Enrollment Continues for Phase 2b AMPLIFI Trial of FcRn Blocker Imeroprubart in Active CIDP

A phase 2b clinical trial (NCT07032662) evaluating an investigational neonatal Fc receptor (FcRn) blocker named imeroprubart (IMVT-1402) in chronic inflammatory demyelinating polyneuropathy (CIDP) is currently recruiting patients, according to a poster presented at the 2026 Peripheral Nerve Society (PNS) Annual Meeting held June 13-16, in Maastricht, Netherlands.¹

Known as AMPLIFI, the multicenter, randomized, double-blind, placebo-controlled study is designed to assess the efficacy and safety of imeroprubart in adults with active CIDP who continue to experience underlying disease activity despite treatment with corticosteroids, intravenous immunoglobulin (IVIg), or subcutaneous immunoglobulin (SCIg).

For context, CIDP is a rare autoimmune neuropathy characterized by progressive weakness and sensory dysfunction. Although corticosteroids, IVIg, SCIg, and plasma exchange remain standard treatment options, a proportion of patients experience incomplete responses or ongoing disease activity, highlighting the need for additional therapeutic approaches.²

Imeroprubart is an investigational FcRn inhibitor designed to reduce circulating immunoglobulin G (IgG) levels by blocking FcRn-mediated recycling. Investigators noted that the approach may facilitate degradation of pathogenic IgG autoantibodies believed to contribute to disease activity in CIDP.³

The AMPLIFI trial is expected to enroll approximately 162 adults aged 18 years or older who meet 2021 European Academy of Neurology/Peripheral Nerve Society diagnostic criteria for typical, multifocal, or motor CIDP. Eligible participants must have evidence of active disease while receiving stable doses of corticosteroids or IVIg/SCIg therapy for at least 3 months before screening.¹

After enrollment, participants will be randomized to receive either imeroprubart or placebo administered subcutaneously once weekly via autoinjector for 24 weeks. Following completion of the double-blind portion of the study, all participants will be eligible to enter a 52-week open-label extension and receive active treatment.

The primary efficacy endpoint is the proportion of patients who remain relapse-free through week 24. Relapse is defined as a worsening of at least 1 point on the adjusted Inflammatory Neuropathy Cause and Treatment (INCAT) score compared with baseline. Investigators noted that results from the trial are expected to help determine the efficacy and safety profile of imeroprubart in patients with active CIDP and further evaluate FcRn blockade as a potential therapeutic strategy for the disease.

Imeroprubart has previously demonstrated biologic activity in a first-in-human phase 1 study that enrolled healthy volunteers and participants with autoimmune diseases (ISRCTN11659633). For background, the trial evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of the FcRn inhibitor. According to publicly reported findings, four weekly subcutaneous doses produced dose-dependent reductions in circulating IgG levels, with mean reductions reaching approximately 74% at the highest dose studied.⁴

In the phase 1 study, the therapy was generally well tolerated and showed minimal effects on serum albumin and low-density lipoprotein (LDL) cholesterol levels. These findings were notable because some earlier FcRn inhibitors had been associated with changes in these laboratory parameters. Overall, the phase 1 results helped support the continued clinical development of imeroprubart in IgG-mediated autoimmune diseases, including CIDP.

Several FcRn-targeting therapies are currently being explored across autoimmune neurologic disorders, reflecting growing interest in approaches aimed at reducing pathogenic IgG antibodies. Whether FcRn inhibition can provide a meaningful treatment alternative for patients with CIDP who continue to experience disease activity despite currently available therapies remains an important question that ongoing studies such as AMPLIFI are designed to address.

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REFERENCES
1. Gourley I., McGrory S., He S., Abberbock J. AMPLIFI: A Phase 2b Study Investigating the FcRn Blocker Imeroprubart in CIDP. Presented at: 2026 Peripheral Nerve Society (PNS) Annual Meeting.; June 13-16, 2026; Maastricht, Netherlands.
2. Mathey EK, Park SB, Hughes RAC, et al. Chronic inflammatory demyelinating polyradiculoneuropathy: from pathology to phenotype. J Neurol Neurosurg Psychiatry. 2015;86(9):973-985. doi:10.1136/jnnp-2014-309697. https://jnnp.bmj.com/content/86/9/973
3. Howard JF Jr, Bril V, Vu T, et al. FcRn inhibition for immunoglobulin G-mediated neurologic diseases. Neurology. 2024;102(5). doi:10.1212/WNL.0000000000209953
4. ISRCTN Registry. Safety, tolerability, pharmacokinetics, and pharmacodynamics of single/multiple doses of IMVT-1402 in healthy participants and participants with autoimmune diseases. ISRCTN11659633. https://www.isrctn.com/ISRCTN11659633