Nivolumab and ipilimumab versus ipilimumab in untreated melanoma

Immuno-oncology combinations: raising the tail of the survival curve

There have been exponential gains in immuno-oncology in recent times through the development of immune checkpoint inhibitors. Already approved by the U.S. Food and Drug Administration for advanced melanoma and non-small cell lung cancer, immune checkpoint inhibitors also appear to have significant antitumor activity in multiple other tumor types. An exciting component of immunotherapy is the durability of antitumor responses observed, with some patients achieving disease control for many years. Nevertheless, not all patients benefit, and efforts should thus now focus on improving the efficacy of immunotherapy through the use of combination approaches and predictive biomarkers of response and resistance. There are multiple potential rational combinations using an immunotherapy backbone, including existing treatments such as radiotherapy, chemotherapy or molecularly targeted agents, as well as other immunotherapeutics. The aim of such antitumor strategies will be to raise the tail on the survival curve by increasing the number of long term survivors, while managing any additive or synergistic toxicities that may arise with immunotherapy combinations. Rational trial designs based on a clear understanding of tumor biology and drug pharmacology remain paramount. This article reviews the biology underpinning immuno-oncology, discusses existing and novel immunotherapeutic combinations currently in development, the challenges of predictive biomarkers of response and resistance and the impact of immuno-oncology on early phase clinical trial design.

Current and future immunotherapeutic approaches in Hodgkin lymphoma

Hodgkin lymphoma (HL) has become a highly curable malignancy even in advanced stages when treated adequately. However, relapsed or refractory disease and treatment-related toxicity constitute a significant clinical challenge. Innovative approaches are thus needed to improve treatment of these mainly young patients. In HL lesions, very few malignant Hodgkin and Reed-Sternberg (HRS) cells are embedded in an immunosuppressive microenvironment of reactive cells. Novel approaches such as bispecific antibodies, antibody-drug conjugates, immune-checkpoint inhibitors or adoptive cellular therapies are currently being investigated with promising results in relapsed or refractory patients. Encouraging response rates and a favorable toxicity profile have recently been reported in early phase clinical trials with antibodies blocking the programed-death receptor 1 (PD1). This review will summarize the current clinical knowledge on mechanism, safety and efficacy of the different agents and discuss potential future strategies, which are partly already investigated within clinical trials.

The role of CTLA-4 and PD-1 in anti-tumor immune response and their potential efficacy against osteosarcoma

Immunotherapy is proved to be a promising therapeutic strategy against human malignancies. Evasion of immune surveillance is considered to be a major factor of malignant progression. Inhibitory receptors, especially CTLA-4 and PD-1, are found to play critical roles in the mediation of anti-tumor immune efficacy. Thus, antibodies targeting these immune checkpoints have emerged as the attractive treatment approaches to those patients with cancer. Osteosarcoma is highly malignant and current treatment remains a challenge, especially for those patients with metastasis. Despite some achievements, the effect of immunotherapy against osteosarcoma is still unsatisfactory. The present review attempts to show the role and mechanism of CTLA-4 and PD-1 in immune response and summarize the recent findings related to the effect of inhibitory receptor antibodies on the immune response against tumors, especially osteosarcoma, and the correlation between PD-1 or/and CTLA-4 expression and outcome of osteosarcoma patients. We further discuss the utilization of the combination therapy against osteosarcoma.

Current status and perspectives in translational biomarker research for PD-1/PD-L1 immune checkpoint blockade therapy

Modulating immune inhibitory pathways has been a major recent breakthrough in cancer treatment. Checkpoint blockade antibodies targeting cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programed cell-death protein 1 (PD-1) have demonstrated acceptable toxicity, promising clinical responses, durable disease control, and improved survival in some patients with advanced melanoma, non-small cell lung cancer (NSCLC), and other tumor types. About 20 % of advanced NSCLC patients and 30 % of advanced melanoma patients experience tumor responses from checkpoint blockade monotherapy, with better clinical responses seen with the combination of anti-PD-1 and anti-CTLA-4 antibodies. Given the power of these new therapies, it is important to understand the complex and dynamic nature of host immune responses and the regulation of additional molecules in the tumor microenvironment and normal organs in response to the checkpoint blockade therapies. In this era of precision oncology, there remains a largely unmet need to identify the patients who are most likely to benefit from immunotherapy, to optimize the monitoring assays for tumor-specific immune responses, to develop strategies to improve clinical efficacy, and to identify biomarkers so that immune-related adverse events can be avoided. At this time, PD-L1 immunohistochemistry (IHC) staining using 22C3 antibody is the only FDA-approved companion diagnostic for patients with NSCLC-treated pembrolizumab, but more are expected to come to market. We here summarize the current knowledge, clinical efficacy, potential immune biomarkers, and associated assays for immune checkpoint blockade therapies in advanced solid tumors.

Quantitative CD3 PET Imaging Predicts Tumor Growth Response to Anti-CTLA-4 Therapy

Immune checkpoint inhibitors have made rapid advances, resulting in multiple Food and Drug Administration-approved therapeutics that have markedly improved survival. However, these benefits are limited to a minority subpopulation that achieves a response. Predicting which patients are most likely to benefit would be valuable for individual therapy optimization. T-cell markers such as CD3-by examining active recruitment of the T cells responsible for cancer-cell death-represent a more direct approach to monitoring tumor immune response than pretreatment biopsy or genetic screening. This approach could be especially effective as numerous different therapeutic strategies emerge, decreasing the need for drug-specific biomarkers and instead focusing on T-cell infiltration, which has been previously correlated with treatment response.

METHODS

A CD3 PET imaging agent targeting T cells was synthesized to test the role of such imaging as a predictive marker. The ⁸⁹Zr-p-isothiocyanatobenzyl-deferoxamine-CD3 PET probe was assessed in a murine tumor xenograft model of anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4) immunotherapy of colon cancer.

RESULTS

Imaging on day 14 revealed 2 distinct groups of mice stratified by PET signal intensity. Although there was no significant difference in tumor volume on the day of imaging, in the high-uptake group subsequent measurements revealed significantly smaller tumors than in either the low-uptake group or the untreated controls. In contrast, there was no significant difference in the size of tumors between the low-uptake and untreated control mice.

CONCLUSION

These findings indicate that high CD3 PET uptake in the anti-CTLA-4-treated mice correlated with subsequent reduced tumor volume and was a predictive biomarker of response.

