AstraZeneca Experimental Drug Shows Significant Survival Benefit in Advanced Stomach Cancer Trial
AstraZeneca has reported positive late-stage clinical trial results for its experimental stomach cancer drug, sone-ve, which significantly extended the lives of patients with advanced disease. The data, presented Sunday at the European Society for Medical Oncology conference in Madrid, indicates that the drug could potentially double the number of patients eligible for targeted claudin 18.2 therapies.
In the study of 532 patients with advanced gastroesophageal cancer, those treated with sone-ve achieved a median overall survival of 10 months. This compared to just 5 months for patients receiving their doctor’s choice of standard chemotherapy. The result represents a 53% reduction in the risk of death, a margin that exceeded the expectations of industry analysts who had anticipated a survival gain of approximately two months and a hazard ratio of 0.7 or lower.
Susan Galbraith, executive vice president of oncology haematology research and development at AstraZeneca, described the five-month improvement as “very clinically significant,” particularly given that the study focused on a difficult-to-treat patient population that had already failed at least two prior lines of therapy.
Sone-ve is an antibody-drug conjugate, a class of medication that works by linking a targeted antibody to a potent chemotherapy payload, delivering the treatment directly to cancer cells. The drug targets claudin 18.2, a protein frequently found on the surface of stomach cancer cells. While currently approved treatments for this target require a protein expression cutoff of 75%, AstraZeneca’s study enrolled patients with a much lower threshold of 25%. This lower requirement could double the pool of eligible patients and supports moving the drug into earlier lines of treatment.
Despite the strong survival data, the trial did not reach statistical significance for its co-primary goal of progression-free survival—the amount of time a patient lives without the disease worsening. The median progression-free survival was 4.2 months for those on sone-ve compared to 3.8 months for the chemotherapy group. Galbraith noted that measuring progression in stomach cancer is notoriously difficult because the tumors often spread in a diffuse manner rather than as solid, easily measured masses.
The miss on the progression-free survival metric has drawn comparisons to rival therapies. Analysts from HSBC noted that the lack of statistical significance in this area makes it more difficult to compare sone-ve to IBI343, a competing claudin 18.2 therapy being developed by Takeda and Innovent, which did meet its progression-free survival targets in late-stage testing.
Regarding safety, serious side effects were less frequent in the sone-ve group, occurring in 36.4% of patients compared to 44.8% of those on standard chemotherapy. However, patients receiving the experimental drug did experience a higher rate of stomach-related side effects, at 11.1% versus 6.3% in the control group.
AstraZeneca is already moving to expand its research into the drug. A larger study involving more than 2,000 patients is currently testing sone-ve in earlier stages of the disease. This clinical momentum follows the company’s recent $2 billion investment in Summit Therapeutics, which includes plans to test sone-ve in combination with Summit’s bispecific antibody, ivonescimab.
