Recent U.S. news: HR-positive/HER2-negative breast cancer

**Camizestrant gained U.S. accelerated approval (September 2026) with a CDK4/6 inhibitor for adults with HR-positive/HER2-negative advanced breast cancer when an ESR1 mutation is detected during aromatase inhibitor plus CDK4/6 inhibitor treatment. In the SERENA-6 trial, median progression-free survival was 16.0 months after switching to camizestrant versus 9.2 months with continued aromatase inhibitor therapy. FDA announcement

**Imlunestrant plus abemaciclib received U.S. approval (September 2026) for ER-positive/HER2-negative advanced or metastatic disease with an ESR1 mutation after progression on endocrine therapy. A reported trial result showed median progression-free survival of 11.1 months with the combination versus 5.5 months with imlunestrant alone. Reuters

**Gedatolisib is a notable targeted-therapy development. Search results report FDA approval for HR-positive/HER2-negative advanced breast cancer without a detected PIK3CA mutation after progression on at least one line of endocrine therapy in the metastatic setting. FDA and treatment updates

**Research is expanding beyond established endocrine options. Merck initiated the phase 3 HERTHENA-Breast04 trial of investigational patritumab deruxtecan in advanced HR-positive/HER2-negative disease after endocrine therapy and a CDK4/6 inhibitor. Merck trial announcement

**Implications for U.S. medical affairs:
** The news points to a fast-changing treatment landscape, particularly around ESR1 mutation testing and treatment selection. Useful reputation priorities include communicating who qualifies for each therapy, explaining trial results and limitations in plain language, and supporting clinicians and patients with balanced, practical education.