Immunotherapy of Melanoma

Arising from melanocytes in skin, mucosal membranes, eye, and meninges, melanoma is a tumor that has been associated with poor prognosis in advanced disease stages. Given the poor response to chemotherapy and radiation therapy, new treatment approaches with targeted therapy, immunotherapy, and adoptive T-cell therapy have revolutionized the standard of care for patients with advanced melanoma. This review provides a short overview of past, present, and future immunotherapeutic approaches and their limitations, with a focus on new combination agents in early clinical trials.

Repeat courses of SRS in patients initially treated with SRS alone for brain-metastatic melanoma

Aim

Stereotactic radiosurgery (SRS) is often used in the treatment of brain metastatic melanoma. Little data exist regarding outcomes of repeat course of SRS in this population. We aimed to identify treatment outcomes and toxicities in melanoma patients treated with repeat SRS after upfront SRS.

Patients & methods

We reviewed ten consecutive patients treated with repeat SRS following upfront SRS alone for brain metastatic melanoma.

Results

The median overall survival from initial treatment was 17.5 months. The median overall survival from repeat SRS was 6.7 months with a 6-month local control rate of 80%. The majority of patients progressed systemically before death. Four patients reported six adverse events, all grade 1.

Conclusion

Prospective study regarding the safety and efficacy of repeat courses of SRS in patients with brain-metastatic melanoma, especially in combination with novel immunotherapies, is warranted.

Neoadjuvant treatment for melanoma: current challenges and future perspectives

There will be an estimated 76,100 new cases of melanoma diagnosed in 2015 and 9710 deaths. Patients with stage I/II disease have excellent outcomes, and the treatment landscape for patients with metastatic disease has been transformed by the approval of several immune checkpoint inhibitors and molecular targeted therapies. Patients with stage III disease, however, continue to have very limited options, as the only agent shown to improve survival in the adjuvant setting is high-dose IFN-α. Neoadjuvant trials of chemotherapy and chemobiotherapy have not been successful, and while neoadjuvant ipilimumab and high-dose interferon have shown promise in small trials, neither agent has been approved. Current trials are testing immune therapy and targeted therapy combinations in the neoadjuvant setting.

Sarcomatoid lung carcinomas show high levels of programmed death ligand-1 (PD-L1) and strong immune-cell infiltration by TCD3 cells and macrophages

OBJECTIVES

Pulmonary sarcomatoid carcinomas (SC) are rare tumors, associated with worse prognosis and resistant to platinum-based regimens. Therapies targeting the PD-1/PD-L1 pathway are an emerging treatment for lung cancer. By characterizing intra-tumoral immune infiltration and evaluating PD-L1 expression, it could be possible to predict the efficacy of these new treatments.

MATERIALS AND METHODS

From 1997 to 2013, data from all patients with SC who underwent lung resection was collected. Tumor-immune infiltration and PD-L1 expression were studied by immunochemistry tests, analyzing CD3 (clone SP7), CD4 (clone 1F6), CD8 (clone C8/144b), CD20 (clone L26), CD163 (clone 10D6), MPO (clone 59A5), and PD-L1 (clone 5H1). Results were compared to those of 54 NSCLC.

RESULTS

In total, 75 SC were included. Forty (53%) SC expressed PD-L1 vs 11 NSCLC (20%) (p<0.0001). CD3+ tumor-infiltrating lymphocytes and CD163+ tumor-associated macrophages were more important in SC than in NSCLC (median 23% [17-30] of tumoral surface vs 17% [7-27], p=0.011 and 23% [17-30] vs 20% [13-23], p=0.002, respectively). In SC, the presence of Kirsten Ras (KRAS) mutations, blood vessel invasion, and TTF1+ positivity were associated with PDL1 expression. On multivariate analysis, only CD163+ macrophages and blood-vessel invasion were associated with tumoral PD-L1 expression. High levels of tumor-infiltrating lymphocytes (CD3+ or CD4+ and not CD8+) constituted a factor of good prognosis on survival. Interestingly, PD-L1 expression distinguishes subpopulations within tumor-infiltrating lymphocytes (CD3+ or CD4+) with different prognosis

CONCLUSIONS

PD-L1 expression was higher in SC than in NSCLC as well as immune-cell infiltration by TCD3 cells and macrophages. This suggests that targeting the PD-1/PD-L1 pathway could represent a new potential therapy.

Nivolumab: A Review in Advanced Melanoma

An improved understanding of cancer genetics and immune regulatory pathways, including those associated with evasion of immune surveillance by tumours, has culminated in the development of several targeted therapies. One such strategy that acts to negate evasion of immune surveillance by tumours is inhibition of the programmed cell death receptor-1 (PD-1) checkpoint pathway. Intravenous nivolumab (Opdivo(®)), a PD-1 checkpoint inhibitor, is approved or in pre-registration in various countries for use in adult patients with advanced melanoma, with the recommended monotherapy dosage being a 60-min infusion of 3 mg/kg once every 2 weeks. In well-designed multinational trials, as monotherapy or in combination with ipilimumab (a cytotoxic T-lymphocyte antigen 4 checkpoint inhibitor), nivolumab significantly improved clinical outcomes and had a manageable tolerability profile in adult patients with advanced melanoma with or without BRAF mutations. Nivolumab monotherapy was associated with a higher objective response rate (ORR) than chemotherapy in treatment-experienced patients and a higher ORR and prolonged progression-free survival (PFS) and overall survival than dacarbazine in treatment-naive patients. In combination with ipilimumab, nivolumab was associated with an improved ORR and prolonged PFS compared with ipilimumab monotherapy in treatment-naive patients. In addition, nivolumab monotherapy significantly prolonged PFS and improved ORRs compared with ipilimumab monotherapy. The optimal combination regimen for immune checkpoint inhibitors remains to be fully elucidated, with various combination regimens and different sequences of individual immunotherapies currently being investigated in ongoing clinical trials. Given the significant improvements in outcomes associated with nivolumab in clinical trials, nivolumab monotherapy or combination therapy is a valuable first-line or subsequent treatment option for adult patients with unresectable or metastatic melanoma, irrespective of BRAF mutation status.

The safety and efficacy of nivolumab for the treatment of advanced renal cell carcinoma

INTRODUCTION

Despite a variety of therapies for advanced advanced renal cell carcinoma (RCC) including vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKIs) and mammalian target of rapamycin (mTOR) inhibitors, outcomes for these patients are still not optimal. Immunotherapy with checkpoint inhibitors such as nivolumab, a fully human immunoglobulin (Ig) G4 PD-1 inhibitor antibody, is a promising development in RCC and provides a new therapeutic option for patients with advanced disease.

