Itolizumab treatment associated with high rates of overall clinical response in the treatment of acute GVHD

Clinical efficacy of itolizumab associated with higher serum concentrations after a single dose

CD6 confirmed as a target to prevent pathogenic T cell recruitment into inflamed organs

Equillium, Inc. (Nasdaq: EQ), a clinical-stage biotechnology company focused on developing novel therapeutics to treat severe autoimmune and inflammatory disorders with high unmet medical need, today announced that three posters were presented over the weekend at the Transplantation & Cellular Meetings of the American Society of Transplantation and Cellular Therapy, and the Center for International Blood & Marrow Transplant Research. The hybrid meetings are taking place virtually and in-person at the Salt Palace Convention Center in Salt Lake City, April 23 – 26, 2022.

“The clinical findings presented this weekend were highlighted by rapid and durable responses and a meaningful reduction in the use of corticosteroids that demonstrate the potential clinical value of itolizumab for patients with high-risk aGVHD,” said Dr. Steve Connelly, chief scientific officer at Equillium. “The data also shows an association between itolizumab serum concentration levels and clinical response that highlights the importance of achieving high concentrations early in the treatment period to maximize pharmacodynamic effects and clinical efficacy. The evidence of this activity at the doses evaluated in the EQUATE study were subsequently used to optimize dose selection for the recently initiated Phase 3 EQUATOR study in the first-line treatment of aGVHD patients.”

Dr. Connelly continued, “Additionally, translational data presented by our team suggests that the CD6-ALCAM pathway is involved in the migration of T cells through endothelial tissue and demonstrates that blockade of CD6 by itolizumab has the potential to prevent pathogenic T cell recruitment into inflamed organs.”

Itolizumab is a first-in-class anti-CD6 monoclonal antibody that selectively targets the CD6-ALCAM pathway, which plays a central role in modulating the activity and trafficking of the pathogenic T cells driving a number of immuno-inflammatory diseases.

Details of Itolizumab Data Presented

Title: Updated Interim Results from the EQUATE Study: Preliminary Safety and Efficacy of Itolizumab, a Novel Targeted Anti-CD6 Therapy, in Newly Diagnosed Acute Graft-Versus-Host Disease

First Author: Dr. John Koreth, associate professor of medicine, Dana Farber Cancer Institute, Harvard Medical School

Poster Number: 372

Key Highlights, Summary and Conclusions from Presentation:

• Itolizumab treatment was associated with high rates of overall clinical response
  • At Day 29, complete response was 52% and overall response was 64% across all doses
  • The highest Day 29 complete response rate (61%) was achieved in subjects treated with itolizumab within 72 hours of starting systemic steroids
• Responses were durable, with 79% of Day 29 Responders maintaining response through 6 months and 50% through 12 months
• Responders tapered steroids by 73% at Day 29, and 96% at Day 169
• Response at Day 29 was associated with 72% overall survival at 12 months and high rates of progression free survival
• Itolizumab was well tolerated across all doses, in the context of a severe aGVHD population
• Itolizumab offers a favorable benefit-risk profile that supports evaluation in a pivotal Phase 3 study (EQUATOR), which has been initiated for the first-line treatment of aGVHD (NCT05263999)

Title: Itolizumab, a Novel Targeted Anti-CD6 Therapy, Induces Cleavage of Cell Surface CD6 and Rapid Onset of Efficacy in Subjects with Newly Diagnosed Acute Graft-Versus-Host Disease

First Author: Cherie Ng, Senior Director of Research, Equillium, Inc.

Poster Number: 371

Key Highlights, Summary and Conclusions from Presentation:

• Itolizumab is associated with rapid and durable decreases in cell surface CD6 and increases in serum sCD6 in subjects with aGVHD
• The observed association between itolizumab serum concentrations and clinical response highlights the importance of achieving high concentrations early in the treatment period to maximize pharmacodynamic effects and clinical efficacy
• These results provide evidence of itolizumab activity at the doses evaluated in the EQUATE study and were used to optimize dose selection for the ongoing Phase 3 EQUATOR study (NCT05263999)

Title: The CD6-ALCAM Pathway Promotes Effector T Cell Migration

First Author: Valeria Marrocco, Scientist, Equillium, Inc.

