Dana-Farber Research Supports FDA Approval of New Therapy for Metastatic Breast Cancer

Sara Tolaney, MD, MPH

Sacituzumab govitecan, a novel antibody drug-conjugate therapy has been granted accelerated approved by the U.S. Food and Drug Administration (FDA) for the treatment of metastatic HR-positive, HER2-negative breast cancer.

The FDA action was based on the results of TROPICS-02, a study in which Dana-Farber's Sara Tolaney, MD, MPH, helped lead and which was presented at the European Society of Medical Oncology annual meeting in September 2022 as well as the American Society of Clinical Oncology meeting in June 2022. Researchers reported that the sacituzumab govitecan produced a statistically significant improvement in overall survival rates compared to chemotherapy. The overall survival rate for patients taking part in the global phase 3 study was 14.4 months for those who received sacituzumab govitecan and 11.2 for those given chemotherapy. The sacituzumab arm of the study also showed superior response rates as well as prolonged median progression free survival when compared to standard chemotherapy. Patients treated with sacituzumab had a 34% lower risk of cancer progression or death than those treated with chemotherapy.

“Sacituzumab is associated with an improvement in both progression-free and overall survival when compared to standard chemotherapy among patients with endocrine refractory metastatic hormone-receptor positive breast cancer,” says Tolaney, chief of the Division of Breast Oncology at the Susan F. Smith Center for Women’s Cancers at Dana-Farber. “Today’s FDA action is very meaningful for these patients who are need of additional, effective treatment options.”

Sacituzumab govitecan is made up of an antibody that targets Trop-2, a receptor abundant on the cell membrane in many types of solid tumors, including breast cancer, and a cancer drug called SN-38. It has been approved by the FDA for certain patients with triple-negative breast cancer and showed encouraging activity in an early-phase clinical trial in patients with HR-positive/HER2-negative metastatic breast cancer that has progressed after at least two prior chemotherapies.

The TROPICS-02 clinical trial involved 543 patients with metastatic HR-positive/HER2-negative breast cancer who previously had been treated with endocrine therapy and chemotherapy. Half were randomly assigned to receive sacituzumab govitecan and half received chemotherapy. The most common adverse effects of treatment were neutropenia (a low count of neutrophils, a type of white blood cell), diarrhea, nausea, alopecia (hair loss), fatigue, and anemia, all of which occurred at a higher rate in patients in the sacituzumab govitecan group than the chemotherapy group.