Riliprubart Shows Sustained Improvements in Fatigue, Pain, and Quality of Life in Phase 2 CIDP Study

New findings from a phase 2 trial (NCT04658472) showed that long-term treatment with riliprubart (Sanofi) was associated with sustained improvements in fatigue, pain, and health-related quality of life (QoL) among patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).¹ The data extend previously reported efficacy findings and provided additional insight into patient-reported outcomes through 76 weeks of treatment.²

Riliprubart, a first-in-class humanized IgG4 monoclonal antibody targeting activated C1s in the classical complement pathway, previously demonstrated reduced fatigue severity and improved quality of life in patients with CIDP through 48 weeks in the phase 2 trial. The current findings, led by Hemali Savla, PhD, of Sanofi, were presented in an abstract at the 2026 Peripheral Nerve Society Annual Meeting, held June 13-16 in Maastricht, Netherlands.

The multicenter, open-label study enrolled 78 participants across 3 cohorts: standard-of-care (SoC)-treated patients (n = 48), SoC-refractory patients (n = 18), and SoC-naïve patients (n = 12). Participants received 24 weeks of treatment during Part A, followed by an optional 52-week extension phase. The current analysis assessed health-related QoL using the EuroQol Visual Analogue Scale (EQ-VAS) and health utility index values, whereas fatigue was measured using the Modified Rasch-built Fatigue Severity Scale (R-FSS).

At week 76, researchers noted that evaluable patient-reported outcome data were available for 37 SoC-treated participants, 11 SoC-refractory participants, and 6 SoC-naïve participants. Across all cohorts, patients demonstrated improvements in QoL measures from baseline. Mean changes in EQ-VAS scores were 12.1 points among SoC-treated participants, 19.1 points among SoC-refractory participants, and 8.5 points among SoC-naïve participants. Similarly, mean changes in health utility index values were 0.18, 0.21, and 0.05, respectively.

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Investigators also observed reductions in pain burden over the study period. The proportion of patients reporting no pain or discomfort increased from 12.8% at baseline to 27.0% at week 76 in the SoC-treated cohort. Corresponding increases were observed in the SoC-refractory group (16.7% to 45.5%) and the SoC-naïve group (16.7% to 33.3%).

Fatigue improvements were likewise maintained through long-term follow-up. Mean changes in R-FSS scores from baseline were –3.7 in the SoC-treated cohort, –2.2 in the SoC-refractory cohort, and –3.3 in the SoC-naïve cohort, with lower scores indicating reduced fatigue severity. These findings build on earlier reports from the phase 2 program, which suggested that riliprubart was associated with clinical improvements across disability and functional outcome measures in both treatment-experienced and treatment-naïve patients with CIDP.²

Notably, the riliprubart development program has recently encountered challenges. In June 2026, Sanofi announced discontinuation of the phase 3 MOBILIZE study (NCT06290128) in treatment-refractory CIDP following an interim analysis indicating that the trial was unlikely to demonstrate sufficient efficacy, although no new safety concerns were identified. The future of the ongoing VITALIZE phase 3 study remains under evaluation.³

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REFERENCES
1. Attarian S, Hartung HP, Yi Lu Y, Alonso MA, Paker A. E Phase 2 Trial of Riliprubart in CIDP: Patient-Reported Quality of Life, Pain and Fatigue Outcomes at Week 76. Presented at: 2026 Peripheral Nerve Society (PNS) Annual Meeting; June 13-16; Maastricht, The Netherlands. P351
2. Querol L, Lewis R, Hartung H, et al. Preliminary Efficacy and Safety Data from the Phase 2 Trial of Riliprubart (SAR445088), a Humanized Monoclonal Antibody Targeting Complement C1s, in Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) [abstract S15.008]. Neurology. 2024;102(17 suppl 1). doi:10.1212/WNL.0000000000204596
3. Press Release: Sanofi provides update on MOBILIZE phase 3 study of riliprubart in chronic inflammatory demyelinating polyneuropathy. News release. Sanofi. June 10, 2026. Accessed June 12, 2026. https://www.sanofi.com/en/media-room/press-releases/2026/2026-06-10-05-00-00-3309444