AstraZeneca's experimental drug disappoints in breast cancer survival trial

AstraZeneca said on Monday its experimental precision drug developed with Japan's Daiichi Sankyo did not significantly improve overall survival for patients with a type of breast cancer in a late-stage trial.

The overall survival, or OS rates, in the TROPION-Breast01 Phase III trial of datopotamab deruxtecan (Dato-DXd), did not achieve statistical significance compared with chemotherapy, AstraZeneca said.

This followed similar disappointing results in key lung cancer trials released earlier this month. AstraZeneca shares had dropped following that trial setback, as investors and analysts had forecast the drug could potentially be the company's next best-selling medicine.

Dato-DXd belongs to a class of drugs known as antibody drug conjugates (ADC) consisting of tumour-seeking monoclonal antibodies that are combined with a cell-killing chemotherapy payload.

"We will continue discussions with regulatory authorities and apply insights from these results to our clinical development programme for datopotamab deruxtecan in breast cancer," said AstraZeneca's Oncology RD Executive Vice President Susan Galbraith.

The drug previously met the main goals of progression-free survival in a late-stage breast cancer study.

"We remain committed to making datopotamab deruxtecan another potential option for patients who can benefit," said Daiichi Sankyo's global head of RD Ken Takeshita.