Claudin 18.2 antibody-drug conjugate prolongs survival in gastro-oesophageal cancer
October 26, 2026
A claudin 18.2 antibody-drug conjugate improved overall survival in later-line gastro-oesophageal cancer, according to phase III CLARITY-Gastric01 results presented at ESMO Congress 2026 (LBA7). In the third- or later-line setting, median overall survival was 10.0 months with sonesitatug vedotin (Sone-Ve) versus 5.0 months with investigator’s choice of therapy (hazard ratio [HR] 0.47). That comparison covered 355 patients whose tumours expressed CLDN18.2 on at least 25% of tumour cells at any staining intensity.
Second-line results for the claudin 18.2 antibody-drug conjugate
The second-line result is less clear. In the intention-to-treat population, median progression-free survival was 4.2 months with Sone-Ve versus 3.8 months with investigator’s choice (HR 0.77; p=0.053), which did not meet the prespecified threshold for statistical significance. Intention-to-treat overall survival was 10.6 months versus 6.4 months (HR 0.58), but subgroup analyses suggest that this gain may reflect later-line patients (HR 0.47) rather than second-line patients (HR 0.88).
Why it matters
For HTA, the strongest evidence is the third-line and later overall survival result, which rests on 355 patients in a subgroup defined by CLDN18.2 expression on at least 25% of tumour cells. The first-line question is still open. CLARITY-Gastric02 is testing Sone-Ve with capecitabine, with or without rilvegostomig, as first-line treatment, and it is not yet known how active Sone-Ve will be after zolbetuximab. Other CLDN18.2 agents are in development: ASP2138, a bispecific antibody targeting CLDN18.2 and CD3, has just entered phase III development, and arcotatug tavatecan reported improved progression-free survival in the G-HOPE-001 study. For the cost-effectiveness side, see our earlier piece on trastuzumab-deruxtecan reimbursement in advanced gastric cancer. Cell therapy is a separate approach in advanced gastric cancer, covered in CAR T-cell therapy for advanced gastric cancer.
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