Zolbetuximab (anti-CLDN18.2 mAb) + chemo extends PFS to 20.5 months in Japanese 1L gastric/GEJ cancer

Zolbetuximab is a monoclonal antibody targeting CLDN18.2 and is combined here with platinum/fluoropyrimidine chemotherapy as first-line therapy for CLDN18.2-positive (typically defined in SPOTLIGHT/GLOW as ≥75% tumor cells with moderate-to-strong membranous staining), HER2-negative, locally advanced unresectable or metastatic gastric/GEJ adenocarcinoma. This combined Japanese subgroup analysis of the double-blind Phase 3 SPOTLIGHT (zolbetuximab+mFOLFOX6) and GLOW (zolbetuximab+CAPOX) trials included 116 Japanese patients (n=65 SPOTLIGHT; n=51 GLOW) and showed median PFS 20.53 vs 8.28 months and median OS 23.06 vs 16.53 months for zolbetuximab+chemo vs placebo+chemo, with no new safety signals reported (NCT03504397; NCT03653507). Versus today’s common 1L benchmark of nivolumab+chemo in HER2-negative disease, this subgroup’s PFS/OS deltas look directionally larger than the ~2–3 month gains typically reported in all-comers populations—though cross-trial comparisons are shaky and this is a small, post hoc subgroup.