Lynk Pharmaceuticals Completes Enrollment in Phase III AS Trial

Lynk Pharmaceuticals said it has finished recruiting patients for a Phase III study of its oral JAK1 inhibitor zemprocitinib in active ankylosing spondylitis, a step toward regulatory submission.

The randomized, double-blind, placebo-controlled trial enrolled 352 patients. The primary endpoint is the proportion of patients who achieve an ASAS40 response at week 16. Treatment and follow-up continue.

Zemprocitinib is a second-generation selective JAK1 inhibitor. The company says its higher selectivity for JAK1 over other JAK enzymes could maintain efficacy while reducing safety risks from off-target inhibition. Lynk has already reported Phase III data in rheumatoid arthritis and atopic dermatitis, where the drug met its primary and key secondary endpoints. Serious adverse events and adverse events of special interest occurred at rates comparable to placebo, the company said.

Ankylosing spondylitis is a chronic inflammatory disease that affects the spine and sacroiliac joints, causing pain and stiffness that impair physical function. Many patients do not achieve adequate control with nonsteroidal anti-inflammatory drugs or biologics, or they worry about long-term safety. An oral JAK1 inhibitor with a favorable profile could address that gap.

Dr. Henry Wu, who oversees the clinical program, said the company looks forward to generating robust evidence to support regulatory submissions. Dr. Zhao-Kui (ZK) Wan, founder and CEO, said the milestone brings Lynk closer to providing a safer and more effective oral treatment option.

Lynk was founded by former R&D leaders from Pfizer, Merck, and Johnson & Johnson. The company focuses on the JAK-STAT and TYK2 pathways. It uses AI-assisted drug design and protein degradation technologies to develop small-molecule therapies for autoimmune and inflammatory diseases.

The company did not disclose when it expects to report top-line results from the study.