EQ

Phase 1 proof-of-mechanism study of EQ504 initiation expected in Q4 2026, with data expected approximately six months thereafter Cash and cash equivalents of $57.2 million expected to fund operations into 2029 LA JOLLA, Calif., Aug. 13, 2026 (GLOBE NEWSWIRE) -- Equillium, Inc. (Nasdaq: EQ), a clinical-stage biotechnology innovator with a mission to develop highly impactful therapies to treat severe autoimmune and inflammatory disorders, today reported financial results for the second quarter ended June 30, 2026, and provided a corporate update highlighting continued progress in support of EQ504, its potent and selective aryl hydrocarbon receptor (AhR) modulator. “We continue to make meaningful progress advancing EQ504 toward the clinic," said Bruce Steel, Chief Executive Officer of Equillium. "Our colon-targeted formulated product has been manufactured, and we plan to submit the dossier for our Phase 1 study in Australia imminently. We expect to initiate this study in the fourth quarter of 2026 and report topline data approximately six months thereafter. The study is designed as a conventional randomized, double-blind, placebo-controlled single and multiple ascending dose study (SAD/MAD) in healthy volunteers, focused on safety, tolerability, pharmacokinetics and pharmacodynamics to assess proof of mechanism. Subject to supportive Phase 1 data, we anticipate expeditiously initiating a placebo-controlled study to assess the safety, tolerability, and efficacy of EQ504 in patients with moderately to severely active ulcerative colitis. Key study parameters are intended to leverage other AhR modulator clinical datasets in ulcerative colitis to facilitate an efficient patient proof-of-concept study.” Recent Corporate & Clinical Highlights: Advancing EQ504 toward the clinic, with the Phase 1 proof-of-mechanism study expected to initiate in the fourth quarter of 2026, and topline data anticipated approximately six months thereafter. Initiated IND-enabling development activities for EQ504 as a potential inhaled therapy to treat inflammatory lung diseases. Initiated IND-enabling development activities for EQ302, an oral, bi-specific inhibitor of IL-15 and IL-21, intended to be developed for celiac disease. Established a Clinical Advisory Board chaired by Professor Bruce Sands, M.D. (Chair, Feinstein IBD Clinical Center, Mount Sinai) to guide the design and execution of the EQ504 clinical program in ulcerative colitis. Second Quarter 2026 Financial Results Cash and cash equivalents totaled $57.2 million as of June 30, 2026, compared to $61.3 million as of March 31, 2026. Equillium believes that its cash and cash equivalents on the balance sheet as of June 30, 2026, are capable of funding its currently planned operations into 2029. Research and development (R&D) expenses for the second quarter of 2026 were $2.8 million, compared with $4.1 million for the same period in 2025. General and administrative (G&A) expenses for the second quarter of 2026 were $2.4 million, compared with $2.1 million for the same period in 2025. Net loss for the second quarter of 2026 was $4.7 million, or $(0.04) per basic and diluted share, compared with a net loss of $5.7 million, or $(0.16) per basic and diluted share for the same period in 2025. About EQ504EQ504 is an investigational potent and selective aryl hydrocarbon receptor (AhR) modulator with a multi-modal, non-immunosuppressive mechanism of action designed to be 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’s preclinical properties provide the potential for targeted, local delivery via enteric coating for the treatment of ulcerative colitis and other gastrointestinal diseases or inhaled formulations for the treatment of inflammatory lung diseases. About Equillium Equillium is a biotechnology innovator with a mission to develop highly impactful therapies to treat severe autoimmune and inflammatory disorders. 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 the advancement of EQ504 toward the clinic; the timing for the submission of Equillium’s dossier for its Phase 1 study in Australia, the timing of the initiation of the study, and the timing for the reporting of topline data from the study, if initiated; Equillium’s initiation of a placebo-controlled study to assess the safety, tolerability, and efficacy of EQ504 in patients, and the timing of the study if initiated; Equillium’s ability to leverage other AhR modulator clinical datasets in ulcerative colitis to facilitate an efficient proof-of-concept study; Equillium’s development of EQ504 as a potential inhaled therapy to treat inflammatory lung diseases; Equillium’s development of EQ302 for celiac disease; and the ability of Equillium’s cash runway to fund its currently planned operations into 2029. 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 raise additional capital on terms acceptable to Equillium, or at all; Equillium’s ability to continue as a going concern; Equillium’s ability to execute its plans and strategies, and to execute its plans and strategies within its budgets; 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 changes in 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. Investor ContactPJ KelleherLifeSci Advisors, [email protected]

