OBJECTIVE
To assess the clinical and economic feasibility of using CDK4/6 inhibitors (abemaciclib, ribociclib) in adjuvant therapy of luminal HER2-negative breast cancer (BC).
MATERIAL AND METHODS
Socio-economic consequences of CDK4/6 inhibitors (abemaciclib and ribociclib) application in adjuvant therapy regimes in patients with HR+HER2-negative BC were evaluated. The analysis included patients with affected lymph nodes, similar in their characteristics to patients from the MonarchE randomized clinical trial (RCT) and patients with N1—3 status of the lymph nodes from the NATALEE RCT. Mathematical modeling was used to evaluate the clinical efficacy of adjuvant endocrine therapy (ET) with CDK4/6 inhibitor and without it in a hypothetical cohort of 1000 people within 5 and 10 years based on a calculated risk of recurrence and death. Direct medical costs for adjuvant therapy, drug treatment of metastatic BC in case of the disease progression, indirect (supplementary) costs associated with loss of gross domestic product (GDP) due to disability, as well as the value of the incremental cost-effectiveness ratio and the return on investment indicator per 1 invested rouble were predicted.
RESULTS
The use of CDK4/6 inhibitors (abemaciclib and ribociclib) in regimens of ET of HR+HER2-negative BC with affected lymph nodes leads to a statistically significant threat of adverse events (death or progression) compared to ET (threat ratio 0.70 (95% CI 0.64; 0.77). Based on a hypothetical cohort of 1000 patients, the decrease in the number of adverse events over 5 and 10 years would be 53 (27.9%) and 89 (25.7%) events, respectively. The estimated costs of CDK4/6 inhibitors application are significantly higher than that of standard adjuvant ET. However, considering the reduced risk of progression of the disease in presence of the therapy with abemaciclib and ribociclib, lower costs for treatment of the progressive disease — metastatic BC — for the population of patients have been noted for 5 and 10 years by 35.0 and 36.8%, respectively. The return on investment indicators per 1 invested rouble, taking into account the avoided loss of GDP and lower costs for therapy at the stage of progression in the group of adjuvant therapy with CDK4/6 inhibitors were 0.14 RUB and 0.52 RUB excluding discount, 0.13 RUB and 0.36 RUB considering 5% discount on the 5- and 10-year modelling horizon, respectively.
CONCLUSION
The use of CDK4/6 inhibitors (abemaciclib, ribociclib) in adjuvant therapy of luminal HER2-negative breast cancer may be clinically and economically feasible, thus the analysis results should be updated in the future taking into account the availability of data from ongoing clinical trials.
