FDA grants pembrolizumab full approval for certain patients with MSI-H/dMMR solid tumors
FDA granted full approval to pembrolizumab for treatment of certain adults and children with unresectable or metastatic microsatellite instability-high or mismatch repair-deficient solid tumors as determined through an FDA-approved test.
The indication, which received accelerated approval in 2017, applies to patients who experience disease progression after previous treatment and have no satisfactory alternative options.
“This approval reinforces the important role of Keytruda in certain patients with MSI-H [microsatellite instability-high] or dMMR [mismatch repair-deficient] solid tumors facing a variety of cancers,” Luis A. Diaz Jr., MD, head of the division of solid tumor oncology at Memorial Sloan Kettering Cancer Center, said in a Merck press release. “These data also further underscore the need for biomarker testing to identify patients who may be eligible for this therapy.”
FDA based full approval of the anti-PD-1 therapy on data from the nonrandomized, multicenter phase 2 KEYNOTE-164, KEYNOTE-158 and KEYNOTE-051 trials, which included 504 adults and children across more than 30 cancer types. A pooled analysis of the trials at median follow-up of 20.1 months (range, 0.1-71.4) showed an objective response rate of 33.3% (95% CI, 29.2-37.6), with a complete response rate of 10.3% and partial response rate of 23%. More than three-quarters of patients (77%) had responses that lasted 1 year or longer, and 39% had responses that lasted 3 years or longer (median duration of response, 63.2 months).
Pembrolizumab conferred ORRs of 34% (95% CI, 26-43) among 124 patients with MSI-H/dMMR colorectal cancer and 33% (95% CI, 28-38) among 380 patients with other MSI-H/dMMR solid tumors.
Immune-mediate adverse reactions that may occur during or after pembrolizumab therapy include pneumonitis, colitis, hepatitis, endocrinopathies, nephritis, dermatologic reactions, solid organ transplant rejection and complications of allogeneic hematopoietic stem cell transplantation, according to the press release.
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