LA JOLLA, Calif. — October 5, 2026
Equillium, Inc. announced that it received Human Research Ethics Committee (HREC) approval and Therapeutic Goods Administration (TGA) clearance under Australia’s Clinical Trial Notification scheme for its Phase 1 clinical trial of EQ504, an investigational aryl hydrocarbon receptor (AhR) modulator. The company expects to begin dosing healthy participants by early November 2026, with topline Phase 1 proof-of-mechanism data anticipated approximately six months after study initiation. The randomized, double-blind, placebo-controlled trial will evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of EQ504.
EQ504 Targets AhR to Modulate Inflammation and Barrier Function
EQ504 is designed as a potent and selective AhR modulator with a multimodal, non-immunosuppressive mechanism of action. AhR plays a role in barrier tissue physiology and immune regulation, including maintenance of barrier function, tissue repair and regulation of resident immune cells. Equillium believes these properties could be relevant to diseases such as ulcerative colitis, where reducing inflammation and supporting mucosal healing are important treatment objectives. For ulcerative colitis, EQ504 is being developed as an oral, colon-targeted delayed-release formulation, while Equillium is also evaluating the candidate for inflammatory lung diseases using inhaled formulations.
Phase 1 Trial Evaluates Safety and Proof of Mechanism
The Phase 1 study will evaluate once-daily oral doses of EQ504 ranging from 0.1 to 3.0 mg in healthy participants. Part A is a single ascending dose study across five sequential cohorts designed to assess initial safety and pharmacokinetics. Part B is a multiple ascending dose study across three cohorts, with participants receiving once-daily treatment for 10 days to evaluate steady-state pharmacokinetics, safety and tolerability. The study also includes longitudinal gastrointestinal mucosal biopsies to measure tissue-specific pharmacodynamic biomarkers, including CYP1A1 expression, providing evidence of localized biological activity and target engagement. Part C is a dedicated food-effect crossover cohort evaluating the impact of a high-fat meal on the bioavailability and systemic exposure of a single oral dose.
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Equillium Targets Ulcerative Colitis Development in 2027
The Phase 1 program is intended to establish the clinical safety and pharmacological profile of EQ504 before patient studies begin. Subject to supportive Phase 1 results, Equillium anticipates initiating a placebo-controlled proof-of-concept study in patients with moderately to severely active ulcerative colitis in the second half of 2027. The company is positioning EQ504 as a potential treatment that could address both immune dysregulation and impaired barrier function while avoiding broad immunosuppression. With Australian regulatory clearance now secured and first dosing expected in early November 2026, the EQ504 program is moving into human clinical development and toward its planned proof-of-mechanism and subsequent ulcerative colitis studies..
Source:Equillium, press release
