According to a commentary, progression-free survival benefits have been clearly shown with the three approved CDK4/6 inhibitors (palbociclib, ribociclib, and abemaciclib) and an overall survival benefit has also been shown in individual trials therefore it asks what more needs to be known?
It notes that a treatment benefit in a particular subgroup in an individual trial is often a chance finding and does not necessarily hold true in a large meta-analysis. It adds that across all CDK4/6 inhibitor studies, there is still a need to further characterise the overall survival outcomes and other exploratory efficacy endpoints in those subgroups of patients with more favourable prognostic factors. It suggests that in combination with results from other studies (e.g. SONIA trial), these data could help to address the question of whether or not CDK4/6 inhibitors should be used as first-line treatment in combination with oestrogen therapy or following initial oestrogen therapy alone. It highlights that most important is the potential use of CDK4/6 inhibitors in the adjuvant setting. Furthermore, translational research biomarker studies could contribute to understanding of appropriate patient selection, especially in early-stage breast cancer, in which a greater clinical benefit with this class of agents might be achieved than in the metastatic setting. It notes large adjuvant studies of CDK4/6 inhibitors in early-stage breast cancer are ongoing and will provide additional insights into improved patient selection and personalised treatment approaches in this setting.