Nicholas P. McAndrew

BACKGROUND: Ribociclib has been shown to have a significant overall survival benefit in patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. Whether this benefit in advanced breast cancer extends to early breast cancer is unclear. METHODS: In this international, open-label, randomized, phase 3 trial, we randomly assigned patients with HR-positive, HER2-negative early breast cancer in a 1:1 ratio to receive ribociclib (at a dose of 400 mg per day for 3 weeks, followed by 1 week off, for 3 years) plus a nonsteroidal aromatase inhibitor (NSAI; letrozole at a dose of 2.5 mg per day or anastrozole at a dose of 1 mg per day for ≥5 years) or an NSAI alone. Premenopausal women and men also received goserelin every 28 days. Eligible patients had anatomical stage II or III breast cancer. Here we report the results of a prespecified interim analysis of invasive disease-free survival, the primary end point; other efficacy and safety results are also reported. Invasive disease-free survival was evaluated with the use of the Kaplan-Meier method. The statistical comparison was made with the use of a stratified log-rank test, with a protocol-specified stopping boundary of a one-sided P-value threshold of 0.0128 for superior efficacy. RESULTS: As of the data-cutoff date for this prespecified interim analysis (January 11, 2023), a total of 426 patients had had invasive disease, recurrence, or death. A significant invasive disease-free survival benefit was seen with ribociclib plus an NSAI as compared with an NSAI alone. At 3 years, invasive disease-free survival was 90.4% with ribociclib plus an NSAI and 87.1% with an NSAI alone (hazard ratio for invasive disease, recurrence, or death, 0.75; 95% confidence interval, 0.62 to 0.91; P = 0.003). Secondary end points - distant disease-free survival and recurrence-free survival - also favored ribociclib plus an NSAI. The 3-year regimen of ribociclib at a 400-mg starting dose plus an NSAI was not associated with any new safety signals. CONCLUSIONS: Ribociclib plus an NSAI significantly improved invasive disease-free survival among patients with HR-positive, HER2-negative stage II or III early breast cancer. (Funded by Novartis; NATALEE ClinicalTrials.gov number, NCT03701334.).

The natural history of hormone receptor-positive breast cancer tends to be more favorable than other subtypes such as human epidermal growth factor receptor 2-amplified and triple-negative. In addition, the natural dependence on steroid hormone signaling has allowed for therapeutic targeting of this pathway and significant improvements in survival while maintaining quality of life: the two main goals in management of the disease. The sequential use of endocrine agents including the selective estrogen receptor modulators (tamoxifen), aromatase inhibitors (letrozole, anastrozole, and exemestane) and the selective estrogen receptor degrader fulvestrant has been the backbone of management for years. In the past decade, the introduction of molecularly targeted agents against intracellular targets such as mammalian target of rapamycin (everolimus), cyclin-dependent kinases 4 and 6 (palbociclib, ribociclib, and abemaciclib), and phosphatidylinositol 3-kinase (alpelisib) has offered patients effective nonchemotherapy-based options, which are improving outcomes. Although knowledge gaps still exist in regard to the optimal sequencing of these new regimens, they have expanded our repertoire of options for patients and have shifted the need for cytotoxic chemotherapy and its associated complications to later lines. Still, formatting a plan for these patients includes taking into account traditional prognostic factors such as menopausal status, previous treatments, disease-free interval for those patients with early breast cancer that has recurred, and tumor burden. To assist in developing this treatment plan, we will review the current data with systemic agents in the management of these patients.

It has been over three decades since anthracyclines took their place as the standard chemotherapy backbone for breast cancer in the curative setting. Though the efficacy of anthracycline chemotherapy is not debatable, potentially life-threatening and long-term risks accompany this class of agents, leading some to question their widespread use, especially when newer agents with improved therapeutic indices have become available. Critically assessing when to incorporate an anthracycline is made more relevant in an era where molecular classification is enabling not only the development of biologically targeted therapeutics but also is improving the ability to better select those who would benefit from cytotoxic agents. This comprehensive analysis will present the problem of overtreatment in early-stage breast cancer, review evidence supporting the use of anthracyclines in the pre-taxane era, analyze comparative trials evaluating taxanes with or without anthracyclines in biologically unselected and selected patient populations, and explore published work aimed at defining anthracycline-sensitive tumor types.