Background: The phase 3 SPOTLIGHT (NCT03504397) and GLOW (NCT03653507) studies showed clinically meaningful, statistically significant improvement in PFS and OS using 1L zolbetuximab + chemotherapy vs placebo (PBO) + chemotherapy in patients (pts) with CLDN18.2+, HER2−, LA unresectable or mG/GEJ adenocarcinoma. N/V were the most common treatment-emergent adverse events (TEAEs) reported in the zolbetuximab arm of these studies. We report an analysis of the incidence and management of N/V in SPOTLIGHT and GLOW. Methods: In SPOTLIGHT, pts (N = 565) were randomized 1:1 to zolbetuximab + mFOLFOX6 vs PBO + mFOLFOX6. In GLOW, pts (N = 507) were randomized 1:1 to zolbetuximab + CAPOX vs PBO + CAPOX. In both studies, neurokinin-1 receptor blockers (NK-1), selective serotonin receptor blockers (5-HT3), and other prophylactic antiemetic regimens were recommended to prevent and mitigate N/V per institutional care and guidelines. Results: A total of 279 pts in SPOTLIGHT and 253 pts in GLOW received zolbetuximab + chemotherapy. In SPOTLIGHT and GLOW combined, nausea occurred in 58% vs 18% of pts, and vomiting occurred in 43% vs 15% of pts in the first vs second zolbetuximab infusions, respectively; lower incidences of N/V were observed thereafter. During the first zolbetuximab infusion, the first episode of N/V occurred within 1 hour (median time, 48.0 min in SPOTLIGHT and 56.5 min in GLOW). Antiemetic usage and associated N/V rates are presented in the Table. The 96 pts in SPOTLIGHT and 52 pts in GLOW who had infusion modifications in cycle 1 due to TEAEs had numerically higher infusion rates than pts without infusion modifications; 85% of these modifications in SPOTLIGHT and 79% in GLOW were due to N/V. Zolbetuximab was discontinued within the first 9 weeks in 11 and 7 pts in SPOTLIGHT and 6 and 4 pts in GLOW due to nausea or vomiting, respectively. Conclusions: In SPOTLIGHT and GLOW, slower infusion rate and use of antiemetic combinations may have helped to mitigate N/V. These strategies will be important to support continued treatment and allow pts to achieve maximum clinical benefit with zolbetuximab + chemotherapy. Clinical trial information: NCT03504397 and NCT03653507.