The FDA yesterday ruled that Merck’s Keytruda (pembrolizumab) can be used for almost any solid tumors with one of two genetic abnormalities that have not responded to first-line treatment. It makes the drug the first to be given the status of first tissue/site-agnostic. It is a victory for proponents of precision medicine, the idea that every cancer is as different as every person battling it and medications should reflect that diversity.
The FDA stated in a press release that the drug could be used “for adult and pediatric patients with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) solid tumors that have progressed following prior treatment and who have no satisfactory alternative treatment options or with MSI-H or dMMR colorectal cancer that has progressed following treatment with a fluoropyrimidine, oxaliplatin, and irinotecan.”
As STAT reports, some biotech companies are trying to follow Merck’s process regarding Keytruda. For instance, there’s Loxo Oncology, pushing its drug larotrectinib, which targets the TRK cellular receptor that’s found in many different tumors. A company called Ignyta last week won approval for its drug entrectinib by the FDA as a breakthrough designation, giving the company better access to FDA experts. Theoretically, entrectinib could be used for a variety of cancer patients who have mutations to the gene that encodes for TRK.
But the medications that those biotech companies are pushing do not have the same track record of real-world success as Keytruda. Keytruda was first approved three years ago based on clinical data on a single tumor type. Other studies followed that measured how Keytruda worked on thousands of patients with different kinds of cancer. Keytruda won approval for treating eight more cancers. Its side effects and efficacy are known quantities, for the most part.
“The approval was based on data from 149 patients with MSI-H or dMMR cancers enrolled across five uncontrolled, multi-cohort, multi-center, single-arm clinical trials,” the FDA states. “Ninety patients had colorectal cancer and 59 patients were diagnosed with one of 14 other cancer types.”