Phase 1 proof-of-mechanism study of EQ504 on track to initiate in mid-2026, with data expected approximately six months thereafter Equillium appoints Snehal Naik, Ph.D., as Chief Development Officer to lead clinical development and medical strategy Cash and cash equivalents expected to fund currently planned operations into 2029 LA JOLLA, Calif., May 13, 2026 (GLOBE NEWSWIRE) -- 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 reported financial results for the first quarter ended March 31, 2026, and provided a corporate update highlighting continued progress in support of EQ504, its potent and selective aryl hydrocarbon receptor (AhR) modulator. “Following our March year-end update and financing, we have remained focused on advancing EQ504 toward the clinic while continuing to expand the scientific foundation supporting its differentiated profile,” said Bruce Steel, Chief Executive Officer of Equillium. “Recent preclinical data presented at IMMUNOLOGY2026 further strengthen our growing body of evidence for EQ504’s ability to modulate immune responses while promoting epithelial repair and barrier restoration. We believe these attributes reinforce the potential of EQ504 as a potentially differentiated, non-immunosuppressive therapeutic approach in ulcerative colitis and other inflammatory diseases. We are also pleased to welcome Snehal Naik, Ph.D., as Chief Development Officer of Equillium. Snehal brings deep expertise leading integrated clinical and medical development strategies across immunology programs, including extensive experience in gastrointestinal diseases, and we welcome her addition to our leadership team as we advance EQ504 into the clinic and expand our development pipeline.” Recent Corporate & Clinical Highlights: Recently appointed Snehal Naik, Ph.D., as Chief Development Officer. Dr. Naik will lead clinical development and medical strategy across Equillium’s pipeline, with responsibility for advancing EQ504 into the clinic and progressing future programs. She brings more than 15 years of biotechnology and pharmaceutical industry experience spanning early discovery through late-stage clinical development and product lifecycle management, including leadership of global development programs in immunology and inflammatory diseases. Most recently, Dr. Naik served as Senior Vice President and Head of Clinical Development at Ventyx Biosciences, where she led all development activities across a portfolio of immunology assets and advanced multiple programs into late-stage readiness. Dr. Naik received her Bachelor of Science in Biology from the University of Kentucky and Ph.D. in Pharmacology from Temple University School of Medicine. She completed NIH-funded postdoctoral fellowships at Thomas Jefferson University and the University of Pennsylvania School of Medicine. In March 2026, completed private placement financing of $35 million with RA Capital Management, providing additional capital to support the advancement of EQ504 through key clinical milestones and the continued execution of the Company’s development strategy. Continuing to advance EQ504, a potent and selective AhR modulator with potential for targeted local delivery in gastrointestinal (GI) diseases, including UC, as well as inhaled formulations for inflammatory lung diseases. Plans to initiate a Phase 1 proof-of-mechanism study in mid-2026, with data expected approximately six months thereafter. Equillium recently presented two EQ504 abstracts at IMMUNOLOGY2026, the annual meeting of the American Association of Immunologists in April 2026. Preclinical findings demonstrate that EQ504 promotes immune tolerance through induction of IL-10 and IL-22, supports anti-inflammatory macrophage polarization, and enhances epithelial repair and barrier function. The data also showed functional differentiation from clinically validated AhR-targeting agents, further supporting EQ504’s potential as a promising therapeutic candidate for ulcerative colitis. Evaluating further advancement of EQ302, its oral, bi-specific inhibitor of IL-15 and IL-21 being developed for GI indications, including celiac disease. First Quarter 2026 Financial Results Research and development (R&D) expenses for the first quarter of 2026 were $3.0 million, compared with $5.9 million for the same period in 2025. The significant decrease in R&D expenses was primarily driven by the wind down of our clinical studies in 2025. General and administrative (G&A) expenses for the first quarter of 2026 were $2.6 million, compared with $2.9 million for the same period in 2025. The decrease in G&A expenses was primarily driven by lower legal and other professional fees. Net loss for the first quarter of 2026 was $5.3 million, or $(0.06) per basic and diluted share, compared with a net loss of $8.7 million, or $(0.24) per basic and diluted share for the same period in 2025. Net loss decreased primarily as a result of lower R&D and G&A expenses, as described above. Cash and cash equivalents totaled $61.3 million as of March 31, 2026, compared to $30.3 million as of December 31, 2025. Equillium believes that its cash and cash equivalents on the balance sheet as of March 31, 2026 are capable of funding its currently planned operations into 2029, based on certain assumptions and estimates that may prove to be inaccurate. About EQ504 EQ504 is an investigational potent and selective aryl hydrocarbon receptor (AhR) modulator with a multi-modal, non-immunosuppressive mechanism of action designed to be 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’s preclinical properties provide the potential for targeted, local delivery via enteric coating for the treatment of ulcerative colitis and other gastrointestinal diseases 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 belief that the cash and cash equivalents on its balance sheet as of March 31, 2026 are capable of funding its currently planned operations into 2029; Equillium’s ability to advance EQ504 through key clinical milestones and continue to execute Equillium’s development strategy; EQ504’s potential as a promising therapeutic candidate for ulcerative colitis; the ability to further advance EQ302; the potential benefits of Equillium’s product candidates; and other statements that are not historical facts. These statements are based on Equillium’s current plans, objectives, estimates, expectations and intentions, are not guarantees of future performance and inherently involve significant risks and uncertainties. 