIFICANCE

This study adds to the growing evidence that oncogenic pathways in tumors can promote resistance to the antitumor immune response. As PTEN loss and PI3K-AKT pathway activation occur in multiple tumor types, the results support the rationale to further evaluate combinatorial strategies targeting the PI3K-AKT pathway to increase the efficacy of immunotherapy.

Loss of PTEN Promotes Resistance to T Cell-Mediated Immunotherapy

T cell-mediated immunotherapies are promising cancer treatments. However, most patients still fail to respond to these therapies. The molecular determinants of immune resistance are poorly understood. We show that loss of PTEN in tumor cells in preclinical models of melanoma inhibits T cell-mediated tumor killing and decreases T-cell trafficking into tumors. In patients, PTEN loss correlates with decreased T-cell infiltration at tumor sites, reduced likelihood of successful T-cell expansion from resected tumors, and inferior outcomes with PD-1 inhibitor therapy. PTEN loss in tumor cells increased the expression of immunosuppressive cytokines, resulting in decreased T-cell infiltration in tumors, and inhibited autophagy, which decreased T cell-mediated cell death. Treatment with a selective PI3Kβ inhibitor improved the efficacy of both anti-PD-1 and anti-CTLA-4 antibodies in murine models. Together, these findings demonstrate that PTEN loss promotes immune resistance and support the rationale to explore combinations of immunotherapies and PI3K-AKT pathway inhibitors.

SIGNIFICANCE

This study adds to the growing evidence that oncogenic pathways in tumors can promote resistance to the antitumor immune response. As PTEN loss and PI3K-AKT pathway activation occur in multiple tumor types, the results support the rationale to further evaluate combinatorial strategies targeting the PI3K-AKT pathway to increase the efficacy of immunotherapy.

The rapidly evolving therapies for advanced melanoma--Towards immunotherapy, molecular targeted therapy, and beyond

The incidence of melanoma in both males and females continues to rise during the past 40 years despite the stable or declining trends for most cancer types. Due to the tremendous advance in immunobiology and molecular biology, breakthroughs in both immunotherapies and molecular targeted therapies have recently revolutionized the standard of care for patients with advanced melanoma. In 2011, US Food and Drug Administration (FDA) approved ipilimumab, an anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4) antibody for metastatic melanoma therapy. Since then, novel drugs including antibodies to programmed cell death 1 (PD-1) such as pembrolizumab and nivolumab (both approved in 2014), selective BRAF inhibitors such as vemurafenib (approved in 2011), dabrafenib (approved in 2013); and MEK inhibitor trametinib (approved in 2013), have greatly extended the potential of immunotherapy and molecular targeted therapy for advanced melanoma. All of which have been demonstrated a significant increase in overall survival rate, and long-term benefits in multiple large clinical trials. Several new agents and novel therapies are currently under phase III clinical trials with the hope of being approved in the near future. We already entered a golden era in oncology that are providing significant survival improvement. In the meantime, new challenges for clinicians also started to emerge. In this review, we presented the existing evidence for the newest treatments for advanced melanoma, including CTLA-4, PD-1/PD-L1 checkpoint inhibitors and BRAF, MEK inhibitors. We also discussed the strengths, limitations and challenges of using these novel therapies, and potential solutions as well as highlighted the areas requiring further research.

Loss of PTEN Promotes Resistance to T Cell-Mediated Immunotherapy

T cell-mediated immunotherapies are promising cancer treatments. However, most patients still fail to respond to these therapies. The molecular determinants of immune resistance are poorly understood. We show that loss of PTEN in tumor cells in preclinical models of melanoma inhibits T cell-mediated tumor killing and decreases T-cell trafficking into tumors. In patients, PTEN loss correlates with decreased T-cell infiltration at tumor sites, reduced likelihood of successful T-cell expansion from resected tumors, and inferior outcomes with PD-1 inhibitor therapy. PTEN loss in tumor cells increased the expression of immunosuppressive cytokines, resulting in decreased T-cell infiltration in tumors, and inhibited autophagy, which decreased T cell-mediated cell death. Treatment with a selective PI3Kβ inhibitor improved the efficacy of both anti-PD-1 and anti-CTLA-4 antibodies in murine models. Together, these findings demonstrate that PTEN loss promotes immune resistance and support the rationale to explore combinations of immunotherapies and PI3K-AKT pathway inhibitors.

