Lynk Pharmaceuticals Co., Ltd. ("Lynk Pharmaceuticals"), a clinical-stage innovative drug development company focused on immune and inflammatory diseases,  announced positive long-term results from its pivotal Phase III clinical trial evaluating zemprocitinib, an investigational, selective, second-generation oral Janus kinase 1 (JAK1) inhibitor, in adult patients with moderate-to-severe active rheumatoid arthritis (RA) who had experienced inadequate response or intolerance to biologic disease-modifying antirheumatic drugs (bDMARDs).

The study met its primary endpoint of ACR20 response and key secondary endpoints at Week 24, demonstrating a statistically significant improvement with zemprocitinib versus placebo (p<0.0001). The Week 52 and Week 76 results further demonstrate continued improvements in all disease activity measurements and physical function during long-term treatment by Week 52 and sustained clinical responses through Week 76.

The double-blind, placebo-controlled Phase III study randomized 430 patients with moderate-to-severe active RA who had experienced an inadequate response or intolerance to prior bDMARDs, of whom 429 received at least one dose of study treatment. During the initial 24-week double-blind treatment period, patients received zemprocitinib 12 mg twice daily or placebo. Following this period, patients continued or transitioned to active treatment, with efficacy and safety assessed through Week 76.

Long-Term Sustained Efficacy Through Week 76

Among patients receiving continuous zemprocitinib treatment, ACR20, ACR50, and ACR70 response rates were 93.0%, 79.9%, and 52.5%, respectively, at Week 52. Responses remained at Week 76, with ACR20 and ACR50 rates of 91.8% and 80.5%, respectively, while ACR70 increased to 62.4%, demonstrating sustained ACR responses during long-term treatment.

Beyond ACR responses, zemprocitinib demonstrated sustained improvements across measures of disease activity, clinical remission and physical function through Week 76 (selected data are presented in the table below). At Week 52 and Week 76, among patients receiving continuous zemprocitinib treatment, 85.5% and 81.4% achieved low disease activity, respectively, defined as disease activity score (DAS28(CRP) ≤3.2). Based on the clinical disease activity index (CDAI), 81.5% and 81.0% of patients achieved low disease activity (CDAI ≤10), respectively. Improvements in physical function were also observed with 84.5% and 86.7% of patients achieving an improvement of at least 0.22 points in the health assessment questionnaire–disability index (HAQ-DI) from baseline at Week 52 and Week 76, respectively.

Selected efficacy results in patients receiving zemprocitinib 12 mg twice daily*:

Abbreviations: ACR, American College of Rheumatology; DAS28(CRP), Disease Activity Score 28 joints using C-reactive protein; CDAI, Clinical Disease Activity Index; HAQ-DI, Health Assessment Questionnaire–Disability Index.

*The 24-week results of efficacy and safety of zemprocitinib, in patients with rheumatoid arthritis from the Phase III COURAGE-RA study, were presented at the EULAR 2026 Congress (Abstract #OP0208). The EULAR 2026 abstract archive can be found here.

Patients who initially received placebo and switched to zemprocitinib at Week 24 also demonstrated increased clinical responses by Week 76, with ACR20, ACR50, and ACR70 response rates of 92.0%, 77.6%, and 55.1%, respectively, and achieved comparable responses in all other efficacy measurements comparing the patients with continuous dosing of zemprocitinib through Week 76. These findings complement the sustained ACR responses and provide a broader picture of long-term clinical outcomes in patients who had an inadequate response or intolerance to bDMARDs.

Long-Term Safety and Tolerability Through Week 76

During the initial 24-week double-blind, placebo-controlled period, the safety profile of zemprocitinib was generally comparable to that of placebo as reported at EULAR 2026*. The safety profile remained consistent through Week 76 with no new safety signals identified during long-term treatment. An additional observation was the cleaner lab parameters suggesting a cleaner profile of zemprocitinib, particularly with the increase in mean hemoglobin levels, rare incidence of grade 3 or 4 in ALT elevations and grade 3 in AST elevations, and the lack of reports on grade 4 AST elevations. These findings provide additional information on the safety and tolerability of zemprocitinib during long-term treatment in patients with RA.

Professor Xiaofeng Zeng, Principal Investigator of the study from Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, said: "Treatment options remain limited for patients with difficult-to-treat rheumatoid arthritis, leaving significant unmet medical needs. The long-term results from the Phase III clinical study of zemprocitinib are very encouraging. We observed favorable efficacy not only in patients who had an inadequate response or intolerance to bDMARDs, but also in patients who had an inadequate response to prior JAK inhibitor therapy. Zemprocitinib also demonstrated a favorable long-term safety profile. These findings suggest that zemprocitinib may offer an important additional treatment option for patients whose disease remains inadequately controlled with existing therapies."

"These long-term results represent an important milestone in the clinical development of zemprocitinib," said Dr. Zhao-Kui (ZK) Wan, Founder and CEO of Lynk Pharmaceuticals. "We are encouraged by the sustained clinical responses and safety profiles observed through Week 76 in patients who had an inadequate response or intolerance to prior biologic therapies. These findings add to the clinical evidence supporting the continued development of zemprocitinib for patients with rheumatoid arthritis."

"We are encouraged by the long-term efficacy and safety results from the Phase III study of zemprocitinib, which provide further clinical evidence of its best-in-class potential as a treatment option for patients with moderate-to-severe rheumatoid arthritis," said Dr. Aik Goh, Chief Medical Officer of Simcere Pharmaceutical Group. "As the commercialization partner for zemprocitinib in Greater China, we look forward to helping address the unmet treatment needs of patients with rheumatoid arthritis in China soon."