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, but are not limited to: market conditions; volatility in the trading price of Equillium’s common stock; the sufficiency of Equillium’s capital resources and need for additional capital to achieve its goals; Equillium’s ability to raise additional capital on terms acceptable to Equillium, or at all; Equillium’s ability to continue as a going concern; risks inherent in achieving clinical milestones and stock price thresholds; Equillium’s ability to initiate or progress a Phase 1 clinical study, or any clinical trials, or the ability of such Phase I clinical study or any clinical trials to generate favorable data, on the anticipated timelines, if at all; Equillium’s ability to execute its plans and strategies; risks related to performing clinical and pre-clinical studies, if and when initiated; 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 changes in Equillium’s strategic plans. The foregoing list of risk factors is not exhaustive. These and other risks and uncertainties are described more fully under the caption "Risk Factors" and elsewhere in Equillium's filings and reports with the Securities and Exchange Commission (SEC), which may be accessed for free by visiting the SEC’s website at www.sec.gov, 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. Investor Contact PJ Kelleher LifeSci Advisors, LLC +1-617-430-7579 [email protected]

Initiation of Phase 1 proof-of-mechanism study of EQ504 planned for mid-2026, with data expected approximately six months thereafter Cash and cash equivalents, inclusive of the March 2026 financing, expected to fund operations into 2029 LA JOLLA, Calif, March 25, 2026 (GLOBE NEWSWIRE) -- 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 financial results for its fourth quarter and fiscal year ended December 31, 2025. “2025 was a transformative year as we sharpened our strategic focus on EQ504 and strengthened our financial position to support its advancement into the clinic,” said Bruce Steel, Chief Executive Officer of Equillium. “Our financing in August 2025 of up to $50 million, together with our recently completed $35 million financing, further reinforces confidence in our strategy and provides the resources to efficiently execute our EQ504 clinical development plan. With operating runway expected into 2029, we are well-positioned to advance EQ504’s differentiated, non-immunosuppressive approach targeting the AhR pathway to address significant unmet needs across inflammatory diseases, and we believe it has the potential to be a best-in-class oral therapy in ulcerative colitis (UC), with additional opportunities across gastrointestinal (GI) and inflammatory lung diseases.” Recent Corporate & Clinical Highlights: In March 2026, announced a private placement financing of $35 million with RA Capital Management. In August 2025, announced a private placement financing of up to $50 million with a syndicate of leading healthcare investors, including ADAR1 Capital Management, Janus Henderson Investors, Adage Capital Partners LP, Coastlands Capital, and Woodline Partners LP. Continuing to advance EQ504, a potent and selective AhR modulator with potential for targeted local delivery in GI diseases including UC, as well as inhaled formulations for inflammatory lung diseases. The Company has completed the preclinical work and plans to initiate a Phase 1 proof-of-mechanism study in mid-2026, with data expected approximately six months thereafter. Evaluating further advancement of EQ302, its oral, bi-specific inhibitor of IL-15 and IL-21 being developed for GI indications, including celiac disease. Hosted a virtual KOL investor event with Dr. Francisco J. Quintana of Harvard Medical School and the late Dr. Brian Feagan of Western Ontario, on Wednesday, November 5, 2025. A replay of the KOL event can be accessed here, and key takeaways include: AhR modulation is i) a differentiated and multi-modal approach to decreasing tissue inflammation while promoting tissue repair; and ii) clinically validated in skin and GI diseases, through VTAMA® and the botanical indigo naturalis, respectively. EQ504 i) is a potent and selective AhR modulator that may be administered orally and is formulated to target the colon, representing a next-generation therapeutic to treat UC locally; and ii) has broad therapeutic potential in UC as a potential standalone oral therapy, or in combination with other therapeutic approaches. Fourth Quarter and Full Year 2025 Financial Results Revenue for the fourth quarter of 2025 was $0, compared with $4.4 million for the same period in 2025. For the full year of 2025, there was no revenue recognized, compared with $41.1 million under the Asset Purchase Agreement with Ono Pharmaceutical for the full year of 2024. Research and development (R&D) expenses