SIGNIFICANCE

This study adds to the growing evidence that oncogenic pathways in tumors can promote resistance to the antitumor immune response. As PTEN loss and PI3K-AKT pathway activation occur in multiple tumor types, the results support the rationale to further evaluate combinatorial strategies targeting the PI3K-AKT pathway to increase the efficacy of immunotherapy.

New toxicity profile for novel immunotherapy agents: focus on immune-checkpoint inhibitors

INTRODUCTION

Tumor development results from a cancer-induced immunosuppression (immune-editing). Immunotherapy has revolutionized the treatment paradigm for many malignancies, putting clinicians before novel toxicities, of immune-mediated etiology (immune-related adverse events).

AREAS COVERED

Immune-mediated toxicity depends on both innate and adaptive immunity mechanisms. Healthy tissue damage depends on an aspecific T-cell hyperactivation response causing cross-reaction with normal tissues, which leads to an overproduction of CD4 T-helper cell cytokines and an abnormal migration of cytolytic CD8 T-cells. By stimulating a diffuse T-cell repertoire expansion, immune-checkpoint inhibitors counteract tumor growth but reduce the self-tolerance, damaging healthy organs. In this review, we summarize the toxicity profile of the novel immune-checkpoint inhibitors and their clinical implications, we are convinced that a deep understanding and a prompt resolution of the paradigmatic toxicities of these drugs will result in clinical benefits to patients and an enhanced antitumor effect.

EXPERT OPINION

A focus on immunotoxicity is important in the education of clinicians and will improve patient safety. There is a willingness to tailor specific immune-therapies to each cancer patient, and to stimulate researchers through understanding of the physiopathogenesis, using the hypothesis that immune-mediated toxicities can be used as predictors of response or a prognostic sign of survival, thereby guiding therapeutic decisions.

Investigation of FOXM1 as a Potential New Target for Melanoma

Recent studies have shown that immunotherapies and molecular targeted therapies are effective for advanced melanoma. Non-antigen-specific immunotherapies such as immunocheckpoint blockades have been shown to be effective in the treatment of advanced melanoma. However, the response rates remain low. To improve their efficacy, they should be combined with antigen-specific immunotherapy. Elevated expression of the transcription factor, Forkhead box M1 (FOXM1), has been reported in various human cancers, and it has been shown to have potential as a target for immunotherapy. The purpose of this study was to investigate the FOXM1 expression in human melanoma samples and cell lines, to evaluate the relationship between the FOXM1 expression and the clinical features of melanoma patients and to investigate the association between the FOXM1 and MAPK and PI3K/AKT pathways in melanoma cell lines. We conducted the quantitative reverse transcription PCR (qRT-PCR) and Western blotting analyses of melanoma cell lines, and investigated melanoma and nevus tissue samples by qRT-PCR and immunohistochemistry. We performed MEK siRNA and PI3K/AKT inhibitor studies and FOXM1 siRNA studies in melanoma cell lines. We found that FOXM1 was expressed in all of the melanoma cell lines, and was expressed in 49% of primary melanomas, 67% of metastatic melanomas and 10% of nevi by performing immunohistochemical staining. Metastatic melanoma samples exhibited significantly higher mRNA levels of FOXM1 (p = 0.004). Primary melanomas thicker than 2 mm were also more likely to express FOXM1. Patients whose primary melanoma expressed FOXM1 had a significantly poorer overall survival compared to patients without FOXM1 expression (p = 0.024). Downregulation of FOXM1 by siRNA significantly inhibited the proliferation of melanoma cells, and blockade of the MAPK and PI3K/AKT pathways decreased the FOXM1 expression in melanoma cell lines. In conclusion, FOXM1 is considered to be a new therapeutic target for melanoma.

The Wnts of change: How Wnts regulate phenotype switching in melanoma

The outgrowth of metastatic and therapy-resistant subpopulations in cancer remains a critical barrier for the successful treatment of this disease. In melanoma, invasion and proliferation are uncoupled, such that highly proliferative melanoma cells are less likely to be invasive, and vice versa. The transition between each state is likely a dynamic rather than a static, permanent change. This is referred to as "phenotype switching". Wnt signaling pathways drive phenotypic changes and promote therapy resistance in melanoma, as well as play roles in the modulation of the immune microenvironment. Three Wnt signaling pathways play a role in melanoma progression, canonical (β-catenin dependent), polar cell polarity (PCP), and the Wnt/Ca²⁺ pathway. Here we summarize phenotype plasticity and its role in therapy resistance and immune evasion. Targeting the Wnt signaling pathways may be an effective way to overcome tumor plasticity in melanoma.

