Merck's Keytruda stumbles again in stomach cancer, this time in new patients

Merck's Keytruda-chemo combo couldn't outdo solo chemo in a trial of previously untreated, PD-L1 positive gastric cancer patients. (Merck)

Gastric cancer is a tough nut to crack, and Merck superstar Keytruda has stumbled in the disease area—again.

Late Thursday, the drugmaker said a phase 3 study had shown a combination of Keytruda plus chemo couldn’t outdo chemo alone at staving off cancer progression or extending the lives of previously untreated patients whose tumors bear biomarker PD-L1.

Keytruda did meet one primary endpoint, showing that when used on its own, it could match chemo at extending the lives of patients in the population.

Merck won’t share the details of the miss until June’s American Society of Clinical Oncology annual meeting, but its senior vice president and head of global clinical development, Dr. Roy Baynes, did note that “gastric cancer is historically difficult to treat.” The company estimates 27,500 new cases will crop up in the U.S. in 2019, and it expects the disease to claim 11,100 lives.

RELATED: Merck's Keytruda misses the mark in second-line stomach cancer study

Gastric cancer has also foiled Keytruda once before. In late 2017, Merck said its immuno-oncology standout had fallen short of its primary endpoint in a second-line study, failing to either keep disease at bay or improve survival for patients with PD-L1-expressing tumors.

After that performance, the New Jersey drugmaker had been looking to the most recent study, dubbed Keynote-062, to confirm an accelerated approval it received back in 2017, when the FDA greenlighted Keytruda as a treatment for PD-L1-positive patients who had already received two other therapies. The company has other phase 3, first-line studies in the works, though, as well as trials in the neoadjuvant and adjuvant settings.

RELATED: Merck's Keytruda resumes regulatory hot streak with stomach cancer approval

Luckily for Merck, Keytruda is rolling in many of its other indications, including the all-important front-line lung cancer market. Earlier this week, the company picked up an OK to challenge archrival Bristol-Myers Squibb in the kidney cancer arena with a combination of Keytruda and Pfizer’s Inlyta, and analysts have said they expect to see immediate uptake.