AREAS COVERED

This article reviews safety and efficacy data from the phase I, II, and III clinical trials that have led to the approval of nivolumab for the treatment of patients with advanced RCC who have previously been treated with VEGF-directed therapy. Expert Commentary: Given the overall survival advantage with nivolumab compared to previously approved therapy, nivolumab is a new standard of care in the second-line setting for patients with advanced RCC. Additional studies are underway to answer important questions including the identification of biomarkes and the use of nivolumab in treatment-naïve patients.

What Is New in Melanoma Genetics and Treatment?

New therapies for advanced melanoma have led to major advances, which, for the first time, showed improved survival for patients with this very challenging neoplasm. These new treatments are based on gene-targeted therapies or stimulation of immune responses. However, these treatments are not without challenges in terms of resistance and toxicity. Physicians should be aware of these side effects as prompt treatment may save lives. Melanoma genetics is also unravelling new genetic risk factors involving telomere genes as well as new gene pathways at the somatic level which may soon become therapeutic targets. It is also shedding new light onto the pathology of this tumour with links to neural diseases and longevity.

Concomitant targeting of programmed death-1 (PD-1) and CD137 improves the efficacy of radiotherapy in a mouse model of human BRAFV600-mutant melanoma

T cell checkpoint blockade with antibodies targeting programmed cell death (ligand)-1 (PD-1/PD-L1) and/or cytotoxic T lymphocyte-antigen 4 (CTLA-4) has improved therapy outcome in melanoma patients. However, a considerable proportion of patients does not benefit even from combined α-CTLA-4 and α-PD-1 therapy. We therefore examined to which extent T cell (co)stimulation and/or stereotactic body radiation therapy (SBRT) could further enhance the therapeutic efficacy of T cell checkpoint blockade in a genetically engineered mouse melanoma model that is driven by PTEN-deficiency, and BRAFV600 mutation, as in human, but lacks the sporadic UV-induced mutations. Tumor-bearing mice were treated with different combinations of immunomodulatory antibodies (α-CTLA-4, α-PD-1, α-CD137) or interleukin-2 (IL-2) alone or in combination with SBRT. None of our immunotherapeutic approaches (alone or in combination) had any anti-tumor efficacy, while SBRT alone delayed melanoma outgrowth. However, α-CD137 combined with α-PD-1 antibodies significantly enhanced the anti-tumor effect of SBRT, while the anti-tumor effect of SBRT was not enhanced by interleukin-2, or the combination of α-CTLA-4 and α-PD-1. We conclude that α-CD137 and α-PD-1 antibodies were most effective in enhancing SBRT-induced tumor growth delay in this mouse melanoma model, outperforming the ability of IL-2, or the combination of α-CTLA-4 and α-PD-1 to synergize with SBRT. Given the high mutational load and increased immunogenicity of human melanoma with the same genotype, our findings encourage testing α-CD137 and α-PD-1 alone or in combination with SBRT clinically, particularly in patients refractory to α-CTLA-4 and/or α-PD-1 therapy.

Roles of regulatory T cells in cancer immunity

CD4(+) regulatory T cells (Tregs) expressing the transcription factor FoxP3 are highly immune suppressive and play central roles in the maintenance of self-tolerance and immune homeostasis, yet in malignant tumors they promote tumor progression by suppressing effective antitumor immunity. Indeed, higher infiltration by Tregs is observed in tumor tissues, and their depletion augments antitumor immune responses in animal models. Additionally, increased numbers of Tregs and, in particular, decreased ratios of CD8(+) T cells to Tregs among tumor-infiltrating lymphocytes are correlated with poor prognosis in various types of human cancers. The recent success of cancer immunotherapy represented by immune checkpoint blockade has provided a new insight in cancer treatment, yet more than half of the treated patients did not experience clinical benefits. Identifying biomarkers that predict clinical responses and developing novel immunotherapies are therefore urgently required. Cancer patients whose tumors contain a large number of neoantigens stemming from gene mutations, which have not been previously recognized by the immune system, provoke strong antitumor T-cell responses associated with clinical responses following immune checkpoint blockade, depending on the resistance to Treg-mediated suppression. Thus, integration of a strategy restricting Treg-mediated immune suppression may expand the therapeutic spectrum of cancer immunotherapy towards patients with a lower number of neoantigens. In this review, we address the current understanding of Treg-mediated immune suppressive mechanisms in cancer, the involvement of Tregs in cancer immunotherapy, and strategies for effective and tolerable Treg-targeted therapy.

Atezolizumab in patients with locally advanced and metastatic urothelial carcinoma who have progressed following treatment with platinum-based chemotherapy: a single-arm, multicentre, phase 2 trial

BACKGROUND

Patients with metastatic urothelial carcinoma have few treatment options after failure of platinum-based chemotherapy. In this trial, we assessed treatment with atezolizumab, an engineered humanised immunoglobulin G1 monoclonal antibody that binds selectively to programmed death ligand 1 (PD-L1), in this patient population.

METHODS

For this multicentre, single-arm, two-cohort, phase 2 trial, patients (aged ≥18 years) with inoperable locally advanced or metastatic urothelial carcinoma whose disease had progressed after previous platinum-based chemotherapy were enrolled from 70 major academic medical centres and community oncology practices in Europe and North America. Key inclusion criteria for enrolment were Eastern Cooperative Oncology Group performance status of 0 or 1, measurable disease defined by Response Evaluation Criteria In Solid Tumors version 1.1 (RECIST v1.1), adequate haematological and end-organ function, and no autoimmune disease or active infections. Formalin-fixed paraffin-embedded tumour specimens with sufficient viable tumour content were needed from all patients before enrolment. Patients received treatment with intravenous atezolizumab (1200 mg, given every 3 weeks). PD-L1 expression on tumour-infiltrating immune cells (ICs) was assessed prospectively by immunohistochemistry. The co-primary endpoints were the independent review facility-assessed objective response rate according to RECIST v1.1 and the investigator-assessed objective response rate according to immune-modified RECIST, analysed by intention to treat. A hierarchical testing procedure was used to assess whether the objective response rate was significantly higher than the historical control rate of 10% at an α level of 0·05. This study is registered with ClinicalTrials.gov, number NCT02108652.

