Dr. Tolaney on the Safety Profile of SAR439859 in ER+/HER2- Metastatic Breast Cancer

Sara M. Tolaney, MD, MPH, associate director, Susan F. Smith Center for Women’s Cancers, director of Clinical Trials, Breast Oncology, and senior physician, Dana-Farber Cancer Institute, and an assistant professor of medicine, Harvard Medical School, discusses the safety profile of SAR439859 in estrogen receptor (ER)–positive, HER2-negative metastatic breast cancer.

The ongoing phase 2 AMEERA-3 trial (NCT04059484) is evaluating the investigational selective ER degrader (SERD) SAR439859 vs endocrine therapy in pre- and postmenopausal patients with ER-positive/HER2-negative locally advanced or metastatic breast cancer with prior exposure to endocrine therapy.

Previous findings suggested that SAR439859 is well tolerated among patients, Tolaney says. Common adverse effects (AEs) include hot flashes and night sweats. Notably, unlike some other SERDs that can cause significant gastrointestinal (GI) toxicity, SAR439859 is associated with low rates of low-grade GI AEs, such as nausea, Tolaney explains. Additionally, other SERDs have demonstrated unique toxicities, such as bradycardia and visual disturbances, says Tolaney. Conversely, no novel safety signals have been observed with SAR439859.

Although the agent is currently being evaluated, it has the potential to introduce an oral, efficacious, and well-tolerated SERD into the paradigm, says Tolaney. Moreover, SAR439859 could potentially offer an alternative to fulvestrant (Faslodex), which requires intramuscular injection and has limited bioavailability, Tolaney concludes.