Simcere and Lynk Pharmaceuticals report positive Phase III results for zemprocitinib in moderate to severe rheumatoid arthritis. The selective JAK1 inhibitor achieved significant ACR20, ACR50, and DAS28 responses with a favorable safety profile in patients with inadequate response to biologic therapies.
Written By: Pharmacally Medical News Desk
Simcere Pharmaceutical Group has announced positive topline results from a Phase III clinical trial evaluating zemprocitinib in patients with moderate to severe active rheumatoid arthritis. The study met its primary and key secondary endpoints with highly significant improvements over placebo and demonstrated a favorable safety and tolerability profile. Zemprocitinib was originally developed by Lynk Pharmaceuticals, and Simcere Pharmaceutical Group is the commercialization partner for Greater China.
The randomized, double-blind, placebo-controlled study (CTR20232969, NCT06276998) enrolled 430 patients with active rheumatoid arthritis who had shown an inadequate response to biologic disease-modifying antirheumatic drugs. Participants were assigned in a 1:1 ratio to receive zemprocitinib 12 mg twice daily or matching placebo. The trial was led by Professor Xiaofeng Zeng from Peking Union Medical College Hospital and the Chinese Academy of Medical Sciences.
The primary endpoint was the proportion of patients achieving an ACR20 response at Week 24. Key secondary endpoints included ACR50 response and achievement of DAS28 using CRP of 3.2 or lower at Week 24. Zemprocitinib showed clear and consistent superiority across all measures.
Results
The study results showed that the primary endpoint, the proportion of patients achieving an American College of Rheumatology 20 percent improvement response (ACR20), reached 74.0% at Week 12 and increased to 79.1% at Week 24 with zemprocitinib, compared with 29.9% and 39.7% with placebo at the same time points.
For the more stringent ACR50, 41.4 percent of patients in the zemprocitinib group achieved this level at Week 12 and 55.8 percent at Week 24, while only 9.3 percent and 22.0 percent of patients in the placebo group reached similar responses.
Disease activity measured using the Disease Activity Score in 28 joints based on C-reactive protein (DAS28 CRP) also showed marked improvement. The proportion of patients achieving DAS28 CRP of 3.2 or lower was 51.2 percent at Week 12 and 67.0 percent at Week 24 with zemprocitinib, compared with 15.0 percent and 23.4 percent with placebo. These findings demonstrate sustained and clinically meaningful reductions in rheumatoid arthritis activity with zemprocitinib treatment.
Safety findings were reassuring. Most treatment emergent adverse events (TEAEs) were mild to moderate in severity. Rates of serious adverse events were comparable between the active treatment and placebo groups, and investigators reported no new safety signals. The overall profile aligned with earlier clinical experience with the molecule.
Professor Xiaofeng Zeng described the results as an important step forward. He noted that rheumatoid arthritis remains a chronic and disabling autoimmune disease that greatly affects quality of life. The robust efficacy combined with good tolerability suggests zemprocitinib could become a valuable new option for patients who have limited choices after failure of biologic therapies.
Dr. Zhao-Kui Wan, Founder and Chief Executive Officer of Lynk Pharmaceuticals, highlighted that this is the first disclosed trial result in China for a selective JAK1 inhibitor in this difficult patient population. He emphasized the potential of an effective oral therapy to address unmet needs and thanked the patients and investigators who contributed to the study.
Gaobo Zhou, Chief Investment Officer of Simcere, confirmed the company’s commitment as commercialization partner to support further development and to bring improved oral treatment options to people living with rheumatoid arthritis.
About Zemprocitinib
Zemprocitinib is a next-generation highly selective JAK1 inhibitor being developed for rheumatoid arthritis, ankylosing spondylitis, atopic dermatitis, and vitiligo. Greater selectivity for JAK1 compared with earlier JAK inhibitors may allow strong anti-inflammatory efficacy with reduced off-target effects. The drug blocks multiple JAK1-mediated signalling pathways involved in chronic inflammation. Lynk Pharmaceuticals and Simcere entered a collaboration in 2022 to develop and commercialize the therapy in Greater China.
References
Simcere Announces Positive Phase III Topline Data of Zemprocitinib (LNK01001) in Rheumatoid Arthritis, 16 January 2026, Simcere
Lynk Pharmaceuticals Announces Positive Phase III Topline Data of Zemprocitinib (LNK01001) in Rheumatoid Arthritis, 12 January 2026, https://www.prnewswire.com/apac/news-releases/lynk-pharmaceuticals-announces-positive-phase-iii-topline-data-of-zemprocitinib-lnk01001-in-rheumatoid-arthritis-302657982.html