FIRST PATIENT DOSED IN CITRYLL’S PHASE IIA HIDRADENITIS SUPPURATIVA TRIAL

FIRST PATIENT DOSED IN CITRYLL’S PHASE IIA HIDRADENITIS SUPPURATIVA TRIAL

• Multi-center, randomized study designed to assess the efficacy, safety, and tolerability of CIT-013 in patients with hidradenitis suppurativa
• Marks the start of the second Phase IIa trial to evaluate first-in-class monoclonal antibody CIT-013 this year, following the rheumatoid arthritis trial

Oss, Netherlands – 08 December 2025 – Citryll, a biotech company pioneering a transformative approach to treating immune-mediated inflammatory diseases by targeting Extracellular Traps (ETs), today announces the dosing of the first patient in its Phase IIa hidradenitis suppurativa (HS) clinical trial, “Citylights”. The trial will evaluate its first-in-class monoclonal antibody CIT-013 in patients with moderate to severe HS. To support this important clinical advancement, Citryll has established a Clinical Advisory Board, which brings together global experts in the field.

HS is a debilitating, chronic autoimmune disease affecting approximately 2% of the population in the US and Europe. Patients with the disease suffer from recurring, painful skin lesions with nodules and pus-draining tunnels, leading to scarring, irreversible tissue destruction and a decreased quality of life. Despite its prevalence, there are currently limited approved treatment options, and these often fall short in providing adequate disease control.

Citryll’s Clinical Advisory Board will provide invaluable strategic guidance as clinical progress is made. The Board includes independent HS experts Dr James Krueger, Head of the Laboratory for Investigative Dermatology at The Rockefeller University in New York; Dr Alexa Kimbal, Professor of Dermatology at Harvard Medical School; and Dr John Frew, Clinical Dermatologist and Director of Research at The Skin Hospital in Sydney, Australia.

Maarten Kraan, Chief Medical Officer of Citryll, commented, “This is an exciting period for Citryll, initiating this HS trial a few months after starting our Phase IIa trial in rheumatoid arthritis. I’m grateful to our team and clinical partners for their tireless efforts to reach this goal. As we advance our investigation of CIT-013 in HS, we look forward to drawing on the expertise of our newly formed Clinical Advisory Board. Underpinning all this work is our desire to deliver a novel, disease modifying therapy for the many HS patients who currently lack suitable treatments.”

Dr. Falk Bechara, lead investigator of Citylights, added, “I am looking forward to advancing this Phase IIa trial, which marks an important step towards delivering effective treatments for HS, a debilitating disease, where treatment options remain limited. CIT-013's novel, ET-targeting approach offers the potential to improve disease control in HS and address a broad range of inflammatory conditions.”

Citylights is a Phase IIa multi-center, double-blind, randomized, placebo-controlled trial, designed to investigate the effects of two dose levels of CIT-013 on disease activity in patients with HS, across Europe and North America. The study will assess efficacy, safety, and tolerability, with 96 participants in this 12-week study. Citryll’s Phase IIa trial in RA was initiated earlier this year.

-ENDS-

About CIT-013

CIT-013 is Citryll’s first-in-class monoclonal antibody targeting Extracellular Traps (ETs), a key driver of inflammation in RA, HS and other immune-mediated inflammatory diseases, which has yet to be addressed therapeutically. It has a unique dual mechanism of action, which enhances the clearance of existing ETs and inhibits the formation of new ETs. CIT-013 is highly selective for its epitope, minimising off-target effects and representing a potentially transformative therapeutic strategy, going beyond individual pathway management and symptom treatment.

About Citryll

Citryll is pioneering a transformative approach to treating inflammatory diseases by targeting Extracellular Traps (ETs), a fundamental component of the inflammatory process that has yet to be addressed therapeutically.

Citryll is developing the first ET-targeting therapy and potentially creating a new class of therapeutics with broad applications across immune-mediated inflammatory diseases.

Our lead asset, CIT-013, is a first-in-class monoclonal antibody with a unique dual mechanism of action: it enhances the clearance of existing ETs and inhibits the formation of new ETs.

By addressing this key driver of inflammation, CIT-013 has the potential to offer a differentiated and comprehensive treatment option for conditions such as rheumatoid arthritis and hidradenitis suppurativa, where current therapies often fall short of providing adequate disease control.

Contacts

Citryll
Sjoerd van Gorp, COO / CFO
Email: info@citryll.com

Citryll Media Contacts
ICR Healthcare
Amber Fennell, Stephanie Cuthbert, Lucy Featherstone
Email: citryll@icrinc.com