Background: The phase 3 SPOTLIGHT (NCT03504397) and GLOW (NCT03653507) studies reported statistically significant improvement in PFS and OS with 1L zolbetuximab (anti-claudin-18 isoform 2 [CLDN18.2]) + mFOLFOX6 or CAPOX in pts with CLDN18.2+, HER2−, LA unresectable or mG/GEJ adenocarcinoma. This network meta-analysis (NMA) indirectly compared the relative efficacy of 1L therapies. Methods: A systematic literature review of phase 2, 3, or unknown phase randomized, global trials of 1L therapies (capecitabine + cisplatin [CX]; capecitabine + oxaliplatin [CAPOX]; fluorouracil + cisplatin [CF]; oxaliplatin + folinic acid + fluorouracil [FOLFOX]; S-1 + cisplatin [SC]; nivolumab + CAPOX/FOLFOX; pembrolizumab + CF/CAPOX or CX; and zolbetuximab + CAPOX/FOLFOX) in adults with LA unresectable or mG/GEJ adenocarcinoma. To form a connected main network, FOLFOX and CAPOX were assumed equally efficacious and combined. In the latest publicly available data, hazard ratios (HRs) of PFS and OS for intent-to-treat (ITT) populations were extracted or reconstructed from Kaplan-Meier curves when not reported as inputs for Bayesian fixed-effects NMAs. Comparative effectiveness was reported using median HR and 95% credible intervals (CrIs). Results: Trials reporting ITT populations were included, resulting in 9 trials (6663 pts) for PFS analysis and 10 trials (6735 pts) for OS analysis representing 8 regimens. Pts were randomly assigned to an experimental arm vs FOLFOX/CAPOX. Pts on 1L zolbetuximab, nivolumab, or pembrolizumab in combination with CF/CAPOX or FOLFOX/CAPOX had significantly reduced risk of disease progression or death vs FOLFOX/CAPOX (Table). Zolbetuximab + FOLFOX/CAPOX had the highest probability of being ranked first in treatment efficacy for both PFS (probability =0.54) and OS (0.36); followed by pembrolizumab + CX (0.27) and pembrolizumab + CF/CAPOX (0.13) for PFS; and by pembrolizumab + CF/CAPOX (0.3) and nivolumab + FOLFOX/CAPOX (0.24) for OS. Conclusions: This NMA examined the relative benefit of different targeted therapies when combined with chemotherapy. Zolbetuximab + FOLFOX/CAPOX for CLDN18.2+, HER2−, LA unresectable or mG/GEJ adenocarcinoma confers a significant PFS and OS benefit, similar to that achieved with PD-1/PD-L1 inhibitors + CF/CAPOX or FOLFOX/CAPOX.

*Based on pts in ITT populations regardless of PD-L1 CPS status.