Cost-Effectiveness of Caplacizumab for Thrombotic Thrombocitopenic Purpura in Brazil

OBJECTIVES: The objective was to evaluate the cost-effectiveness of caplacizumab for the treatment of patients with acquired thrombocytopenic thrombotic purpura (aTTP) from the perspective of the Brazilian Unified Health System (SUS). The comparator was standard of care, which consists mainly of therapeutic plasma exchange, rituximab and corticosteroids.

METHODS: A Markov model with 3-month cycle length and a lifetime horizon was developed. Patients entered the model if presenting an acute aTTP event and at admission, all patients are admitted to the hospital, and patients can either respond to treatment or die. The model contains three health states: remission, true relapse or death. Input data were obtained from literature searches and the effectiveness of caplacizumab was based on the HERCULES trial results. The incremental cost-effectiveness ratio (ICER) was calculated in Brazilian Reais (R$)/QALY and compared to the Brazilian willingness-to-pay (WTP) threshold of R$ 120,000/QALY for rare diseases.

RESULTS: In the base case, caplacizumab results in 0.78 QALYs gained, and costs R$ 805,986 more, with an ICER of R$ 1,029,792/QALY. Sensitivity analyses showed that the cost per caplacizumab vial is the most influential parameter, and a discount of 64,5% would be needed to reach the WTP threshold. Probabilistic analysis showed that, although most iterations fall into the upper right quadrant (costlier and more effective), caplacizumab was cost-effective in less than 10% of iterations for a WTP threshold.

CONCLUSIONS: Caplacizumab is the first targeted therapy to patients with aTTP, and results in faster normalization of platelet count, and consequently reduces in-hospital length-of-stay. However, this cost-effectiveness analysis shows that high cost of the medication will be a barrier for adoption. Based on the proposed cost, caplacizumab is not cost-effective from the perspective of the SUS. This analysis can support price negotiations for the incorporation of caplcacizumab to the minimum benefit list in Brazil.