OBJECTIVES : Breast cancer is the most commonly diagnosed malignancy in women worldwide. In a phase 2 trial, palbociclib plus letrozole was shown to significantly improve overall survival, hence accelerating the international approval of palbociclib. Several international studies however reported that palbociclib plus letrozole is not a cost-effective therapy. The price of palbociclib in Ecuador was recently reduced to the point where it becomes an affordable and acceptable therapy for advanced breast cancer for the Ecuadorian health system. The aim of this study was to evaluate the cost-effectiveness of palbociclib with letrozole versus letrozole for the management of HR-positive/ HER2-negative advanced or metastatic breast cancer as initial endocrine-based therapy in postmenopausal women in the public healthcare system of Ecuador.

METHODS : A Markov model was developed. The efficacy was evaluated based on progression free survival (Finn 2016 study) and ranking SUCRA (Chirila 2017 meta-analysis). Costs were derived from the Ecuadorian Reference costs (2017). The dosage evaluated was 125mg of palbociclib with 2.5mg for letrozole daily versus 2.5 mg of letrozole per day. A stochastic sensitivity analysis was also performed.

RESULTS : Total costs per year were 52,394.7 USD for palbociclib with letrozole versus 251.9 USD for letrozole only. The ICER of progression free survival for palbociclib plus letrozole was 60,631.2 USD (2.1 vs. 1.2 years) compared with letrozole and ranking SUCRA reported an ICER for palbociclib plus letrozole of -392630,51 USD (49.1 vs 99.9) vs. letrozole.

CONCLUSIONS : The addition of palbociclib to letrozole, which is associated with increased efficacy in progression free survival, yields a cost-effectiveness that allows the drug coverage in the Ecuadorian health system.