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

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. 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. 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. 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. ClinicalTrials.gov identifier: NCT05817435. Efgartigimod is a medication that reduces immunoglobulin G, a protein that can attack the body by mistake in some autoimmune diseases. Previously, efgartigimod injected under the skin (efgartigimod PH20 SC) was only available in a vial, and health care providers needed to fill a separate syringe to give the medication to a patient. Now, an efgartigimod PH20 SC prefilled syringe is available, which lets patients give themselves their medication more easily. The goals of these studies were to look at: (1) how the body processes efgartigimod PH20 SC once it is injected from either the prefilled syringe or a vial and syringe, (2) how safe it was to quickly inject efgartigimod PH20 SC (between 20–60 s), and (3) whether patients with generalized myasthenia gravis or chronic inflammatory demyelinating polyradiculoneuropathy (both autoimmune diseases) and their caregivers could safely use the prefilled syringe at home. These studies found that the same amount of efgartigimod PH20 SC enters the body whether it is injected using the prefilled syringe or a vial and syringe. Efgartigimod PH20 SC was also safely injected over 20, 30, 45, or 60 s. Lastly, untrained participants with autoimmune diseases or caregivers were able to use the instructions given and inject all the medication from the prefilled syringe without error. A prefilled syringe of efgartigimod PH20 SC may provide patients with certain autoimmune diseases and their caregivers with a quick, convenient, and flexible option for receiving their medication in a health care facility or at home.