Toxicities of the anti-PD-1 and anti-PD-L1 immune checkpoint antibodies

Immune checkpoint antibodies that augment the programmed cell death protein 1 (PD-1)/PD-L1 pathway have demonstrated antitumor activity across multiple malignancies, and gained recent regulatory approval as single-agent therapy for the treatment of metastatic malignant melanoma and nonsmall-cell lung cancer. Knowledge of toxicities associated with PD-1/PD-L1 blockade, as well as effective management algorithms for these toxicities, is pivotal in order to optimize clinical efficacy and safety. In this article, we review selected published and presented clinical studies investigating single-agent anti-PD-1/PD-L1 therapy and trials of combination approaches with other standard anticancer therapies, in multiple tumor types. We summarize the key adverse events reported in these studies and their management algorithms.

Immunotherapy meets targeted therapy: will this team end the war against cancer?

Cancer treatment as we know it today has dramatically changed over the last couple of decades. It has moved from non-specific treatment to personalized approaches. As oncologist, we now have further understanding of the processes leading to carcinogenesis; this has led to develop new therapeutic options. We have cytotoxic treatments, targeted therapy and in recent years, immunotherapy; the time to "mix and match" has begun.

Systemic Chemotherapy for Advanced Hepatocellular Carcinoma: Past, Present, and Future

Systemic chemotherapy is one of the most important treatment modalities for advanced hepatocellular carcinoma (HCC). Before the introduction of sorafenib, cytotoxic agents, hormonal therapies, or many combinations of these were the mainly used modalities for systemic chemotherapy of advanced HCC. However, such regimens were of only limited value in clinical practice, because some randomized controlled studies comparing promising regimens with no treatment or doxorubicin alone failed to show any overall survival advantage. In two pivotal phase III placebo-controlled studies, the SHARP trial and the Asia-Pacific trial, sorafenib was demonstrated to significantly delay the time to progression and the overall survival time in patients with advanced HCC. Therefore, sorafenib therapy has come to be acknowledged as a standard therapy for advanced HCC worldwide. After the introduction of sorafenib, a number of phase III trials of various molecular-targeted agents vs. sorafenib as first-line chemotherapy and of various molecular-targeted agents vs. placebo as second-line chemotherapy have been conducted to determine if any of these agents could offer a survival benefit, however, none of the agents examined so far has been demonstrated to provide any survival benefit over sorafenib or placebo. Recently, favorable treatment efficacies have been reported in some clinical trials of molecular-targeted agents in the biomarker-enriched population. Development of individualized cancer treatments using molecular-targeted agents based on the results of genome-sequencing is aggressively ongoing. Furthermore, immune-oncologic agents, such as anti-CTLA-4 antibody and anti-PD-1/PD-L1 antibody, have been reported to provide promising outcomes. Thus, various novel systemic chemotherapeutic agents are currently under development, and further improvements in the treatment outcomes are expected.

IL15 and T-cell Stemness in T-cell-Based Cancer Immunotherapy

Preclinical models revealed that the immune system can mediate rejection of established tumors, but direct evidence in humans has been limited to largely immunogenic tumors, such as melanoma. The recent success of immune checkpoint inhibitors and adoptive T-cell transfer immunotherapy in clinical trials has instilled new hope for the use of T-cell immunotherapy in the treatment of cancer. IL15, a potent immunostimulatory cytokine, both potentiates host T-cells and natural killer (NK) cell immune responses and promotes the generation of long-lived memory T cells with superior functional capacity, with potential use in adoptive T-cell transfer protocols. IL15 has been recently tested in the clinic and showed dramatic effects at the level of responding NK and CD8(+) memory T cells. The recent advances in the knowledge of IL15-dependent regulation of T-cell responses, gene expression, and metabolic adaptation have important implications for the use of IL15 in T-cell-based immunotherapy of cancer.

