Efficacy and Safety of a New Formulation of Oral Cladribine Compared With Placebo in Participants With Generalized Myasthenia Gravis (MyClad)

Inclusion Criteria:

• Adults of ≥ 18 years of age at the time of signing the informed consent.

• Diagnosis of Myasthenia Gravis with generalized muscle weakness, meeting clinicalcriteria for Myasthenia Gravis Foundation of America Class II to IVa classification.

• In participants positive for Acetylcholine receptor antibody (anti-AChR) ormuscle-specific kinase antibody(anti-MuSK)

• In participants that are autoantibody seronegative i.e. not positive foranti-AChR and anti-MuSK antibodies and participants who are positive foranti-low-density lipoprotein receptor-related protein 4 antibodies (anti-LRP4)

• Has a Screening and Baseline MG-ADL score more than or equal to (>=) 6 with >= 50percentage (%) of the total score due to non-ocular symptoms. Screening and BaselineMG-ADL scores must be stable. The difference between the Screening and Baselinescores should not be more than 2 and there should be no reported MG exacerbationduring the Screening period

• If treated with oral corticosteroids: should be on a stable daily dose for at least 3 months prior to and during screening. In such case, the daily dose of oralsteroids should not exceed 20 milligrams(mg)/day for prednisone/ prednisolone, 16mg/day for methylprednisolone, 3 mg/day for dexamethasone, or 80 mg forhydrocortisone or equivalent doses for other corticosteroids.

• If treated with acetylcholinesterase inhibitor should be on a stable daily dose (pyridostigmine dose ≤ 480 mg/day or neostigmine ≤ 300 mg/day) for at least 3 monthsprior to and during screening

• Have a body weight >= 40 kilograms

• Other protocol defined inclusion criteria could apply

Exclusion Criteria:

• Immunologic disorder other than MG or any other condition requiring chronic oral,intravenous, intramuscular, or intraarticular corticosteroid therapy.Well-controlled thyroid disease, as per the Treating Investigator or theparticipants regular treating physician recorded in the source documents, is notexclusionary

• Molecularly characterized or suspected congenital myasthenic syndrome, Lambert-Eatonmyasthenic syndrome, inherited myopathy, muscular dystrophy, acquired myopathy orany other neurologic or systematic disease that mimics MG muscular weakness

• Active, clinically significant viral, bacterial, or fungal infection, includingbrain MRI or chest X-ray findings consistent with signs of infection such as PML orTB, or any major episode of infection requiring hospitalization or treatment withparenteral anti-infectives within 8 weeks prior or during Screening, or completionof oral anti-infectives within 8 weeks prior or during Screening. Vaginalcandidiasis, onychomycosis, and genital or oral herpes simplex virus considered bythe Investigator to be sufficiently controlled would not be exclusionary

• Has a history of or current diagnosis of active tuberculosis (TB) or is currentlyundergoing treatment for latent TB infection or has an untreated latent TB infectionas determined by documented results within 3 months of the Screening Visit of apositive TB skin test .

• Active malignancy, or history of cancer or signs of malignancy in any Screeningassessment

• Treatment with nonsteroidal immunosuppressants, used in gMG, such as azathioprine,mycophenolate mofetil, methotrexate, cyclosporine, cyclophosphamide, tacrolimuswithin 4 weeks prior to randomization

• Treatment with FcRn or complement inhibitors (such as eculizumab, rozanolixizumabefgartigimod, ravulizumab, zilucoplan or nipocalimab) within 8 weeks prior torandomization

• History of thymectomy within 6 months prior to Screening.

• History of generalized seizures (except for history of febrile seizures during theparticipant's childhood).

• Negative or indeterminate for Varicella Zoster Virus antibodies at screening

• History of myasthenic crisis in the last 12 months prior to and during screening

• History of recurrent infections (that is 3 or more infections per year documented inavailable source data) within the last 2 years

• Discontinuation of treatment with any non-steroidal immunosuppressants used in gMG,such as azathioprine, mycophenolate mofetil, methotrexate, cyclosporine,cyclophosphamide, tacrolimus within the last 6 months prior to Screening

• If treated with non-steroidal immunosuppressants for gMG, the dose at Screeninghigher than 50 mg/day for azathioprine, 500 mg/day for mycophenolate mofetil, 1mg/day for tacrolimus, 50 mg/day for cyclosporine, 25 mg/day for cyclophosphamide,or 7.5 mg/week for methotrexate

• Participation in clinical study of any investigational drug within 6 months, or 5half-lives of the investigational drug used in the previous clinical study prior torandomization, whichever is longer. However, participants with any prior exposure tocladribine may not enter the study regardless of timing of exposure

• Other protocol defined exclusion criteria could apply