Data Leading Up to the Next MONARCH 1 Analysis in mBC

Erika P. Hamilton, MD, director of the Breast Cancer and Gynecologic Cancer Research Program and principal investigator at the Sarah Cannon Research Institute, discusses the data leading up to the Next MONARCH 1 study (NCT02747004) of abemaciclib (Verzenio) plus tamoxifen or abemaciclib alone with metastatic breast cancer.

According to Hamilton, there are lots of data in the first- and second-line setting around the use of CDK4/6 inhibitors such as abemaciclib, palbociclib (Ibrance), and ribociclib (Kisqali). Abemaciclib is the only CDK4/6 inhibitor that has a single-agent approval.

A similar study to Next MONARCH 1 was MONARCH 1 (NCT02102490), which evaluated abemaciclib in patients with hormonally driven breast cancer who had received at least 2 prior lines of chemotherapy. This study was very different from other studies of CDK4/6 inhibitors in the first- and second-line setting. The MONARCH 1 study showed that abemaciclib does have single-agent activity.

Next MONARCH 1 was split into 3 arms. In arm 1, patients were given abemaciclib and tamoxifen (Nolvadex). In arm 2, patients were given abemaciclib alone. In arm 3, they were given abemaciclib and a prophylactic.

Results found that while progression-free survival did not change significantly between the arms, overall survival in arm A ranged from 17 to 24 months. According to Hamilton, abemaciclib could be a good option for patients who do not respond to endocrine therapy.