Hyaluronidase-Facilitated Subcutaneous Immunoglobulin 10% as Maintenance Therapy for Japanese Patients with Chronic Inflammatory Demyelinating Polyradiculoneuropathy and Multifocal Motor Neuropathy: A Phase 3, Open-label Clinical Trial.

Objective　This study investigated the efficacy, safety, and tolerability of hyaluronidase-facilitated subcutaneous immunoglobulin (fSCIG) 10% as maintenance therapy in Japanese patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy (MMN).Methods　This phase 3, multicenter, open-label study (NCT05084053, jRCT2051210110) comprised a ≤8-week screening/baseline period, a 6-month fSCIG 10% treatment period (Epoch 1), and ≥6 months' extended treatment (Epoch 2). fSCIG 10% was administered at each patient's previous intravenous immunoglobulin (IVIG) dose and interval. The primary endpoints were relapse rate (≥1-point increase in adjusted Inflammatory Neuropathy Cause and Treatment disability score) for CIDP and change from baseline in maximum handgrip strength (more affected hand) for MMN.Patients　Adults with CIDP (N=19) or MMN (N=7) on stable IVIG dose.Results　In the CIDP group, no patient developed a relapse during Epoch 1; the upper bound of the 95% confidence interval (CI) was 17.65%, below the preset efficacy threshold (57%). For MMN, median (range) and mean (95% CI) change from baseline in maximum grip strength (more affected hand) was 0.0 (-16, 18) and -1.1 (-12.9, 10.6) kPa, respectively. In the CIDP/MMN combined safety analysis across 12 months, 262 treatment-emergent adverse events (TEAEs; 96 systemic, 166 local) in 18 patients (69.2%) were considered fSCIG 10% related. No severe or serious TEAEs occurred.Conclusion　fSCIG 10% prevented CIDP relapse and maintained a stable disease course in MMN in Japanese patients. The treatment was well tolerated, with no severe or serious adverse events related to the treatment.