Background: Before new cancer drugs are available to patients, they must obtain regulatory approval by international authorities. In many countries new drugs are also subject to health technology assessment procedures to decide on the reimbursement. When these procedures are completed, new drugs need to be adopted into clinical practice. All these processes take time and may delay or hamper patient access. In this study we investigated the access to CDK4/6 inhibitors for HR+Her2- metastatic breast cancer patients in daily practice in the Netherlands and explored whether certain policy procedures may have influenced accessibility. Method: For this study we used a mixed method approach. For our qualitative analysis, we used publicly available documents describing drug approval and reimbursement decisions and clinical practice recommendations. Information from these documents were used to provide a timeline of procedures involved and decisions made to make CDK4/6 inhibitors available to patients in the Netherlands. For our quantitative analysis we used monthly prescription data to calculate the number of patients treated with CDK4/6 inhibitors each month, to describe the trends over time and to calculate annual drug expenses. The monthly number of patients treated were compared to an estimated number of patients eligible for the drugs as per European Medicine Association (EMA) label. The trends were compared to the decision timeline in order to identify as to whether certain procedures and/or decisions may have been associated with accessibility to CDK4/6 inhibitors in the Netherlands. Results: In June 2017, the first approved CDK4/6 inhibitor - palbociclib - was prescribed for breast cancer for the first time in the Netherlands. This was approximately 7 months after the EMA gave a positive opinion for marketing authorization. This delay was caused by pricing and reimbursement procedures which involved a thorough evaluation of the costs and effects of the drug and negotiations with the manufacturer. After prescribing palbociclib for the first time, the utilization of CDK4/6 inhibitors in clinical practice increased rapidly with a gradual increase from zero to approximately 1400 patients over a period of 30 months. The majority of patients were treated with palbociclib even after the approval of other drugs of this class (i.e. in December 2019: palbociclib 94% ribociclib 6% and abemaciclib <1%). In addition, approximately 63% of patients were treated with a CKD4/6 inhibitor combined with fulvestrant. The pattern of utilization over time appeared to correspond quite well to the estimated number of patients eligible but these estimates were surrounded by a substantial amount of uncertainty. The total expenses of the CDK4/6 inhibitors from 2017 to 2019 were approximately 3.5 times smaller than the estimates made by the health authorities in the Netherlands prior to the decision to reimburse the drugs. Conclusion: Pricing and reimbursement decisions caused a significant delay in access to the newest drugs for HR+/HER2- metastatic breast cancer. Nevertheless, after palbociclib - the first approved CDK4/6 inhibitor - received a positive reimbursement decision, the prescription in daily practice increased rapidly, a pattern not seen in the other drugs of this class. Though the number of patients treated appeared to be in line with the projected number of patients eligible for these drugs, detailed information regarding metastatic breast cancer patients, their treatments and the decision making process in daily practice is needed to fully understand access to the newest drugs.

Citation Format: Marianne Luyendijk, Hedwig Blommestein, Agnes Jager, Sabine Siesling, Carin Uyl-de Groot. Accessibility of CDK4/6 inhibitors for breast cancer patients in the Netherlands [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-18-31.