Early-Stage Breast Cancer: Phase III Interim Analysis of Ribociclib Combination Therapy

By: Amanda E. Ruffino, BA
Posted: Wednesday, April 24, 2024

In the randomized phase III NATALEE trial, Dennis Slamon, MD, PhD, of David Geffen School of Medicine at the University of California, Los Angeles, and colleagues investigated whether the benefits of the CDK4/6 inhibitor ribociclib observed in advanced breast cancer might extend to early-stage breast cancer. In The New England Journal of Medicine, the investigators reported their results from a prespecified interim analysis, which showed a significantly lower risk of invasive disease, recurrence, or death with adjuvant ribociclib plus a nonsteroidal aromatase inhibitor (NSAI) than with an NSAI alone in patients with stage II or III hormone receptor–positive, HER2-negative early-stage breast cancer. Further research and longer follow-up may provide additional insights into the durability and long-term effects of ribociclib in the management of early-stage breast cancer.

The interim analysis, as of January 2023, involved 426 patients who experienced invasive disease, recurrence, or death. At the 3-year mark, invasive disease–free survival was 90.4% with ribociclib plus a NSAI and 87.1% with a NSAI alone; this translated to a hazard ratio of 0.75, indicating a 25% reduction in the risk of invasive disease, recurrence, or death with the ribociclib combination (95% confidence interval = 0.62–0.91; P = .003). Furthermore, secondary endpoints, including distant disease–free survival and recurrence-free survival, also favored the ribociclib combination. The safety profile of the 3-year regimen of ribociclib plus a NSAI did not reveal any new signals.

Participants were assigned either ribociclib plus a NSAI or a NSAI alone. Ribociclib was administered at a dose of 400 mg daily for 3 weeks followed by 1 week off, for a total of 3 years. Premenopausal women and men also received goserelin every 28 days.

Disclosure: For full disclosures of the study authors, visit www.nejm.org.

The New England Journal of Medicine

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