A Study of CNTY-101 in Participants With Refractory B Cell-mediated Autoimmune Diseases

Inclusion Criteria:

General Inclusion Criteria:

1. 17 years of age and older.

2. Participants must have adequate organ function as defined in the protocol.

SLE/LN-specific Inclusion Criteria:

1. Participants must have a diagnosis of SLE according to the 2019 European LeagueAgainst Rheumatism/American College of Rheumatology classification criteria forsystemic lupus erythematosus for at least 6 months.

2. Participants must have current or history of elevated anti-double strandeddeoxyribonucleic acid (anti-dsDNA), anti-Smith, anti-histone, and/or anti-nucleosomeantibodies.

SLE-specific Inclusion Criteria:

1. Participants who have:

2. A Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score of ≥8 (including at least 4 points from non-laboratory assessments; excluding alopecia,mucosal ulcers, and fever) and at least 2 British Isles Lupus Assessment Group B (BILAG B) organ system scores and/or

3. At least one British Isles Lupus Assessment Group A (BILAG A) organ system score,including cardiac (peri- or myocarditis), respiratory (pleuritis or lunginvolvement), vascular and renal.

LN-specific Inclusion Criteria:

1. Participants with active, biopsy-proven, proliferative LN Class III or IV, eitherwith or without the presence of class V, according to the 2018 revised InternationalSociety of Nephrology/Renal Pathology Society (ISN/RPS) criteria. Biopsy must bewithin 12 months prior to Screening or during Screening.

IIM-specific Inclusion Criteria:

1. Classification of IIM (juvenile-onset IIM may be included):

2. For Dermatomyositis (DM), meet 2017 American College of Rheumatology/EuropeanAlliance of Associations of Rheumatology (ACR/EULAR) diagnostic criteria fordefinite or probable DM.

3. For participants with anti-synthetase syndrome (ASyS), meet Classification Criteriafor anti-synthetase syndrome per the Classification Criteria for Anti-SynthetaseSyndrome (CLASS) Project with a positive tRNA synthetase autoantibody at Screeningor per medical history.

4. For Polymyositis (PM)/ necrotizing myopathy (NM), meet 2017 ACR/ EULARclassification criteria for definite or probable PM/NM and meet one of the followingcriteria:

i. Positive myositis specific antibody (MSA) at Screening or per medical history or ii. Muscle biopsy at Screening or per medical history available for review

DcSSc-specific Inclusion Criteria:

1. Meets the 2013 ACR/EULAR criteria for SSc with a total score of ≥9.

2. Meets criteria for DcSSc, including skin involvement proximal to the elbow and/orknee.

3. mRSS units ≥15 at Screening; for participants agreeing to biopsy, skin thickeningfrom SSc in the forearm suitable for biopsy.

Exclusion Criteria:

General Exclusion Criteria:

1. Participants on hemodialysis.

2. Other comorbid conditions as defined in the protocol.

3. History of allogeneic bone marrow/hematopoietic stem cell or solid organ transplantat any time. History of autologous stem cell transplant >100 days prior to Screeningis allowed.

4. Recent or clinically significant central nervous system (CNS) disease, including butnot limited to cerebrovascular accident, epilepsy, severe brain injury, dementia,Parkinson's disease, cerebellar disease, seizures, organic brain syndrome, lupusheadache, or psychosis at any time prior to study.

5. Thromboembolic events within last 12 months.

6. Participants with severe hepatic dysfunction, defined as grade C-Child-Pugh.

SLE-specific Exclusion Criteria:

1. Participants with BILAG A for neuropsychiatric SLE.

2. Any current, acute, and severe lupus-related flare that needs immediate treatment.

3. Drug-induced SLE rather than idiopathic SLE.

4. Participants with a diagnosis of LN Classes III, IV, V, or VI on the most currentbiopsy according to the 2018 revised ISN/RPS criteria.

5. Participants with estimated glomerular filtration rate (eGFR) <45 milliliters perminute per 1.73 square meter (mL/min/1.73 m^2) (measured by Chronic Kidney DiseaseEpidemiology Collaboration Creatinine Equation) or serum creatinine >2.5 milligramsper deciliter (mg/dL).

LN-specific Exclusion Criteria:

1. Participants with BILAG A for neuropsychiatric SLE.

2. Any severe lupus-related flare such as acute CNS lupus (eg, psychosis, seizure),catastrophic antiphospholipid syndrome, or rapidly progressive glomerulonephritisthat, in the opinion of the Investigator, would cause an unacceptable safety risk.

3. Drug-induced SLE rather than idiopathic SLE.

4. Participants with predominantly LN Class V, or Class VI on the most recent biopsyaccording to the 2018 revised ISN/RPS criteria.

5. Participants with estimated glomerular filtration rate <30 mL/min/1.73 m^2 (measuredby Chronic Kidney Disease Epidemiology Collaboration Creatinine Equation) or serumcreatinine >2.5 mg/dL.

IIM- specific Exclusion Criteria:

1. Participants on hemodialysis or estimated glomerular filtration rate <45 mL/min/1.73m^2 (measured by Chronic Kidney Disease Epidemiology Collaboration CreatinineEquation) or serum creatinine >2.5 mg/dL.

2. Have severe muscle damage as defined in the protocol.

3. Participants with ILD will be excluded if there is severe end stage lung disease asdefined in the protocol.

DcSSc-specific Exclusion Criteria

1. Participants on hemodialysis or estimated glomerular filtration rate <45 mL/min/1.73m^2 (measured by Chronic Kidney Disease Epidemiology Collaboration CreatinineEquation) or serum creatinine >2.5 mg/dL.

2. Participants with ILD will be excluded if there is severe end stage lung disease asdefined in the protocol.