The FDA has granted traditional approval to pembrolizumab (Keytruda) in combination with trastuzumab (Herceptin) and fluoropyrimidine- and platinum-containing chemotherapy for the first-line treatment of adult patients with locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma whose tumors express PD-L1 with a combined positive score (CPS) of at least 1.1
The full approval was supported by data from the phase 3 KEYNOTE-811 trial (NCT03615326), which showed that in patients with a PD-L1 CPS of at least 1, the median progression-free survival (PFS) was 10.9 months (95% CI, 8.5-12.5) in the pembrolizumab arm (n = 200) v 7.3 months (95% CI, 6.8-8.4) in the placebo arm (n = 296; HR, 0.72; 95% CI, 0.60-0.87).1,2
The combination received accelerated approval from the FDA in May 2021 for use in patients with locally advanced unresectable or metastatic HER2-positive gastric/GEJ cancer regardless of PD-L1 expression.