Dr. Gabriel Hortobagyi on the Impact of MONALEESA-2 Trial in HR+ Breast Cancer

Gabriel N. Hortobagyi, MD, professor of Medicine at the University of Texas MD Anderson Cancer Center, discusses the MONALEESA-2 trial, which has shown that the addition of ribociclib to letrozole significantly improved progression-free survival (PFS) in postmenopausal women with hormone receptor (HR)­-positive advanced breast cancer.

Patients in the ribociclib arm had a 44% reduction in the risk of progression or death compared with patients who recieved placebo plus hormone therapy. This difference satisfied prespecified statistical requirements for superiority.

These findings are practice-changing, says Hortobagyi. Up until the development of the CDK4/6 inhibitors, the standard of care for managing patients with HR-positive metastatic breast cancer was an aromatase inhibitor such as letrozole or anastrozole. Based on these findings, going forward, the treatment of choice for these same postmenopausal women with HR-positive breast cancer will be a combination of a drug like letrozole with a CDK4/6 inhibitor such as ribociclib, he says.

This is a major change because with letrozole alone, the best data was about a 14-month PFS. With the addition of ribociclib, patients are expected to live significantly longer, says Hortobagyi.