PD-1/PD-L1 pathway inhibitors in advanced prostate cancer

ABSTRACT

Introduction: Pharmacological inhibition of immune checkpoint receptors or their ligands represents a transformative breakthrough in the management of multiple cancers. However, immune checkpoint inhibitors have yet to be FDA-approved for the management of metastatic prostate cancer (PCa), the commonest non-cutaneous malignancy in men.

Areas covered: We review our current understanding of the PD-1/PD-L1 pathway in cancer, the use of anti-PD-1/PD-L1 therapeutics in PCa, and potential subgroups of PCa patients who may derive the greatest benefit from these agents (such as men with tumors that have expression of PD-L1 and/or high mutational load). We also review the prior and current clinical trials evaluating the blockade of PD-1/PD-L1 in PCa, highlighting some of the key ongoing studies of greatest relevance to the field.

Expert commentary: Clinical trials investigating PD-1/PD-L1 inhibitors should be encouraged in patients with PCa. While it is unlikely that immune checkpoint monotherapies will produce long-lasting responses in a substantial proportion of patients, there is early evidence of activity in some patient subsets. These subgroups may include those with high PD-L1 expression, those with hypermutated or microsatellite-unstable tumors, and those enriched for germline and/or somatic DNA-repair gene mutations (e.g. intraductal/ductal histology, primary Gleason pattern 5, and perhaps AR-V7-positive tumors).

KEYWORDS:

• Cancer
• prostate
• PD-1
• PD-L1
• immunotherapy

Declaration of interest

ES Antonarakis is a paid consultant/advisor to Janssen, Astellas, Sanofi, Dendreon, Medivation, ESSA, AstraZeneca, Clovis and Merck; he has received research funding to his institution from Janssen, Johnson & Johnson, Sanofi, Dendreon, Genentech, Novartis, Tokai, Bristol Myers-Squibb, AstraZeneca, Clovis and Merck; and he is the co-inventor of a biomarker technology that has been licensed to Tokai and Qiagen. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. A reviewer on this manuscript discloses that own a patent on PD-L1 and PD-1 methylation as a predictive biomarker for response to immune checkpoint inhibitors.

Additional information

Funding

ES Antonarakis is partially supported by National Institutes of Health grants R01 CA185297 and P30 CA006973, and Department of Defense Prostate Cancer Research Program grants W81XWH-15-2-0050.