12:18 PM EDT, 09/13/2024 (MT Newswires) -- AstraZeneca ( AZN ) said its phase IIIb/IV trial with Daiichi Sankyo of Enhertu showed "substantial clinical activity" in patients with HER2-positive metastatic breast cancer with brain metastases.

The trial's primary endpoint of progression-free survival revealed a 12-month rate of 61.6% for patients with brain metastases at baseline, the company said.

For central nervous system progression-free survival, patients with brain metastases showed a 12-month rate of 58.9%, the company said.

Among patients without brain metastases at baseline, the trial showed an objective response rate of 62.7%, including 23 complete and 128 partial responses, the company said.

A post-hoc analysis revealed that patients with active brain metastases who had not received prior local CNS therapy showed an objective response rate of 82.6%, the company said.

Enhertu's safety profile was consistent with previous studies with no new concerns identified, including for patients with brain metastases, the company said.

"The data as well as the results in patients without brain metastases further build confidence in the clinical profile of Enhertu for the second-line treatment of HER2-positive metastatic breast cancer," said Sunil Verma, AstraZeneca's ( AZN ) global head of oncology franchise.

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