Brucea javanica oil emulsion significantly improved the effect of anti-programmed cell death protein-1 immunotherapy

BACKGROUND

Brucea javanica oil (BJO) is the active substance extracted from the dry and mature fruit of Brucea javanica. Its pharmaceutical preparation, BJO emulsion (BJOE), is one of the most widely studied traditional Chinese medicine preparations for the treatment of malignancy. However, the unrevealed anti-tumor mechanism immensely limits further development of BJOE.

PURPOSE

In this study, we delved into the anti-tumor mechanism of commercial BJOE, including its influence on the tumor microenvironment (TME) and the treatment effect when combined with anti-programmed cell death protein-1 (PD-1) therapy.

METHODS

The cytotoxicity of BJOE was tested in different cells in vitro, and a Förster resonance energy transfer system was also constructed to predict the release behavior of BJOE in vivo. Then, a B16 melanoma mouse model was used to explore the combination of BJOE and anti-mouse PD-1 antibody therapy. In addition, mass cytometry was used to test the impact of both drugs on the TME.

RESULTS

Out data revealed that BJOE did not directly kill tumor cells in vitro. However, BJOE was mainly released at the tumor site, converting an immunosuppressive TME into an immune-activated state, and its combination with anti-PD-1 therapy significantly inhibited the growth of melanoma and prolonged the survival time of the mice due to an increase in cytotoxic T lymph (CD8⁺ T) and helper/inducible T lymph (CD4⁺ T) cells in lymph nodes and tumors.

CONCLUSIONS

Our work explored the anti-tumor mechanism of commercial BJOE and the regulation of cytokines by BJOE when it was combined with anti-PD-1 therapy in vivo. The combination of these therapies could increase the numbers of CD4⁺ T-cells, CD8⁺ T-cells, and effective natural killer cells and the ratio of MI/M2 macrophages in tumor tissues, promoting inflammatory activity and enhancing the anti-tumor effect. This study provides a theoretical basis for advancing the modern development of traditional Chinese medicine preparations and stands as a reference for clinically improving the efficacy of PD-1 antibodies.

Brief Report of Anti-Programmed Cell Death Protein-1 in Human Immunodeficiency Virus Setting: Relevant and Breaking Results in First-Line NSCLC Therapy

In the recent past, we observed an increased risk of cancer in the population with human immunodeficiency virus (HIV) owing to the development of antiretroviral therapies that decreased mortality caused by HIV-specific infections. This particularly fragile population is frequently excluded from clinical trials, and up-to-date recommendations for these patients are lacking. Only few cases of patients with HIV suffering from cancer and undergoing first-line immunotherapy have been reported so far. Here, we report the largest known study of patients with HIV with NSCLC (five patients) undergoing first-line immunotherapy by pembrolizumab, after CANCERVIH group selection. Our results are consistent with those of previous case reports concerning safety of immunotherapy in patients with HIV, revealing no severe or fatal toxicity, opportunistic infections, or immune reconstitution inflammatory syndrome. Moreover, pembrolizumab did not seem to modify HIV viral parameters. We also evaluated the effectiveness of immunotherapy in these HIV-immunosuppressed patients: the average survival was 9.8 months, with three patients having rapid progression and two partial response. Nevertheless, besides safety and drug-to-drug interactions, the effectiveness of first-line immunotherapy in people living with HIV needs to be supported by larger studies.

Novel PD-1 inhibitor prolgolimab: expanding non-resectable/metastatic melanoma therapy choice

BACKGROUND

Prolgolimab is an IgG1 anti-PD-1 (programmed cell death protein 1) monoclonal antibody containing the Fc-silencing 'LALA' mutation. We assessed the efficacy and safety of two dosing regimens of prolgolimab in patients with advanced melanoma in a multicenter open-label parallel-arm phase II trial (MIRACULUM). We present the final analysis after 1 year of follow-up and additional efficacy results from 2 years of follow-up.

METHODS

Patients with advanced cutaneous or non-cutaneous melanoma, including stable brain metastasis, without autoimmune disease and who underwent no prior targeted therapy, anti-PD-(L)1 or anti-CTLA-4 (cytotoxic T-lymphocyte-associated protein 4) therapy were randomly assigned (1:1) to receive prolgolimab in 2 dosing regimens, 1 mg/kg every 2 weeks (arm 1) or 3 mg/kg every 3 weeks (arm 2), until disease progression or intolerable toxicity. Randomisation was stratified based on performance status (Eastern Cooperative Oncology Group 0 or 1), lactate dehydrogenase levels (elevated or normal) and prior systemic therapy (naive or previously treated). The primary outcome was the objective response rate, assessed as per immune-related Response Evaluation Criteria in Solid Tumours by independent central review. The hypothesis that each dosing regimen of prolgolimab has an overall response rate >28% was tested independently for each study arm comprising all patients who received at least one dose of prolgolimab. Exploratory assessment of efficacy, including subgroup analysis, at 2 years of follow-up was not specified in the protocol. This study is registered withClinicalTrials.gov(NCT03269565).

