Phase 3 PROPEL Trial to Test Imeroprubart in Generalized Myasthenia Gravis

Immunovant presented the design of PROPEL, a phase 3 trial evaluating imeroprubart (IMVT-1402), an investigational neonatal Fc receptor (FcRn) blocker, in adults with generalized myasthenia gravis (gMG). Researchers described the trial at the 2026 American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) Annual Meeting and MGFA Scientific Session in Orlando, Florida.¹

An estimated 10% to 20% of patients with gMG have inadequate disease control or intolerable side effects with conventional treatments, according to the investigators. FcRn blockade is a newer approach that reduces circulating immunoglobulin G (IgG), including the pathogenic IgG autoantibodies that underlie gMG.

Imeroprubart binds FcRn differently than Immunovant's earlier FcRn blocker, batoclimab, a distinction the company has said allows it to reduce IgG levels without the accompanying drop in serum albumin that drove cholesterol elevations seen with batoclimab. The FDA had been reviewing batoclimab for thyroid eye disease, but Immunovant discontinued that program in April 2026 after 2 phase 3 trials failed to meet their primary proptosis-responder endpoint, and the company has since prioritized imeroprubart as its lead FcRn asset across multiple autoimmune indications, including gMG.²

PROPEL trial design

Led by Richard Nowak, MD, MS, director of the Yale Myasthenia Gravis Clinic at Yale University, and colleagues, PROPEL (NCT07039916) is a phase 3, multicenter, randomized, placebo-controlled, double-blind trial enrolling approximately 231 adults aged 18 to 80 years with mild to severe gMG (Myasthenia Gravis Foundation of America Class II, III, or IVa) and an MG-ADL score of 6 or higher at screening and baseline. The trial includes both antibody-positive patients, those positive for anti-acetylcholine receptor, anti-muscle-specific kinase, or anti-low-density lipoprotein receptor-related protein 4 antibodies, and seronegative patients.¹

READ MORE: Single Infusion of Rese-Cel Yields Meaningful Responses Off Immunomodulators in Phase 1/2 RESET-MG Trial

Participants will be randomized 1:1:1 to 12 weekly subcutaneous doses of imeroprubart 600 mg, imeroprubart 300 mg, or placebo, each administered by autoinjector. All participants will then receive 66 additional weeks of blinded active treatment. The primary endpoint is change from baseline in MG-ADL score at week 12 among antibody-positive participants. Key secondary endpoints include change in Quantitative Myasthenia Gravis score, the proportion of patients achieving an MG-ADL score of 0 or 1, and the proportion with an MG-ADL improvement of 50% or more at week 12.

PROPEL began enrolling in May 2025 and remains open across more than 120 sites, with an estimated primary completion date of December 2028.^1,3

Prior to AANEM, Immunovant has reported interim data for imeroprubart in several other autoimmune conditions over the past year. In difficult-to-treat rheumatoid arthritis, an open-label study of 170 adults who had failed at least 2 prior advanced therapies showed week 16 American College of Rheumatology 20% response (ACR20) in 72.7% of patients, with ACR50 and ACR70 rates of 54.5% and 35.8%, respectively; response rates were similar among the subset who had failed both a JAK inhibitor and an anti-tumor necrosis factor agent.⁴

In cutaneous lupus erythematosus, a proof-of-concept study did not reach statistical significance on its primary endpoint, change in Cutaneous Lupus Erythematosus Disease Area and Severity Index activity score at week 12, though the company reported numerical trends favoring imeroprubart over placebo on several measures. Immunovant discontinued the cutaneous lupus program following that result but said development timelines for its other indications, including gMG, remained on track.⁵

Imeroprubart is also being studied in chronic inflammatory demyelinating polyneuropathy, where enrollment continues in the phase 2b AMPLIFI trial, and in Graves' disease and Sjogren's disease. As of Immunovant's most recent corporate update, the company expected topline data from the potentially registrational gMG program during calendar year 2027.⁴

Click here for more AANEM 2026 coverage.

REFERENCES
1. Nowak R, Benatar M, Patel S, Lee LY, Wiendl H. PROPEL: a phase 3 study investigating the neonatal fragment crystallizable receptor blocker imeroprubart in generalized myasthenia gravis. Presented at: 2026 AANEM Annual Meeting and MGFA Scientific Session; September 29-October 2, 2026; Orlando, FL.
2. Immunovant announces phase 3 study results for batoclimab in thyroid eye disease (TED). News release. Published April 2, 2026. Accessed September 30, 2026. https://www.globenewswire.com/news-release/2026/04/02/3267162/0/en/Immunovant-Announces-Phase-3-Study-Results-for-Batoclimab-in-Thyroid-Eye-Disease-TED.html
3. ClinicalTrials.gov. Study to assess the efficacy and safety of IMVT-1402 in participants with mild to severe generalized myasthenia gravis. ClinicalTrials.gov identifier: NCT07039916. Accessed September 30, 2026. https://clinicaltrials.gov/study/NCT07039916
4. Immunovant provides corporate updates and reports financial results for the fourth quarter and fiscal year ended March 31, 2026. News release. Published May 20, 2026. Accessed September 30, 2026. https://www.globenewswire.com/news-release/2026/05/20/3298332/0/en/immunovant-provides-corporate-updates-and-reports-financial-results-for-the-fourth-quarter-and-fiscal-year-ended-march-31-2026.html
5. Immunovant announces topline results from proof-of-concept study of IMVT-1402 in cutaneous lupus erythematosus. News release. Published September 23, 2026. Accessed September 30, 2026. https://www.globenewswire.com/news-release/2026/09/23/3367346/0/en/immunovant-announces-topline-results-from-proof-of-concept-study-of-imvt-1402-in-cutaneous-lupus-erythematosus.html