A Phase 1 Study of SYNCAR-001 + STK-009 Without Conditioning Chemotherapy (Lymphodepletion) in Subjects With Severe, Refractory Systemic Autoimmune Rheumatic Disease

General Inclusion Criteria:

Age ≥18 years at screening.

SLE Inclusion Criteria:

1. Clinical diagnosis of SLE according to the 2019 European League Rheumatism EULAR/ACRclassification criteria.

2. Subject must be positive for at least one of the following at screening: Anti-dsDNA (above the upper limit of normal [ULN]); or anti-Sm (above the ULN); oranti-Chromatin (above the ULN).

3. Subjects with active, severe, non-renal SLE or subjects with active proliferative LN

SSc Inclusion Criteria:

1. Classified as SSc according to the ACR/EULAR classification criteria.

2. Diffuse cutaneous SSc (dcSSc) or SSc-associated ILD (SSc-ILD; significant orprogressive).

General Exclusion Criteria:

1. History of or active central nervous system manifestations of autoimmune disease.

2. Prior treatment with anti-CD19 adoptive T cell therapy, or any prior gene therapyproduct (e.g., CAR T cell therapy).

SLE Exclusion Criteria:

1. Rapidly progressive glomerulonephritis.

2. End stage renal failure requiring dialysis or most recent renal biopsy with purelychronic lesions (Class III[C], IV-S[C], or IV-G[C]) if isolated renal disease.

SSc Exclusion Criteria:

1. FVC <50% of predicted or DLCO <40% of predicted.

2. Pulmonary arterial hypertension (PAH) requiring PAH-specific treatment.

Other protocol-defined criteria apply.