AstraZeneca and Daiichi Sankyo's Datroway Shows Promise in Hard-to-Treat Breast Cancer

Breakthrough Results in TROPION-Breast02 Trial

AstraZeneca and Daiichi Sankyo have announced groundbreaking results from their Phase 3 TROPION-Breast02 trial, evaluating the efficacy of Datroway in patients with inoperable metastatic triple-negative breast cancer (TNBC). The study, presented at the European Society for Medical Oncology, demonstrated significant improvements in overall survival and progression-free survival compared to chemotherapy.

Datroway, an antibody-drug conjugate targeting the TROP2 protein, extended median overall survival to 23.7 months, compared to 18.7 months for patients receiving chemotherapy. The drug also nearly doubled the time without disease progression, with a median progression-free survival of 10.8 months versus 5.6 months in the chemotherapy arm.

Mohit Manrao, head of AstraZeneca's U.S. oncology division, emphasized the importance of these results, stating, "For triple negative patients, whose disease moves very progressively every day, every week, every month, [this data] is a huge hope that science is delivering for them."

Efficacy and Safety Profile

The TROPION-Breast02 trial enrolled nearly 650 participants for whom immunotherapy was not a treatment option. Datroway demonstrated superior efficacy across multiple metrics:

• 63% of patients treated with Datroway experienced tumor shrinkage, compared to 29% in the chemotherapy group.
• The risk of death was reduced by 21% in the Datroway arm.
• The study met its primary endpoints, showing a 43% reduction in patients' risk of disease progression or death.

Safety data revealed Grade 3 or higher treatment-related adverse events in 33% of Datroway-treated patients, compared to 29% in the chemotherapy group. Common side effects included mouth inflammation, fatigue, anemia, and low white blood cell counts. One death due to interstitial lung disease was reported in the Datroway group, though disease progression was also cited as a factor.

Competitive Landscape and Future Outlook

Datroway's success positions it as a direct competitor to Gilead's Trodelvy, another TROP2-targeting antibody-drug conjugate approved for TNBC patients who have tried at least two systemic therapies. Recent data from Trodelvy's first-line treatment trial showed a median progression-free survival of 9.7 months compared to 6.9 months for chemotherapy.

Leerink analysts suggest that while both trials have nuanced differences, Datroway may have demonstrated "a slightly better clinical profile" compared to Trodelvy, potentially leading to greater commercial share.

AstraZeneca plans to share the TROPION-Breast02 results with global regulators to determine the next steps toward approval. If approved, Datroway could offer a new treatment option for patients with one of the most challenging forms of breast cancer, potentially reshaping the therapeutic landscape for TNBC.