Merck Reports Findings From Cohort 1 Of Phase 2 Registrational KEYNOTE-059 Trial

(RTTNews) - Merck (MRK) announced findings from Cohort 1 of the phase 2 registrational KEYNOTE-059 trial investigating KEYTRUDA (pembrolizumab), the company's anti-PD-1 therapy, as monotherapy in previously-treated patients with advanced gastric or gastroesophageal junction adenocarcinoma.

Results showed an overall response rate (ORR) of 11.6 percent (95% CI, 8.0-16.1) in patients treated with KEYTRUDA who had received two or more prior lines of treatment, with higher response rates among patients with PD-L1 positive tumors.

Data from this Cohort support Merck's supplemental Biologics License Application (sBLA) for KEYTRUDA - currently under Priority Review with the U.S. Food and Drug Administration (FDA) - seeking approval for the treatment of patients with recurrent or advanced gastric or gastroesophageal junction adenocarcinoma who have already received two or more lines of chemotherapy.

KEYNOTE-059 is a registrational, phase 2 non-randomized, multi-cohort study investigating KEYTRUDA in patients with advanced gastric or gastroesophageal junction adenocarcinoma. In patients who received at least two prior chemotherapies (Cohort 1), KEYTRUDA is being investigated as a monotherapy (200 mg every three weeks for up to 24 months).

The primary endpoints are ORR as assessed by Blinded Independent Central Review (BICR) using Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 and safety; secondary endpoints include duration of response and overall survival. Data were further assessed based on PD-L1 expression; tumors were considered to have positive PD-L1 expression if the combined positive score (CPS) - as examined by tumor and immune cells - was equal to or greater than one.