FINDINGS

Between May 13, 2014, and Nov 19, 2014, 486 patients were screened and 315 patients were enrolled into the study. Of these patients, 310 received atezolizumab treatment (five enrolled patients later did not meet eligibility criteria and were not dosed with study drug). The PD-L1 expression status on infiltrating immune cells (ICs) in the tumour microenvironment was defined by the percentage of PD-L1-positive immune cells: IC0 (<1%), IC1 (≥1% but <5%), and IC2/3 (≥5%). The primary analysis (data cutoff May 5, 2015) showed that compared with a historical control overall response rate of 10%, treatment with atezolizumab resulted in a significantly improved RECIST v1.1 objective response rate for each prespecified immune cell group (IC2/3: 27% [95% CI 19-37], p<0·0001; IC1/2/3: 18% [13-24], p=0·0004) and in all patients (15% [11-20], p=0·0058). With longer follow-up (data cutoff Sept 14, 2015), by independent review, objective response rates were 26% (95% CI 18-36) in the IC2/3 group, 18% (13-24) in the IC1/2/3 group, and 15% (11-19) overall in all 310 patients. With a median follow-up of 11·7 months (95% CI 11·4-12·2), ongoing responses were recorded in 38 (84%) of 45 responders. Exploratory analyses showed The Cancer Genome Atlas (TCGA) subtypes and mutation load to be independently predictive for response to atezolizumab. Grade 3-4 treatment-related adverse events, of which fatigue was the most common (five patients [2%]), occurred in 50 (16%) of 310 treated patients. Grade 3-4 immune-mediated adverse events occurred in 15 (5%) of 310 treated patients, with pneumonitis, increased aspartate aminotransferase, increased alanine aminotransferase, rash, and dyspnoea being the most common. No treatment-related deaths occurred during the study.

INTERPRETATION

Atezolizumab showed durable activity and good tolerability in this patient population. Increased levels of PD-L1 expression on immune cells were associated with increased response. This report is the first to show the association of TCGA subtypes with response to immune checkpoint inhibition and to show the importance of mutation load as a biomarker of response to this class of agents in advanced urothelial carcinoma.

FUNDING

F Hoffmann-La Roche Ltd.

Cancer immunotherapy: the beginning of the end of cancer?

These are exciting times for cancer immunotherapy. After many years of disappointing results, the tide has finally changed and immunotherapy has become a clinically validated treatment for many cancers. Immunotherapeutic strategies include cancer vaccines, oncolytic viruses, adoptive transfer of ex vivo activated T and natural killer cells, and administration of antibodies or recombinant proteins that either costimulate cells or block the so-called immune checkpoint pathways. The recent success of several immunotherapeutic regimes, such as monoclonal antibody blocking of cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD1), has boosted the development of this treatment modality, with the consequence that new therapeutic targets and schemes which combine various immunological agents are now being described at a breathtaking pace. In this review, we outline some of the main strategies in cancer immunotherapy (cancer vaccines, adoptive cellular immunotherapy, immune checkpoint blockade, and oncolytic viruses) and discuss the progress in the synergistic design of immune-targeting combination therapies.

Nivolumab in combination with ipilimumab for the treatment of melanoma

Melanoma patients develop resistance to most therapies, including chemo- and targeted-therapy drugs. Single-agent therapies are ineffective due to the heterogeneous nature of tumors comprising several subpopulations. Treatment of melanoma with immune-based therapies such as anti-cytotoxic T-lymphocyte activation-4 and anti-programmed death-1 antibodies has shown modest but long-lasting responses. Unfortunately, only subsets of melanoma patients respond to antibody-based therapies. Heterogeneity in lymphocyte infiltration and low frequency of anti-melanoma-reactive T-cells in tumor lesions are partly responsible for a lack of response to antibody-based therapies. Both antibodies have same biological function but they bind to different ligands at various phases of T-cell activity. Thus, combination therapy of antibodies has shown superior response rates than single-agent therapy. However, toxicity is a cause of concern in these therapies. Future identification of therapy-response biomarkers, mobilization of tumor-reactive T-cell infiltration using cancer vaccines, or non-specific targeted-therapy drugs will minimize toxicity levels and provide long-term remissions in melanoma patients.

Harnessing the immune system for the treatment of melanoma: current status and future prospects

When malignant melanoma is diagnosed early, surgical resection is the intervention of choice and is often curative, but many patients present with unresectable disease at later stages. Due to its complex etiology paired with well-documented chemoresistance and high metastatic potential, patients with advanced melanoma had a poor prognosis, and the treatment of this disease remained unsatisfactory for many years. Recently, targeted therapy, immune checkpoint inhibition, or combinatory approaches have revolutionized the therapeutic options of melanoma allowing considerable improvement in disease control and survival. In this review we will summarize these novel therapeutic strategies with particular focus on combinatory immunotherapies and further discuss recent data derived from immunogenomic studies and potential options to improve the therapeutic efficacy of immune modulatory approaches.

Ipilimumab (Anti-Ctla-4 Mab) in the treatment of metastatic melanoma: Effectiveness and toxicity management

In the last years the onset of new therapies changed the management of malignant melanoma. Anti CTLA-4 antibody ipilimumab was the first drug to achieve a significant improvement in survival of advanced stage melanoma. This new therapeutic agent is characterized by a number of side effects that are totally different from those of traditional chemotherapy, mainly caused by the immune system activation. The purpose of this paper is to underline the central role of ipilimumab in the treatment of metastatic melanoma and to characterize related adverse events in terms of incidence, duration and severity of presentation. The early recognition of these side effects is crucial in order to ensure an appropriate management of the toxicities, thus reducing the long term clinical sequelae and the inappropriate treatment discontinuation.

Current Challenges in Cancer Treatment

PURPOSE

In this review, we highlight the current concepts and discuss some of the current challenges and future prospects in cancer therapy. We frequently use the example of lung cancer.

METHODS

We conducted a nonsystematic PubMed search, selecting the most comprehensive and relevant research articles, clinical trials, translational papers, and review articles on precision oncology and immuno-oncology. Papers were prioritized and selected based on their originality and potential clinical applicability.

FINDINGS

Two major revolutions have changed cancer treatment paradigms in the past few years: targeting actionable alterations in oncogene-driven cancers and immuno-oncology. Important challenges are still ongoing in both fields of cancer therapy. On the one hand, druggable genomic alterations are diverse and represent only small subsets of patients in certain tumor types, which limits testing their clinical impact in biomarker-driven clinical trials. Next-generation sequencing technologies are increasingly being implemented for molecular prescreening in clinical research, but issues regarding clinical interpretation of large genomic data make their wide clinical use difficult. Further, dealing with tumor heterogeneity and acquired resistance is probably the main limitation for the success of precision oncology. On the other hand, long-term survival benefits with immune checkpoint inhibitors (anti-programmed death cell protein-1/programmed death cell ligand-1[PD-1/L1] and anti-cytotoxic T lymphocyte antigen-4 monoclonal antibodies) are restricted to a minority of patients, and no predictive markers are yet robustly validated that could help us recognize these subsets and optimize treatment delivery and selection. To achieve long-term survival benefits, drug combinations targeting several molecular alterations or cancer hallmarks might be needed. This will probably be one of the most challenging but promising precision cancer treatment strategies in the future.