for the fourth quarter of 2025 were $1.5 million, compared with $7.3 million for the same period in 2024. For the full year of 2025, R&D expenses were $12.8 million, compared with $37.4 million for the full year of 2024. The significant year-over-year decrease in R&D expenses was primarily driven by the wind down of our clinical studies in 2025. General and administrative (G&A) expenses for the fourth quarter of 2025 were $2.4 million, compared with $1.8 million for the same period in 2024. For the full year of 2025, G&A expenses were $10.8 million, compared with $11.9 million for the full year of 2024. The year-over-year decrease was primarily driven by lower general overhead expenses. Net loss for the fourth quarter of 2025 was $3.8 million, or $(0.04) per basic and diluted share, compared with a net loss of $5.8 million, or $(0.16) per basic and diluted share for the same period in 2024. Net loss for the full year of 2025 was $22.4 million, or $(0.39) per basic and diluted share, compared with a net loss of $8.1 million, or $(0.23) per basic and diluted share for the full year of 2024. The increase in net loss for the year-over-year period was primarily due to lower revenue, partially offset by lower operating expenses. Cash, cash equivalents and short-term investments totaled $30.3 million as of December 31, 2025, compared to $22.6 million as of December 31, 2024. Equillium believes that its cash and cash equivalents on the balance sheet as of December 31, 2025, together with the recently completed financing of $35 million in March 2026, are capable of funding its currently planned operations into 2029, based on certain assumptions and estimates that may prove to be inaccurate. About EQ504 EQ504 is an investigational potent and selective aryl hydrocarbon receptor (AhR) modulator with a multi-modal, non-immunosuppressive mechanism of action designed to be 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’s preclinical properties provide the potential for targeted, local delivery via enteric coating for the treatment of ulcerative colitis and other gastrointestinal diseases 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 expectation that the cash and cash equivalents on its balance sheet as of December 31, 2025, together with the recently completed financing of $35 million in March 2026, are capable of funding its currently planned operations into 2029; Equillium’s ability to efficiently execute or advance its EQ504 clinical development plan; the potential benefits of Equillium’s product candidates; and other statements that are not historical facts. These statements are based on Equillium’s current plans, objectives, estimates, expectations and intentions, are not guarantees of future performance and inherently involve significant risks and uncertainties. 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, but are not limited to: market conditions; volatility in the trading price of Equillium’s common stock; the sufficiency of Equillium’s capital resources and need for additional capital to achieve its goals; Equillium’s ability to raise additional capital on terms acceptable to Equillium, or at all; Equillium’s ability to continue as a going concern; risks inherent in achieving clinical milestones and stock price thresholds; Equillium’s ability to initiate or progress a Phase 1 clinical study, or any clinical trials, or the ability of such Phase I clinical study or any clinical trials to generate favorable data, on the anticipated timelines, if at all; Equillium’s ability to execute its plans and strategies; risks related to performing clinical and pre-clinical studies, if and when initiated; 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 changes in Equillium’s strategic plans. The foregoing list of risk factors is not exhaustive. These and other risks and uncertainties are described more fully under the caption "Risk Factors" and elsewhere in Equillium's filings and reports with the Securities and Exchange Commission (SEC), which may be accessed for free by visiting the SEC’s website at www.sec.gov, 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. Investor Contact PJ Kelleher LifeSci Advisors, LLC +1-617-430-7579 [email protected]

Closed financing of up to $50 million; initial tranche of $30 million provides runway through 2027 Hosted key opinion leader event highlighting the important role of the Aryl Hydrocarbon Receptor (AhR) in intestinal inflammation, the unmet medical need in ulcerative colitis, and the potential clinical utility of EQ504, a novel oral AhR modulator EQ504 Phase 1 clinical study initiation planned for mid-2026 LA JOLLA, Calif., Nov. 13, 2025 (GLOBE NEWSWIRE) -- 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 financial results for its third fiscal quarter ended September 30, 2025. The Company has filed its quarterly report on Form 10-Q with the U.S. Securities and Exchange Commission. “Our recent financing has enabled us to accelerate the development of our novel AhR modulator, EQ504, which we believe has potential to be a first-in-class, oral and colon-targeted therapeutic for ulcerative colitis (UC),” said Bruce Steel, chief executive officer at Equillium. “We are advancing rapidly through our preclinical work and expect to be ready to initiate the Phase 1 clinical study in mid-2026 with the potential to achieve proof-of-concept with the addition of UC patient cohorts following the SAD/MAD portion of the study.” Recent Corporate & Clinical Highlights: On August 11th 2025, the