A Study of LNK01001 Capsule in Subjects With Active Rheumatoid Arthritis

Brief Summary: This is a randomized, double-blind study comparing LNK01001 to placebo in Chinese participants with moderately to severely active rheumatoid arthritis who are on a stable dose of conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) and have an inadequate response or Intolerance to biologic DMARDs(bDMARDs).

The study objective of Period 1 (Day 1 to Week 24) is to compare the safety and efficacy of LNK01001 12 mg twice daily (BID) versus placebo for the treatment of signs and symptoms of participants with moderately to severely active rheumatoid arthritis (RA) who are on a stable dose of csDMARDs and had an inadequate response to or intolerance to at least 1 bDMARD.

The study objective of Period 2 (Week 24 to Week 76) is to evaluate the long-term safety, tolerability, and efficacy of LNK01001 12 mg BID in participants with RA who completed Period 1.

This study includes a 35-day screening period; a 24-week randomized, double-blind, parallel-group, placebo-controlled treatment period (Period 1); a 52-week open label long-term extension period (Period 2); and a 28 to 35-day follow-up period (FU).

Participants who meet eligibility criteria will be randomized in a 1:1 ratio to two treatment groups:

Group 1: LNK01001 12 mg BID (Day 1 to Week 24)， LNK01001 12 mg BID (Week 24 and thereafter)

Group 2: Placebo (Day 1 to Week 24)， LNK01001 12 mg BID (Week 24 and thereafter)

Participants who complete the Week 24 visit (end of Period 1) will enter the extension portion of the study, Period 2, and continue to receive LNK01001 12 mg BID treatment. Starting at Week 12, rescue therapy is allowed if there's less than 20% improvement in both swollen joint count (SJC) and tender joint count (TJC) compared to Baseline. Starting at Week 24, initiation of or change in corticosteroids, non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen, or adding or increasing doses in up to 2 csDMARDs (concomitant use of up to 2 csDMARDs except the combination of methotrexate and leflunomide) is allowed.

Eligibility Criteria:
Inclusion Criteria:

* Participants aged 18 and above.
* Diagnosis of rheumatoid arthritis (RA) for ≥ 3 months.
* ≥ 6 swollen joints (based on 66 joint counts) and ≥ 6 tender joints (based on 68 joint counts) at Screening and baseline visit.
* Erythrocyte sedimentation rate (ESR) ≥ 28mm/h or high-sensitivity C-Reactive Protein (hsCRP) ≥ ULN at Screening.
* Participants have been receiving csDMARD therapy ≥ 3 months and on a stable dose for ≥ 4 weeks prior to the first dose of study drug.
* Have an inadequate response to ≥ 1 bDMARD.

Exclusion Criteria:

* Subjects who were prior exposure to Janus Kinase (JAK) inhibitor (including but not limited to tofacitinib, baricitinib, and filgotinib) and have evidence showing an inadequate response or intolerance.
* Subjects who received intra-articular, intramuscular, intravenous, trigger point or tender point, intracapsular, or intra-tendon injections of glucocorticoids within 4 weeks before randomization.
* Current diagnosis of systemic inflammatory disease other than RA.
* History of malignancy or current diagnosis of malignancy within 5 years before screening visit.
* Uncontrolled diabetes, hypertension, kidney disease, liver disease, severe heart disease.