140 Relationship between programmed death ligand 1 (PD-L1) expression and clinical outcome in patients (pts) with melanoma (MEL) treated with pembrolizumab (pembro; MK-3475)

Find the Flame: Predictive Biomarkers for Immunotherapy in Melanoma

Immunotherapy has revolutionized the therapeutic landscape of melanoma. In particular, checkpoint inhibition has shown to increase long-term outcome, and, in some cases, it can be virtually curative. However, the absence of clinically validated predictive biomarkers is one of the major causes of unpredictable efficacy of immunotherapy. Indeed, the availability of predictive biomarkers could allow a better stratification of patients, suggesting which type of drugs should be used in a certain clinical context and guiding clinicians in escalating or de-escalating therapy. However, the difficulty in obtaining clinically useful predictive biomarkers reflects the deep complexity of tumor biology. Biomarkers can be classified as tumor-intrinsic biomarkers, microenvironment biomarkers, and systemic biomarkers. Herein we review the available literature to classify and describe predictive biomarkers for checkpoint inhibition in melanoma with the aim of helping clinicians in the decision-making process. We also performed a meta-analysis on the predictive value of PDL-1.

The role of pembrolizumab in the treatment of PD-L1 expressing gastric and gastroesophageal junction adenocarcinoma

Gastric cancer is a leading cause of cancer-related death worldwide. Recent evidence suggests that gastric cancer is a complex and heterogenous disease with emerging subtypes shown to affect response to treatment and survival. Immunotherapy is an advancing field and immune checkpoint inhibitors have become standard treatment options in numerous tumor types. In this review, we discuss the current and evolving use of checkpoint blockade, focusing on the anti-PD-1 inhibitor, pembrolizumab, for use in advanced gastric and gastroesophageal cancers.

PD-L1 expression in cancer patients receiving anti PD-1/PD-L1 antibodies: A systematic review and meta-analysis

BACKGROUND

Despite the success of immunotherapy directed at inhibiting of programmed death-1 (PD-1)/PD-ligand (L)1 signaling, it is not established whether PD-L1 expression correlates with the clinical response and outcome in different tumors. The present meta-analysis investigates whether the PD-L1 status, detected by immunohistochemistry, is associated with clinical response and mortality in patients treated with anti-PD-1/PD-L1 therapy.

METHODS

A systematic literature search and quantitative analysis were planned, conducted and reported following CONSORT and QUORUM checklists, up to December 2015, to identify clinical trials with information on cancer outcome by PD-L1 immunohistochemical expression in tumor tissues. We used random effects models to estimate Summary Objective Response Rates (SORRs) and Summary Odd Ratio (SOR) for the comparison of PD-L1 positive and negative patients.

RESULTS

We summarized 20 trials carried out in metastatic melanoma (MM), non-small cell lung cancer (NSCLC), and renal cell carcinoma (RCC) patients receiving anti-PD-1/PD-L1 antibodies (4230 MM, 1417 NSCLC and 312 RCC patients). Positive PD-L1 MM patients showed a significant decrease (53%) in the risk of mortality vs. negative cases with no heterogeneity. Furthermore, SORRs were 45% and 27% in PD-L1 positive and negative patients, respectively, and SOR indicates a significant difference in term of responses: 2.14 (95% CI: 1.65, 2.77), with low between-study heterogeneity (I(2)=35%). Furthermore, results from randomized clinical trials on MM showed that PD-L1 expression is significantly associated with greater clinical response rates to anti-PD1 treatments (SOR 1.89; 95%CI: 1.35, 2.64) but not to other treatments (SOR 0.96; 95%CI: 0.5, 1.87). In non-squamous NSCLC SORRs were 29% and 11% in PD-L1 positive and negative patients, respectively, and SOR indicates a significant difference between responses: 3.78 (1.54, 9.24), with no between-study heterogeneity. Squamous NSCLC and RCC did not show any significant difference in response according to the PD-L1 status.

CONCLUSION

PD-L1 expression is significantly associated with mortality and clinical response to anti-PD-1/PD-L1 antibodies in MM patients and with clinical response in patients with non-squamous NSCLC.

Pembrolizumab for the treatment of melanoma

The immune system plays a vital role in regulating tumor growth, and the oncology community has witnessed an exciting resurgence in clinical research to develop effective immunotherapeutic strategies. The utility of these strategies in advanced melanoma has been at the forefront of these developments. In particular, blockade of programmed cell death protein 1 (PD-1) in advanced melanoma has proven to be a most promising new anticancer strategy. Pembrolizumab is a humanized IgG4 anti-PD-1 antibody that exerts its anti-tumor effect through blocking the interaction of the immune inhibitory molecule PD-1 with its ligands. Its effect has been most convincingly demonstrated in the setting of advanced melanoma, with growing evidence of clinical responses across a broad spectrum of other solid and hematological malignancies.