Subacute CNS Demyelination after Treatment with Nivolumab for Melanoma

Immunotherapy with monoclonal antibodies targeting cytotoxic T-lymphocyte antigen 4 (CTLA-4) or programmed cell death 1 (PD-1) has improved the survival of patients with metastatic melanoma. These agents carry a certain risk of adverse immune-related events. We present a patient with widely metastatic melanoma who was initially treated with ipilimumab and subsequently with nivolumab. After four infusions of nivolumab, he developed subacute multifocal central nervous system (CNS) demyelination. Nivolumab was discontinued and, despite immunosuppressive therapy, the largest lesion progressed significantly, whereas another lesion showed radiographic improvement. After further progression, the patient succumbed to his CNS lesions 4 months later. Autopsy revealed extensive demyelination, a mild multifocal T-cell-rich perivascular lymphoid infiltrate, abundant macrophages, and necrosis. There was no metastatic melanoma in the brain. CNS demyelination has not been described in association with nivolumab. We hypothesize that the combination therapy of ipilimumab and subsequent nivolumab accounted for the severity of the demyelinating process in this patient. This case, with comprehensive clinical, molecular, and neuropathologic characterization, illustrates the need for awareness of these potential CNS complications with the use of multiple checkpoint inhibitors.

Immune checkpoint inhibitors: therapeutic advances in melanoma

In recent years, new strategies for treating melanoma have been introduced, improving the outlook for this challenging disease. One of the most important advances has been the development of immunotherapy. The better understanding of the role of the immunological system in tumor control has paved the way for strategies to enhance the immune response against cancer cells. Monoclonal antibodies (mAbs) against the immune checkpoints cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed cell death protein 1 (PD-1) and its ligand (PD-L1) have demonstrated high activity in melanoma and other tumors. Ipilimumab, an anti CTLA-4 antibody, was the first drug of this class that was approved. Although the response rate with ipilimumab is low (less than 20% of patients have objective responses), 20% of patients have long survival, with similar results in the first and second line settings. Nivolumab and pembrolizumab, both anti PD-1 inhibitors, have been approved for the treatment of melanoma, with response rates of 40% and a demonstrated survival advantage in phase III trials. This has marked a new era in the treatment of metastatic melanoma and much research is now ongoing with other drugs targeting checkpoint inhibitors. In addition, the agonist of activating molecules on T cells and their combinations are being investigated. Herein we review the clinical development of checkpoint inhibitors and their approval for treatment of metastatic melanoma.

The immune mechanisms of abscopal effect in radiation therapy

Radiation therapy (RT) is a cornerstone in oncologic management and is employed in various curative and palliative scenarios for local-regional control. RT is thought to locally control tumor cells by direct physical DNA damage or indirect insults from reactive oxygen species. Therapeutic effects apart from those observed at the treatment target, that is, abscopal effect, have been observed for several decades, though the underlying mechanisms regulating this phenomenon have been unclear. Accumulating evidence now suggests that the immune system is a major determinant in regulating the abscopal effect. It is now evident that RT may also enhance immunologic responses to tumors by creating an in situ vaccine by eliciting antigen release from dying tumor cells. Harnessing the specificity and dynamic nature of the immune system to target tumors in conjunction with RT is an emerging field with much promise. To optimize this approach, it is important to systematically evaluate the intricacies of the host immune system, the new generation of immunotherapeutics and the RT approach. Here we will discuss the current biologic mechanisms thought to regulate the RT-induced abscopal effect and how these may be translated to the clinical setting.

Immune suppressive mechanisms in the tumor microenvironment

Effective immunotherapy, whether by checkpoint blockade or adoptive cell therapy, is limited in most patients by a key barrier: the immunosuppressive tumor microenvironment. Suppression of tumor-specific T cells is orchestrated by the activity of a variety of stromal myeloid and lymphoid cells. These often display inducible suppressive mechanisms that are triggered by the same anti-tumor inflammatory response that the immunotherapy intends to create. Therefore, a more comprehensive understanding of how the immunosuppressive milieu develops and persists is critical in order to harness the full power of immunotherapy of cancer.

Radiologic Heterogeneity in Responses to Anti-PD-1/PD-L1 Therapy in Metastatic Renal Cell Carcinoma

Radiologic assessment of tumor response remains a challenge in patients treated with immune checkpoint inhibitors. In metastatic melanoma, for example, a spectrum of imaging patterns in response to immunotherapies have been recognized and associated with clinical benefit. In metastatic renal cell carcinoma (mRCC), less than half of patients treated with immune checkpoint inhibitors achieve objective responses, but some of the responses have been durable. In this series, five different imaging patterns of response and progression are described in mRCC patients treated with anti-PD-1/PD-L1 agents: (i) early and complete response, (ii) pseudoprogression, (iii) disease stability before ultimate response, (iv) mixed response with new lesions, and (v) early progression/primary refractory disease. The implications of the different imaging patterns of patient responses on disease prognosis are discussed and highlight the need for individualized patient assessment when using these novel immune-targeted agents.

