AstraZeneca’s (AZN) experimental drug sonesitatug vedotin, known as sone-ve, helped patients with advanced stomach cancer who had received at least two prior treatments to live longer than analysts had expected, according to late-stage trial data.
Patients on the drug lived a median of 10 months, compared with five months on their doctor’s choice of chemotherapy, a 53 per cent reduction in the risk of death. Analysts had expected a hazard ratio of about 0.7 or lower, with a gain of at least two months.
“A five-month improvement in overall survival is very clinically significant in a difficult-to-treat patient population,” said Susan Galbraith, executive vice-president of oncology haematology research and development at AstraZeneca.
The result could bolster confidence in the drug’s commercial potential, as it did not reach statistical significance on its other goal of progression-free survival. AstraZeneca has said it expects the drug could generate peak sales of $3bn to $5bn, but analyst estimates are closer to $1bn.
Sone-ve belongs to a class of treatments known as antibody drug conjugates, often described as guided missiles because they deliver therapy to cancer cells while sparing healthy ones. “It’s another data set that reinforces our vision that we’ve had for a long time, that ADCs can replace and improve on backbone chemotherapy in many different tumour types,” Galbraith said.
Detailed data from the 532-patient study was presented at the European Society for Medical Oncology conference in Madrid, a month after AstraZeneca agreed to invest $2bn in biopharmaceutical company Summit Therapeutics and to test sone-ve alongside Summit’s bispecific antibody ivonescimab.
Patients with gastroesophageal cancer were enrolled if at least 25 per cent of their tumor cells showed claudin 18.2, a protein found on many cancer cells. The approved treatment for this target requires a 75 per cent cutoff. Galbraith said the lower threshold could double the number of patients eligible for treatment.
“I think that bodes well for the opportunity to move it into the earlier line setting,” she said. A separate study of more than 2,000 patients is already testing the drug earlier in the course of therapy.
Analysts at HSBC said the miss on progression-free survival makes it harder to compare the drug with IBI343, a rival claudin 18.2 therapy being developed by Takeda (TAK) and Innovent (1801.HK), which succeeded on its progression-free survival goal in a late-stage study.
Serious side effects were less common with AstraZeneca’s drug, at 36.4 per cent versus 44.8 per cent for chemotherapy, though stomach-related side effects were more frequent, at 11.1 per cent versus 6.3 per cent.