Objective:

To assess the successful and safe transition to subcutaneous (SC) efgartigimod PH20 (co-formulated with recombinant human hyaluronidase PH20) treatment 1 week after last intravenous immunoglobulin (IVIg) infusion in adults with chronic inflammatory demyelinating polyneuropathy (CIDP).

Background:

Efgartigimod, a human IgG1 antibody Fc fragment, blocks the neonatal Fc receptor, preventing IgG recycling and increasing its degradation without affecting IgG production/function. Results from the ADHERE trial demonstrated a significant, clinically meaningful benefit of efgartigimod PH20 SC in participants with CIDP, regardless of prior CIDP therapy. Participants in ADHERE underwent a washout period during which they were required to show disease worsening before initiation of efgartigimod treatment. However, research on the transition from IVIg to efgartigimod without requiring disease worsening is needed to inform clinical practice.

Design/Methods:

This phase 4, open-label, single-group, multicenter trial (NCT06637072) will investigate whether adults with CIDP can effectively and safely transition from stable IVIg doses (administered once every 3–6 weeks) to efgartigimod PH20 SC within 1 week after last IVIg dose. Approximately 25 participants will be enrolled. After a ≤3-week screening period, participants will receive efgartigimod PH20 SC 1000 mg once weekly for a 12-week treatment period. Following study completion, participants may receive treatment at the investigator’s discretion per their routine clinical practice and will complete a safety follow-up visit 4 weeks after the final study dose of efgartigimod PH20 SC.

The primary endpoint is the percentage of participants who continue receiving efgartigimod PH20 SC during the 12-week treatment period after transitioning to efgartigimod PH20 SC within 1 week of stopping IVIg. Secondary endpoints include changes from baseline in quality-of-life assessments, perception of disease improvement/severity, treatment satisfaction, and safety/tolerability.

Results:

Enrollment began in Q4 2024.

Conclusions:

This study will evaluate an approach to transitioning from IVIg to efgartigimod PH20 SC 1 week after a last IVIg infusion in patients with CIDP.