First patient dosed in phase 3 trial of breast cancer drug

Published 27/08/2025, 12:06
First patient dosed in phase 3 trial of breast cancer drug

BASKING RIDGE & RAHWAY, N.J. - Daiichi Sankyo and Merck announced Wednesday that the first patient has been dosed in the HERTHENA-Breast04 phase 3 trial evaluating patritumab deruxtecan against physician’s choice of treatment for patients with hormone receptor positive, HER2 negative breast cancer.

The trial targets patients whose disease has progressed following endocrine and CDK4/6 inhibitor therapy in either adjuvant or first-line metastatic settings.

Patritumab deruxtecan is a HER3 directed antibody drug conjugate being jointly developed by Daiichi Sankyo (TSE:4568) and Merck.

"Despite significant development in the treatment landscape, HR positive, HER2 negative metastatic breast cancer is a highly complex and challenging disease with an overall poor prognosis," said Mark Rutstein, Head of Therapeutic Area Oncology Development at Daiichi Sankyo, in a press release statement.

The HERTHENA-Breast04 trial will enroll approximately 1,000 patients across Asia, Europe, North America, and South America. Participants will be randomized to receive either patritumab deruxtecan or physician’s choice of treatment, which may include chemotherapy options or trastuzumab deruxtecan.

The dual primary endpoints are progression-free survival and overall survival. Secondary endpoints include objective response rate, duration of response and safety.

The trial initiation follows promising results from earlier studies including ICARUS-Breast01 and a phase 1/2 breast cancer trial published in 2022.

According to the companies, approximately 70% of diagnosed breast cancer cases are considered HR positive, HER2 negative. Survival rates for patients with metastatic breast cancer are poor, with only about 30% expected to live five years following diagnosis. For investors tracking pharmaceutical developments, InvestingPro offers comprehensive analysis of Merck and other healthcare leaders, with detailed research reports covering key metrics, growth prospects, and industry positioning. Subscribers gain access to 12+ exclusive ProTips and in-depth financial analysis tools.

In other recent news, Merck reported its second-quarter 2025 earnings, surpassing expectations with earnings per share (EPS) of $2.13, compared to the forecasted $2.03, resulting in a 4.93% surprise. However, the company’s revenue slightly missed projections, coming in at $15.81 billion against an expected $15.87 billion. Merck also announced plans to present new cardiovascular disease data at the European Society of Cardiology Congress 2025 in Madrid, focusing on atherosclerotic cardiovascular disease, pulmonary hypertension, and heart failure with reduced ejection fraction. These presentations will include discussions on clinical and economic burdens in patients with myocardial infarction and trends in lipid-lowering therapy. Additionally, the company experienced a decline in pre-market trading, though no specific reasons were given in the report. Despite the revenue shortfall, the earnings beat could be seen as a positive indicator by some analysts. Investors may find the upcoming cardiovascular data presentations noteworthy for future developments.

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