Rituximab versus placebo for chronic inflammatory demyelinating polyradiculoneuropathy: a randomized trial

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) often requires prolonged ongoing treatment to prevent worsening. The efficacy of rituximab in preventing worsening after the discontinuation of immunoglobulin therapy in CIDP patients was assessed. In this randomized, double-blind, placebo-controlled study, conducted at seven Italian hospitals, CIDP patients under immunoglobulin therapy were assigned to receive either rituximab (1g on days 1, 15, and 180±7) or placebo. Both groups continued their regular immunoglobulin doses for six months post-intervention. The primary endpoint was the proportion of patients who worsened in any of the following three measures at month 12, within six months after immunoglobulin discontinuation: a decrease of at least one point on the adjusted INCAT score, two points on the MRC sum score, or four points on the RODS centile score. Secondary endpoints included the proportion of patients deteriorating at month 18 (within 12 months after immunoglobulin discontinuation), treatment cessation due to adverse events or voluntary reasons, and the time until deterioration after immunoglobulin discontinuation. This study was registered with ClinicalTrials.gov (NCT06325943) and EUDRACT (number 2017-005034-36), and it is complete. From April 2019 to March 2022, 39 patients were recruited; two withdrew consent. The remaining 37 patients were assigned to rituximab (n=19) or placebo (n=18). Median age was 53 (IQR 45-64), with 11 (30%) females. A similar proportion of patients in both the rituximab (12/19, 63.2%) and placebo (12/18, 66.6%) groups worsened at month 12 (OR 0.86; 95% CI 0.22-3.32). No significant differences were noted at month 18 (OR 0.62; 95% CI 0.14-2.70), or in the mean scores of each scale at months 6, 12, and 18. The median time to worsening was 5 months for rituximab and 2 months for placebo (Log-rank p=0.4372). Treatment was suspended due to adverse events in one rituximab patient. In this study, rituximab was not more effective than placebo in preventing clinical deterioration following the discontinuation of immunoglobulin therapy in CIDP. Further studies might evaluate the efficacy of more frequent or earlier administration of rituximab.