OBJECTIVES: Paroxysmal Nocturnal Hemoglobinuria (PNH), a rare life-threatening disease caused by dysregulation of the complement system, is treated by C5-inhibitor: eculizumab, with a 2 weeks injection schedule; ravulizumab, me-too drug with a 8 weeks injection schedule. This study is a budget impact analysis of the switch of eculizumab originator by a biosimilar in PNH although the increasing use of me-too drug ravulizumab according perspective of French hospital public budget.

METHODS: Data are collected from a Markov chain Monte Carlo method. The model is validated on French national electronic records according to four scenarios: A. 50%-50% respective use of eculizumab and ravulizumab (observed in France, 2022), B. 50-50% with a 80% switch for ravulizumab per year (observed locally, 2023), C. full use of ravulizumab and D. full use of eculizumab. Drug acquisition costs are collected from national public tender, with a hypothesis of 30% discount on drug price for biosimilars vs originator. The chosen duration of Budget impact analysis is 3 years (duration of tender). Session remuneration is based on national activity-based payment.

RESULTS: Simulation results with a total of 398 ± 6 patients on treatment in 2026. Purchase costs grow with the proportion of patients treated with ravulizumab. Without discount, scenario B increases purchasing costs of 44M€ vs scenario A. Discount saves 11,6M€ ± 4,1 in B (p = 0,0076), vs 56,2M€ ±2,0 in D (p < 0,001). French hospitals are losing 7,71 M€ ± 0,10 in scenario C vs D because of bigger injection schedule for ravulizumab with less administration sessions.

CONCLUSIONS: According to French public hospital budget perspective, eculizumab biosimilar approval leads savings damped down by ravulizumab use growth. According to patient's perspective, ravulizumab seems to improve quality of life with less infusions. This study will go on with other perspectives and other indications.