Challenges of phase 1 clinical trials evaluating immune checkpoint-targeted antibodies

BACKGROUND

Immunostimulatory monoclonal antibodies (imAbs) targeting immune checkpoint molecules are revolutionizing oncology not only regarding cancer therapeutics and clinical care, but also from a drug development point of view. A handful of first-generation molecules have been approved so far based on their tremendous efficacy, after an expedited development phase that has challenged most paradigms established in the era of conventional cytotoxic therapy and to some extent molecularly targeted agents. A huge wave of second-generation imAbs is just entering into phase 1 trials now, in monotherapy or in combination. In order to maximize their chances of success in early phase trials, and eventually for patients' benefit, their clinical development has to benefit from lessons learnt from previous imAbs phase 1 trials.

MATERIALS AND METHODS

We reviewed the early clinical development of anti-cytotoxic T-lymphocyte antigen 4 and anti-programmed death-1 receptor/ligand. Particularities of each agent, including safety, dose--toxicity and dose--efficacy relationships, scheduling, pharmacokinetics (PK), pharmacodynamics (PD), trial design, biomarkers, response assessment and overall drug development strategies, are described and challenged.

RESULTS

As opposed to conventional cytotoxic agents, dose of imAbs is not linearly associated with efficacy and toxicity. Therefore, the definition of a minimal immunologically active dose could be proposed. Traditional patient eligibility criteria might also be revisited as the toxicity profile and mechanism of toxicity--immune-related adverse events--are mostly known and their physiopathology somehow less unexpected than with molecularly targeted small molecules. Most challenging are the comprehensive investigation of complex PK and PD characteristics as well as the definition of patient selection biomarkers. Finally, the early focus on efficacy (and not only dose confirmation) in expansion cohorts challenges the traditional phase 1/2/3 drug development process.

CONCLUSION

Several drug development paradigms have been challenged by imAbs. Here, we discuss novel approaches for an efficient and successful drug development of these agents.

Pembrolizumab in the management of metastatic melanoma

Pembrolizumab is a humanized IgG4 anti-PD-1 antibody that plays a major role in the treatment of advanced melanoma. Through blockade of PD-1, it leads to an increase in effector T-cell activity in the tumor microenvironment. Clinical trial outcomes for pembrolizumab in addition to pharmacokinetics, pharmacodynamics and safety of the compound are discussed in this article. Phase I trials have demonstrated safety and efficacy of pembrolizumab in advanced, pretreated melanoma patients. When compared with chemotherapy in a Phase II trial of ipilimumab-refractory patients, those treated with pembrolizumab showed superior progression-free survival. In addition, in the pivotal Phase III trial pembrolizumab improved overall survival compared with ipilimumab in patients naive to immune checkpoint inhibition. Pembrolizumab is well tolerated and has a favorable safety profile. Common adverse events are fatigue, rash, itching and diarrhea. Less frequent immune-related adverse events include hypothyroidism, colitis, hepatitis and pneumonitis.

Open-label, multicenter, single-arm phase II DeCOG-study of ipilimumab in pretreated patients with different subtypes of metastatic melanoma

BACKGROUND

Ipilimumab is an approved immunotherapy that has shown an overall survival benefit in patients with cutaneous metastatic melanoma in two phase III trials. As results of registrational trials might not answer all questions regarding safety and efficacy of ipilimumab in patients with advanced melanoma seen in daily clinical practice, the Dermatologic Cooperative Oncology Group conducted a phase II study to assess the efficacy and safety of ipilimumab in patients with different subtypes of metastatic melanoma.

PATIENTS AND METHODS

We undertook a multicenter phase II study in melanoma patients irrespective of location of the primary melanoma. Here we present data on patients with pretreated metastatic cutaneous, mucosal and occult melanoma who received up to four cycles of ipilimumab administered at a dose of 3 mg/kg in 3 week intervals. Tumor assessments were conducted at baseline, weeks 12, 24, 36 and 48 according to RECIST 1.1 criteria. Adverse events (AEs), including immune-related AEs were graded according to National Cancer Institute Common Toxicity Criteria (CTC) v.4.0. Primary endpoint was the OS rate at 12 months.

