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AstraZeneca Reports Survival Gain, Misses PFS Endpoint

lite News Desk 2 min read

AstraZeneca said sonesitatug vedotin met the overall-survival primary endpoint in the third-line-or-later group of its Phase III CLARITY-Gastric01 trial, while the other primary endpoint, progression-free survival across the second-line-or-later population, did not achieve statistical significance. The company published the detailed results on October 25, 2026, before their presentation at Madrid’s ESMO Congress.

The global study compared sonesitatug vedotin, known as Sone-Ve, with treatment chosen by investigators. According to AstraZeneca, eligibility covered previously treated patients with advanced or metastatic gastric cancer, gastroesophageal-junction cancer or esophageal adenocarcinoma. Tumors had to show CLDN18.2 expression in at least 25% of cells, with any staining intensity accepted.

AstraZeneca’s planned interim analysis used a May 31, 2026 data cutoff. For patients receiving third-line or subsequent treatment, median overall survival reached 10.0 months on Sone-Ve, compared with 5.0 months on investigator-selected therapy. The company reported a hazard ratio of 0.47, with a 95% confidence interval of 0.36–0.62, meeting that primary endpoint.

Across the full second-line-or-later population, overall survival was a key secondary endpoint rather than a primary measure. AstraZeneca reported medians of 10.6 months for Sone-Ve and 6.4 months for the comparator, with a hazard ratio of 0.58 and a 95% confidence interval of 0.47–0.73.

The progression-free-survival primary endpoint used blinded independent central review across that full population. Median values were 4.2 months for Sone-Ve and 3.8 months for investigator-selected treatment. AstraZeneca reported a hazard ratio of 0.77, a 95% confidence interval of 0.62–0.96 and p=0.053193; the result did not meet the statistical-significance threshold.

A separate, exploratory assessment by investigators produced progression-free-survival medians of 4.4 months and 3.0 months, respectively. Its hazard ratio was 0.59, with a 95% confidence interval of 0.48–0.73. This was not the primary progression-free-survival analysis.

In comments to Fierce Biotech reported October 25, Susan Galbraith, AstraZeneca’s oncology and hematology R&D chief, said the company considered the findings sufficiently developed for regulatory discussions, citing survival and investigator-assessed progression-free survival despite the primary endpoint miss. Galbraith also said diffuse spread across the abdominal lining complicates gastric-cancer progression assessments, and independent reviewers may not have the clinical context available to treating investigators.

AstraZeneca reported 594 randomized participants overall. The published treatment comparison comprised 267 participants assigned Sone-Ve at 2.2 mg/kg and 265 assigned investigator-selected therapy.

Separately, Takeda announced on October 23, 2026, that arcotatug tavatecan met both primary measures, overall survival and progression-free survival, in its Phase III G-HOPE-001 study. Takeda said the trial enrolled 464 participants in China and Japan with previously treated CLDN18.2-positive gastric or gastroesophageal-junction adenocarcinoma. It was not a head-to-head comparison with Sone-Ve.

* This article is based on publicly available information at the time of writing.

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