AstraZeneca’s experimental stomach cancer drug, sonesitatug vedotin (Sone-Ve), reduced the risk of death by 42% in a Phase 3 clinical trial involving patients with advanced stomach and related cancers. This AstraZeneca stomach cancer drug trial, called CLARITY-Gastric01, found that patients receiving the drug lived a median of 10.6 months, compared with 6.4 months for those receiving their doctors’ choice of treatment.
The findings offer a potential new option for patients whose cancer progresses after previous treatment. However, the drug remains investigational, and the results did not establish a statistically significant improvement in progression-free survival.
What the AstraZeneca Stomach Cancer Drug Trial Found?
The global Phase 3 stomach cancer trial enrolled 532 patients with locally advanced or metastatic gastric cancer, gastroesophageal junction (GEJ) cancer, or oesophageal adenocarcinoma. Participants had cancer that progressed after earlier treatment and tumours expressing a protein called CLDN18.2 in at least 25% of tumour cells.
Researchers reported two key overall survival findings:
- Across the overall trial population: Median overall survival was 10.6 months with Sone-Ve, compared with 6.4 months with the doctors’ choice of therapy, representing a 42% lower risk of death.
- Among patients treated in the third line or later: Median overall survival was 10 months with Sone-Ve versus five months with the comparison treatment, representing a 53% lower risk of death.
The findings from the AstraZeneca stomach cancer drug trial were presented at the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid, Spain. Rui-Hua Xu, the trial’s principal investigator, said the results were significant for a disease in which patients often face a poor prognosis after initial treatment fails.
How Does AstraZeneca’s Sonesitatug Vedotin Drug Work?
AstraZeneca’s Sone-Ve is an antibody-drug conjugate (ADC), a type of treatment that combines an antibody with a cancer-killing drug. The antibody targets CLDN18.2, a protein found on certain tumour cells, helping deliver the drug to cancer cells.
The AstraZeneca stomach cancer drug trial included patients whose tumours showed CLDN18.2 expression in at least 25% of cells. This threshold could make the treatment relevant to a broader group of patients than approaches that use a higher expression threshold. However, patients would need appropriate testing to determine whether their cancer meets the study’s biomarker criteria.
Safety & Limitation of AstraZeneca Stomach Cancer Drug Trial
Although the overall survival findings were positive, the Sone-Ve clinical trial did not meet statistical significance for its other primary endpoint: progression-free survival (PFS). PFS measures how long patients live without their cancer growing or spreading.
Median PFS, assessed by an independent review, was 4.2 months with Sone-Ve and 3.8 months with the comparison treatment. The difference did not reach the trial’s threshold for statistical significance. This means the AstraZeneca stomach cancer drug study did not establish a statistically significant improvement in this measure, despite the survival benefit.
The safety analysis found that treatment-related adverse events rated Grade 3 or higher occurred in 36.4% of patients receiving Sone-Ve, compared with 44.8% of those receiving the comparison therapy. Stomach-related adverse events, however, were more frequent with Sone-Ve, affecting 11.1% of patients versus 6.3% in the comparison group.
What Comes Next for AstraZeneca’s Cancer Drug Development?
AstraZeneca’s cancer drug Sone-Ve remains an investigational drug and is not established as a routine treatment based on these results alone. Regulatory authorities will need to assess the evidence before determining whether it should receive approval.
AstraZeneca is also studying the drug in the Phase 3 CLARITY-Gastric02 trial. That study evaluates Sone-Ve with capecitabine, a chemotherapy medicine, with or without rilvegostomig, as a first-line treatment for advanced or metastatic gastric, GEJ and oesophageal adenocarcinoma.
The ongoing AstraZeneca stomach cancer drug trial will help determine whether Sone-Ve can benefit patients earlier in treatment and how it may fit into future care.
