Japanese healthcare company Daiichi Sankyo Co Ltd (TYO:4568) and British-Swedish biopharmaceutical company AstraZeneca plc (STO:AZN) (LON:AZN) (Nasdaq:AZN) on Monday reported positive topline results from the DESTINY-Breast09 phase 3 trial evaluating ENHERTU (trastuzumab deruxtecan) combined with pertuzumab in HER2 positive metastatic breast cancer.

According to the two companies, this combination demonstrated a highly statistically significant and clinically meaningful improvement in progression-free survival compared to the current first-line standard of care -- taxane, trastuzumab, and pertuzumab (THP).

It marks the first trial in over a decade to show superior efficacy across a broad HER2 positive metastatic patient population relative to THP.

Progression-free survival benefit was consistent across all pre-specified patient subgroups.

Although overall survival data were not mature at this interim stage, early trends favoured the ENHERTU combination.

Regulatory submission plans are currently underway.

The study's second arm, comparing ENHERTU monotherapy to THP, remains blinded and will continue to final analysis.

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