Discussion
tumours, cancers, death
CPS, CANCERS, TUMOURS
In this subpopulation analysis of the phase 3 KEYNOTE-062 trial, first-line pembrolizumab monotherapy was associated with numerically improved OS compared with chemotherapy for patients enrolled in Asia with PD-L1–positive GC/GEJC. A greater benefit was observed with pembrolizumab monotherapy in this subgroup analysis compared with the overall KEYNOTE-062 study population, where OS with pembrolizumab monotherapy was found to be noninferior to chemotherapy in patients with PD-L1 CPS ≥1 but associated with longer OS in patients with PD-L1 CPS ≥10 (Longer survival times were expected in this analysis because Asian ethnicity, and residing in Asia, are favourable prognostic factors for patients with GC (PFS outcomes for patients enrolled in Asia were also similar to the overall study population for patients receiving chemotherapy, but the median PFS for patients receiving pembrolizumab plus chemotherapy was better for patients enrolled in Asia than the overall study population, especially amongst patients with PD-L1 CPS ≥10. Furthermore, no difference was apparent between treatment arms. However, more objective responses were achieved with pembrolizumab plus chemotherapy. Objective response rate amongst patients randomly assigned to receive pembrolizumab also appeared to be higher in the PD-L1 CPS ≥10 population, which is consistent with the overall population in KEYNOTE-062, as well as observations made in the KEYNOTE-061 study of second-line pembrolizumab monotherapy (The incidence of treatment-related AEs was also similar in this analysis compared to the overall study population analysis, with substantially lower rates observed in the pembrolizumab monotherapy arm. This finding suggests a treatment option for previously untreated patients who may be suitable candidates for chemotherapy; there is concern, however, regarding potential AEs, especially given that AEs occurring with chemotherapy may be more likely to occur in individuals from East Asian countries compared with individuals from Western countries (The role of pembrolizumab in the treatment of advanced GC remains to be determined; however, the current analysis adds to the existing body of evidence and is especially informative because GC is one of the most commonly diagnosed cancers and is a leading cause of death in Asia (Ongoing studies in the first-line treatment setting are evaluating pembrolizumab plus chemotherapy (KEYNOTE-859; NCT03675737) and pembrolizumab plus trastuzumab and chemotherapy (KEYNOTE-811; NCT03615326) and will provide additional support for the efficacy and safety of pembrolizumab in patients with GC/GEJC, including patients enrolled in Asia.In conclusion, although statistical comparisons were not conducted, this subpopulation analysis of data for patients enrolled in Asia in the KEYNOTE-062 study indicates that pembrolizumab monotherapy was associated with numerically improved OS outcomes compared with chemotherapy alone for patients with advanced GC/GEJC with PD-L1 CPS ≥1 and CPS ≥10 tumours. Pembrolizumab monotherapy was also associated with a favourable tolerability profile compared with chemotherapy, which is consistent with observations from the overall KEYNOTE-062 study population.