Disparity in survival benefits of pembrolizumab between Asian and non-Asian patients with advanced cancers: A systematic review and meta-regression analysis.

BACKGROUND: Immune checkpoint inhibitors have revolutionized the treatment of malignancies. However, disproportionate enrollment among races and ethnicities places the generalizability of global trial results in doubt. METHODS: In this systematic review, phase 3 randomized controlled trials investigating pembrolizumab in advanced cancers and providing subgroup analyses of Asian and non-Asian participants were included. The primary and secondary effect measures were the mean differences (MDs) in the natural logarithms of the hazard ratios (HRs) for overall survival (OS) and progression-free survival (PFS) between these two subgroups, respectively. We used random-effects meta-analysis to calculate the pooled ratios of HRs (i.e., exp(MD)) and implemented a meta-regression analysis to identify significant covariates. RESULTS: A total of 17 and 11 trials were included in the meta-analyses of OS and PFS, respectively. These trials included 2732 (25.49%) Asian and 7000 (65.32%) non-Asian participants in the OS analysis and 1438 (22.5%) Asian and 4129 (64.61%) non-Asian participants in the PFS analysis. The pooled ratio of HRs for OS was 0.87 (95% CI: 0.76-0.99; p = 0.0391), favoring Asian participants, but no significant difference was found in PFS (pooled ratio of HRs: 0.93; 95% CI: 0.82-1.07; p = 0.2391). Both linear meta-regression analyses revealed an open-label design as a crucial covariate, which indicated more benefits for non-Asian participants. CONCLUSIONS: Compared with non-Asian patients, Asian patients with advanced cancers may derive superior OS benefits from pembrolizumab. Although the results warrant further exploration, this meta-analysis provides insight into clinical research design.

Maintenance therapy of low-dose nivolumab, S-1, and leucovorin in metastatic pancreatic adenocarcinoma with a germline mutation of MSH6: A case report.

Immune checkpoint inhibitors (ICIs) provide substantial benefits to a small subset of patients with advanced cancer with mismatch repair deficiency (MMRD) or microsatellite instability (MSI), including patients with pancreatic ductal adenocarcinoma (PDAC). However, the long duration of ICI treatment presents a considerable financial burden. We present the case of a 63-year-old woman with metastatic PDAC refractory to conventional chemotherapy. Genetic analyses identified an MSH6 germline mutation and a high tumor mutation burden (TMB). Complete response (CR) was achieved after a short course of low-dose nivolumab (20 mg once every 2 weeks) with chemotherapy. CR was maintained for over 1 year with low-dose nivolumab and de-escalated chemotherapy without any immune-related adverse events. This case supports the further exploration of low-dose, affordable ICI-containing regimens in patients with advanced MSI-high/TMB-high cancer.