CIT-013 / Citryll - LARVOL DELTA

CIT-013 as a Novel Therapeutic Strategy in Rheumatoid Arthritis Through Extracellular Trap Opsonization and Macrophage Modulation (ACR Convergence 2026) - No abstract available

Immunology • Inflammatory Arthritis • Rheumatoid Arthritis • Rheumatology

Extracellular Traps as a Therapeutic Target in Hidradenitis Suppurativa: Mechanistic Rationale and Clinical Development of CIT-013 (EADV 2026) - No abstract available

Clinical • Dermatology • Hidradenitis Suppurativa • Immunology

Phase I trial in participants with rheumatoid arthritis and healthy volunteers with CIT-013, a first-in-class extracellular traps targeted therapy. (PubMed, EULAR Rheumatol Open) - No abstract available

Journal • P1 data • Immunology • Inflammatory Arthritis • Rheumatoid Arthritis • Rheumatology

Immunothrombosis promotes the interaction between neutrophils and synovial fibroblasts in rheumatoid arthritis. (PubMed, Transl Res) - "Furthermore, we showed that RA SF stimulates IL-8 (CXCL8) expression in control FLS through PAR-1 signaling, and this response was attenuated by DNase I treatment and CIT-013, a monoclonal antibody targeting anti-citrullinated histones H2A and H4 in neutrophil extracellular traps (NETs), supporting the hypothesis that the effect is mediated by NETs. Notably, FLS derived from RA patients exhibit enhanced CXCL8 expression, and elevated IL-8 levels were detected in RA SF, both contributing to neutrophil recruitment, a process that could be mitigated through blockade with an anti-CXCL-8 neutralizing antibody. These results suggest an amplification loop in which TF expression, thrombin activity, and NET formation converge to activate FLS, sustain IL-8 mediated neutrophil migration, and perpetuate synovial inflammation, revealing how stromal and immune cells interact to propagate RA pathophysiology."

Journal • Hematological Disorders • Immunology • Inflammation • Inflammatory Arthritis • Osteoarthritis • Pain • Rheumatoid Arthritis • Rheumatology • Thrombosis • CXCL8 • JAK1

Radiolabelled anti-citrullinated histone antibody CIT-013 as a tool to visualize extracellular trap rich inflamed joints in a collagen induced arthritis mouse model (EULAR 2026) - "This proof of principle imaging study enabled an ongoing human whole body PET CT imaging clinical study in RA and hidradenitis suppurativa patients. This clinical study will lead to further insights in CIT-013’s distribution, target engagement and mechanism of action in patients with immune mediated inflammatory diseases."

Preclinical • Hidradenitis Suppurativa • Immunology • Inflammation • Inflammatory Arthritis • Rheumatoid Arthritis • Rheumatology

Calprotectin Serum levels: a potential neutrophil activation biomarker to monitor treatment response in Rheumatoid Arthritis (EULAR 2026) - "Citryll is developing a novel antibody therapeutic mAb (CIT-013) that targets release of extracellular traps from neutrophils. It is our intention to further probe the utility of calprotectin, along with other conventionally used biomarkers, as a marker of response to therapy in an RA phase 2a proof of concept study which is currently running."

Biomarker • Gastrointestinal Disorder • Immunology • Inflammation • Inflammatory Arthritis • Rheumatoid Arthritis • Rheumatology • KEAP1 • S100A8

CITRYLL006 - Citysky: 150 mg CIT-013 phase 1 trial (clinicaltrialsregister.eu) - P1 | N=10 | Not yet recruiting | Sponsor: Citryll B.V.

New P1 trial • Inflammation

Cityview: PET-Based Imaging of Radiolabeled CIT-013 (clinicaltrials.gov) - P2 | N=12 | Recruiting | Sponsor: Citryll BV

Trial initiation date • Immunology

Citylights: A Study With CIT-013 in HS Patients (clinicaltrials.gov) - P2 | N=96 | Recruiting | Sponsor: Citryll BV

Trial initiation date • Dermatology • Hidradenitis Suppurativa • Immunology

Citysky: Phase 1 Trial to Evaluate 150 mg Subcutaneous CIT-013 (clinicaltrials.gov) - P1 | N=10 | Not yet recruiting | Sponsor: Citryll BV

New P1 trial

Cityview: PET-Based Imaging of Radiolabeled CIT-013 (clinicaltrialsregister.eu) - P1/2 | N=12 | Recruiting | Sponsor: Citryll B.V.

New P1/2 trial • Immunology • CRP

CITRYLL003: A Phase 2a double blind, randomized, parallel arm, placebo-controlled trial to investigate the effects of two dose levels of CIT-013 on disease activity in patients with Hidradenitis Suppurativa (HS) (clinicaltrialsregister.eu) - P1/2 | N=64 | Recruiting | Sponsor: Citryll B.V.

New P1/2 trial • Dermatology • Hidradenitis Suppurativa • Immunology

Targeting Neutrophil Function as Therapy for Hidradenitis Suppurativa. (PubMed, Int J Mol Sci) - "Strategies advancing through clinical trials include inhibition of chemokine-mediated trafficking, neutrophil serine protease inactivation and suppression of neutrophil extracellular traps (NETs), which amplify inflammatory and autoimmune responses. These emerging therapies mark a significant shift toward targeted neutrophil modulation, offering new opportunities to improve outcomes for patients with HS."

