Dr. Tripathy on Frontline Endocrine Therapies in HR+ Breast Cancer

Debu Tripathy, MD, professor and chairman, Department of Breast Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, discusses frontline endocrine therapies for patients with hormone receptor (HR)-positive breast cancer.

The question of what the best endocrine therapy is in the first-line setting is still evolving, says Tripathy. The FALCON trial compared anastrozole (Arimidex) with fulvestrant (Faslodex) and showed a slight benefit with fulvestrant in terms of progression-free survival (PFS). Patients who did not have visceral disease—bone-only or soft tissue disease—showed significantly better outcomes. However, the study was done in patients who had not previously received endocrine therapy, including in the adjuvant setting, says Tripathy. Most of the patients were de novo or had not had adjuvant therapy. That is one caveat that has led physicians to question whether fulvestrant should be paired with some of the biological drugs, such as CDK4/6 inhibitors.

The MONALEESA-3 trial looked at fulvestrant and the CDK4/6 inhibitor ribociclib (Kisqali) as first- or second-line therapy. The trial showed that in the first-line setting, the PFS was very favorable. There was not a head-to-head comparison of fulvestrant to an aromatase inhibitor in this trial. These findings suggest that fulvestrant and CDK4/6 inhibitors may be an optimal first-line therapy, though there is still some controversy there, says Tripathy.