AstraZeneca’s experimental drug sone-ve extended survival for patients with advanced stomach cancer beyond what analysts had predicted, according to late-stage trial data presented on Sunday. All participants had already received at least two earlier treatments.
Patients taking the drug had a median survival of 10 months, compared with 5 months for those given chemotherapy chosen by their doctor. That gap corresponds to a 53% lower risk of death.
Survival gains and the drug’s commercial outlook
Susan Galbraith, executive vice president of oncology haematology research and development at AstraZeneca, said a 5-month improvement in overall survival is “very clinically significant” in a hard-to-treat patient group.
The drug did not reach statistical significance on its other goal, progression-free survival, so the overall survival result may carry extra weight for its market prospects. AstraZeneca has said it expects peak sales of between $3 billion and $5 billion, while analysts’ estimates are closer to $1 billion.
How sone-ve works and who can enrol
Sone-ve, formally called sonesitatug vedotin, belongs to a class of medicines known as antibody drug conjugates, or ADCs. These are often described as guided missiles because they deliver treatment to cancer cells while sparing healthy ones.
Galbraith said the findings support the company’s long-standing view that ADCs can replace and improve on standard chemotherapy across many tumour types. Patients with gastroesophageal cancer qualified if at least 25% of their tumour cells showed claudin 18.2, a protein found on many cancer cells. The approved treatment for this target requires 75%, and Galbraith said the lower threshold could double the number of eligible patients.
Galbraith said the data “bodes well” for moving the drug into earlier lines of therapy. Another study of more than 2,000 patients is already testing it earlier in a patient’s course of treatment.
Analyst expectations, rival therapy and side effects
Analysts had expected an overall survival hazard ratio, a measure of risk of death, of about 0.7 or lower, with a gain of at least two months. HSBC analysts said the missed progression-free goal makes it harder to compare sone-ve with IBI343, a rival claudin 18.2 therapy developed by Takeda and Innovent that succeeded on that endpoint in a late-stage study.
Serious side effects were less common with sone-ve, occurring in 36.4% of patients compared with 44.8% on chemotherapy. Stomach-related side effects were more frequent, however, at 11.1% versus 6.3%.