RESULTS

103 pretreated patients received at least one dose of ipilimumab, including 83 cutaneous, seven mucosal and 13 occult melanomas. 1-year OS rates for cutaneous, mucosal and occult melanoma were 38 %, 14 % and 27 %, respectively. Median OS was 6.8 months (95 % CI 5.3-9.9) for cutaneous, 9.6 months (95 % CI 1.6-11.1) for mucosal, and 9.9 months (lower 95 % CI 2.3, upper 95 % CI non-existent) for occult melanoma. Overall response rates for cutaneous, mucosal and occult melanoma were 16 %, 17 % and 11 %, respectively. Eleven patients had partial response (16 %) and ten patients experienced stable disease (14 %), none achieved a complete response. Treatment-related AEs were observed in 71 patients (69 %), including 20 grade 3-4 events (19 %). No new and unexpected safety findings were noted.

CONCLUSIONS

Ipilimumab is a treatment option for pretreated patients with advanced cutaneous melanoma seen in daily routine. Toxicity was manageable when treated as per protocol-specific guidelines.

TRIAL REGISTRATION

Clinical Trials.gov NCT01355120.

Immunotherapy in hepatocellular carcinoma: Primed to make a difference?

Advanced hepatocellular carcinoma (HCC) carries a dismal prognosis and the current treatment is limited to sorafenib, an agent with modest benefit. Preclinical data have indicated that several immunologic mechanisms are at play to promote HCC development and growth while impairing effective antitumor immune surveillance. Several novel approaches geared toward manipulating the immune response to HCC have suggested a therapeutic benefit in early-stage clinical trials, indicating a real potential to augment tumor-specific immunity and improve outcomes in patients with this disease. In the current study, the authors reviewed the barriers to an effective immune response against HCC and contemporary clinical investigations that may be "primed" to alter the natural history of HCC.

Novel immunotherapies in lymphoid malignancies

The success of the anti-CD20 monoclonal antibody rituximab in the treatment of lymphoid malignancies provided proof-of-principle for exploiting the immune system therapeutically. Since the FDA approval of rituximab in 1997, several novel strategies that harness the ability of T cells to target cancer cells have emerged. Reflecting on the promising clinical efficacy of these novel immunotherapy approaches, the FDA has recently granted 'breakthrough' designation to three novel treatments with distinct mechanisms. First, chimeric antigen receptor (CAR)-T-cell therapy is promising for the treatment of adult and paediatric relapsed and/or refractory acute lymphoblastic leukaemia (ALL). Second, blinatumomab, a bispecific T-cell engager (BiTE(®)) antibody, is now approved for the treatment of adults with Philadelphia-chromosome-negative relapsed and/or refractory B-precursor ALL. Finally, the monoclonal antibody nivolumab, which targets the PD-1 immune-checkpoint receptor with high affinity, is used for the treatment of Hodgkin lymphoma following treatment failure with autologous-stem-cell transplantation and brentuximab vedotin. Herein, we review the background and development of these three distinct immunotherapy platforms, address the scientific advances in understanding the mechanism of action of each therapy, and assess the current clinical knowledge of their efficacy and safety. We also discuss future strategies to improve these immunotherapies through enhanced engineering, biomarker selection, and mechanism-based combination regimens.

TIGIT predominantly regulates the immune response via regulatory T cells

Coinhibitory receptors are critical for the maintenance of immune homeostasis. Upregulation of these receptors on effector T cells terminates T cell responses, while their expression on Tregs promotes their suppressor function. Understanding the function of coinhibitory receptors in effector T cells and Tregs is crucial, as therapies that target coinhibitory receptors are currently at the forefront of treatment strategies for cancer and other chronic diseases. T cell Ig and ITIM domain (TIGIT) is a recently identified coinhibitory receptor that is found on the surface of a variety of lymphoid cells, and its role in immune regulation is just beginning to be elucidated. We examined TIGIT-mediated immune regulation in different murine cancer models and determined that TIGIT marks the most dysfunctional subset of CD8+ T cells in tumor tissue as well as tumor-tissue Tregs with a highly active and suppressive phenotype. We demonstrated that TIGIT signaling in Tregs directs their phenotype and that TIGIT primarily suppresses antitumor immunity via Tregs and not CD8+ T cells. Moreover, TIGIT+ Tregs upregulated expression of the coinhibitory receptor TIM-3 in tumor tissue, and TIM-3 and TIGIT synergized to suppress antitumor immune responses. Our findings provide mechanistic insight into how TIGIT regulates immune responses in chronic disease settings.

