The main objective of the study is to determine the recommended phase 2 dose (RP2D) of Azercabtagene zapreleucel (azer-cel).

Inclusion Criteria:

PMS and RMS inclusion criteria:

1. Age 18 years to ≤60 years (inclusive) at screening.
2. Expanded Disability Status Scale (EDSS) score 3.0 - 6.5 (inclusive) at screening.
3. Diagnosis of primary progressive multiple sclerosis (PPMS), secondary progressive multiple sclerosis (non-active or active), or Relapsing MS (RMS).
4. Documented evidence of disability progression independent of relapse (PIRA) at any point over the 12 months prior to the screening visit.

NMOSD inclusion criteria:

1. Between age 18 and 65 years, inclusive at the time of signing the informed consent.
2. EDSS score between 2.0 and 7.0 at screening, inclusive (for higher EDSS, the Investigator must assess that the participant is reasonably able to participate in the study).
3. Diagnosis of anti-aquaporin-4 immunoglobulin G (AQP4-IgG) seropositive at screening (verified by the allocated central laboratory) and Neuromyelitis Optica Spectrum Disorder (NMOSD).
4. Must meet the appropriate NMOSD treatment washout criteria prior to receiving lymphodepletion.

MG Inclusion criteria:

1. Age ≥18 and ≤70 years of age at the time of signing the informed consent.

2. Diagnosed with gMG at least 1 year prior to the date of signing the informed consent.

3. Confirmation of MG Diagnosis:

   1. Positive serologic test for anti-acetylcholine receptor (AChR) antibodies or anti-muscle-specific kinase (MuSK) antibodies confirmed at screening AND

   2. One of the following (either historical or during screening):

      • Abnormal neuromuscular transmission test demonstrated by single-fiber electromyography or repetitive nerve stimulation.
      • Positive anticholinesterase test (e.g., edrophonium chloride test).
      • Demonstrated improvement in MG signs on oral cholinesterase inhibitors, as assessed by the treating physician.

4. MG activities of daily living (MG-ADL) score ≥6 at screening.

CIDP Inclusion criteria

1. Age ≥18 and ≤70 years of age at the time of signing the informed consent.
2. Participant must have either typical CIDP, or one of the following two CIDP variants: motor CIDP, multifocal CIDP (also known as Lewis Sumner Syndrome).
3. CIDP Disease Activity Status (CDAS): CDAS score ≥3 at screening.
4. INCAT Disability Score: INCAT disability score ≥4 to ≤9 score at screening.

General Exclusion Criteria:

1. History of malignancy that has not been in remission for at least 2 years.

2. Viral Screening

   1. Evidence of chronic active or history of hepatitis B virus (HBV).
   2. Seropositive for human immunodeficiency virus (HIV) antibody.

3. History of bone marrow/hematopoietic stem cell or solid organ transplantation.

4. Prior treatment with adoptive T-cell therapy or any gene therapy product directed at any target (e.g. CAR T-cell therapy).

Note: Other protocol-specified Inclusion/Exclusion criteria may apply.