Pharmacokinetics, safety and tolerability, and efficacy of hyaluronidase-facilitated subcutaneous immunoglobulin 10% (HyQvia®) in Japanese patients with primary immunodeficiency diseases.

This phase 3 open-label study (jRCT2031210457; NCT05150340; January 2022-August 2023) evaluated pharmacokinetics, safety and tolerability, and efficacy of recombinant hyaluronidase-facilitated subcutaneous immunoglobulin (fSCIG) 10% in Japanese patients with primary immunodeficiency diseases (PID) transitioning from intravenous immunoglobulin (IVIG) or conventional SCIG (cSCIG). Patients received fSCIG 10% (HyQvia®) with dose ramp-up (Epoch 1) and 3- or 4-week dosing intervals (Epoch 2; 24 weeks). Assessments included IgG trough levels, infusion-related tolerability, validated acute serious bacterial infections (VASBIs), and treatment-emergent adverse events (TEAEs). Sixteen patients completed the study (median age: 21 years; range: 5-62). Prior treatments included cSCIG (62.5%), IVIG (31.3%), and SCIG (human) 20% solution (Ig20Gly; Cuvitru®) (6.3%). Geometric mean IgG trough levels during the evaluation period (Epoch 2) remained stable across all visits (1254-1351 mg/dL, 3-week dosing; 874-937 mg/dL, 4-week dosing). No tolerability events or VASBIs were observed. Annual infection rate was 2.74 per patient-year. TEAEs related to fSCIG 10% occurred in 68.8% of patients, all mild or moderate. No serious TEAEs related to fSCIG 10% or deaths occurred. No TEAEs led to study discontinuation. fSCIG 10% effectively maintained IgG levels, prevented infections, and was well tolerated in Japanese patients with PID transitioning from IVIG or cSCIG.