Efficacy Of Cdk 4/6 Inhibitors In Er Positive Metastatic Breast Cancer: Systematic Review And Meta-Analysis Of Randomized Clinical Trials.

e13040Background: The introduction of cyclin-dependent kinase (CDK) 4/6 inhibitors led to a significant paradigm shift in the management of Estrogen Receptor (ER) positive metastatic breast cancer (MBC). The purpose of this analysis was to evaluate the effect of CDK 4/6 inhibitors (palbociclib, ribociclib, abemaciclib) in ER positive MBC patients across trials in terms of progression free (PFS) and OS. Methods: We searched literature databases to identify randomized controlled trials that compared endocrine therapy (ET) with ET plus CDK4/6 inhibitors in ER positive MBC. The main outcome measures for this analysis were OS and PFS. Log hazard ratios (HRs) for OS and PFS were pooled across the studies by inverse variance weighting. Primary analyses were done with a fixed effects model, since no heterogeneity was found among studies. Results: We found seven randomised clinical trials including 3854 patients. Of these, 4 included only first line therapy and 3 allowed prior treatments for MBC. Overall, the addi...