RESULTS

Between August 2017 and March 2018, 126 patients with advanced melanoma were enrolled. At main 1-year data cut-off, the median follow-up was 13.8 and 14.5 months in arm 1 and 2, respectively. An objective response was observed in 38.1% of patients (arm 1) and in 28.6% (arm 2). Grade III-IV treatment-related adverse events occurred in 12.7% and 3.2% of patients in arm 1 and 2, respectively. For exploratory efficacy analysis, the median follow-up was 25.4 and 25.7 months in arm 1 and 2, respectively. The 2-year progression-free survival was 33.3% in arm 1 and 30.2% in arm 2, and the 2-year overall survival was 57.1% and 46.0%, respectively.

CONCLUSIONS

The MIRACULUM study met its primary end-point in both the study arms. Prolgolimab showed significant antitumour activity and a manageable safety profile in patients with advanced melanoma.

Phase 1b Study of Sintilimab Plus Anlotinib as First-line Therapy in Patients With Advanced NSCLC

INTRODUCTION

Although the interaction between tumor immune microenvironment and angiogenesis has been well established, evidence supporting the chemo-free combination of immune checkpoint inhibitors plus antiangiogenic tyrosine kinase inhibitors in treatment-naive patients with advanced NSCLC is insufficient. This report provides the efficacy and safety of sintilimab combined with anlotinib as first-line therapy for advanced NSCLC from a phase 1b trial (NCT03628521).

METHODS

Eligible patients who were treatment-naive and had unresectable stage IIIB/C or IV NSCLC without EGFR/ALK/ROS1 mutations received sintilimab (200 mg, day 1) and anlotinib (12 mg, day 1-14) every 3 weeks till disease progression or unacceptable toxicity. Baseline programmed death-ligand 1 expression and tumor mutation burden status was assessed in all patients. The primary end points were objective response rate and safety.

RESULTS

A total of 22 patients received sintilimab and anlotinib. Median follow-up was 15.8 months (range: 8.3-19.3). Sixteen patients achieved confirmed partial response with an objective response rate of 72.7% (95% confidence interval [CI]: 49.8%-89.3%) and disease control rate of 100% (95% CI: 84.6%-100%). Median progression-free survival was 15 months (95% CI: 8.3 m, not reached), and the 12-month progression-free survival rate was 71.4% (95% CI: 47.2%-86.0%). The incidence rate of grade 3 or higher treatment-related adverse events was 54.5%, and grade 3 hypertension was predominant (two of 22, 9.1%). No grade 4 treatment-related adverse events were observed, and one case of grade 5 immune-related pneumonitis occurred.

CONCLUSIONS

To the best of our knowledge, this is the first study that assessed an anti-programmed cell death protein 1 antibody combined with a multitarget antiangiogenic tyrosine kinase inhibitor in the frontline setting for patients with NSCLC. In view of its encouraging efficacy, durability, and safety profile, sintilimab plus anlotinib represents a novel chemotherapy-free regimen in this patient population.

Cancer and the Microbiome-Influence of the Commensal Microbiota on Cancer, Immune Responses, and Immunotherapy

The commensal microbiota has been implicated in the regulation of a diverse array of physiological processes, both within the gastrointestinal tract and at distant tissue sites. Cancer is no exception, and distinct aspects of the microbiota have been reported to have either pro- or anti-tumor effects. The functional role of the microbiota in regulating not only mucosal but also systemic immune responses has led to investigations into the impact on cancer immunotherapies, particularly with agents targeting the immunologic checkpoints PD-1 and CTLA-4. Microbial sequencing and reconstitution of germ-free mice have indicated both positive and negative regulatory bacteria likely exist, which either promote or interfere with immunotherapy efficacy. These collective findings have led to the development of clinical trials pursuing microbiome-based therapeutic interventions, with the hope of expanding immunotherapy efficacy. This review summarizes recent knowledge about the relationship between the host microbiota and cancer and anti-tumor immune response, with implications for cancer therapy.

