In Brief: Pembrolizumab (Keytruda) for Cancers with Biomarkers (online only)

Date: January 1, 2018 Issue #:  1537Summary:  The immune checkpoint inhibitor pembrolizumab (Keytruda– Merck), a programmed death receptor-1 (PD-1) inhibitor, has been granted accelerated approval by the FDA for use in adults and children who have unresectable or metastatic microsatellite-instability-high (MSI-H) or mismatch-repair-deficient (dMMR) solid tumors that have progressed following trea tment, and do not have any satisfactory alternative treatment options. For metastatic colorectal cancer, the indication is limited to tumors that have progressed following combination treatment with a fluoropyrimidine, oxaliplatin, and irinotecan. This is the first approval of a cancer drug based so lely on the presence of certain biomarkers, regardless of the organ in which the cancer originated or the histology of the tumor.MSI-H and dMMR are markers for abnormalities in cancer cells that prevent DNA replication and postreplicative DNA repair.1 These biomarkers are found most commonly in cancers of the endometrium, stomach, and colon. The incidence of MSI-H or dMMR in these tumors appears to be lower in advanced disease than in early-stage disease; about 5% of patients with metastatic colorectal cancer have MSI-H or dMMR tumors.2FDA approval was based on data from five unpublished, single-arm trials of pembrolizumab (summarized in the package insert) that included a total of 149 previously treated adults with various MSI-H or dMMR metasta...
Source: The Medical Letter - Category: Drugs & Pharmacology Authors: Source Type: research