OBJECTIVES: Recently, the treatment paradigm of plaque psoriasis (PsO) has evolved with the advent of biologic therapies, mainly novel interleukin inhibitors. This study aims to estimate the cost per responder of ustekinumab (UST) compared to secukinumab (SEC) in patients with moderate to severe PsO from the Brazilian private healthcare system perspective. METHODS: Treatment costs and cost per PASI response were calculated and compared between UST and SEC in year 1 and year 2 of treatment onwards. Annual treatment costs included only drug acquisition costs, gathered from the official price list, and were calculated for an average patient weighting ≤ 100kg, following dosage described in each drug label. Efficacy data on PASI responses were derived from the CLEAR study, a head-to-head 52-week trial. Cost per PASI response was calculated as the annual cost divided by the proportion of patients reaching PASI 90 response at week 52. Univariate sensitivity analysis was performed to test the robustness of the model. RESULTS: Treatment costs were lower for UST when compared to SEC in both year 1 and year 2 of treatment onwards, resulting in savings of BRL 66,107 after 2 years of treatment. UST also presented lower cost per PASI 90 response compared to SEC in both year 1 (BRL 93,527 versus BRL 127,013) and year 2 of treatment onwards (BRL 80,433 versus