IMPLICATIONS

Targeting single molecular abnormalities or cancer pathways has achieved good clinical responses that have modestly affected survival in some cancers. However, this approach to cancer treatment is still reductionist, and many challenges need to be met to improve treatment outcomes with our patients.

Immunotherapy of cancer: from monoclonal to oligoclonal cocktails of anti-cancer antibodies: IUPHAR Review 18

Antibody-based therapy of cancer employs monoclonal antibodies (mAbs) specific to soluble ligands, membrane antigens of T-lymphocytes or proteins located at the surface of cancer cells. The latter mAbs are often combined with cytotoxic regimens, because they block survival of residual fractions of tumours that evade therapy-induced cell death. Antibodies, along with kinase inhibitors, have become in the last decade the mainstay of oncological pharmacology. However, partial and transient responses, as well as emergence of tumour resistance, currently limit clinical application of mAbs. To overcome these hurdles, oligoclonal antibody mixtures are being tested in animal models and in clinical trials. The first homo-combination of two mAbs, each engaging a distinct site of HER2, an oncogenic receptor tyrosine kinase (RTK), has been approved for treatment of breast cancer. Likewise, a hetero-combination of antibodies to two distinct T-cell antigens, PD1 and CTLA4, has been approved for treatment of melanoma. In a similar vein, additive or synergistic anti-tumour effects observed in animal models have prompted clinical testing of hetero-combinations of antibodies simultaneously engaging distinct RTKs. We discuss the promise of antibody cocktails reminiscent of currently used mixtures of chemotherapeutics and highlight mechanisms potentially underlying their enhanced clinical efficacy.

TG4010: a vaccine with a therapeutic role in cancer

One of the strategies to enhance immune response against tumors has been the use of vaccines against tumor-associated antigens (TAAs). MUC1 is a TAA that is overexpressed in many malignancies being linked to worse prognosis. Moreover, tumor MUC1 is hypoglycosylated revealing new epitopes that are antigenic and potential T-cell targets. TG4010 is a recombinant viral vaccine targeting MUC1, also encoding for IL-2. TG4010 has been tested in Phase I-II trials demonstrating a consistent safety profile with mild local reactions as main side effect. These studies have confirmed immune responses to the vaccine product. Clinical efficacy has been observed mainly in patients with non-small-cell lung cancer in combination with chemotherapy. Peripheral activated NK cells are currently being validated as biomarkers of response.

Mechanism-driven biomarkers to guide immune checkpoint blockade in cancer therapy

With recent approvals for multiple therapeutic antibodies that block cytotoxic T lymphocyte associated antigen 4 (CTLA4) and programmed cell death protein 1 (PD1) in melanoma, non-small-cell lung cancer and kidney cancer, and additional immune checkpoints being targeted clinically, many questions still remain regarding the optimal use of drugs that block these checkpoint pathways. Defining biomarkers that predict therapeutic effects and adverse events is a crucial mandate, highlighted by recent approvals for two PDL1 diagnostic tests. Here, we discuss biomarkers for anti-PD1 therapy based on immunological, genetic and virological criteria. The unique biology of the CTLA4 immune checkpoint, compared with PD1, requires a different approach to biomarker development. Mechanism-based insights from such studies may guide the design of synergistic treatment combinations based on immune checkpoint blockade.

HemOnc Today Melanoma and Cutaneous Malignancies and American College of Cardiology

Key sessions at HemOnc Today covered systemic and locoregional use of immunotherapies. At the cardiology meeting, preventive strategies took center stage.

Immune checkpoint blockade: Releasing the brake towards hematological malignancies

Tumor cells utilize co-inhibitory molecules to avoid host immune destruction. Checkpoint blockade has emerged as a promising approach to treat cancer by restoring T cell effector function and breaking a tumor permissive microenvironment. Patients with hematological malignancies often have immune dysregulation, thus the role of checkpoint blockade in treatment of these neoplasms is particularly intriguing. In early trials, antibodies targeting cytotoxic T lymphocyte antigen 4 (CTLA-4) or the programmed death 1 (PD-1) signaling pathway have displayed significant efficacy with minimal toxicity in patients with relapsed and refractory hematological neoplasms. In this review, we provide evidence of dysregulation of CTLA-4 and PD-1/PD-Ls in the context of several major types of hematological neoplasms and summarize relevant clinical practice points for checkpoint blockade. The preclinical rationale and preliminary clinical data of potential combination approaches designed to optimize checkpoint antagonists are well presented.

Use of big data in drug development for precision medicine

Drug development has been a costly and lengthy process with an extremely low success rate and lack of consideration of individual diversity in drug response and toxicity. Over the past decade, an alternative "big data" approach has been expanding at an unprecedented pace based on the development of electronic databases of chemical substances, disease gene/protein targets, functional readouts, and clinical information covering inter-individual genetic variations and toxicities. This paradigm shift has enabled systematic, high-throughput, and accelerated identification of novel drugs or repurposed indications of existing drugs for pathogenic molecular aberrations specifically present in each individual patient. The exploding interest from the information technology and direct-to-consumer genetic testing industries has been further facilitating the use of big data to achieve personalized Precision Medicine. Here we overview currently available resources and discuss future prospects.

Metastatic colonization by circulating tumour cells

Metastasis is the main cause of death in people with cancer. To colonize distant organs, circulating tumour cells must overcome many obstacles through mechanisms that we are only now starting to understand. These include infiltrating distant tissue, evading immune defences, adapting to supportive niches, surviving as latent tumour-initiating seeds and eventually breaking out to replace the host tissue. They make metastasis a highly inefficient process. However, once metastases have been established, current treatments frequently fail to provide durable responses. An improved understanding of the mechanistic determinants of such colonization is needed to better prevent and treat metastatic cancer.

Trametinib in metastatic melanoma

The treatment of metastatic melanoma is rapidly changing. In 2002, the BRAF mutation was described in over 50% of melanomas and led to the first BRAF inhibitor, vemurafenib, being approved for clinical use in 2011. Clinical responses are often rapid but duration of response is limited due to the development of resistance. MEK is the next downstream target from BRAF in the MAP kinase pathway. Trametinib was the first MEK inhibitor to be approved for clinical use in 2013. Preclinical studies demonstrated a delay in resistance and a reduction in cutaneous toxicity by combined BRAF and MEK inhibition. Here, we review the rationale for clinical development of trametinib and give an update on recent clinical trials of trametinib alone and in combination with braf inhibition in melanoma.

