The Food and Drug Administration (FDA) has granted accelerated approval to Keytruda (pembrolizumab), in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy, for the first-line treatment of patients with locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma.
The accelerated approval was based on data from the KEYNOTE-811 study (ClinicalTrials.gov: NCT03615326), which compared the safety and efficacy of pembrolizumab, a programmed death receptor-1 (PD-1)-blocking antibody, plus trastuzumab in combination with standard of care (SOC) chemotherapy to trastuzumab in combination with SOC chemotherapy.
Interim analysis of the first 264 patients (median age: 62 years; 82% male; 63% White, 31% Asian, 0.8% Black) demonstrated an overall response rate (ORR) of 74% (95% CI, 66-82) in the pembrolizumab arm and 52% (95% CI, 43-61) in the placebo arm (P <.0001). For pembrolizumab-treated patients, the median duration of response (DoR) was 10.6 months (range 1.1+, 16.5+), while the DoR in the placebo arm was 9.5 months (range 1.4+, 15.4+). Adverse reactions to pembrolizumab were found to be similar to those previously seen in other trials.
Under the accelerated approval pathway, tumor response rate and durability of response, endpoints believed to predict clinical benefit, were used as the basis for approval. Continued approval may be contingent upon verification and description of clinical benefit in a confirmatory trial.
Keytruda is supplied as a 100mg/4mL solution in single-dose vials.
FDA grants accelerated approval to pembrolizumab for HER2-positive gastric cancer. [press release]. Silver Spring, MD: U.S. Food and Drug Administration; May 5, 2021.