OBJECTIVES:: To estimate and compare the long-term cost per responder based on the Assessment of Spondyloarthritis International Society (ASAS) outcomes following one year of treatment of ankylosing spondylitis (AS) with Secukinumab (fully human anti-IL-17A antibody) relative to Adalimumab (anti-TNF antibody). METHODS:: The cost per responder for each treatment (Secukinumab and Adalimumab), was estimated by dividing the retail/private cost of the drug, in Chilean Pesos (CLP), for the course of treatment with its response rate. One year response rates were estimated from a matching-adjusted indirect comparison (MAIC) based on data from MEASURE 2 and ATLAS clinical trials of Secukinumab and Adalimumab, respectively. A sensitivity analyses was also conducted by varying the choice of the matching characteristics. RESULTS:: MAIC analysis showed that ASAS (20, 40 and 5/6) response rates were significantly higher for Secukinumab compared to Adalimumab at one year. ASAS 20, ASAS 40 and ASAS 5/6 response rates were 81% vs. 65%, 62% vs. 47%, and 74% vs. 55% for Secukinumab vs. Adalimumab, respectively. The cost per ASAS 20 responder was $14,511 vs. $29,047, the cost per ASAS40 responder was $18,864 vs. $40,386, whereas, the cost per ASAS 5/6 responder was $16,224 vs. $34,556 for Secukinumab vs. Adalimumab, respectively. The costs per ASAS (20, 40 and 5/6) responders were about 50%, 47%, and 47% lower for Secukinumab compared to Adalimumab after one year. Sensitivity analyses for ASAS response rates and cost per responder showed similar results, confirming the robustness of the main analysis. CONCLUSIONS:: The long term cost per responder for all ASAS response rates at one year were consistently lower for Secukinumab vs. Adalimumab. These findings indicate that it is more efficient to treat AS patients with Secukinumab vs. Adalimumab. In addition, more AS patients could be effectively treated in Chile with Secukinumab vs. Adalimumab with a given budget, due to the cost-offsets.