Dr Hamilton on the Benefit Derived From Adjuvant Ribociclib in HR+/HER2– Breast Cancer

Erika P. Hamilton, MD, director, Breast Cancer and Gynecologic Cancer Research, Sarah Cannon Research Institute, discusses the benefit seen with adjuvant ribociclib (Kisqali) in patients with hormone receptor (HR)–positive,HER2-negative breast cancer.

Preliminary data from the phase 3 NATALEE trial (NCT03701334) produced encouraging outcomes that were presented at the 2023 ASCO Annual Meeting, Hamilton begins. Abemaciclib (Verzenio) is currently the only FDA-approved CDK4/6 inhibitor in the adjuvant setting for patients who have high-risk disease,, she says. This agent was brought into practice following positive data from the phase 3 monarchE trial (NCT03155997), Hamilton highlights. 

The NATALEE trial is investigating the efficacy of the CDK4/6 inhibitor ribociclib in the adjuvant setting, but. Unlike monarchE, NATALEEincluded patients with both high- and intermediate-risk disease, Hamilton explains. Notably, the trial enrolled patients who had fewer lymph nodes involved in their disease and had more intermediate-risk features, Hamilton notes.

This was a very early look at this trial, as 78% of patients are still receiving ribociclib. However, an initial read-out showed a 3.3% difference in invasive disease-free survival in favor of adjuvant ribociclib and an aromatase inhibitor (AI) vs an AI alone, Hamilton continues. As these data mature, investigators hope that ribociclib will confer greater benefit and lead to more patients being cured, she says.

Notably, ribociclib was administeredon for 3 years in the NATALEE, whereas abemaciclib was administered for 2 years in the monarchE trial, Hamilton expands. Additionally, ribociclib can lead to neutropenia. The agent is administered at a dose of 600 mg in the metastatic setting, and 400 mg in the adjuvant setting.

Although ribociclib is not currently FDA approved in the adjuvant setting, Hamilton believes that it may eventually gain approval based on the data from the NATALEE trial. It will be beneficial to have more than one CDK4/6 inhibitor widely available in the adjuvant setting, Hamilton concludes.