On May 23, 2017, the FDA granted accelerated approval to pembrolizumab (Keytruda; Merck) for the treatment of metastatic, microsatellite instability–high (MSI-H) or mismatch repair–deficient (dMMR) solid tumors that have progressed after previous treatment and have no appropriate alternative treatments, or for colorectal cancer that has progressed after treatment with a fluoropyrimidine, oxaliplatin, and irinotecan. This is the first time the FDA approved a cancer drug for use in any solid tumor with a specific genetic feature.
“This is an important first for the cancer community. Until now, the FDA has approved cancer treatments based on where in the body the cancer started—for example, lung or breast cancers. We have now approved a drug based on a tumor’s biomarker without regard to the tumor’s original location,” said Richard Pazdur, MD, Director of the FDA’s Oncology Center of Excellence.
The FDA approval of pembrolizumab for this indication was based on data from patients with MSI-H or dMMR solid tumors who participated in 1 of 5 uncontrolled, open-label, multicohort, multicenter, single-arm clinical trials. The overall response rate was 39.6%, and 78% of patients who responded to pembrolizumab had a duration of response lasting ≥6 months. The median duration of response had not been reached at the time of the analysis.
Pembrolizumab can cause serious immune-mediated adverse events, including pneumonitis, colitis, hepatitis, endocrinopathies, and nephritis. Complications or death related to allogeneic hematopoietic stem-cell transplantation has occurred after therapy with pembrolizumab.