Poster Number: 362

Key Highlights, Summary and Conclusions from Presentation:

• CD4+ and CD8+ T cells that migrate in response to CXCL12 express higher levels of CD6 and that the amount of migration correlates with levels of CD6 expression, suggesting that CD6 is engaged during T cell migration across the endothelial monolayer
• Decreasing CD6 expression led to decreased migration of TEM and TEMRA cells while migration of T regulatory cells was unaffected, thus suggesting targeting CD6 in aGVHD would decrease infiltration of pathogenic T cells while still permitting modulation of the immune response by T regulatory cells
• Data suggests that CD6-ALCAM pathway is involved in the movement of T cells through the endothelial tissues and confirms CD6 as a target to prevent pathogenic T cell recruitment into inflamed organs

All presentations are available on the Presentations page of Equillium’s website.

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 five-year survival of approximately 53% in patients who respond to steroid treatment and mortality as high as 95% in patients who do not respond to steroids. There are no approved treatments for first-line aGVHD. Published literature (MacMillan et al., 2015) describes background response rates to high-dose steroid administration in severe high-risk patients as 43% overall response and 27% complete response.

About the EQUATE Study

EQUATE is a Phase 1b open-label dose escalation study to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics and clinical activity of itolizumab for first-line treatment in adult patients who present with high-risk aGVHD (NCT 03763318).

About Itolizumab

Itolizumab is a clinical-stage, first-in-class anti-CD6 monoclonal antibody that selectively targets the CD6-ALCAM signaling pathway to selectively downregulate pathogenic effector T cells while preserving regulatory T 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. Equillium acquired rights to itolizumab through an exclusive partnership with Biocon Limited.

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 the following novel immunomodulatory assets targeting immuno-inflammatory pathways. Itolizumab, a first-in-class monoclonal antibody that targets the CD6-ALCAM signaling pathway which plays a central role in the modulation of effector T cells, is currently in a Phase 3 study for patients with acute graft-versus-host disease (aGVHD) and is in a Phase 1b study for patients with lupus/lupus nephritis. EQ101, a first-in-class tri-specific cytokine inhibitor that selectively targets IL-2, IL-9, and IL-15, is Phase 2 ready and expected to begin enrolling patients in an alopecia areata study in the second half of 2022. EQ102, a bi-specific cytokine inhibitor that selectively targets IL-15 and IL-21, is ready for clinical development and expected to begin enrolling patients in a Phase 1 study to include patients with celiac disease in the second half of 2022.

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” and "project" and other similar expressions that predict or indicate future events or trends or that are not statements of historical matters. Because such statements are subject to risks and uncertainties, many of which are outside of the Company’s control, actual results may differ materially from those expressed or implied by such forward-looking statements. Such statements include, but are not limited to statements regarding the potential benefit of treating patients with aGVHD or lupus/lupus nephritis with itolizumab, Equillium’s plans and expected timing for developing itolizumab including the expected timing of initiating, completing and announcing further results from the EQUATE, EQUIP, EQUALISE and EQUATOR studies, Equillium’s plans and expected timing for developing EQ101 and EQ102 including the expected timing of initiating, completing and announcing further results from Phase 2 and Phase 1 studies, respectively, the potential for any of Equillium’s ongoing or planned clinical studies to show safety or efficacy, Equillium’s anticipated timing of regulatory review and feedback, and Equillium’s plans and expected timing for developing its product candidates and potential benefits of its product candidates. Risks that contribute to the uncertain nature of the forward-looking statements include: uncertainties related to the abilities of the leadership team to perform as expected; Equillium’s ability to execute its plans and strategies; risks related to performing clinical studies; the risk that interim results of a clinical study do not necessarily predict final results and that one or more of the clinical outcomes may materially change as patient enrollment continues, following more comprehensive reviews of the data, and as more patient data become available; potential delays in the commencement, enrollment and completion of clinical studies and the reporting of data therefrom; the risk that studies will not be completed as planned; Equillium’s plans and product development, including the initiation and completion of clinical studies and the reporting of data therefrom; whether the results from clinical studies will validate and support the safety and efficacy of Equillium’s product candidates; changes in the competitive landscape; uncertainties related to Equillium’s capital requirements; and having to use cash in ways or on timing other than expected and the impact of market volatility on cash reserves. 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 EDGAR on the SEC web site at http://www.sec.gov and on the Company’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.

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