British-Swedish biopharmaceutical company AstraZeneca plc (STO:AZN) (LON:AZN) (NYSE:AZN) and Japanese healthcare company Daiichi Sankyo Co Ltd (TYO:4568) on Tuesday announced European Commission approval for Enhertu (trastuzumab deruxtecan) in combination with pertuzumab as a first-line treatment for adults with unresectable or metastatic HER2-positive breast cancer.

This approval, based on the DESTINY-Breast09 Phase III trial, marks the second new EU indication for Enhertu in two months.

In the trial, the combination reduced the risk of disease progression or death by 44% versus taxane, trastuzumab and pertuzumab, with median progression-free survival of 40.7 months compared with 26.9 months. The safety profile was consistent with the known profiles of the individual treatments, with no new safety concerns identified.

Following the results, the regimen has been included in the ESMO Clinical Practice Guidelines as a Category IA first-line treatment option for metastatic HER2-positive breast cancer regardless of hormone receptor status.

Enhertu is a specifically engineered HER2-directed DXd antibody drug conjugate (ADC) discovered by Daiichi Sankyo and being jointly developed and commercialised with AstraZeneca.

Following the EU approval, AstraZeneca will pay Daiichi Sankyo a USD100m milestone for the first-line unresectable or metastatic HER2-positive breast cancer indication. Sales of Enhertu in most EU territories are recognised by Daiichi Sankyo.