AstraZeneca (AZN) and Daiichi Sankyo said Monday that an interim analysis of a phase III trial showed that Enhertu combined with pertuzumab significantly improved progression-free survival in a certain type of breast cancer, compared with standard of treatment.

The progression-free survival benefit was seen across all pre-specified patient subgroups treated with the combination.

Although the key secondary endpoint of overall survival was not mature at the time of the analysis, interim data showed an early trend favoring the Enhertu combination, compared with the standard of treatment, the companies said.