Company announced it entered into a private placement with leading healthcare investors providing up to $50 million in gross proceeds. The private placement was comprised of an initial upfront financing of approximately $30 million in gross proceeds, with the potential for up to an additional $20 million in gross proceeds at the initiation of clinical studies with EQ504 and the occurrence of the other milestones set forth in the purchase agreement for the private placement. The initial tranche of the financing is expected to fund Company operations through 2027. The financing was led by new investors ADAR1 Capital Management and Janus Henderson Investors, and included participation from additional new investors Adage Capital Partners LP, Coastlands Capital, and Woodline Partners LP. On November 5th 2025, the Company hosted a virtual KOL investor event featuring Dr. Francisco Quintana (Harvard Medical School, Broad Institute) and Dr. Brian Feagan (Western University, Alimentiv). The session focused on the growing importance of AhR modulation as a next-generation therapeutic strategy for immune-mediated diseases and reviewed the potential of EQ504 in UC. Key highlights include: AhR modulation is i) a differentiated and multi-modal approach to decreasing tissue inflammation while promoting tissue repair; and ii) clinically validated in skin and GI diseases, through VTAMA® and the botanical indigo naturalis, respectively. EQ504 i) is a potent and selective AhR modulator that may be administered orally and is formulated to target the colon, representing a next-generation therapeutic to treat UC locally; and ii) has broad therapeutic potential in UC as a potential standalone oral therapy, or in combination with other therapeutic approaches. A replay of the KOL event is available here. Anticipated Upcoming Milestones: EQ504 Phase 1 study is expected to initiate in mid-2026. Third Quarter 2025 Financial Results Revenue for the third quarter of 2025 was $0, compared with $12.2 million for the same period in 2024. Revenue in 2024 consisted entirely of itolizumab development funding and amortization of the upfront payment from Ono Pharmaceutical related to the Asset Purchase Agreement that was terminated in October 2024. Research and development (R&D) expenses for the third quarter of 2025 were $1.3 million, compared with $9.6 million for the same period in 2024. The significant decrease in R&D expenses was primarily driven by lower clinical development expenses, lower CMC activities, and lower consulting expenses primarily related to the wind down of our EQUATOR study as well as lower employee compensation and benefits due to lower headcount caused by the wind down of our clinical studies. General and administrative (G&A) expenses for the third quarter of 2025 were $3.3 million, unchanged from $3.3 million for the same period in 2024. Net loss for the third quarter of 2025 was $4.2 million, or $(0.06) per basic and diluted share, compared with a net loss of $7,000, or $(0.00) per basic and diluted share for the same period in 2024. The increase in net loss for the period was primarily due to lower revenue partially offset by lower operating expenses. Cash, cash equivalents and short-term investments totaled $33.1 million as of September 30, 2025, compared to $22.6 million as of December 31, 2024. Equillium believes that its cash and cash equivalents on the balance sheet as of September 30, 2025 are capable of funding its currently planned operations through 2027, based on certain assumptions and estimates that may prove to be inaccurate. About EQ504 EQ504 is an investigational potent and selective aryl hydrocarbon receptor (AhR) modulator with a multi-modal, non-immunosuppressive mechanism of action designed to be 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’s preclinical properties provide the potential for targeted, local delivery via enteric coating for the treatment of ulcerative colitis and other gastrointestinal diseases 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 the potential for Equillium to receive the additional $20 million in gross proceeds from the private placement upon the completion of the milestones set forth in the purchase agreement for the private placement; Equillium’s expectation that the net proceeds from the private placement will fund its operations through 2027; Equillium’s expected use of the net proceeds from the private placement; Equillium’s intent to prioritize development of EQ504 and the ability to accelerate such development; the potential benefits of Equillium’s product candidates; and other statements that are not historical facts. These statements are based on Equillium’s current plans, objectives, estimates, expectations and intentions, are not guarantees of future performance and inherently involve significant risks and uncertainties. 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, but are not limited to: market conditions; volatility in the trading price of Equillium’s common stock; the sufficiency of Equillium’s capital resources and need for additional capital to achieve its goals; Equillium’s ability to raise additional capital on terms acceptable to Equillium, or at all; Equillium’s ability to continue as a going concern; risks inherent in achieving clinical milestones and stock price thresholds; Equillium’s ability to initiate or progress a Phase 1 clinical study, or any clinical trials, on the anticipated timelines, if at all; Equillium’s ability to execute its plans and strategies; risks related to performing clinical and pre-clinical studies, if and when initiated; 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 changes in Equillium’s strategic plans. The foregoing list of risk factors is not exhaustive. These and other risks and uncertainties are described more fully under the caption "Risk Factors" and elsewhere in Equillium's filings and reports with the Securities and Exchange Commission (SEC), which may be accessed for free by visiting the SEC’s website at www.sec.gov, 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. Investor Contact PJ Kelleher LifeSci Advisors, LLC +1-617-430-7579 [email protected]

