Datroway Approved: New Targeted Therapy Offers Hope for Metastatic Breast Cancer

A new therapeutic horizon has arrived for patients battling metastatic breast cancer that has progressed despite hormone and chemotherapy. With the recent approval of a targeted chemotherapy drug, significant shifts in treatment strategies are expected for the hormone receptor (HR) positive and HER2 negative patient group—a demographic that represents the majority of breast cancer cases in South Korea.

Korea Daiichi Sankyo and Korea AstraZeneca announced that the Ministry of Food and Drug Safety granted product approval for Datroway (datopotamab deruxtecan) on the 9th. The approval specifically targets patients with unresectable or metastatic HR-positive, HER2-negative breast cancer who have previously undergone endocrine-based therapy and systemic chemotherapy.

Bridging the Gap in Conventional Treatment

This approval is a landmark moment for a patient group that has long faced a shortage of effective alternatives. HR-positive, HER2-negative breast cancer is the most common subtype, accounting for approximately 70% of all diagnoses. Traditionally, once endocrine therapy fails, patients have relied on single-agent chemotherapy, which often lacks long-term efficacy and significantly impacts the patient's quality of life.

Datroway is an antibody-drug conjugate (ADC) designed to target TROP2 (trophoblast cell surface antigen-2). It utilizes the deruxtecan (DXd) ADC technology developed by Daiichi Sankyo and is being co-developed and commercialized globally with AstraZeneca. It marks the second deruxtecan-based ADC to receive the green light in the country.

"It is estimated that only one in three patients with HR-positive, HER2-negative breast cancer survives more than five years after metastasis," noted Professor Jeong Kyung-hae of the Department of Oncology at Asan Medical Center. "For those whose cancer progresses despite standard care, Datroway represents a significant alternative that improves survival while maintaining quality of life."

Clinical Breakthrough: The TROPION-Breast01 Trial

The regulatory approval was supported by data from the global Phase 3 TROPION-Breast01 clinical trial. The study evaluated the efficacy and safety of Datroway (6 mg/kg) against investigator-selected single-agent chemotherapies (including eribulin and capecitabine) in 732 patients.

The findings were decisive:

• Reduced Risk: Datroway reduced the risk of disease progression or death by 37%.

• Progression-Free Survival (PFS): The median PFS was 6.9 months for the Datroway group, compared to 4.9 months in the control group.

• Tumor Reduction: The Objective Response Rate (ORR) reached 36.4%, significantly higher than the 22.9% seen with traditional chemotherapy.

• Quality of Life: The median time to deterioration (TTD) in quality of life was nearly doubled, extending from 4.8 months to 9.0 months.

Safety Profile and Market Entry

While the drug showed superior efficacy, researchers monitored common adverse reactions, which included stomatitis (63.7%), nausea (56.9%), and fatigue (45.1%). Serious adverse reactions were rare, occurring in 3.1% of patients, with interstitial lung disease reported at 1.1%.

"Providing a new option for patients who had exhausted their alternatives is deeply meaningful," said Lee Sun-jin, Executive Director of the Anticancer Drug Division at Korea Daiichi Sankyo. "We are committed to a prompt domestic launch to ensure patients receive treatment in a timely manner."

Datroway is scheduled for a domestic market launch in the first half of 2026. Korea Daiichi Sankyo will manage distribution, while joint development and sales will be shared with Korea AstraZeneca.