AstraZeneca and Daiichi Sankyo win FDA approval for Datroway in breast cancer, edging ahead of Gilead

Antibody-drug conjugate becomes first in class to demonstrate survival benefit in front-line treatment setting

AstraZeneca (AZN) and its Japanese partner Daiichi Sankyo (DSNKY) have secured US regulatory approval for Datroway in triple-negative breast cancer, marking a significant milestone in an intensifying battle with Gilead Sciences (GILD) for dominance in one of oncology's most contested markets.

The FDA cleared Datroway — a TROP2-directed antibody-drug conjugate — for patients who are not candidates for PD-1/L1 inhibitor therapy. The two companies were quick to highlight that Datroway is the only agent of its class to have demonstrated an improvement in overall survival against chemotherapy in this first-line setting.

Data from the phase 3 Tropion-Breast02 trial showed Datroway reduced the risk of death by 21 per cent compared with chemotherapy, extending median overall survival by five months to 23.7 months, with a 43 per cent improvement in progression-free survival.

The approval arrives at a particularly pointed moment for Gilead. When the Tropion-Breast02 data were presented at the European Society for Medical Oncology congress last October, Gilead's rival drug Trodelvy failed to meet statistical significance on overall survival in a comparable patient population in its Ascent-03 trial. By cross-trial comparison — a methodology analysts caution is imprecise — Datroway's progression-free survival benefit also edged ahead of Trodelvy's 38 per cent improvement.

Gilead, however, is expected to raise a robust challenge. The company has submitted two indications to the FDA — one from Ascent-03 and a second from the Ascent-04 trial, which tested Trodelvy alongside Merck & Co's (MRK) Keytruda in PD-L1-positive patients — with decisions anticipated in the second half of 2026. Johanna Mercier, Gilead's chief commercial officer, noted on the company's first-quarter earnings call that Trodelvy had already begun to see uptake in the first-line setting following its inclusion in National Comprehensive Cancer Network guidelines, where both drugs hold the highest-tier preferred recommendation.

The clinical and commercial stakes are significant. Seven in ten patients with metastatic triple-negative breast cancer are ineligible for immunotherapy, representing a substantial underserved population. AstraZeneca and Daiichi are expected to leverage both Datroway's survival data and the reputational tailwind from their HER2-targeting drug Enhertu to establish physician preference.

A third competitor is also emerging. Kelun-Biotech's (HKG:6990) sacituzumab tirumotecan, partnered with Merck (MRK), recently posted a positive phase 3 readout in China, with a global trial also testing the drug alongside Keytruda. Analysts have flagged that Datroway's approval may complicate US enrolment for that study, where control-arm patients receive chemotherapy.

Datroway's application was reviewed under Project Orbis, enabling concurrent regulatory assessment in Australia, Canada, Singapore, Switzerland, the EU, China and Japan.