Investigating the Pharmacokinetics, Injection Speed, and Usability of Subcutaneous Efgartigimod PH20 Administered with a Prefilled Syringe.

INTRODUCTION: Efgartigimod is a human immunoglobulin G1 (IgG) antibody Fc fragment that reduces levels of circulating IgG, including pathogenic autoantibodies, by blocking neonatal Fc receptor. The original 1000-mg fixed-dose formulation of efgartigimod coformulated with recombinant human hyaluronidase PH20 for subcutaneous injection (PH20 SC) is supplied in a single-dose vial and administered with a separate syringe (V + S). To increase patient convenience, a 5-ml prefilled syringe (PFS) of efgartigimod PH20 SC has been developed. These studies examined the pharmacokinetics, injection speed, and usability of the efgartigimod PH20 SC PFS. METHODS: Bioequivalence of efgartigimod PH20 SC administered via PFS or V + S was assessed in an open-label study in healthy participants. Feasibility, safety, and tolerability of injecting efgartigimod PH20 SC at different injection speeds ranging from 20 to 60 s was examined in a separate open-label study in healthy participants. Finally, two human factor (HF) validation studies investigated usability of the efgartigimod PH20 SC PFS by participants with generalized myasthenia gravis (gMG) or chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and lay caregivers in a simulated at-home environment. RESULTS: Pharmacokinetic bioequivalence was established between efgartigimod PH20 SC administered by PFS and V + S. No meaningful differences were observed between mean fluid leakage/backflow volume at the injection site between the injection speed groups, and no meaningful differences in tolerability across injection speeds occurred. All participants in the HF studies successfully used the efgartigimod PH20 SC PFS and associated instructional materials without training to deliver the full injection volume in an average of 30 s. CONCLUSION: These studies support the bioequivalence, safety, and feasibility of an efgartigimod PH20 SC PFS. Both participants with gMG or CIDP and lay caregivers successfully administered the full dose of the efgartigimod PH20 SC PFS. Rapid-administration efgartigimod PH20 SC PFS is safe and feasible for both patients with autoimmune diseases and lay caregivers. TRIAL IDENTIFICATION NUMBER: ClinicalTrials.gov identifier: NCT05817435.