A Perspective of Immunotherapy for Breast Cancer: Lessons Learned and Forward Directions for All Cancers

Immunotherapy for cancer has been a focus 50 years ago. At the time, this treatment was developed prior to cloning of the cytokines, no knowledge of regulatory T-cells, and very little information that mesenchymal stem cells (MSCs) (originally colony forming unit-fibroblasts [CFU-F]) could be licensed by the inflammatory microenvironment to suppress an immune response. Given the information available at that time, mononuclear cells from the peripheral blood were activated ex vivo and then replaced in the patients with tumor. The intent was to harness these activated immune cells to target the cancer cells. These studies did not lead to long-term responses because the activated cells when reinfused into the patients were an advantage to the resident MSCs, which can home the tumor and then become suppressive in the presence of the immune cells. The immune suppression caused by MSCs would also expand regulatory T-cells, resulting instead in tumor protection. As time progressed, these different fields converged into a new approach to use immunotherapy for cancer. This article discusses these approaches and also reviews chimeric antigen receptor in the context of future treatments for solid tumors, including breast cancer.

European Cancer Congress 2015

The European Cancer Congress, which attracts a range of European cancer groups, reflected intense interest in immunotherapies. we review key sessions, including three on the anti-programmed death-1 agent nivolumab, each in a different disease setting.

Long term survival with cytotoxic T lymphocyte-associated antigen 4 blockade using tremelimumab

PURPOSE

One of the hallmarks of cancer immunotherapy is the long duration of responses, evident with cytokines like interleukin-2 or a variety of cancer vaccines. However, there is limited information available on very long term outcomes of patients treated with anti-cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) antibodies. Tremelimumab is an anti-CTLA-4 antibody of immunoglobulin G2 (IgG2) isotype initially tested in patients with advanced melanoma over 12 years ago.

METHODS

We reviewed the outcomes of patients with advanced melanoma enrolled in four phase 1 and 2 tremelimumab trials at two sites to determine response rates and long-term survival.

RESULTS

A total of 143 patients were enrolled at two institutions from 2002 to 2008. Tremelimumab administration varied between a single dose of 0.01 mg/kg and 15 mg/kg every 3 months. Median overall survival was 13 months (95% confidence interval (CI), 10-16.6), ranging from less than a month to 12+ years. An objective response rate of 15.6% was observed, with median duration of response of 6.5 years, range of 3-136+ months. The Kaplan-Meier estimated 5 year survival rate was 20% (95% CI, 13-26%), with 10 and 12.5 year survival rates of 16% (95% CI, 9-23%).

CONCLUSIONS

CTLA-4 blockade with tremelimumab can lead to very long duration of objective anti-tumour responses beyond 12 years.

Nivolumab plus ipilimumab in the treatment of advanced melanoma

Advanced melanoma has historically been a difficult disease to treat due to few effective systemic treatment options. However, over the past few years, scientific advancements in immune checkpoint inhibition have resulted in several novel approaches that have changed front-line management of advanced melanoma. Despite these exciting developments, there remains room for improvement in treatment outcomes. Combination immunotherapy, in particular combined cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed death 1 (PD-1) blockade, represents an important first step in this direction.

The use of combinations of monoclonal antibodies in clinical oncology

Treatment with monoclonal antibodies is becoming increasingly important in clinical oncology. These antibodies specifically inhibit signaling pathways in tumor growth and/or induce immunological responses against tumor cells. By combining monoclonal antibodies several pathways may be targeted simultaneously, potentially leading to additive or synergistic effects. Theoretically, antibodies are very suitable for use in combination therapy, because of limited overlapping toxicity and lack of pharmacokinetic interactions. In this article an overview is given of preclinical and clinical data on twenty-five different combinations of antibodies in oncology. Some of these combinations have proven clinical benefit, for example the combination of trastuzumab and pertuzumab in HER2-positive breast cancer, which exemplifies an additive or synergistic effect on antitumor activity in clinical studies and the combination of nivolumab and ipilimumab, which results in significant increases in progression-free and overall survival in patients with advanced melanoma. However, other combinations may lead to unfavorable results, such as bevacizumab with cetuximab or panitumumab in advanced colorectal cancer. These combinations result in shorter progression-free survival and increased toxicity compared to therapy with a single antibody. In summary, the different published studies showed widely varying results, depending on the combination of antibodies, indication and patient population. More preclinical and clinical studies are necessary to unravel the mechanisms behind synergistic or antagonistic effects of combining monoclonal antibodies. Most research on combination therapies is still in an early stage, but it is expected that for several tumor types the use of combination therapy of antibodies will become standard of care in the near future.