Treatment with itolizumab did not improve complete or overall response rates at Day 29 Itolizumab achieved statistical significance in multiple secondary endpoints demonstrating compelling clinical benefit in longer-term outcomes, including complete response at Day 99, duration of complete response and failure-free survival Breakthrough Therapy designation and meeting requests to discuss potential for Accelerated Approval submitted to FDA, feedback expected during May 2025 Management will host a conference call and webcast today at 8:30 am ET LA JOLLA, Calif., March 27, 2025--(BUSINESS WIRE)--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 topline data from the Phase 3 EQUATOR study evaluating itolizumab in first-line treatment of patients with acute graft-versus-host disease (aGVHD). The study results did not demonstrate a meaningful difference in complete response (CR) or overall response rate (ORR) at Day 29 between patients treated with itolizumab and placebo; however, statistically significant and clinically meaningful benefit in longer-term outcomes were achieved, including complete response at Day 99, duration of complete response and failure-free survival. Itolizumab exhibited a favorable safety and tolerability profile and did not increase the risk of clinical sequelae, including infection or sepsis, primary drivers of the high mortality associated with aGVHD. "While we did not observe improvements in Day 29 outcomes, itolizumab demonstrated compelling clinical results in several important longer-term outcomes, conferring potential patient benefit where there are no approved therapies," said Bruce Steel, chief executive officer at Equillium. "Based on these data and prior FDA guidance, we have filed for Breakthrough Therapy designation and have been granted a meeting to discuss the potential for Accelerated Approval of itolizumab for first-line treatment of aGVHD, a rare disease where one-year mortality exceeds 40 percent and itolizumab has already received Orphan Drug and Fast Track designations. We expect feedback from the FDA during May and, if positive, we would plan to submit a biologics license application during the first half of 2026." "The longer-term outcomes are important," said Dr. John Koreth, Professor of Medicine, Dana-Farber Cancer Institute, Harvard Medical School. "There are no approvals in first-line therapy for aGVHD, and no drug candidates have been able to demonstrate efficacy beyond four weeks. To demonstrate statistical significance in pre-specified endpoints of duration of complete response and failure-free survival, compared to standard of care therapy, is clinically meaningful." The Phase 3 EQUATOR study in first-line aGVHD demonstrated a favorable safety and tolerability profile, and clinically meaningful longer-term outcomes. There was no meaningful difference in CR or ORR, the primary endpoint and a key secondary endpoint of the study (respectively), at Day 29 between patients treated with itolizumab and placebo, but statistical significance was achieved in several critically important secondary endpoints demonstrating improvement in longer term outcomes: Statistical significance in duration of CR favoring itolizumab, with a median 336 days vs. 72 days, p-value 0.017. Statistical significance in failure-free survival favoring itolizumab, with a median 154 vs. 70 days, p-value 0.043. Statistical significance in complete response at Day 99 favoring itolizumab, with 35 (44.9%) vs. 22 (28.6%) patients, p-value 0.035. Positive trend in overall survival favoring itolizumab, with mortality of 19 (24.4%) vs. 25 (32.5%) patients. Steroid tapering and rates of primary disease relapse and chronic GVHD were similar for both treatment arms. The safety profile observed in the EQUATOR study was consistent with that observed in previously reported studies of itolizumab, and itolizumab did not increase the risk of clinical sequelae, including rates of infection and sepsis. Webcast and Conference Call Management will host a conference call accompanied by a slide presentation to provide an overview of the data from the Phase 3 EQUATOR study in first-line aGVHD, for analysts and institutional investors, at 8:30 am ET today, March 27, 2025. To access the call, please dial (800) 715-9871 or (646) 307-1963 for international callers, and if needed provide conference ID number 2574379. A live webcast of the call will also be available on the company’s Investor Relations page. The webcast will be archived for 180 days. About Graft-Versus-Host Disease (GVHD) GVHD is a multisystem disorder that is a common complication of allogeneic hematopoietic stem cell transplants (allo-HSCT) caused by the transplanted immune system recognizing and attacking the recipient’s body. Symptoms of GVHD include rash, itching, skin discoloration, nausea, vomiting, diarrhea, and jaundice, as