A Study to Test How Safe Pozelimab and Cemdisiran Combination Therapy and Cemdisiran Alone Are and How Well They Work in Adult Patients With Generalized Myasthenia Gravis

Key Inclusion Criteria:

1. Male or female participants ≥18 years of age at screening (or ≥ legal age ofadulthood based on local regulations, whichever is older)

2. Participant with documented diagnosis of Myasthenia Gravis (MG) based on medicalhistory and supported by previous evaluations as described in the protocol

3. Documented prior history of positive serologic test or a positive result duringscreening of Anti-acetylcholine Receptor (AChR) antibodies or anti-LipoproteinReceptor-related Protein 4 (LRP4) antibodies.

4. Myasthenia Gravis Foundation of America (MGFA) Clinical Classification Class II toIVa at screening

5. Myasthenia Gravis-Activities of Daily Living (MG-ADL) score ≥6 at screening. Ocularitems should not contribute more than 50% of MG-ADL total score as described in theprotocol

6. Currently receiving an acetylcholinesterase inhibitor or documented reason for notusing acetylcholinesterase inhibitor therapy per investigator

7. Currently receiving an Immunosuppressive Therapy (IST) for MG, or documented reasonwhy the participant is not taking an IST per investigator

8. If currently receiving an IST, not anticipated to have IST dosage changed beforerandomization or during Double-Blind Treatment Period (DBTP).

9. Willing and able to comply with clinic visits and study-related procedures,including completion of the primary series of the meningococcal vaccinationsrequired per protocol

Key Exclusion Criteria:

1. Patients with antibody profile that is only positive for Muscle-Specific tyrosineKinase (MuSK) (MuSK positivity is based on a documented prior history of positiveserologic test for antibodies to MuSK or a positive result during screening

2. History of thymectomy within 12 months prior to screening or planned during thestudy

3. History of malignant thymoma (patients with stage 1 may be enrolled), or history ofcancer within the past 5 years, except for adequately treated basal cell skincancer, squamous cell skin cancer, or in situ cervical cancer

4. Myasthenic crisis or MGFA Class V within 1 month of screening

5. Not meeting meningococcal vaccination requirements and, at a minimum, documentationof quadrivalent meningococcal vaccination within 5 years prior to randomization andserotype B vaccine (when available) within 3 years prior to randomization asdescribed in the protocol

6. Known contraindication to meningococcal vaccines (group ACWY conjugate and group Bvaccines) as described in the protocol

7. Participants who require antibiotics for meningococcal prophylaxis and have acontraindication, warning, or precaution precluding the use of penicillin class andpenicillin-alternative antibiotics planned to be used for prophylaxis, or a historyof intolerance leading to the discontinuation of these antibiotics

8. Positive hepatitis B surface antigen or hepatitis C virus Ribonucleic Acid (RNA)during screening. NOTE: Cases with unclear interpretation should be discussed withthe medical monitor

9. History of Human Immunodeficiency Virus (HIV) infection or a positive test atscreening per local requirements

NOTE: Other protocol-defined Inclusion/ Exclusion Criteria apply