Regulatory Approval, Reimbursement, and Clinical Use of Cyclin-Dependent Kinase 4/6 Inhibitors in Metastatic Breast Cancer in the Netherlands

IMPORTANCE: The number of new cancer medicines that are being approved by regulatory agents is increasing exponentially. Yet little is known about the pace at which these medicines reach eligible patients in daily clinical practice during different phases of the postapproval access pathway. OBJECTIVE: To describe the entire postapproval access pathway of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors in the Netherlands, from regulatory approval to reimbursement and to investigate the adoption of these medicines in clinical practice among patients with metastatic breast cancer. DESIGN, SETTING, AND PARTICIPANTS: This cohort study reviewed approval and reimbursement decisions of the CDK4/6 inhibitors palbociclib, ribociclib, and abemaciclib and estimated the number of patients with metastatic breast cancer who were eligible for these medicines compared with the actual use in clinical practice. The study used nationwide claims data that were obtained from the Dutch Hospital Data. Claims and early access data for patients with hormone receptor–positive and ERBB2 (formerly HER2)–negative metastatic breast cancer who were treated with CDK4/6 inhibitors from November 1, 2016, to December 31, 2021, were included. MAIN OUTCOMES AND MEASURES: Description of the postapproval access pathway, monthly number of patients who were treated with CDK4/6 inhibitors in clinical practice, and estimated number of patients who were eligible for treatment. Aggregated claims data were used, and patient characteristics and outcomes data were not collected. RESULTS: Three CDK4/6 inhibitors have received European Union–wide regulatory approval for the treatment of HR-positive and ERBB2-negative metastatic breast cancer since November 2016. In the Netherlands, the number of patients who have been treated with these medicines increased to approximately 1847 (based on 1 624 665 claims over the entire study period) from approval to the end of 2021. Reimbursement for these medicines was granted between 9 and 11 months after approval. While awaiting reimbursement decisions, 492 patients received palbociclib, the first approved medicine of this class, via an expanded access program. By the end of the study period, 1616 patients (87%) were treated with palbociclib, whereas 157 patients (7%) received ribociclib, and 74 patients (4%) received abemaciclib. The CKD4/6 inhibitor was combined with an aromatase inhibitor in 708 patients (38%) and with fulvestrant in 1139 patients (62%). The pattern of use over time appeared to be somewhat lower compared with the estimated number of eligible patients (1847 vs 1915 in December 2021), especially in the first 2.5 years after approval. CONCLUSIONS AND RELEVANCE: This study found that CDK4/6 inhibitors rapidly reached many eligible patients with metastatic breast cancer and were adopted gradually over time in the Netherlands. Adoption of innovative medicines may be further optimized, and better transparency of the availability of new medicines during different phases of the postapproval access pathway is needed.