Phase 4 Study Evaluates Direct IVIg-to-Efgartigimod Transition in CIDP Without Disease Worsening Requirement

A phase 4, open-label, multicenter trial examining the direct transition from intravenous immunoglobulin (IVIg) to efgartigimod alfa and hyaluronidase-qvfc (Vyvgart Hytrulo; argenx) in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) was among the abstracts featured at the 2026 Peripheral Nerve Society (PNS) Annual Meeting in Maastricht, Netherlands.¹

The study (NCT06637072) was designed to address a practical gap left by the pivotal ADHERE trial, in which patients were required to demonstrate disease worsening before initiating efgartigimod, a condition that does not apply in real-world clinical practice.

Study Design and Rationale

Led by Arjun Seth, MD, Assistant Professor of Neurology (Neuromuscular Disease) at Northwestern University Feinberg School of Medicine, 23 participants aged 18 years or older with a CIDP diagnosis and stable IVIg doses (0.5 to 2 g/kg once every 3 to 6 weeks for at least 3 doses) were enrolled. After a screening period of up to 3 weeks, participants received efgartigimod PH20 SC 1000 mg once weekly for 12 weeks, initiated within 1 week of their last IVIg dose. A safety follow-up visit was completed 4 weeks after the final study dose.

The study commenced December 10, 2024, with last patient last visit expected by the end of February 2026 and topline results to be reported thereafter.¹ No efficacy or safety data were available at the time of the abstract submission.

The primary endpoint was the percentage of participants who continued receiving efgartigimod PH20 SC throughout the full 12-week treatment period, functioning as a measure of both tolerability and feasibility of the transition approach. Secondary endpoints included changes from baseline in quality-of-life assessments, patient perception of disease improvement and severity, and treatment satisfaction.

The rationale for the study reflects a real-world clinical challenge. Efgartigimod PH20 SC received FDA approval in June 2024 as the first neonatal Fc receptor (FcRn) blocker indicated for CIDP, based on data from the phase 3 ADHERE trial (NCT04281472), in which it reduced the relative risk of relapse by 61% versus placebo (P = .00039).²

In ADHERE, however, participants underwent a washout period and had to exhibit disease worsening before treatment initiation. IVIg remains the most widely used maintenance therapy for CIDP, and most patients being considered for a transition to efgartigimod in practice will be stable, not deteriorating. This study was designed to determine whether a direct switch is safe and effective in that population.

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REFERENCES
1. Seth A, Lerman A, Remmerie A, et al. Intravenous Immunoglobulin to Efgartigimod PH20 SC Transition in CIDP: A Phase 4 Study in Progress. Abstract submitted to: Peripheral Nerve Society Annual Meeting; 2026; Maastricht, Netherlands. Abstract P 510.
2. argenx announces FDA approval of Vyvgart Hytrulo for chronic inflammatory demyelinating polyneuropathy. News release. argenx. June 21, 2024. Accessed June 11, 2026. https://www.us.argenx.com/news/argenx-announces-fda-approval-vyvgart-hytrulo-chronic-inflammatory-demyelinating-polyneuropathy
3. argenx reports positive topline data from ADHERE study of Vyvgart Hytrulo in patients with chronic inflammatory demyelinating polyneuropathy. News release. argenx. July 17, 2023. Accessed June 11, 2026. https://www.globenewswire.com/news-release/2023/07/17/2705309/0/en/argenx-Reports-Positive-Topline-Data-from-ADHERE-Study-of-VYVGART-Hytrulo-in-Patients-with-Chronic-Inflammatory-