Zolbetuximab + CAPOX in 1L claudin-18.2+ (CLDN18.2+)/HER2− locally advanced (LA) or metastatic gastric or gastroesophageal junction (mG/GEJ) adenocarcinoma: Primary phase 3 results from GLOW

• Published in: Journal of clinical oncology Vol. 41; no. 36_suppl; p. 405736
• Main Authors: Xu, Rui-hua, Shitara, Kohei, Ajani, Jaffer A., Bang, Yung-Jue, Enzinger, Peter C., Ilson, David H., Lordick, Florian, Van Cutsem, Eric, Gallego Plazas, Javier, Huang, Jing, Shen, Lin, Oh, Sang Cheul, Sunpaweravong, Patrapim, Soo Hoo, Hwoei Fen, Turk, Haci M., Park, Jung Wook, Moran, Diarmuid Martin, Bhattacharya, Pranob P., Arozullah, Ahsan, Shah, Manish A.
• Format: Journal Article
• Language: English
• Published: 20.04.2023
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/JCO.2023.41.36_suppl.405736

405736 Background: There is an unmet need for novel targeted therapies that improve outcomes for pts with HER2− LA unresectable or mG/GEJ adenocarcinoma. CLDN18.2 is expressed in normal gastric mucosa cells and retained in most G/GEJ adenocarcinomas. In the phase 3 SPOTLIGHT study, zolbetuximab, a CLDN18.2-targeted chimeric monoclonal antibody, significantly prolonged PFS and OS in pts with CLDN18.2+/HER2− LA unresectable or mG/GEJ adenocarcinoma when combined with mFOLFOX6. GLOW (NCT03653507) is a phase 3 global, double-blind study comparing zolbetuximab or PBO with capecitabine and oxaliplatin (CAPOX) as 1L treatment for this pt population. Methods: Pts with CLDN18.2+ (moderate-to-strong membranous CLDN18 staining in ≥75% tumor cells by IHC)/HER2− LA unresectable or mG/GEJ adenocarcinoma were randomized 1:1 to zolbetuximab IV 800 mg/m 2 (cycle 1, day [D] 1) followed by 600 mg/m 2 (D1 in subsequent cycles) + CAPOX (oral capecitabine 1000 mg/m 2 BID on D1−14 of each cycle; oxaliplatin IV 130 mg/m 2 on D1 of each cycle) for eight 21-day cycles vs PBO + CAPOX; pts continued for >8 cycles with zolbetuximab or PBO, plus capecitabine (investigator decision), until PD or a discontinuation criterium was met. The primary endpoint (EP) was PFS per RECIST v1.1 by IRC. OS was a key secondary EP; other secondary EPs included ORR and safety. Differences between treatment arms in PFS and OS were tested by stratified log-rank tests; OS was tested if PFS was significant. Results: 507 pts were randomized 1:1 to zolbetuximab + CAPOX (N = 254) or PBO + CAPOX (N = 253). Both PFS (median 8.21 vs 6.80 mo, HR 0.687, P=0.0007) and OS (median 14.39 vs 12.16 mo, HR 0.771, P=0.0118) were significantly prolonged with zolbetuximab + CAPOX (Table); in pts with measurable disease, ORR (95% CI) was 53.8% (46.58−60.99) vs 48.8% (41.76−55.84) in zolbetuximab vs PBO arm. The most common TEAEs with zolbetuximab + CAPOX were nausea (68.5% vs 50.2% in zolbetuximab vs PBO arm), vomiting (66.1% vs 30.9%), and decreased appetite (41.3% vs 33.7%); serious TEAEs (47.2% vs 49.8%), grade ≥3 TEAEs (72.8% vs 69.9%), and drug-related TEAEs leading to death (2.4% vs 2.8%) were similar in both arms. Conclusions: Targeting CLDN18.2 with zolbetuximab combined with CAPOX significantly prolonged PFS and OS in 1L pts with CLDN18.2+/HER2− LA unresectable or mG/GEJ adenocarcinoma. These results align with those observed in SPOTLIGHT and establish zolbetuximab + chemotherapy as a potential new standard-of-care option for these pts. Clinical trial information: NCT03653507 . [Table: see text]