Pharmacokinetics of hyaluronidase-facilitated subcutaneous immunoglobulin 10% in pediatric patients with primary immunodeficiency disease.

Introduction: Hyaluronidase-facilitated subcutaneous immunoglobulin 10% (fSCIG 10%) is a unique and effective treatment for primary immunodeficiency disease (PID), allowing for less frequent administration than conventional subcutaneous immunoglobulin therapies. Methods: The pharmacokinetics (PK) of fSCIG 10% in pediatric patients (aged 2 to <16 years at screening) with PID was assessed in a prospective, phase 3, open-label, multicenter, clinical trial conducted in the USA. Patients previously treated with intravenous or conventional subcutaneous immunoglobulin therapy (consistent dose for ≥3 months) received fSCIG 10% via a dose ramp-up schedule for ≤6 weeks (Epoch 1), then at full target dose every 3-4 weeks for ≤3 years (Epoch 2). Serum total immunoglobulin G (IgG) trough levels were reported throughout Epoch 2 across pediatric age groups (2 to <6, 6 to <12, and 12 to ≤16 years); serial PK were characterized at the Month 6 infusion. In total, 44 patients (mean age: 9.0 years; 59% male and 91% White) were eligible for the study. Results: Mean total IgG trough levels during Epoch 2 were similar across age groups. Geometric mean area under the IgG concentration-time curve per week ranged from 63.4 to 76.8 g·day/L, and body weight-adjusted apparent clearance ranged from 1.5 to 1.9 ml/day/kg. Conclusion: This study showed that serum total IgG trough levels were effectively maintained in pediatric patients with PID treated with fSCIG 10%, regardless of age. The dosing strategy for pediatric patients should be informed by assessing individual IgG levels and clinical status as for adults. Clinical trials registration: The study is registered with the ClinicalTrials.gov registry at https://clinicaltrials.gov/ct2/study/NCT03277313 (ClinicalTrials.gov Identifier: NCT03277313).