This study is an open-label, multi-center Phase IIa study. The study is divided into two phases. The first phase is a safety exploration phase. Participants with active rheumatoid arthritis were enrolled and treated with JAB-8263 alone for 4 weeks. The purpose is to evaluate the safety, PK/PD characteristics and preliminary effectiveness of JAB-8263 in participants with active RA.

Inclusion Criteria:

1. Age ≥18 years old and <75 years old at the time of signing the informed consent form, regardless of gender;
2. Active rheumatoid arthritis, ESR or C-reactive protein> upper limit of normal
3. Meets the 2010 American College of Rheumatology ACR/EULAR RA classification standards
4. Participants have recovered from adverse reactions to previous antirheumatic treatment.

Exclusion Criteria:

1. Use of topical glucocorticoids within 2 weeks before the first dose of investigational product or have received epidural, intraarticular, intramuscular, oral or intravenous glucocorticoids within 4 weeks, and do not use adrenocorticotropin;
2. Use of NSAIDs within 1 week before first dose of investigational product
3. Known or suspected allergies to the investigational product or any of its components;
4. Current active shingles virus infection, including shingles or herpes simplex types 1 and 2 (confirmed by physical examination and medical history); participants had a history of severe herpes infection, including any disseminated disease, shingles in multiple skin areas, herpes encephalitis, ocular herpes, or recurrent shingles (2 episodes greater than or equal to 2 episodes within 2 years);
5. Have evidence of active tuberculosis (TB) or have previously had evidence of active TB and have not received appropriate documented treatment;