well as eye dryness and irritation. GVHD is the leading cause of non-relapse mortality in cancer patients receiving allo-HSCT, and its risk limits the number and type of patients receiving HSCT. GVHD results in high morbidity and mortality, with one year survival as low as 40%. There are no approved treatments for first-line aGVHD. About the EQUATOR Study The Phase 3, randomized, double-blind, placebo-controlled multicenter study (NCT05263999) compared the efficacy and safety of intravenous administered itolizumab versus placebo (randomized 1:1) as a first-line therapy in 158 adult and adolescent patients with Grade III-IV aGVHD, or Grade II aGVHD with lower gastrointestinal involvement, in combination with high doses of corticosteroids, the current standard of care. The primary study endpoint was complete response rate (CR) at Day 29; key secondary endpoints included overall response rate (ORR) at Day 29 and rate of durable CR from Day 29 through Day 99. Additional secondary outcomes included CR at Day 99, duration of CR, failure free survival, and overall survival. Per the study protocol, patients received itolizumab within 3-days of the first administration of high-dose corticosteroids with a treatment period from Days 1-99, and a follow-up period from Days 100-365. Subjects received 2 mg/kg methylprednisolone or equivalent on Day 1 and were randomized in a 1:1 ratio to the following two treatment groups: The EQUATOR study remains ongoing with all patients having completed dosing, and 30 patients in the follow-up period per protocol. An independent data monitoring committee oversees the study and regularly reviews safety data. About Itolizumab Itolizumab is a clinical-stage, first-in-class anti-CD6 monoclonal antibody that selectively targets the CD6-ALCAM signaling pathway to downregulate pathogenic T effector cells while preserving T regulatory cells critical for maintaining a balanced immune response. This pathway plays a central role in modulating the activity and trafficking of T cells that drive a number of immuno-inflammatory 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 itolizumab (EQ001), the encouraging impact of the positive data in the context of Equillium’s Phase 3 EQUATOR study in aGVHD, Equillium’s ability to raise additional capital to support filing of a biologics license application, the expected timing of FDA feedback, and the potential benefits of Equillium’s product candidates. 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; whether the topline results from the EQUATOR study will support accelerated approval and Breakthrough Therapy designation; changes in the competitive landscape; Equillium’s ability to raise additional funding; and changes in 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. View source version on businesswire.com: https://www.businesswire.com/news/home/20250327334273/en/ Contacts Corporate Contact Michael MooreVice President, Investor Relations & Corporate [email protected]

Announced topline data from the Phase 3 EQUATOR study in first-line acute graft-versus-host disease Breakthrough Therapy designation and meeting request to discuss potential for Accelerated Approval submitted to FDA, feedback expected during May 2025 LA JOLLA, Calif., March 27, 2025--(BUSINESS WIRE)--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 financial results for the fourth quarter and full year 2024, as well as corporate and clinical highlights. "This morning, following considerable efforts by our clinical team, we announced topline data from the Phase 3 EQUATOR study evaluating itolizumab in first-line treatment of acute graft-versus-host disease," said Bruce Steel, chief executive officer at Equillium. "While we did not meet Day 29 outcomes of complete response - our primary endpoint - and overall response rate, itolizumab did demonstrate statistically significant and clinically meaningful benefit in important longer-term outcomes, including complete response at Day 99, duration of complete response and failure-free survival. These longer-term outcomes are critically important for aGVHD patients – a rare disease with no approved therapies and overall survival at one-year as low as 40 percent. Based on these data and prior FDA guidance, we have submitted a request for Breakthrough Therapy designation and have been granted a meeting with the FDA to discuss the potential for Accelerated Approval of itolizumab for first-line treatment of aGVHD, an indication where itolizumab has already received Orphan Drug and Fast Track designations. We expect feedback from the FDA during May 2025 and, if positive, subject to raising additional capital, we would plan to submit a biologics license application during the first half of 2026." Recent Corporate & Clinical Highlights: Announced topline data from the Phase 3 EQUATOR study in first-line acute graft-versus-host disease (aGVHD) demonstrating a favorable safety and tolerability profile, and clinically meaningful longer-term outcomes. There was no meaningful difference in complete response (CR) and overall response rate (ORR) at Day 29 between itolizumab patients and placebo patients, but statistical significance and/or clinically meaningful benefit in longer term outcomes were achieved by itolizumab in the following measurements1: Statistical significance in duration of CR favoring itolizumab, with a median 336 days vs. 72 days, p-value 0.017 Statistical significance in failure-free survival favoring itolizumab, with a median 154 days vs. 70 