Dose exploration results from Phase 1 study of cemiplimab, a human monoclonal programmed death (PD)-1 antibody, in Japanese patients with advanced malignancies

PURPOSE

Part 1 of this two-part, open-label, Phase 1 study (NCT03233139) assessed the safety, tolerability, pharmacokinetics, immunogenicity, and clinical activity of cemiplimab in Japanese patients with advanced malignancies.

METHODS

Patients received cemiplimab 250 mg (n = 6) or 350 mg (n = 7) every 3 weeks intravenously for up to 108 weeks in Part 1. Tumor responses were assessed by investigators every 9 weeks using the Response Evaluation Criteria in Solid Tumors version 1.1.

RESULTS

Of 13 patients enrolled, median age was 62 years (range 33-75) and eight patients were female. Median duration of cemiplimab exposure was 13.1 weeks (range 3.0‒113.6). At the time of data cut-off, 11 patients (84.6%) had discontinued treatment (majority due to disease progression: n = 8, 61.5%). The most common treatment-emergent adverse events (TEAEs) of any grade were contact dermatitis, rash, and viral upper respiratory tract infection (each n = 3, 23.1%). Five grade ≥ 3 TEAEs were reported in four patients: autoimmune colitis, dehydration, hyponatremia, hypophosphatemia, and muscular weakness. No dose-limiting toxicities were reported and no TEAEs led to death. Cemiplimab concentrations in serum were consistent with previously reported pharmacokinetic characteristics of cemiplimab. No anti-drug antibodies were detected in serum. Objective response rate [ORR; complete response + partial response (PR)] was 30.8% (four PR) and disease control rate [ORR + stable disease (SD)] was 46.2% (6/13; two SD).

CONCLUSION

Cemiplimab exhibited antitumor activity in Japanese patients with advanced malignancies. The safety profile was comparable to those previously reported for cemiplimab and other PD-1 inhibitors.

TRIAL REGISTRATION

NCT03233139 at ClinicalTrials.gov.

Balancing Cancer Immunotherapy Efficacy and Toxicity

Anti-programmed cell death-1 receptor/programmed cell death-1 receptor ligand-directed therapies are transforming cancer care, with durable antitumor responses observed in multiple cancer types. Toxicities arising from therapy are autoimmune in nature and may affect essentially any organ system. The immunologic basis of such toxities is complex, with contributions from T-cell activation and autoantibody generation. Although less recognized, hypersensitivity reactions are also possible. Although most toxicities resolve with systemic corticosteroids, some require second-line immunosuppression. Furthermore, the safety of drug rechallenge is not well characterized, with variable rates of toxicity flares arising with re-exposure. Herein, we review toxicities of immune checkpoint inhibitor therapies, particularly focusing on issues that allergists/immunologists may clinically encounter, including interstitial nephritis, skin toxicity, and risks associated with immunotherapy rechallenge.

Survivorship in immune therapy: Assessing toxicities, body composition and health-related quality of life among long-term survivors treated with antibodies to programmed death-1 receptor and its ligand

AIM

Antibodies to programmed death-1 receptor and its ligand (anti-PD-1/PD-L1) produce durable responses in many cancers. However, the long-term effects of anti-PD-1/PD-L1 blockade are not well defined. We identified the toxicities, health outcomes and health-related quality of life (HRQoL) amongst long-term survivors treated with anti-PD-1/PD-L1.

METHODS

We assessed 217 patients who received anti-PD-1/PD-L1 for melanoma, renal cell carcinoma or non-small-cell lung carcinoma between 2009 and 2017, with survival greater than two years after treatment. Patient and tumour characteristics, immune-related adverse events (irAEs), cardiometabolic parameters (glucose, blood pressure, body mass index [BMI]), body composition (using automated body composition analyser, computed tomography and Slice-o-matic software) and HRQoL outcomes were tracked.

RESULTS

Among the included patients, most were men (70.3%) and at anti-PD-1/PD-L1 initiation had an average age of 61.0 years and median BMI of 28.5. Median overall survival was not reached; 33 (15.2%) died during the follow-up primarily from progressive cancer (n = 28). At the last follow-up, most patients' Eastern Cooperative Oncology Group performance status was 0 (38%) or 1 (41%). There was no difference in blood pressure, glucose or BMI from baseline to two years after treatment initiation. Body composition showed increased adiposity (p = 0.05), skeletal muscle mass (p = 0.03) and skeletal muscle gauge (p = 0.04). We observed chronic irAEs at the last follow-up including hypothyroidism (10.6%), arthritis (3.2%), adrenal insufficiency (3.2%) and neuropathy (2.8%). New diagnoses of type 2 diabetes (6.5%) and hypertension (6.0%) were observed, with uncertain relationship to anti-PD-1/PD-L1. Patient-reported outcomes compared favourably with cancer and general populations, although younger age (p = 0.003) and need for subsequent therapy (p = 0.03) were associated with worse HRQoL outcomes.