Risk of gastrointestinal complications in cancer patients treated with immune checkpoint inhibitors: a meta-analysis

AIM

We performed a meta-analysis of the risk of selected gastrointestinal toxicities associated with immune checkpoint inhibitors.

PATIENTS & METHODS

Eligible studies included randomized trials of patients with solid tumors on ipilimumab, nivolumab, pembrolizumab, tremelimumab, pidilizumab and atezolizumab, describing events of diarrhea, vomiting or colitis.

RESULTS

After exclusion of ineligible studies, a total of ten clinical trials were considered eligible for the meta-analysis. The relative risk of all-grade diarrhea, vomiting and colitis was 1.64 (95% CI: 1.19-2.26; p = 0.002), 0.72 (95% CI: 0.49-1.07; p = 0.1), 10.35 (95% CI: 5.78-18.53; p < 0.00001), respectively.

CONCLUSION

Our meta-analysis has demonstrated that immune checkpoint inhibitors are associated with a significantly increased risk of all grade and high-grade colitis.

Immunotherapy Combinations With Checkpoint Inhibitors in Metastatic Melanoma: Current Approaches and Future Directions

Based on the complexity of the immune response to cancer and the mechanisms of tumor evasion, it is likely that therapeutic modulation of multiple immune-mediated pathways will be needed to maximally induce tumor regression in patients with advanced melanoma. The rationale of using combination checkpoint inhibitor-based regimens may include the concomitant effects on re-activation of T cells, increased trafficking of tumor reactive lymphocytes into the tumor tissue, and enhanced killing of cancer cells. The administration of nivolumab in combination with ipilimumab demonstrated increased response rates, tumor shrinkage, and median progression-free survival using combined therapy compared with either treatment alone. Although toxicity was also increased, this trial established proof of principle that combination immunotherapy could enhance the efficacy seen with single-agent programmed cell death protein-1 (PD-1) pathway blockade for the unselected patient. Current and future trials are evaluating alternative schedules and other combinations of immunotherapies to determine if they could provide similar efficacy with less toxicity. In addition, efforts are underway to determine how best to integrate combination immunotherapy with other treatment approaches for patients with advanced melanoma.

Combination cancer immunotherapy and new immunomodulatory targets

Targeting immune checkpoints such as programmed cell death protein 1 (PD1), programmed cell death 1 ligand 1 (PDL1) and cytotoxic T lymphocyte antigen 4 (CTLA4) has achieved noteworthy benefit in multiple cancers by blocking immunoinhibitory signals and enabling patients to produce an effective antitumour response. Inhibitors of CTLA4, PD1 or PDL1 administered as single agents have resulted in durable tumour regression in some patients, and combinations of PD1 and CTLA4 inhibitors may enhance antitumour benefit. Numerous additional immunomodulatory pathways as well as inhibitory factors expressed or secreted by myeloid and stromal cells in the tumour microenvironment are potential targets for synergizing with immune checkpoint blockade. Given the breadth of potential targets in the immune system, critical questions to address include which combinations should move forward in development and which patients will benefit from these treatments. This Review discusses the leading drug targets that are expressed on tumour cells and in the tumour microenvironment that allow enhancement of the antitumour immune response.

Fueling the engine and releasing the break: combinational therapy of cancer vaccines and immune checkpoint inhibitors

Immune checkpoint inhibitors are increasingly drawing much attention in the therapeutic development for cancer treatment. However, many cancer patients do not respond to treatments with immune checkpoint inhibitors, partly because of the lack of tumor-infiltrating effector T cells. Cancer vaccines may prime patients for treatments with immune checkpoint inhibitors by inducing effector T-cell infiltration into the tumors and immune checkpoint signals. The combination of cancer vaccine and an immune checkpoint inhibitor may function synergistically to induce more effective antitumor immune responses, and clinical trials to test the combination are currently ongoing.