FT839 in Autoimmune Diseases

Inclusion Criteria: * Age ≥18 to ≤70 years * Must have active B-cell mediated autoimmune disease (AAV, IIM, RA, SLE, or SSc) confirmed by standard criteria * Moderate to severe disease, requiring at least two prior treatments that were ineffective * Adequate organ function to tolerate treatment * Able to provide informed consent and comply with study procedures Exclusion Criteria: * Diagnosis of more than 1 disease under study (AAV, IIM, RA, SSc, or SLE) or overlap syndrome * Women must not be pregnant or nursing * Severe Organ Dysfunction: Significant heart, lung, liver, or kidney impairment. * Active or chronic infections * Active or recent malignancies * Prior CAR T-cell therapy or organ transplantation * Known allergies to study treatments * Body weight \<45 kg * Active central nervous system (CNS) symptoms attributable to autoimmune disease or nonmalignant CNS disease within 12 months prior to trial intervention * Receipt of any anti-CD19- or anti-CD20-directed therapy within 6 months prior to trial intervention