AstraZeneca and Daiichi Sankyo's Datroway Secures FDA Approval for Breast Cancer, Despite Mixed Data

AstraZeneca and Daiichi Sankyo's antibody-drug conjugate (ADC) datopotamab deruxtecan, now branded as Datroway, has received its first U.S. Food and Drug Administration (FDA) approval for the treatment of certain types of breast cancer. This milestone comes amid a landscape of mixed clinical data and strategic repositioning in the competitive oncology market.

FDA Approval and Market Entry

The FDA greenlit Datroway on Friday for adult patients with unresectable or metastatic HR-positive, HER2-negative breast cancer who have undergone prior lines of chemotherapy and endocrine-based therapy. This approval arrives two weeks ahead of the agency's original target decision date and follows a similar approval in Japan three weeks prior.

Datroway, priced at nearly $4,900 per vial, is expected to be available by prescription in the United States within approximately two weeks. This pricing strategy and swift market entry underscore the partners' confidence in the drug's potential, despite facing a competitive landscape in breast cancer treatment.

Clinical Data and Market Positioning

The approval was based on results from the Phase III TROPION-Breast01 study, which demonstrated that Datroway reduced the risk of disease progression or death by 37% compared to chemotherapy. Patients treated with Datroway experienced a median progression-free survival of 6.9 months, compared to 4.9 months for those receiving chemotherapy.

However, the drug's clinical profile is not without controversy. In a follow-up readout in September 2024, Datroway failed to significantly improve overall survival in the same patient population. This mixed data presents a complex picture for clinicians and patients considering treatment options.

Analysts at Leerink Partners predict "modest peak revenues" of approximately $540 million worldwide for Datroway in its current indication. The drug is expected to compete with AstraZeneca and Daiichi Sankyo's own Enhertu in the HR-positive, HER2-low expression breast cancer space, potentially relegating Datroway to later lines of therapy in certain patient subgroups.

Future Prospects and Ongoing Trials

Despite the setbacks in overall survival data for breast cancer, AstraZeneca and Daiichi Sankyo continue to explore Datroway's potential in other cancer types. The partners are anticipating a readout for triple-negative breast cancer in the first half of this year, which analysts at Leerink see as a greater opportunity for the drug.

Additionally, a new Biologics License Application for Datroway in non-small cell lung cancer (NSCLC) is currently under FDA review, with a decision expected in the third quarter of 2025. This comes after a previous setback in May 2024, when the drug failed to improve overall survival in a Phase III NSCLC trial, leading to the withdrawal of an earlier regulatory filing.

The companies are also investigating a new biomarker, developed with the assistance of artificial intelligence, to better identify patients likely to respond to Datroway. This biomarker has been incorporated into the ongoing Avanzar trial, which has been expanded to increase statistical power in demonstrating Datroway's efficacy in first-line NSCLC treatment.

As AstraZeneca and Daiichi Sankyo navigate the complex landscape of oncology drug development, Datroway's first FDA approval marks a significant milestone. However, the drug's ultimate place in the treatment paradigm will depend on forthcoming clinical data and its performance in real-world settings.