OBJECTIVES Natalizumab is covered as second line therapy for relapsing-remitting multiple sclerosis (RRMS) in the Brazilian private healthcare system. Its other label indication, first line therapy for highly active RRMS (HARRMS), does not have mandatory coverage. This study aims at evaluating the cost-utility of natalizumab as first line for HARRMS compared to initiating treatment with platform therapies in the public system and migrating to natalizumab after therapeutic failure.

METHODS A microsimulation model built in TreeAge® was used to simulate the treatment of a cohort of patients with HARRMS. Two arms were compared: one initiating treatment with natalizumab in the private system and the other initiating treatment with platform therapies in the public system and migrating to natalizumab in the private system. Natural history transition probabilities and relapse rates were derived from the placebo arm of Tysabri’s pivotal trial and drug efficacy data was obtained from each product’s pivotal clinical trial. For Tysabri, efficacy data was specific to the HARRMS population. For comparators, we used efficacy data for overall population. In the comparator arm, and as a conservative assumption, treatment initiation was assumed to have a three-month delay since diagnosis, lower than the observed in real life.Natalizumab’s cost was calculated based on the Brazilian drug price regulator official list. Platform therapies had no cost from the private payer perspective. Disease management costs were obtained through micro-costing based on published burden of illness study.

RESULTS The analysis resulted in greater effectiveness of the treatment being initiated with natalizumab (5.81 vs 4.36). Incremental cost was BRL 115.8 thousand in a 20-year horizon, resulting in an ICER of BRL 79.7 thousand/QALY.

CONCLUSIONS Initiating treatment with natalizumab in the private healthcare system is cost-effective vs initiating treatment in the public healthcare system, assuming a three times per capita GDP willingness-to-pay threshold (BRL 90 thousand/QALY).