CONCLUSION

Durable responses to anti-PD-1/PD-L1 therapy and favourable HRQoL outcomes are encouraging. Chronic events may be more common than previously thought although no clear chronic adverse cardiometabolic effects were observed.

Circulating MicroRNAs and Extracellular Vesicle-Containing MicroRNAs as Response Biomarkers of Anti-programmed Cell Death Protein 1 or Programmed Death-Ligand 1 Therapy in NSCLC

INTRODUCTION

Anti-programmed cell death protein 1 (PD-1) or programmed death-ligand 1 (PD-L1) antibody therapy is a standard treatment for advanced NSCLC, and PD-L1 immunohistochemistry is used as a predictive biomarker for therapeutic response. However, because not all patients with NSCLC with high PD-L1 respond, and some patients with low PD-L1 expression exhibit durable benefit, more accurate predictive biomarkers are needed. Circulating microRNA (miRNA) and miRNA packaged in extracellular vesicles (EVs) are believed to play a role in intercellular communication among immune cells and between immune cells and tumor cells and may represent a good source of mechanism-related biomarkers.

METHODS

Pretreatment plasma of patients with advanced NSCLC treated with single-agent anti-PD-1 or anti-PD-L1 antibody was used in this study. Plasma EVs were isolated using size-exclusion chromatography. Whole plasma and EV-containing RNAs were extracted. The miRNA profile was analyzed with a next-generation sequencing platform.

RESULTS

Samples from 14 responders (patients who exhibited partial response or stable disease ≥6 mo) and 15 nonresponders (patients who exhibited progressive disease as per Response Evaluation Criteria in Solid Tumors) were analyzed. In total, 32 miRNAs (p = 0.0030-0.0495) from whole plasma and seven EV-associated miRNAs (p = 0.041-0.0457) exhibited significant concentration differences between responders and nonresponders. The results of some of these circulating miRNAs were validated in a separate cohort with eight responders and 13 nonresponders. The tumor PD-L1 level was also assessed using immunohistochemistry for patients involved in both cohorts.

CONCLUSIONS

Specific circulating miRNAs in whole plasma and plasma EVs are differentially expressed between responders and nonresponders and have potential as predictive biomarkers for anti-PD-1/PD-L1 treatment response.

Immune checkpoint inhibitors: a physiology-driven approach to the treatment of coronavirus disease 2019

While confirmed cases of the deadly coronavirus disease 2019 (COVID-19) have exceeded 4.7 million globally, scientists are pushing forward with efforts to develop vaccines and treatments in an attempt to slow the pandemic and lessen the disease's damage. Although no proven effective therapies for treating patients with COVID-19 or for managing their complications currently exist, the rapidly expanding knowledge regarding severe acute respiratory syndrome coronavirus 2 and its interplay with hosts provides a significant number of potential drug targets and the potential to repurpose drugs already tested in other diseases. Herein, we report the biological rationale of immune-activating drugs and a brief summary of literature data on the potential therapeutic value of immune checkpoint inhibitors that have been recently tested beyond cancer treatment for their potential to restore cellular immunocompetence.

Real-World Experience of Nivolumab in Non-small Cell Lung Cancer in Korea

Purpose

The introduction of immune checkpoint inhibitors represents a major advance in the treatment of lung cancer, allowing sustained recovery in a significant proportion of patients. Nivolumab is a monoclonal anti–programmed death cell protein 1 antibody licensed for the treatment of locally advanced or metastatic non-small cell lung cancer (NSCLC) after prior chemotherapy. In this study, we describe the demographic and clinical outcomes of patients with advanced NSCLC treated with nivolumab in the Korean expanded access program.

Materials and Methods

Previously treated patients with advanced non-squamous and squamous NSCLC patients received nivolumab at 3 mg/kg every 2 weeks up to 36 months. Efficacy data including investigator-assessed tumor response, progression data, survival, and safety data were collected.