The steady progress of targeted therapies, promising advances for lung cancer

Lung cancer remains one of the most complex and challenging cancers, being responsible for almost a third of all cancer deaths. This grim picture seems however to be changing, for at least a subset of lung cancers. The number of patients who can benefit from targeted therapies is steadily increasing thanks to the progress made in identifying actionable driver lesions in lung tumours. The success of the latest generation of EGFR and ALK inhibitors in the clinic not only illustrates the value of targeted therapies, but also shows how almost inevitably drug resistance develops. Therefore, more sophisticated approaches are needed to achieve long-term remissions. Although there are still significant barriers to be overcome, technological advances in early detection of relevant mutations and the opportunity to test new drugs in predictive preclinical models justify the hope that we will overcome these obstacles.

Cellular Immune Responses and Immune Escape Mechanisms in Breast Cancer: Determinants of Immunotherapy

More recently, immunotherapy has emerged as a novel potentially effective therapeutic option also for solid malignancies such as breast cancer (BC). Relevant approaches, however, are determined by the 2 main elements of cancer immunoediting - the elimination of nascent transformed cells by immunosurveillance on the one hand and tumor immune escape on the other hand. Correspondingly, we here review the role of the various cellular immune players within the host-protective system and dissect the mechanisms of immune evasion leading to tumor progression. If the immune balance of disseminated BC cell dormancy (equilibrium phase) is lost, distant metastatic relapse may occur. The relevant cellular antitumor responses and translational immunotherapeutic options will also be discussed in terms of clinical benefit and future directions in BC management.

Timing of CSF-1/CSF-1R signaling blockade is critical to improving responses to CTLA-4 based immunotherapy

Colony stimulating factor-1 (CSF-1) is produced by a variety of cancers and recruits myeloid cells that suppress antitumor immunity, including myeloid-derived suppressor cells (MDSCs.) Here, we show that both CSF-1 and its receptor (CSF-1R) are frequently expressed in tumors from cancer patients, and that this expression correlates with tumor-infiltration of MDSCs. Furthermore, we demonstrate that these tumor-infiltrating MDSCs are highly immunosuppressive but can be reprogrammed toward an antitumor phenotype in vitro upon CSF-1/CSF-1R signaling blockade. Supporting these findings, we show that inhibition of CSF-1/CSF-1R signaling using an anti-CSF-1R antibody can regulate both the number and the function of MDSCs in murine tumors in vivo. We further find that treatment with anti-CSF-1R antibody induces antitumor T-cell responses and tumor regression in multiple tumor models when combined with CTLA-4 blockade therapy. However, this occurs only when administered after or concurrent with CTLA-4 blockade, indicating that timing of each therapeutic intervention is critical for optimal antitumor responses. Importantly, MDSCs present within murine tumors after CTLA-4 blockade showed increased expression of CSF-1R and were capable of suppressing T cell proliferation, and CSF-1/CSF-1R expression in the human tumors was not reduced after treatment with CTLA-4 blockade immunotherapy. Taken together, our findings suggest that CSF-1R-expressing MDSCs can be targeted to modulate the tumor microenvironment and that timing of CSF-1/CSF-1R signaling blockade is critical to improving responses to checkpoint based immunotherapy.

SIGNIFICANCE

Infiltration by immunosuppressive myeloid cells contributes to tumor immune escape and can render patients resistant or less responsive to therapeutic intervention with checkpoint blocking antibodies. Our data demonstrate that blocking CSF-1/CSF-1R signaling using a monoclonal antibody directed to CSF-1R can regulate both the number and function of tumor-infiltrating immunosuppressive myeloid cells. In addition, our findings suggest that reprogramming myeloid responses may be a key in effectively enhancing cancer immunotherapy, offering several new potential combination therapies for future clinical testing. More importantly for clinical trial design, the timing of these interventions is critical to achieving improved tumor protection.

Phase II Study of Autologous Monocyte-Derived mRNA Electroporated Dendritic Cells (TriMixDC-MEL) Plus Ipilimumab in Patients With Pretreated Advanced Melanoma

Purpose

Autologous monocyte-derived dendritic cells (DCs) electroporated with synthetic mRNA (TriMixDC-MEL) are immunogenic and have antitumor activity as a monotherapy in patients with pretreated advanced melanoma. Ipilimumab, an immunoglobulin G1 monoclonal antibody directed against the cytotoxic T-lymphocyte-associated protein 4 receptor that counteracts physiologic suppression of T-cell function, improves the overall survival of patients with advanced melanoma. This phase II study investigated the combination of TriMixDC-MEL and ipilimumab in patients with pretreated advanced melanoma.

Patients and Methods

Thirty-nine patients were treated with TriMixDC-MEL (4 × 106 cells administered intradermally and 20 × 106 cells administered intravenously) plus ipilimumab (10 mg/kg every 3 weeks for a total of four administrations, followed by maintenance therapy every 12 weeks in patients who remained progression free). Six-month disease control rate according to the immune-related response criteria served as the primary end point.

Results

The 6-month disease control rate was 51% (95% CI, 36% to 67%), and the overall tumor response rate was 38% (including eight complete and seven partial responses). Seven complete responses and one partial tumor response are ongoing after a median follow-up time of 36 months (range, 22 to 43 months). The most common treatment-related adverse events (all grades) consisted of local DC injection site skin reactions (100%), transient post–DC infusion chills (38%) and flu-like symptoms (84%), dermatitis (64%), hepatitis (13%), hypophysitis (15%), and diarrhea/colitis (15%). Grade 3 or 4 immune-related adverse events occurred in 36% of patients. There was no grade 5 adverse event.

Conclusion

The combination of TriMixDC-MEL and ipilimumab is tolerable and results in an encouraging rate of highly durable tumor responses in patients with pretreated advanced melanoma.

Tumor control with PD-1 inhibition in a patient with concurrent metastatic melanoma and renal cell carcinoma

Blockade of the immunological checkpoint programmed death 1 (PD-1) using monoclonal antibodies has shown robust anti-tumor activity across a broad range of solid and hematological malignancies including melanoma and renal cell carcinoma (RCC). Characteristic markers such as the presence of tumor infiltrating lymphocytes, PD-L1 status, and mutational load may be equally or even more important in predicting clinical benefit from PD-1 pathway blockade than tumor histology. This case of a patient with concurrent metastatic melanoma and metastatic RCC, both of which were controlled for more than a year after a single dose of the anti-PD-1 antibody pembrolizumab, illustrates the potential to simultaneously treat distinct immunogenic tumors with anti-PD-1 agents.

