This clinical trial is designed as a single - arm, open - label, single - center, investigator - initiated early - phase clinical study. The primary objective is to evaluate the safety of UTAA91 injection in treating subjects with refractory moderate - to - severe active rheumatoid arthritis.

Inclusion Criteria:

• Aged ≥18 years (inclusive of the boundary value), with no restriction on gender.
• Expected survival time of at least 3 months.
• Subjects with refractory moderate - to - severe active rheumatoid arthritis who have failed standard treatment or lack effective therapeutic options.
• Meet the requirements for liver and kidney function, as well as cardiopulmonary function.
• Free from severe psychiatric disorders.
• Able to understand the trial and have signed the informed consent form.

Exclusion Criteria:

• A history of malignant tumors other than relapsed/refractory autoimmune diseases (R/R AID) within 5 years prior to screening.
• Subjects with positive results in virus/syphilis tests.
• Severe cardiac diseases or unstable systemic diseases.
• Active or uncontrollable infections requiring systemic treatment within 7 days before administration; evidence of central nervous system invasion at screening.
• Pregnant or breastfeeding women, female subjects planning to become pregnant within 2 years after cell infusion, or male subjects whose partners plan to become pregnant within 2 years after their cell infusion.
• Subjects who have received CAR - T therapy or other gene - modified cell therapies before screening.
• Subjects who participated in other clinical studies within 1 month before screening.
• Other conditions deemed unsuitable for enrollment by the investigator.