Results

Two hundred ninety-nine patients were treated across 36 Korean centers. The objective response rate and disease control rate were 18% and 49%, respectively; the median progression-free survival was 2.1 months (95% confidence interval [CI], 1.87 to 3.45), and the overall survival (OS) was 13.2 months (95% CI, 10.6 to 18.9). Patients with smoking history and patients who experienced immune-related adverse events showed a prolonged OS. Cox regression analysis identified smoking history, presence of immune-related adverse events as positive factors associated with OS, while liver metastasis was a negative factor associated with OS. The safety profile was generally comparable to previously reported data.

Conclusion

This real-world analysis supports the use of nivolumab for pretreated NSCLC patients, including those with an older age.

Impact of aging on immune-related adverse events generated by anti-programmed death (ligand)PD-(L)1 therapies

BACKGROUND

Aging is an important risk factor for cancers and is associated with poor prognosis. Weakness of the immune system, also called immunosenescence may occur with older age. The impact of aging on efficacy and safety of immune checkpoint blockers, such as anti-programmed death (ligand) PD-(L)1, remains undetermined. This study aims to evaluate the incidence of immune-related adverse events (irAEs) in patients aged 70 years or older than their younger counterparts.

METHODS

Patients with advanced solid tumors treated at Gustave Roussy with an anti-PD-(L)1 monotherapy between June 2014 and October 2017 were prospectively included within the dedicated irAEs pharmacovigilance registry REISAMIC (Registre des Effets Indésirables Sévères des Anticorps Monoclonaux Immunomodulateurs en Cancérologie). The incidence of irAEs of grade ≥II was compared between patients aged ≥70 (old patients, OP) versus patients aged < 70 years (young patients, YP) using a chi-squared test. Survivals were estimated using the Kaplan-Meier method.

RESULTS

Among the 603 patients treated by anti-PD(L)1, 191 were ≥70 y.o (OP) and 424 < 70 y.o (YP). The median (range) age of OP and YP were respectively 77 (70-93) and 59 years old (17-69). A total of 165 irAEs occurred in these patients (103 grade II and 58 grade III-IV). The overall incidence of grade ≥II irAEs was higher in OP than in YP (33% versus 25%, p = 0.03). In addition, OP were more prone of having multiples irAEs compared with YP (p = 0.037). Skin toxicities were more frequent in OP than in YP (p = 0.007) but endocrine toxicities were less frequent in OP than in YP (p = 0.044). This higher level of irAEs seems to be responsible for a higher rate of treatment discontinuation in OP (p = 0.2). There was no statistical difference in median time to toxicity, exposure to steroids or survival between the two groups.

CONCLUSION

Although anti-PD-(L)1 immunotherapies remain an acceptable treatment option for older patients, prescribers should be aware that irAEs are more frequent in the elderly. Further translational studies are warranted to better understand the relationship between aging and irAEs.

A systematic literature review and network meta-analysis of effectiveness and safety outcomes in advanced melanoma

BACKGROUND

Although a myriad of novel treatments entered the treatment paradigm for advanced melanoma, there is lack of head-to-head evidence. We conducted a network meta-analysis (NMA) to estimate each treatment's relative effectiveness and safety.

METHODS

A systematic literature review (SLR) was conducted in Embase, MEDLINE and Cochrane to identify all phase III randomised controlled trials (RCTs) with a time frame from January 1, 2010 to March 11, 2019. We retrieved evidence on treatment-related grade III/IV adverse events, progression-free survival (PFS) and overall survival (OS). Evidence was synthesised using a Bayesian fixed-effect NMA. Reference treatment was dacarbazine. In accordance with RCTs, dacarbazine was pooled with temozolomide, paclitaxel and paclitaxel plus carboplatin. To increase homogeneity of the study populations, RCTs were only included if patients were not previously treated with novel treatments.

RESULTS

The SLR identified 28 phase III RCTs involving 14,376 patients. Nineteen and seventeen treatments were included in the effectiveness and safety NMA, respectively. For PFS, dabrafenib plus trametinib (hazard ratio [HR] PFS: 0.21) and vemurafenib plus cobimetinib (HR PFS: 0.22) were identified as most favourable treatments. Both had, however, less favourable safety profiles. Five other treatments closely followed (dabrafenib [HR PFS: 0.30], nivolumab plus ipilimumab [HR PFS: 0.34], vemurafenib [HR PFS: 0.38], nivolumab [HR PFS: 0.42] and pembrolizumab [HR PFS: 0.46]). In contrast, for OS, nivolumab plus ipilimumab (HR OS: 0.39), nivolumab (HR OS: 0.46) and pembrolizumab (HR OS: 0.50) were more favourable than dabrafenib plus trametinib (HR OS: 0.55) and vemurafenib plus cobimetinib (HR OS: 0.57).

