OBJECTIVES: To estimate the cost-effectiveness of the combined treatment ribociclib plus letrozole compared to other CDK4/6 inhibitor, aromatase inhibitors, and an estrogen receptor inhibitor; for the treatment of postmenopausal women with HR+/HER2- advanced or metastatic breast cancer from the perspective of Colombian health system.

METHODS: A partitioned survival model with 3 states (stable disease, progressed disease and death) was developed to estimate the cost-effectiveness for a time horizon of 5 years with monthly cycles. Effectiveness data were obtained from clinical trials and a systematic literature review. Only direct medical costs and those associated with each health status were considered, and they included the second and third line of treatment. Costs were expressed in 2018 Colombian pesos and were obtained from SISMED and ISS 2001 tariff manual. A discount rate of 5% was applied for both outcomes and costs. QALY was the outcome selected and utility data were obtained from international literature.

RESULTS: Ribociclib plus letrozole has a cost of $ 368 MM COP and was associated with 27.66 QALY. The technology of interest had a higher effectiveness compared to palbociclib plus letrozole, fulvestrant, letrozole, anastrozole and exemestane. Fulvestrant proved to be a dominated strategy despite having the lowest expected cost. The ICER vs. letrozole, anastrozole and exemestane were COP $56.558.846, $109.735.504 and $105.266.187 respectively. Palbociclib plus letrozole was also dominated in comparison with ribociclib plus letrozole with an ICER of -$9.3 MM COP (Diff. -$5.7 MM COP, Diff. 0.61 QALY).

CONCLUSIONS: Ribociclib plus letrozole is likely to be a cost-effective alternative in Colombia's health system compared to fulvestrant and palbociclib plus letrozole. Regarding other comparators, specifically vs. anatrozole and exemestane, ribociclib plus letrozole provides more gains in QALYs but the ICER is above the willingness to pay threshold in Colombia.