Adapting Cancer Immunotherapy Models for the Real World

Early experiments in mice predicted the success of checkpoint blockade immunotherapy in cancer patients. However, these same animal studies failed to accurately predict many of the limitations and toxicities of treatment. One of the likely reasons for this discrepancy is the nearly universal use of young healthy mice, which stand in stark contrast to diverse patient populations varying in age, weight, diet, and hygiene. Because these variables impact immunity and metabolism, they also influence outcomes during immunotherapy and should be incorporated into the study design of preclinical experiments. Here, we discuss recent findings that highlight how efficacy and toxicity of cancer immunotherapy are affected by patient variation, and how distinct host environments can be better modeled in animal studies.

Immune checkpoint inhibitors: a patent review (2010-2015)

INTRODUCTION

Immune checkpoint inhibitors, like anti-PD-1/PD-L1 antibodies, are revolutionizing therapeutic concepts in the treatment of cancer. Said class of drugs will represent a multi-billion dollar market over the coming decade. Many companies have therefore developed important patent activities in the field.

AREAS COVERED

The present review gives an overview of the patent literature during the period 2010-2015 in the field of immune checkpoint inhibitors. In particular, the review presents a selection of international patent applications related to inhibitors of PD-1/PD-L1, CTLA-4, IDO, TIM3, LAG3, TIGIT, BTLA, VISTA, ICOS, KIRs and CD39.

EXPERT OPINION

Immune checkpoint inhibitors are now widely accepted as a key component of the therapeutic strategies in cancer. This fervent activity creates a maze of third-party patents that pose considerable risks for both newcomers and established companies. We can thus anticipate that the number of patent conflicts and disputes will increase in the near future. Treatments will involve combination therapy comprising at least one immune checkpoint inhibitor and companies will multiply patent filings in this field. Finally, we can expect that patents related to biomarkers that will render a patient eligible to a treatment with an immune checkpoint inhibitor will have tremendous commercial value.

Isolation of Pancreatic Cancer Cells from a Patient-Derived Xenograft Model Allows for Practical Expansion and Preserved Heterogeneity in Culture

Commercially available, highly passaged pancreatic cancer (PC) cell lines are of limited translational value. Attempts to overcome this limitation have primarily consisted of cancer cell isolation and culture directly from human PC specimens. However, these techniques are associated with exceedingly low success rates. Here, we demonstrate a highly reproducible culture of primary PC cell lines (PPCLs) from patient-derived xenografts, which preserve, in part, the intratumoral heterogeneity known to exist in PC. PPCL expansion from patient-derived xenografts was successful in 100% of attempts (5 of 5). Phenotypic analysis was evaluated with flow cytometry, immunofluorescence microscopy, and short tandem repeat profiling. Importantly, tumorigenicity of PPCLs expanded from patient-derived xenografts was assessed by subcutaneous injection into nonobese diabeteic.Cg-Prkdc(scid)Il2rg(tm1Wjl)/SzJ mice. Morphologically, subcutaneous injection of all PPCLs into mice yielded tumors with similar characteristics to the parent xenograft. PPCLs uniformly expressed class I human leukocyte antigen, epithelial cell adhesion molecule, and cytokeratin-19. Heterogeneity within each PPCL persisted in culture for the frequency of cells expressing the cancer stem cell markers CD44, CD133, and c-Met and the immunologic markers human leukocyte antigen class II and programmed death ligand 1. This work therefore presents a reliable method for the rapid expansion of primary human PC cells and, thereby, provides a platform for translational investigation and, importantly, potential personalized therapeutic approaches.

The significance and therapeutic potential of PD-1 and its ligands in ovarian cancer: A systematic review

Surgery, radiotherapy and chemotherapy are the mainstay of malignant cancer treatments. However, with the development of immunology, the emerging immunotherapy represents a rational and alternative approach for the treatment of human cancer, including ovarian cancer (OC). Based on a body of evidence and the clinical success of immunotherapy in many malignancies, it is confirmed that blocking the programmed death 1 (PD-1) and its ligands in OC is feasible and valid both in animal models and patients. Immunotherapy may play a significant role in the future clinical management and improve the prognosis of OC. This review will focus on the biological functions, treatment response, toxicity and viable target of PD-1 and its ligands in OC. Recognition of the multiple functions of PD-1 and its ligands in ovarian cancer will serve to deepen our understanding of the nature of OC, develop novel immunotherapy approaches and discover possible diagnostic and prognostic biomarkers in future clinical decisions.

Cutaneous, gastrointestinal, hepatic, endocrine, and renal side-effects of anti-PD-1 therapy

BACKGROUND

Anti-programmed cell death receptor-1 (PD-1) antibodies represent an effective treatment option for metastatic melanoma as well as for other cancer entities. They act via blockade of the PD-1 receptor, an inhibitor of the T-cell effector mechanisms that limit immune responses against tumours. As reported for ipilimumab, the anti-PD-1 antibodies pembrolizumab and nivolumab can induce immune-related adverse events (irAEs). These side-effects affect skin, gastrointestinal tract, liver, endocrine system and other organ systems. Since life-threatening and fatal irAEs have been reported, adequate diagnosis and management are essential.

METHODS AND FINDINGS

In total, 496 patients with metastatic melanoma from 15 skin cancer centers were treated with pembrolizumab or nivolumab; 242 side-effects were described in 138 patients. In 116 of the 138 patients, side-effects affected the skin, gastrointestinal tract, liver, endocrine, and renal system. Rare side-effects included diabetes mellitus, lichen planus, and pancreas insufficiency due to pancreatitis.

CONCLUSION

Anti-PD1 antibodies can induce a plethora of irAEs. The knowledge of them will allow prompt diagnosis and improve the management resulting in decreased morbidity.

Embracing rejection: Immunologic trends in brain metastasis

Brain metastases represent the most common type of brain tumor. These tumors offer a dismal prognosis and significantly impact quality of life for patients. Their capacity for central nervous system (CNS) invasion is dependent upon induced disruptions to the blood-brain barrier (BBB), alterations to the brain microenvironment, and mechanisms for escaping CNS immunosurveillance. In the emerging era of immunotherapy, understanding how metastases are influenced by the immunologic peculiarities of the CNS will be crucial to forging therapeutic advances. In this review, the immunology of brain metastasis is explored.

Long-term drug costs per life-month gained associated with first-line treatments for unresectable or metastatic melanoma

BACKGROUND

For unresectable or metastatic melanoma, first-line ipilimumab has demonstrated long-term survival benefits over a 7-year period. First-line treatment with BRAF inhibitors has demonstrated efficacy in clinical trials with up to 3 years of follow-up. The long-term comparative efficacy and costs of ipilimumab and BRAF inhibitors are unknown.