CONCLUSIONS

Our NMA identified the most effective treatment options for advanced melanoma and provided valuable insights into each novel treatment's relative effectiveness and safety. This information may facilitate evidence-based decision-making and may support the optimisation of treatment and outcomes in everyday clinical practice.

Safety and antitumor activity of the anti-PD-1 antibody pembrolizumab in patients with advanced, PD-L1-positive papillary or follicular thyroid cancer

BACKGROUND

Treatment options for advanced thyroid cancer refractory to standard therapies are limited. The safety and efficacy of pembrolizumab were evaluated in patients with advanced differentiated thyroid cancer expressing programmed death ligand 1 (PD-L1).

METHODS

Patients with advanced thyroid cancer were enrolled in the nonrandomized, phase Ib KEYNOTE-028 trial conducted to evaluate safety and antitumor activity of the anti-programmed death 1 (PD-1) antibody pembrolizumab in advanced solid tumors. Key eligibility criteria were advanced papillary or follicular thyroid cancer, failure of standard therapy, and PD-L1 expression in tumor or stroma cells (assessed by immunohistochemistry). Pembrolizumab 10 mg/kg was administered every 2 weeks up to 24 months or until confirmed progression or intolerable toxicity. The primary endpoint was objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors, version 1.1.

RESULTS

Twenty-two patients were enrolled: median age was 61 years; 59% were women; and 68% had papillary carcinoma. Median follow-up was 31 months (range, 7-34 months). Treatment-related adverse events were observed in 18 (82%) patients; those occurring in ≥15% of patients were diarrhea (n = 7) and fatigue (n = 4). One grade ≥ 3 treatment-related adverse event occurred (colitis, grade 3); no treatment-related discontinuations or deaths occurred. Two patients had confirmed partial response, for an ORR of 9% (95% confidence interval [CI], 1-29%); response duration was 8 and 20 months. Median progression-free survival was 7 months (95% CI, 2-14 months); median overall survival was not reached (95% CI, 22 months to not reached).

CONCLUSIONS

Results of this phase Ib proof-of-concept study suggest that pembrolizumab has a manageable safety profile and demonstrate evidence of antitumor activity in advanced differentiated thyroid cancer in a minority of patients treated. Further analyses are necessary to confirm these findings.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02054806 . Registered 4 February 2014.

DNA Mismatch Repair Deficiency and Immune Checkpoint Inhibitors in Gastrointestinal Cancers

In the recent few years, significant efforts have been undertaken for the development of different immunotherapeutic approaches against cancer. In this context, immune checkpoint inhibitors (ICIs), a novel class of immunotherapeutic drugs with the potential to unleash the immune system, have emerged as authentic game-changers for managing patients with various cancers, including gastrointestinal malignancies. Although the majority of gastrointestinal cancers are generally considered poorly immunogenic, basic research findings and data from clinical trials have proven that subset(s) of patients with various digestive tract cancers are highly responsive to ICI-based therapy. In this context, a better understanding on the role of various DNA repair pathway alterations, especially the evidence supporting the significant importance of DNA mismatch repair deficiencies and the efficacy of the anti-programmed cell death 1 drugs, have led to US Food and Drug Administration approval of 2 anti-programmed cell death 1 antibodies (pembrolizumab and nivolumab) for the treatment of patients with microsatellite instability. This review aims to provide a comprehensive and up-to-date summary for the role of DNA mismatch repair deficiency in cancer, and its importance in the development of ICI therapy. In addition, we provide insights into the spectrum of various genetic alterations underlying ICI resistance, together with the important influence that the tumor microenvironment plays in mediating the therapeutic response to this new class of drugs. Finally, we provide a comprehensive yet succinct glimpse into the most exciting preclinical discoveries and ongoing clinical trials in the field, highlighting bench-to-beside translational impact of this exciting area of research.

Immune checkpoint blockade

Since the development and approval of Ipilimumab, the first immune checkpoint inhibitor licensed for the treatment of metastatic melanoma, clinicians have gained a better understanding of the mode of action, management of toxicities, and assessment of response to this class of drugs. Several antibodies are now in development, aimed at blocking novel immune checkpoint molecules, such as PD-1 and it's corresponding ligand PD-L1. This article summarizes the mechanism of action, preclinical development, and subsequent clinical studies of immune checkpoint antibodies in melanoma.