days, p-value 0.043 Statistical significance in CR at Day 99 favoring itolizumab, with 35 (44.9%) vs. 22 (28.6%) patients, p-value 0.035 Positive trend in overall survival favoring itolizumab, with mortality of 19 (24.4%) vs. 25 (32.5%) patients Steroid tapering and rates of primary disease relapse and chronic graft-versus-host disease were similar for both treatment arms Announced positive topline data from a Phase 2 study evaluating itolizumab in the treatment of moderate to severe ulcerative colitis (UC). Itolizumab demonstrated clinical efficacy after 12 weeks of treatment, achieving a clinical remission rate of 23.3% compared to 20.0% for adalimumab and 10.0% for placebo. Itolizumab also achieved key secondary endpoint of endoscopic remission of 16.7% compared to 16.7% for adalimumab and 6.7% for placebo and was generally well tolerated consistent with prior clinical experience. Presented data on the dual and synergistic signaling of IL-15 and IL-21 – targets of EQ302 - highlighting that a single agent would be optimal to inhibit or activate both cytokines known to drive aggressive T and NK cell responses that promote the cytolytic activity and interferon gamma production observed in multiple inflammatory diseases. Anticipated Upcoming Milestones: Itolizumab: Feedback from the FDA on request for Breakthrough Therapy designation and outcome from the FDA meeting to review EQUATOR data and Accelerated Approval pathway expected during May 2025 _____________________1 mITT: data shown under modified intent-to-treat analysis (removes three enrolled patients that did not receive any study treatment) Fourth Quarter and Full Year 2024 Financial Results Revenue for the fourth quarter of 2024 was $4.4 million, compared with $9.2 million for the same period in 2023. For the full year of 2024, revenue was $41.1 million, compared with $36.1 million for the full year of 2023. Revenue in 2024 and 2023 consisted entirely of itolizumab development funding and amortization of the upfront payment from Ono Pharmaceutical related to the terminated Asset Purchase Agreement. Research and development (R&D) expenses for the fourth quarter of 2024 were $7.3 million, compared with $9.2 million for the same period in 2023. For the full year of 2024, R&D expenses were $37.4 million, compared with $37.0 million for the full year of 2023. The nominal year-over-year increase in R&D expenses was driven by increases in preclinical and clinical development expenses and consulting expenses, which were partially offset by a decrease in employee compensation. General and administrative (G&A) expenses for the fourth quarter of 2024 were $1.8 million, compared with $3.2 million for the same period in 2023. For the full year of 2024, G&A expenses were $11.9 million, compared with $13.6 million for the full year of 2023. The year-over-year decrease was driven by lower employee compensation, audit and tax professional fees, consulting expenses, and overhead costs. Net loss for the fourth quarter of 2024 was $5.8 million, or $(0.16) per basic and diluted share, compared with a net loss of $2.3 million, or $(0.07) per basic and diluted share for the same period in 2023. Net loss for the full year of 2024 was $8.1 million, or $(0.23) per basic and diluted share, compared with a net loss of $13.3 million, or $(0.38) per basic and diluted share for the full year of 2023. The decrease in net loss for the full year was primarily due to greater revenue and to a lesser extent, lower operating expenses, which were partially offset by a decrease in other income and an increase in income tax expense. Cash, cash equivalents and short-term investments totaled $22.6 million as of December 31, 2024, compared to $40.9 million as of December 31, 2023. Equillium believes that its cash, cash equivalents and short-term investments on the balance sheet as of December 31, 2024, are capable of funding its currently planned operations into the third quarter of 2025, based on certain assumptions and estimates that may prove to be inaccurate. About Itolizumab Itolizumab is a clinical-stage, first-in-class anti-CD6 monoclonal antibody that selectively targets the CD6-ALCAM signaling pathway to downregulate pathogenic T effector cells while preserving T regulatory cells critical for maintaining a balanced immune response. This pathway plays a central role in modulating the activity and trafficking of T cells that drive a number of immuno-inflammatory 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 itolizumab, the impact of the data from Equillium’s Phase 3 EQUATOR study in aGVHD, the expected timeline for the presentation of additional data from clinical studies and for a potential biologics license application submission, the potential benefits of Equillium’s product candidates, the expected timing and impact of FDA feedback, including potential Accelerated Approval pathway, Equillium’s ability to raise additional capital, and Equillium’s cash runway. 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 raise additional capital on terms acceptable to Equillium, or at all; Equillium’s ability to continue as a going concern; Equillium’s ability to execute its plans and strategies; 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 changes in 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.   View source version on businesswire.com: https://www.businesswire.com/news/home/20250327561276/en/ Contacts Investor Contact Michael MooreVice President, Investor Relations & Corporate [email protected]