Myasthenia Gravis Inebilizumab Trial

A Randomized, Double-blind, Multicenter, Placebo-controlled Phase 3 Study With Open-label Period to Evaluate the Efficacy and Safety of Inebilizumab in Adults With Myasthenia Gravis

Randomized, double-blind, placebo-controlled, Phase 3, parallel-group study with optional open-label extension.

This study is a phase 3, randomized, double-blind, placebo-controlled study, to be conducted at approximately 120 study sites. Approximately 230 participants (188 acetylcholine receptor antibody positive [AChR-Ab+] and 42 muscle-specific tyrosine kinase antibody positive [MuSK-Ab+]) will be enrolled. Participants with Myasthenia Gravis (MG) who are positive for anti-AChR or anti-MuSK antibodies will be enrolled and analyzed. Patients who do not have anti-AChR or anti-MuSK antibodies will not be enrolled. Patients with Myasthenia Gravis Foundation of America (MGFA) classification II, III, or IV disease, Myasthenia Gravis Activities of Daily Living (MG-ADL) score at screening and randomization between 6 and 10 with > 50% of this score attributed to non-ocular items, or an MG-ADL score >=11, Quantitative Myasthenia Gravis (QMG) score >= 11 at the time of screening and randomization, and use of a corticosteroid and/or non-steroidal immunosuppressant will be included in the study.

All subjects who complete the randomized controlled period (RCP) will have the option to enroll in a 3-year (156 weeks) open-label period.

Study acquired from Horizon in 2023.

Inclusion Criteria:

1. Diagnosis of MG with anti-AChR or anti-MuSK antibody.

2. MGFA Clinical Classification Class II, III, or IV.

3. MG-ADL score of 6 or greater at screening and at randomization with > 50% of this score attributed to non-ocular items.

4. QMG score of 11 or greater.

5. Participants must be on:

   1. Corticosteroids only, with no dose increase within 4 weeks prior to randomization, or
   2. One allowed non-steroidal immunosuppressive therapy (IST), with continuous use for at least 6 months prior to randomization and no dose increase within 4 months prior to randomization, or
   3. Combination of (1) corticosteroids with no dose increase within 4 weeks prior to randomization and (2) one allowed non-steroidal IST with continuous use for at least 6 months prior to randomization and no dose increase within 4 months prior to randomization.

Allowed ISTs, alone or in combination with corticosteroids, are azathioprine, mycophenolate mofetil, and mycophenolic acid.

Exclusion Criteria:

1. Receipt of the following medications within the 4 weeks prior to Day 1:

   1. Cyclosporine (except eye drops)
   2. Tacrolimus (except topical)
   3. Methotrexate

2. Current use of:

   1. Corticosteroids (Prednisone > 40 milligram (mg)/day or > 80 mg over a 2-day period (or equivalent dose of other corticosteroids).
   2. Acetylcholinesterase inhibitors (pyridostigmine) > 480 mg/day) or unstable dose in the 2 weeks prior to Day 1.
   3. Azathioprine > 3 mg/kilogram (kg)/day
   4. Mycophenolate mofetil > 3 grams/day or mycophenolic acid > 1440 mg/day
   5. Any IST, alone or in combination with corticosteroids, except for azathioprine, mycophenolate mofetil, and mycophenolic acid.