Adjuvant CDK4/6 inhibitors improve invasive Disease-Free Survival regardless of patient menopausal statusCDK4/6 inhibitors show consistent results for both pre and postmenopausal women

This systematic review and meta-analysis evaluated the efficacy of adjuvant CDK4/6 inhibitors (including ribociclib and abemaciclib) in a large cohort of 17,748 patients diagnosed with hormone receptor-positive (HR+), HER2-negative early breast cancer. The primary objective was to determine if menopausal status influenced the clinical outcomes associated with adjuvant CDK4/6 inhibition.

The study analyzed invasive Disease-Free Survival (iDFS) as the primary outcome and Overall Survival (OS) as a secondary outcome. The analysis specifically compared pre- or peri-menopausal patients against postmenopausal patients to assess whether hormonal status acted as a modifier of treatment effect for CDK4/6 inhibitors in this specific breast cancer population.

Regarding the primary outcome, the meta-analysis reported favorable results for iDFS in both patient subgroups. For pre- and peri-menopausal patients, the Hazard Ratio (HR) was 0.80 (95% CI 0.67-0.97, I2=64%). In postmenopausal patients, the HR for iDFS was 0.79 (95% CI 0.72-0.86, I2=0%). Additionally, at the 5-6 year mark, there were 3.0% fewer absolute iDFS events in premenopausal patients compared to postmenopausal patients.

Secondary outcomes for Overall Survival showed mixed results based on menopausal status. In pre- and peri-menopausal patients, the HR was 1.02 (95% CI 0.67-1.54, I2=80%), indicating a neutral effect. Conversely, in postmenopausal patients, the OS result was favorable with an HR of 0.89 (95% CI 0.78-1.03, I2=0%).

Safety and tolerability data were not reported in the included studies for this meta-analysis. Consequently, specific rates for adverse events, serious adverse events, or treatment discontinuations are not available to determine the impact of menopausal status on the tolerability profile of CDK4/6 inhibitors.

These findings suggest that the efficacy of adjuvant CDK4/6 inhibition in HR+ and HER2-negative early breast cancer is consistent across different menopausal statuses. While some differences were noted in OS results between groups, the primary endpoint of iDFS showed similar magnitude improvements for both pre- and postmenopausal women.

Methodological limitations included higher heterogeneity in the pre- and peri-menopausal cohort (I2=64%) compared to the postmenopausal cohort (I2=0%). This suggests that while the results are consistent, the data for pre- and peri-menopausal patients may be derived from a more diverse set of clinical contexts or study designs.

Clinical implications suggest that clinicians can consider adjuvant CDK4/6 inhibitors as an effective treatment for HR+ and HER2-negative early breast cancer regardless of whether the patient is pre- or postmenopausal. The consistency in iDFS results across both groups suggests that menopausal status does not significantly alter the primary efficacy of these agents.

Questions remain regarding the long-term durability of these outcomes and the specific factors contributing to the higher heterogeneity observed in the pre- and peri-menopausal population. Furthermore, more detailed safety data are needed to confirm if tolerability profiles differ between these patient groups.