May 5, 2021
The U.S. FDA has approved a new indication for Keytruda® (pembrolizumab), manufactured by Merck. Keytruda is now indicated for use in combination with trastuzumab and fluoropyrimidine- and platinum-containing chemotherapy to provide first-line treatment for locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma. The indication was granted accelerated approval, and continued approval may be contingent on verification and description of clinical benefit in confirmatory trials.
Gastric adenocarcinoma is a cancer that begins in the stomach, while GEJ adenocarcinoma is a cancer that begins where the stomach meets the esophagus – the tube that connects the stomach to the throat. Survival rates for locally advanced or metastatic gastric and GEJ adenocarcinoma, in which the cancer has spread beyond the site of origin to other parts of the body, are generally poor.
In a clinical trial, Keytruda plus trastuzumab and chemotherapy delivered an objective response rate (ORR) of 74% versus an ORR of 52% for trastuzumab and chemotherapy alone. The complete response rate was 11% and the partial response rate was 63% with Keytruda plus trastuzumab and chemotherapy. Trastuzumab and chemotherapy alone had a complete response rate of 3.1% and a partial response rate of 49%.
Recommended dosing under the new indication is 200mg of Keytruda once every three weeks or 400mg once every six weeks until disease progression or unacceptable toxicity occur, up to a maximum of two years. Keytruda is given as a 30-minute intravenous infusion.
First FDA approved in 2014, Keytruda has more than two dozen indications to treat cancer.