AstraZeneca said 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.
Dato-DXd belongs to a class of drugs known as antibody drug conjugates 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 R&D 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 R&D Ken Takeshita.