ALTB-268 demonstrated therapeutic potential in murine models of colitis and GvHD, supporting its role as an immune checkpoint enhancer in T cell-mediated inflammatory diseases
Findings reinforce ALTB-268’s ability to downregulate T cell effector function and restore immune balance
SAN FRANCISCO, June 23, 2025 (GLOBE NEWSWIRE) — AltruBio Inc. (“AltruBio” or “the Company”), a clinical stage biotech company developing novel immune checkpoint enhancers to address the unmet need in immunological and inflammatory diseases, with a lead candidate in ulcerative colitis (UC), today announced new preclinical data for its lead candidate ALTB-268 at the Federation of Clinical Immunology Societies (FOCIS) 2025 Annual Meeting, taking place in Boston from June 24–27, 2025.
The data demonstrate ALTB-268’s in vivo efficacy and confirm its mechanism of action as an immune checkpoint enhancer in non-clinical disease models of colitis and graft-versus-host disease (GvHD), further supporting its clinical development for UC and other T cell-driven inflammatory conditions.
“These findings presented at FOCIS 2025 further validate ALTB-268’s therapeutic potential as a differentiated immune checkpoint enhancer,” said Dr. Judy Chou, President and Chief Executive Officer of AltruBio. “By demonstrating anti-inflammatory effects in both GvHD and colitis models, this data adds to the growing body of evidence supporting ALTB-268’s development in ulcerative colitis and other immunological diseases. We remain focused on advancing the Phase 2a clinical trial evaluating ALTB-268 in UC and are excited about the potential for this unique mechanism to deliver lasting benefit to patients with high unmet need.”
Title: ALTB-268, a PSGL-1 Agonist Antibody, Ameliorated the Disease Severity in a Murine Model of Colitis and a Human-Mouse Xeno GvHD Model by Down-regulating T Effector Functions
Date: Tuesday, June 24, 2025
Time: 6:00 p.m. – 7:30 p.m. ET
Poster Number: Tu114
Location: Boston Marriott Copley Place, Salon E (4th Floor)
Key data highlights include:
- In vitro, ALTB-268 downregulated T cell activation, including reduced CD25 expression, diminished T cell proliferation, and decreased secretion of inflammatory cytokines such as IFN-γ, IL-2, TNFα, IL-6, and IL-12.
- In a human-mouse xenogeneic GvHD (xGvHD) model, ALTB-268 significantly improved survival, reduced disease severity score and body weight loss, and decreased human CD4+ and CD8+ T cells, while increasing apoptotic (7-AAD⁺) T cells in the spleen.
- ALTB-268 also significantly inhibited T cell expansion and CD25 expression in the spleen in vivo, demonstrating its immune-modulating effect.
- In a DSS-induced colitis model using human PSGL-1 knock-in mice, ALTB-268 reduced Disease Activity Index (DAI) scores, colon weight/length ratio, histopathologic inflammation scores, and colonic infiltration of CD8+ T cells.
- Treatment led to marked reductions in pro-inflammatory cytokines and leukocyte infiltration in colon tissue, indicating suppression of local immune activation.
About ALTB-268
ALTB-268 is a subcutaneously administered, tetravalent agonist antibody targeting PSGL-1, a key immune checkpoint regulator. It acts as an immune checkpoint enhancer (ICE), preferentially downregulating chronically activated late-stage T effector cells, leading to their exhaustion and/or apoptosis. Its unique mechanism of action is the same as AltruBio’s bivalent, intravenously administered ICE, ALTB-168, which previously demonstrated promising Phase 2 results in ulcerative colitis, psoriasis, psoriatic arthritis, and steroid-refractory/ treatment-refractory acute graft-versus-host disease (SR/TR-aGvHD), including improved patient outcomes and clinically meaningful efficacy. A Phase 2a exploratory biomarker study for ALTB-268 in biologics-refractory ulcerative colitis patients is currently enrolling patients (NCT06109441). A randomized global Phase 2b study open to both advanced therapy experienced and naïve patients is planned to be initiated in 2026. Both studies have the same primary and secondary end points in clinical remission and endoscope improvement. Given that T-cell modulation is key in the management of multiple immunological diseases, ALTB-268 has broad indication expansion potential, making it a promising “pipeline-in-a-product.”
About AltruBio Inc.
AltruBio is a clinical-stage biotechnology company developing novel therapies leveraging immune checkpoint agonism to address unmet medical needs in immunological and inflammatory diseases. The Company’s lead candidate, ALTB-268, acts as an immune checkpoint enhancer, designed to activate natural pathways that downregulate a chronically overactivated immune system to restore balance. ALTB-268 operates through a unique mechanism of action, targeting PSGL-1, a key immune checkpoint regulator. It preferentially targets and downregulates chronically activated late-stage effector T cells, leading to their exhaustion and apoptosis. Currently being evaluated in a Phase 2 trial in ulcerative colitis, ALTB-268 holds the potential to be a pipeline in a product to address a range of inflammatory diseases, which AltruBio plans to explore in upcoming Phase 2 trials. Led by an expert team with successful track records in drug development and commercialization in immunology, AltruBio is dedicated to delivering safer, more effective, and durable biologic treatments to improve the lives of patients.
Contacts
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Media Contact:
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