EQ504 protects against gut damage in a mouse model of ulcerative colitis

EQ504 increases T_reg stability and function while suppressing pathogenic T_h17 responses

EQ504 promotes healing of intestinal epithelial cells by promoting anti-inflammatory cytokines

Equillium, Inc. (Nasdaq: EQ), a clinical-stage biotechnology company leveraging a deep understanding of immunobiology to develop novel therapeutics to treat severe autoimmune and inflammatory disorders, today announced that three posters were presented at IMMUNOLOGY2025, the annual meeting of The American Association of Immunologists taking place at the Hawaiʻi Convention Center in Honolulu, Hawaii, May 3 – 7.

“Decades of independent research have validated AhR as an important physiological regulator of immune homeostasis in barrier tissues such as the gut,” said Dr. Stephen Connelly, chief scientific officer at Equillium. “These data demonstrate the potent activity of EQ504 in suppressing inflammation and repair of intestinal tissues highlighting its potential as a powerful approach to treating ulcerative colitis, where poor mucosal healing limits the majority of patients achieving full clinical remission.”

Title: EQ504: A Novel AhR Agonist That Promotes Immune Tolerance Through Modulating T Cell Function

Abstract Number: 4678

Session Title: BA3P – Emerging Concepts in B Cell and T Cell Role in Autoimmune Disease II

Poster Number: P107

Lead Author: Jeanette Ampudia, Director, Immunology & Research Operations in Non-clinical Research, Equillium, Inc.

Presentation Type: Poster Session

Presentation Summary: EQ504 drives Treg stability and function while suppressing pathogenic Th17 responses, highlighting AhR modulation as a promising strategy to rebalance Teff/Treg ratios in immunoinflammatory diseases.

Title: EQ504: A Potent Derivative of the AhR Ligand ITE Demonstrates Efficacy in Modulating Inflammation and Promoting Healing in DSS-Colitis

Abstract Number: 9835

Session Title: IRM7P – Late-Breaking

Poster Number: P1076

Lead Author: Dalena Chu, Associate Scientist in Non-clinical Research, Equillium, Inc.

Presentation Type: Poster Session

Presentation Summary: EQ504 is a more potent inducer of CYP1A1 activity compared to its parent compound, ITE, is a stronger inducer of IL-10 and IL-22 gene expression compared to indirubin and effectively alleviates gut pathology in a mouse model of ulcerative colitis (UC), suggesting its potential as a potent therapeutic for UC patients via modulation of immune and gut epithelial cell function.

Title: Potent AhR Agonist EQ504 Facilitates Gut Epithelial Repair in Inflammatory Disease Models

Abstract Number: 4507

Session Title: MUC6P – Regulation of Mucosal Immunity

Poster Number: P1114

Lead Author: Valeria Marrocco, Senior Scientist in Non-clinical Research, Equillium, Inc.

Presentation Type: Poster Session

Presentation Summary: EQ504 is a strong inducer of the AhR pathway in intestinal epithelial cells, preserves the barrier function and promotes healing of intestinal epithelial cells by promoting IL22RA and IL10 expression.

The poster presentations are available on the Presentations page of Equillium’s website under the “EQ504” tab.

About EQ504

EQ504 is a potent and selective AhR modulator with a unique, multi-modal, non-immunosuppressive mechanism of action that is complementary to other inflammation and immunology agents. AhR is critical to barrier organ tissue physiology and immunology, maintaining barrier function and promoting tissue repair and regeneration, while regulating resident immune cells with anti-inflammatory responses. EQ504 has excellent drug-like properties making it amenable to be formulated for targeted, local delivery such as enteric coating for the treatment of ulcerative colitis or inhaled formulations for the treatment of inflammatory lung diseases.

About Equillium

Equillium is a clinical-stage biotechnology company leveraging a deep understanding of immunobiology to develop novel therapeutics to treat severe autoimmune and inflammatory disorders with high unmet medical need. The company’s pipeline consists of several novel immunomodulatory assets and product platform targeting immuno-inflammatory pathways.

For more information, visit www.equilliumbio.com.

Forward Looking Statements

Statements contained in this press release regarding matters that are not historical facts are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements may be identified by the use of words such as “anticipate”, “believe”, “could”, “continue”, “expect”, “estimate”, “may”, “plan”, “outlook”, “future”, “potential” and “project” and other similar expressions that predict or indicate future events or trends or that are not statements of historical matters. These statements include, but are not limited to, statements regarding Equillium’s plans and strategies with respect to developing EQ504, including the initiation of clinical studies and the reporting of data therefrom; the expected timeline for initiating and reporting data from a Phase 1 study of EQ504; the ability to raise additional capital to fund development of EQ504; and the potential benefits of EQ504. Because such statements are subject to risks and uncertainties, many of which are outside of Equillium’s control, actual results may differ materially from those expressed or implied by such forward-looking statements. Risks that contribute to the uncertain nature of the forward-looking statements include: Equillium’s ability to execute its plans and strategies; Equillium’s ability to continue as a going concern; risks related to performing clinical and pre-clinical studies; whether the results from clinical and pre-clinical studies will validate and support the safety and efficacy of Equillium’s product candidates; changes in the competitive landscape; and Equillium’s ability to raise sufficient financing, which may not be available on acceptable terms or at all, to advance EQ504 and fund Equillium’s strategic plans. These and other risks and uncertainties are described more fully under the caption "Risk Factors" and elsewhere in Equillium's filings and reports, which may be accessed for free by visiting the Securities and Exchange Commission’s website and on Equillium’s website under the heading “Investors.” Investors should take such risks into account and should not rely on forward-looking statements when making investment decisions. All forward-looking statements contained in this press release speak only as of the date on which they were made. Equillium undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made, except as required by law.

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