Notes This article was published on June 1, 2025, and updated on July 24, 2025, at NEJM.org. A data sharing statement provided by the authors is available with the full text of this article at NEJM.org. Supported by AstraZeneca. Dr. Bidard is supported by a grant (ANR-23-IAHU-0006) from the Women’s Cancer Institute of Institut Curie. Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.