Ribociclib efficacy in special populations and analysis of patient-reported outcomes in the MONALEESA trials

Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors abemaciclib, palbociclib, and ribociclib radically modified the treatment of hormone receptor-positive/human epidermal growth factor 2-negative advanced breast cancer. Ribociclib efficacy was proved in the phase III MONALEESA-2, -3, and -7 trials. In the first-line setting, ribociclib plus endocrine therapy determined statistically significant improvements in progression-free (PFS) and overall survival (OS) in pre-menopausal (MONALEESA-7) and post-menopausal (MONALEESA-2) women. Likewise, ribociclib and fulvestrant induced a significant PFS and OS benefit in post-menopausal women previously treated with endocrine therapy (MONALEESA-3). Additionally, ribociclib did not affect patients health-related quality of life in all the MONALEESA trials.We reviewed the results of the available randomized phase III trials testing ribociclib and endocrine therapy in advanced breast cancer, focusing on different patient subgroups and then on health-related quality of life.The benefit of ribociclib is consistent across patient subgroups and is maintained in populations with unfavorable features, such as those with endocrine resistance or visceral metastases. Furthermore, the addition of ribociclib to endocrine therapy delays quality of life deterioration and improves pain scores. These results represent a pivotal improvement for the treatment of advanced breast cancer patients receiving CDK4/6 inhibitors.