METHODS

Patient-level data from 12 clinical studies for ipilimumab were used. Survival data were extracted from included clinical trials for BRAF inhibitors based on a systematic literature review. Different parametric survival models, including exponential, Gompertz, log-normal, and Weibull models, were used to fit reported overall survival (OS) data and to project long-term survival for BRAF inhibitors. Survival benefits were measured in terms of total life-months gained as calculated by the area under the curve of OS Kaplan-Meier curves for the observed ipilimumab data and projected BRAF inhibitor data. Total life-months gained and cumulative costs per life-month gained were compared between ipilimumab and BRAF inhibitors.

RESULTS

The systematic literature review identified six randomized-controlled trials of BRAF inhibitors for subsequent analyses. With 7-year follow-up, ipilimumab was associated with a total of 28.5 life-months gained. Based on the Weibull model, the extrapolated total life-months gained for BRAF inhibitors were 26.5 months for dabrafenib, 21.3 months for trametinib, 14.3 months for vemurafenib, and 24.6 months for dabrafenib + trametinib. In sensitivity analyses, extrapolated total life-months gained varied across the three other models, ranging from 13.7 to 36.8 months across therapies. Cumulative costs per life-month gained with ipilimumab decreased steadily over time, while the costs remained constant for BRAF inhibitors due to continuous dosing. By year 3, cumulative costs per life-month gained were the lowest with ipilimumab; by year 7, the costs were $4281 for ipilimumab, compared with $8920 for dabrafenib, $10,211 for trametinib, $11,002 for vemurafenib, and $19,132 for the dabrafenib + trametinib combination therapy.

CONCLUSIONS

Ipilimumab was associated with a better long-term cost-per-life month compared to BRAF agents. Long-term extrapolation of survival with BRAF agents was uncertain, and showed no evidence of prolonged survival compared to ipilimumab.

The role of neoantigens in response to immune checkpoint blockade

Immune checkpoint blockade has demonstrated substantial promise for the treatment of several advanced malignancies. These agents activate the immune system to attack tumor cells. For example, agents targeting CTLA4 and programmed cell death 1 (PD-1) have resulted in impressive response rates and, in some cases, durable remissions. Neoantigens are mutations that encode immunologically active proteins that can cause the immune system to recognize the affected cell as foreign. Recent data have made it clear that these mutations are, in large part, the functional targets of immune checkpoint blockade. This review summarizes the key discoveries leading up to this important conclusion and discusses possible applications of neoantigens in cancer therapy.

Predictive and Prognostic Clinical Variables in Cancer Patients Treated With Adenoviral Oncolytic Immunotherapy

The development of oncolytic viruses has recently made great progress towards being available to cancer patients. With the breakthrough into clinics, it is crucial to analyze the existing clinical experience and use it as a basis for treatment improvements. Here, we report clinical data from 290 patients treated with oncolytic adenovirus. Using clinical variables and treatment characteristics, we constructed statistical models with regard to treatment response and overall survival (OS). Additionally, we investigated effects of neutralizing antibodies, tumor burden, and peripheral blood leucocyte counts on these outcomes. We found the absence of liver metastases to correlate with an improved rate of disease control (P = 0.021). In multivariate evaluation, patients treated with viruses coding for immunostimulatory granulocyte macrophage colony-stimulating factor were linked to better prognosis (hazard ratio (HR) 0.378, P < 0.001), as well as women with any cancer type (HR 0.694, P = 0.017). In multivariate analysis for imaging response, patients treated via intraperitoneal injection were more likely to achieve disease control (odds ratio (OR) 3.246, P = 0.027). Patients with low neutrophil-to-lymphocyte ratio before treatment had significantly longer OS (P < 0.001). These findings could explain some of the variation seen in treatment outcomes after virotherapy. Furthermore, the results offer hypotheses for treatment optimization and patient selection in oncolytic adenovirus immunotherapy.

Combination Therapies for Melanoma: A New Standard of Care?

Recent data have demonstrated improved survival with targeted and immune therapies in patients with advanced melanoma, leading to much excitement amongst the oncology community and the widespread use of these drugs in combination regimens. However, the place of these combination therapies in the treatment of advanced melanoma remains to be fully determined. In this perspectives article, we critically review the available data and outline the rationale for these combinations being adopted as the standard of care for patients with advanced melanoma in the future.

Prospective identification of neoantigen-specific lymphocytes in the peripheral blood of melanoma patients

Detection of lymphocytes that target tumor-specific mutant neoantigens--derived from products encoded by mutated genes in the tumor--is mostly limited to tumor-resident lymphocytes, but whether these lymphocytes often occur in the circulation is unclear. We recently reported that intratumoral expression of the programmed cell death 1 (PD-1) receptor can guide the identification of the patient-specific repertoire of tumor-reactive CD8(+) lymphocytes that reside in the tumor. In view of these findings, we investigated whether PD-1 expression on peripheral blood lymphocytes could be used as a biomarker to detect T cells that target neoantigens. By using a high-throughput personalized screening approach, we identified neoantigen-specific lymphocytes in the peripheral blood of three of four melanoma patients. Despite their low frequency in the circulation, we found that CD8(+)PD-1(+), but not CD8(+)PD-1(-), cell populations had lymphocytes that targeted 3, 3 and 1 unique, patient-specific neoantigens, respectively. We show that neoantigen-specific T cells and gene-engineered lymphocytes expressing neoantigen-specific T cell receptors (TCRs) isolated from peripheral blood recognized autologous tumors. Notably, the tumor-antigen specificities and TCR repertoires of the circulating and tumor-infiltrating CD8(+)PD-1(+) cells appeared similar, implying that the circulating CD8(+)PD-1(+) lymphocytes could provide a window into the tumor-resident antitumor lymphocytes. Thus, expression of PD-1 identifies a diverse and patient-specific antitumor T cell response in peripheral blood, providing a novel noninvasive strategy to develop personalized therapies using neoantigen-reactive lymphocytes or TCRs to treat cancer.

Emerging Tissue and Blood-Based Biomarkers that may Predict Response to Immune Checkpoint Inhibition

The immune system plays an essential role in the surveillance and eradication of neoplastic cells. This interaction is modulated via immunologic regulators (checkpoints). Antibodies that block the checkpoints cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), and the programmed cell death protein 1 pathway (PD1/PD-L1) have demonstrated efficacy in a number of malignancies. However, response rates are variable, and administration of these antibodies can be associated with immune-related adverse events. Therefore, researchers are engaged in an effort to discover biomarkers that may predict response to these agents. This review focuses on potential blood and tumor-based biomarkers that have been assessed in patients treated with these checkpoint-blocking antibodies.