The Food and Drug Administration has approved pembrolizumab (Keytruda) for the treatment of patients with recurrent locally advanced or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma, in cases where tests confirm that the tumors contain programmed death–ligand 1 and where the disease is progressing on or after two or more prior lines of therapy.
Pembrolizumab has been approved in the United States since 2014 for the treatment of melanoma, with subsequent approvals for treatment of non–small-cell lung cancer, head and neck squamous cell carcinoma, Hodgkin lymphoma, and several other advanced cancers.
The approval comes on the basis of the nonrandomized, open label KEYNOTE-059 trial, which enrolled 259 patients with gastric or GEJ adenocarcinoma that progressed on at least two prior systemic treatments for advanced disease. Of the enrollees, 143 patients had tumors with a PD-L1 Combined Positive Score of 1 or greater. The primary trial outcome, the objective response rate for these 143 patients, was 13.3% (95% confidence interval; 8.2-20), with a complete response rate of 1.4% and a partial response rate of 11.9%. The duration of response ranged from at least 2.8 months to at least 19.4 months.
Continued approval for the new indication will depend upon further demonstration of a clinical benefit in confirmatory trials.