Merck's Keytruda wins first FDA nod to treat genetically ID'd tumors anywhere in the body

New Keytruda image
Before winning its MSI-H go-ahead, Merck's Keytruda netted May green lights in bladder cancer and first-line non-small cell lung cancer.

Talk about going on a roll. Merck’s Keytruda nabbed its third FDA approval in two weeks on Tuesday, becoming the first checkpoint inhibitor to pick up an approval to treat microsatellite instability-high (MSI-H) cancer, a rare tumor type identified with genetic testing.

Keytruda’s other indications—in bladder cancer and lung cancer, for instance—depend upon the part of the body where a tumor originated. This time, Keytruda won a go-ahead to treat any solid tumor in any part of the body, as long as it bears specific genetic features.

MSI-H tumors contain abnormalities that affect proper repair of DNA inside cells, the FDA said, and they’re most commonly found in colorectal, endometrial and gastrointestinal cancers. About 5% of colorectal tumors can be classified as MSI-H, the agency said.

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Those are far from the only places they can pop up, however, the agency noted. They can also appear in the breast, prostate, bladder, thyroid, and elsewhere.

The thumbs-up comes ahead of the FDA's June 9 deadline; regulators had originally scheduled a March decision date after granting Keytruda priority review status in MSI-H. That date was pushed back automatically after Merck added additional data and analyses to its application.

RELATED: Merck's Keytruda nabs FDA's 'priority' tag in microsatellite instability-high cancer

The MSI-H blessing, meanwhile, marks the third approval this month for the high-flying drug. The week before last, the New Jersey drugmaker bolstered its leadership position in non-small cell lung cancer by winning a Keytruda-chemo combo approval in previously untreated patients. And last week, Keytruda joined the rest of its checkpoint inhibitor class in bladder cancer by snagging the FDA’s third immuno-oncology approval in the field since the beginning of May.

The FDA approval wasn't the only good regulatory news Merck got on Tuesday, either. Earlier in the day, it announced that the agency had granted it a priority tag in two types of recurrent or advanced stomach cancer.