AACR: Merck's Keytruda, up for new FDA nod, spurs lengthy responses in small cell lung cancer

ATLANTA—Merck & Co. is awaiting an FDA decision for Keytruda in previously treated small cell lung cancer, and it has new numbers to boost its case.

Monday at the American Association for Cancer Research annual meeting, the New Jersey drugmaker trotted out results from a pooled analysis of two studies that showed Keytruda could provoke a response in nearly one-fifth of small cell patients.

Researchers looked at 83 SCLC patients drawn from the phase 2 Keynote-158 and phase 1 Keynote-028 studies, all of whom had been treated with two or more lines of therapy. Of these, 19.3% responded to Keytruda, Merck said, and more than half of those responders experienced benefits that lasted 18 months or longer.

“Those patients who respond actually have very durable responses,” Roy Baynes, Merck senior vice president and head of global clinical development, said in an interview, adding “this is typically a group of patients that don’t do very well.”

Keytruda extended patients’ lives by a median 7.7 months, with 34% of patients still alive at the one-year mark and 21% making it to the two-year mark, Merck said.

Keytruda already bears an FDA priority review for a new indication in previously treated SCLC patients based on Keynote-158 data, which showed 35.7% patients with tumors expressing PD-L1 responded to therapy. Merck is expecting the FDA to hand down a decision by June 17. A green light would set up a showdown with Bristol-Myers Squibb's Opdivo, which boasts an approval in the setting but has since failed two small-cell trials. 

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And next up? Results from the phase 3 Keynote-604 trial, which is examining the immuno-oncology star paired with chemo in previously untreated small-cell patients. If those come data up positive, Merck will have to challenge Roche, whose Tecentriq earlier this month became the first PD-1/PD-L1 player into the arena with a blockbuster FDA approval.