Onco3R Therapeutics, a Belgium-based clinical-stage immunology and oncology biotech company, announced on Thursday the approval of a clinical trial application by the Belgian regulatory authorities for its SIK3 inhibitor O3R-5671.

The trial will be conducted at the SGS Clinical Pharmacology Unit in Antwerp, a clinical research centre in Belgium.

O3R-5671 was developed based on more than 12 years of preclinical and clinical data on SIK inhibitors for autoimmune diseases, and is expected to have applications across a broad range of conditions, including ulcerative colitis, Crohn's disease, psoriasis, psoriatic arthritis, and rheumatoid arthritis. The company says that preclinical data showed that O3R-5671 has an improved toxicity profile, enhanced efficacy, and greater SIK isoform specificity, thereby overcoming the key shortcomings that hindered the development of first-generation SIK inhibitors for autoimmune diseases.

The first-in-human trial will evaluate O3R-5671 in healthy volunteers using a single ascending dose (SAD) and multiple ascending dose (MAD) design. In addition to assessing safety and pharmacokinetics, the trial includes extensive biomarker tests that will provide insights into how O3R-5671 modulates immune responses. The results from the trial will inform the design of subsequent patient trials across a range of autoimmune diseases, which are planned to commence in 2026.

"At Onco3R, we are dedicated to improving patients' lives through best-in-class medicines and by building a deep pipeline in immunology and oncology," said Pierre Raboisson, PhD, Onco3R Therapeutics CEO and founder. "We are very excited to achieve this significant milestone, marking our transition into a clinical-stage company with the initiation of our first clinical trial. While effective therapies exist for many autoimmune diseases, too many patients relapse or cannot tolerate treatments due to toxicities. With O3R-5671, we believe we are uniquely positioned to develop a well-tolerated, effective, and convenient oral therapy for these patients, and we look forward to advancing the programme."

The first-in-human trial is expected to start enrolling subjects over the coming weeks, with dosing of the first subject anticipated later in September. Final data from the study are expected to be available in the first half of 2026.