- Phase I trial data in rheumatoid arthritis patients demonstrates favorable safety, encouraging clinical activity, and robust biomarker responses
- Data provides strong validation for the advancement of CIT-013 into Phase IIa studies
Oss, Netherlands – 27 October 2025 – Citryll, a biotech company pioneering a transformative approach to treating immune-mediated inflammatory diseases by targeting Extracellular Traps (ETs), has shared positive data from its first-in-human Phase I clinical trial of CIT-013 in participants with rheumatoid arthritis (RA) and healthy volunteers, as well as data from preclinical studies in three posters at the American College of Rheumatology (ACR) Convergence 2025, currently underway in Chicago.
The featured poster highlights findings from Citryll’s Phase I clinical trial of CIT-013 in participants with RA and healthy volunteers, which demonstrated that CIT-013 was generally well tolerated across all participants, with no serious treatment-related events reported. Importantly, clinically meaningful reductions in disease activity were seen in all active RA participants treated with CIT-013.
Two additional posters provided details from preclinical studies supporting the clinical program. The first outlines the use of radiolabelled CIT-013 as an imaging tool, with data indicating CIT-013 is a targeted therapy which accumulates specifically in inflamed tissue. The second evaluates calprotectin as a biomarker of disease activity, with a correlation seen between treatment response and serum calprotectin levels, supporting its use as a biomarker in RA.
Maarten Kraan, Chief Medical Officer of Citryll, commented, “Together, this data provides a compelling picture of CIT-013’s potential as a first-in-class therapeutic targeting ETs for the treatment of RA and other immune-mediated diseases. We are encouraged by the favorable safety and early efficacy signals observed in our Phase I study, validating our decision to advance CIT-013 through to Phase IIa studies. Additionally, the expanding body of translational evidence supports ET inhibition as a potential treatment option in autoimmune and inflammatory disease, strengthening our confidence in the ongoing clinical development program.”
A Phase IIa study – Citydream – is currently underway in RA, with an additional Phase IIa trial in hidradenitis suppurativa expected to start later this year.