CARTIMMUNE: Study of Patients With Autoimmune Diseases Receiving KYV-101

The purpose of this study is to assess the safety, tolerability, and clinical activity of KYV 101 (a fully-human anti-CD19 CAR T-cell therapy) in adult subjects with B cell-driven autoimmune diseases. The trial anticipates enrolling participants to reach a maximum of 24 participants who will receive 1 dose of KYV-101 and will be followed for 2 years.

Inclusion criteria Idiopathic inflammatory myopathy (including dermatomyositis, antisynthetase syndrome, immune mediated necrotizing myopathy, and polymyositis): 1. Diagnosis of probable or definite (\>55%) idiopathic inflammatory myopathy, including dermatomyositis, anti-synthetase myopathy, immune-mediated necrotizing myopathy (including anti-HMGCoR-myopathy, anti-SRP myopathy), polymyositis, according to the 2017 ACR/EULAR Classification Criteria for idiopathic inflammatory myopathies (Lundberg, Tjarnlund et al. 2017). 2. Disease severity and minimal core set measure criteria: MMT-8 score \2) relapses of AAV despite treatment with immunosuppressive agents OR * Requiring prolonged and/or repeated courses of unacceptable doses (as per investigator judgment) of glucocorticoids to maintain adequate control. Other Inclusion Criteria: 1. Subject must sign a written ICF prior to any screening procedures. 2. Subject must be ≥18 years of age. 3. Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1 or 2. 4. Adequate organ function as per table below. Hematology * Hemoglobin ≥8.5 g/dL without any transfusion support\[a\] * Platelets ≥75,000/uL (without transfusion support within 7 days before the laboratory test). * Absolute Lymphocyte Count (ALC) ≥500/uL (with detectable circulating B cells: \>5 cells/mL) * Absolute Neutrophil Count (ANC) ≥1,200/µL (prior growth factor support is permitted but must be without support in the 7 days prior to the laboratory test) Hepatic * AST and ALT ≤2.5×upper limit of normal (ULN) * Total bilirubin ≤1.5xULN, except in subjects with congenital bilirubinemia, such as Gilbert syndrome (in which case direct bilirubin ≤1.5×ULN is required) Renal - Creatinine clearance Estimated glomerular filtration rate ≥30 mL/min/1.73 m2 (measured by CKD-EPI Creatinine Equation) Cardiac * Left Ventricular Ejection Fraction (LVEF) ≥ 40% confirmed by ECHO/MUGA 1. For subjects who meet the inclusion criteria at screening, transfusion of red blood cells is permitted after screening as needed to maintain a hemoglobin level ≥8.0 g/dL. 1. Women of childbearing potential must have a negative pregnancy test at screening using a highly sensitive serum pregnancy test (β-human chorionic gonadotropin \[β-hCG\]) at screening and prior to lymphodepletion chemotherapy. 2. Female subjects of childbearing potential who have a fertile male sexual partner must agree to use highly effective methods of contraception (failure rate of \