Protein A immunoadsorption for refractory neuromyelitis optica spectrum disorder: A prospective single-center study

Protein A immunoadsorption (IA) is a promising alternative for the clearance of soluble plasmatic complexes and has entered clinical routine in autoimmune neurological diseases. This study aimed to explore the efficacy and safety of Protein A IA in neuromyelitis optica spectrum disorder (NMOSD) refractory to first-line immunotherapy.

Patients with refractory NMOSD treated with Protein A IA were prospectively enrolled. Clinical characteristics, expanded disability status scale (EDSS), modified Rankin scale (mRs), and aquaporin-4 (AQP4) IgG levels were evaluated before and after IA. Clinical improvements were defined as significant decreases in EDSS, mRs scores, and the level of AQP4-antibody from baseline after the last session of IA treatment. Incidences of adverse events were documented throughout the study.

Seven patients were recruited for the present study. After an average of 6.3 IA sessions, the patients' EDSS decreased from 6.77 ± 2.16 before treatment to 5.00 ± 2.72 after the last IA (P = 0.005). Five patients exhibited improvement with a reduction in mRs of≥ 1 after IA treatment. Patients with NMOSD who received IA showed no significant decrease in mRs scores(median mRs 4.0 [IQR, 3.0-4.0] vs. 2.0 [IQR, 1.0-4.0], P = 0.063). The level of AQP4-IgG decreased significantly after IA treatment(P＜0.05). Only one patient experienced transient thrombocytopenia.

Protein A IA for the treatment of refractory NMOSD suggests a potential benefit and appears to be well tolerated in this small prospective study. Further large, prospective, controlled studies are warranted to provide further evidence for the improvement and optimization of NMOSD treatment.