Dr Lim on the Significance of the FDA Approval of Adjuvant Ribociclib in HR+/HER2– Breast Cancer

Bora Lim, MD, associate professor, chief, Translational Research section, Department of Breast Medical Oncology, Division of Cancer Medicine, The University of MD Anderson Cancer Center, discusses how the FDA approval of adjuvant ribociclib (Kisqali) plus an aromatase inhibitor (AI) impacts the treatment paradigm for patients with hormone receptor (HR)–positive, HER2-negative breast cancer.

The regimen was approved for this indication on September 17, 2024, for patients with HR-positive, HER2-negative stage II/III early breast cancer at high risk of recurrence, including those with node-negative disease. This regulatory decision was supported by data from the phase 3 NATALEE trial (NCT03701334), in which the combination of ribociclib and endocrine therapy demonstrated a statistically significant and clinically meaningful improvement in invasive disease-free survival (IDFS) compared with endocrine therapy alone.

At the final iDFS analysis, the ribociclib regimen produced an IDFSrate of 90.7% at 36 months (95% CI, 89.3%-91.8%) compared with 87.6% (95% CI, 86.1%-88.9%) in the AI-only group (HR, 0.749; 95% CI, 0.628-0.892). Overall survival data were not yet mature at the time of this analysis.

Abemaciclib (Verzenio) was the first CDK4/6 inhibitor approved for use by the FDA in the adjuvant breast cancer setting based on data from the phase 3 monarchE trial (NCT03155997). Although cross-trial comparisons are discouraged, there are distinctions between the populations eligible for ribociclib under NATALEE vs those eligible for abemaciclib under monarchE, Lim says. For instance, patients with node-negative disease with other high-risk features, such as a T3 tumor, might not have been eligible for abemaciclib but could now benefit from ribociclib.

Lim states that she and her colleagues have been eagerly awaiting this approval, as it expands the treatment arsenal for patients with high-risk early breast cancer who did not qualify for abemaciclib based on trial eligibility criteria but may still benefit from adjuvant CDK4/6 inhibition. As a result, oncologists will likely spend the next few months paying close attention to differences in trial criteria to determine who will benefit from this newly approved treatment, according to Lim. This decision marks an important step forward in offering additional protective measures to a broader group of high-risk patients in the adjuvant setting, she concludes.