The FDA on Tuesday awarded accelerated approval to Merck & Co.'s Keytruda (pembrolizumab) for the treatment of any metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) solid tumour, marking the first time the agency cleared a cancer drug based on the presence of a specific biomarker as opposed to its location in the body. Richard Pazdur, acting director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation, described the approval as "an important first for the cancer community."
The approval was based on data from patients with tumours featuring MSI-H or dMMR who were enrolled in one of five clinical studies. According to the agency, a total of 15 different cancer types were identified from 149 patients included in these five studies. Further, Keytruda produced a complete or partial response in 39.6 percent of patients, with the response lasting for at least six months in 78 percent of those patients.
The FDA granted priority review to Merck's application seeking approval of Keytruda for the treatment of previously treated patients with advanced MSI-H cancer in November last year. The agency later extended its review of the therapy by three months after Merck submitted additional data and analyses.
Keytruda was initially approved in the US in 2014 for the treatment of advanced or unresectable melanoma, marking the first approval of a PD-1 inhibitor by the FDA. The therapy was later authorised for the treatment of recurrent or metastatic head and neck squamous cell carcinoma, metastatic non-small-cell lung cancer (NSCLC) and refractory classical Hodgkin lymphoma. The drug was also recently cleared in the US in combination with Eli Lilly's Alimta (pemetrexed) and carboplatin for first-line metastatic non-squamous NSCLC irrespective of PD-L1 expression and last week, the FDA approved Keytruda as a first- and second-line treatment for certain patients with bladder cancer (for related analysis, read ViewPoints: Keytruda poised to hit the ground running after US bladder cancer approval).
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