Journal • Review • Dermatology • Hidradenitis Suppurativa • Immunology • Inflammation • Pain • IL17A • TNFA

Citryll...announces that the first patient has been successfully dosed in its imaging study, ‘Cityview’, evaluating the distribution of radiolabeled CIT-013 in participants with rheumatoid arthritis (RA) and hidradenitis suppurativa (HS). (Yahoo Finance) - "Cityview is a Phase IIa, open-label, single-center study planned to enroll 12 participants in two sequential groups starting with participants with active RA, followed by participants with RA in remission and participants with active HS. Following a single dose of radiolabeled CIT-013, participants will undergo PET-CT imaging at intervals over a week follow-up period."

Trial status • Hidradenitis Suppurativa • Rheumatoid Arthritis

Cityview: PET-Based Imaging of Radiolabeled CIT-013 (clinicaltrials.gov) - P2 | N=12 | Recruiting | Sponsor: Citryll BV | Not yet recruiting ➔ Recruiting

Enrollment open • Immunology

Citryll…announces the dosing of the first patient in its Phase IIa hidradenitis suppurativa (HS) clinical trial, 'Citylights' (GlobeNewswire) - "The trial will evaluate its first-in-class monoclonal antibody CIT-013 in patients with moderate to severe HS."

Trial status • Hidradenitis Suppurativa

Neutrophil Extracellular Traps in Hidradenitis Suppurativa Skin and Serum as Target for CIT-013, a Novel NET Inhibiting Therapy (ISDS 2025) - "Collectively, the data support the therapeutic rationale for CIT-013 in HS. A Phase 2 proof-of-concept trial in HS will start this year."

Dermatology • Hidradenitis Suppurativa • Immunology • Inflammation

Citylights: A Study With CIT-013 in HS Patients (clinicaltrials.gov) - P2 | N=96 | Recruiting | Sponsor: Citryll BV | Not yet recruiting ➔ Recruiting

Enrollment open • Dermatology • Hidradenitis Suppurativa • Immunology

Two additional posters provided details from preclinical studies supporting the clinical program. (GlobeNewswire) - "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."

Preclinical • Rheumatoid Arthritis

CIT-013…Additional Phase IIa trial in hidradenitis suppurativa expected to start later this year (GlobeNewswire)

Trial status • Hidradenitis Suppurativa

Citryll Presents Positive Data from Phase I Study of CIT-013 in Rheumatoid Arthritis at ACR Convergence 2025 (GlobeNewswire) - "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."

P1 data • Rheumatoid Arthritis

Radiolabelled anti-citrullinated histone antibody CIT-013 as a tool to visualize NET rich inflamed joints in a collagen induced arthritic mouse model (ACR Convergence 2025) - "mACHA can be used as a radiotracer to visualize NETs in sites of inflammation. This proof of principle imaging study enables a human whole body PET CT imaging clinical study in RA and hidradenitis suppurativa patients during 2025. This clinical study will lead to further insights in CIT-013's distribution, target engagement and mechanism of action in patients with immune mediated inflammatory diseases."

Preclinical • Dermatology • Hidradenitis Suppurativa • Immunology • Inflammation • Inflammatory Arthritis • Rheumatoid Arthritis • Rheumatology

Phase I Trial in Participants with Rheumatoid Arthritis and Healthy Volunteers with CIT-013, a First in Class NETosis Inhibitor (ACR Convergence 2025) - "CIT-013 was well tolerated and a DAS28-CRP reduction was observed in participants with RA and active disease. These findings support further clinical development."

Clinical • P1 data • Immunology • Inflammatory Arthritis • Musculoskeletal Diseases • Orthopedics • Rheumatoid Arthritis • Rheumatology

Calprotectin Serum levels: a potential neutrophil activation biomarker to monitor treatment response in Rheumatoid Arthritis (ACR Convergence 2025) - "Our data obtained from the analyses of two longitudinal RA cohorts demonstrate that serum calprotectin and its change can be used as a biomarker for disease activity and response to treatment. Citryll is developing a novel antibody therapeutic mAb (CIT-013) that targets release of extracellular traps from neutrophils. It is our intention to further probe the utility of calprotectin, along with other conventionally used endpoints, as a marker of response to therapy in an RA phase 2a proof of concept study which will begin in 2025."

Biomarker • Gastrointestinal Disorder • Immunology • Inflammation • Inflammatory Arthritis • Rheumatoid Arthritis • Rheumatology • KEAP1 • S100A8

FIRST PATIENT DOSED IN CITRYLL’S PHASE IIA TRIAL EVALUATING CIT-013 IN RHEUMATOID ARTHRITIS (GlobeNewswire) - "Citydream is a Phase IIa, randomized, double-blind, placebo-controlled, multi-center study conducted across multiple sites in Europe....The trial will enroll 88 patients who will undergo a 6-week treatment period, followed by an open-label extension phase to further assess safety and efficacy."

Trial status • Rheumatoid Arthritis