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FDA Approves Foundation Medicine Test as CDx for Merck's Keytruda to Identify MSI-H Solid Tumors

NEW YORK – Roche subsidiary Foundation Medicine said on Tuesday that its FoundationOne CDx test has been approved by the US Food and Drug Administration as a companion diagnostic with Merck's Keytruda (pembrolizumab).

The test can now be used to identify patients with solid tumors that are classified as microsatellite instability high, or MSI-H, and may benefit from treatment with Keytruda. It's the first and so far only FDA-approved companion diagnostic to detect patients with MSI-H solid tumors who may benefit from immunotherapy, Foundation said in a statement. 

Keytruda was granted accelerated approval to treat certain patients with MSI-H solid tumors in May 2017 and was the first targeted therapy approved to treat patients based on a genomic signature instead of where the tumor originated in the body, Foundation added. While MSI-H status is more commonly found in colorectal, endometrial, and gastrointestinal cancers, it can also be seen in other types of cancer, Foundation said.

FoundationOne CDx was approved in 2020 to identify patients with solid tumors that have high tumor mutational burden and may benefit from treatment with Keytruda. This is the third tumor agnostic companion diagnostic approval for the test, and it now has 26 companion diagnostic claims and two group claims across 27 targeted therapies.

"Immunotherapy has huge promise as a potential treatment option for patients with advanced cancer; however, identifying those who may benefit is complex and requires high-quality diagnostics," Mia Levy, Foundation's chief medical officer, said in a statement. "Not only could this approval allow more patients to benefit from Keytruda, but it also underscores an important shift toward tumor-agnostic cancer care."