• TRB-061 is an investigational TNFR2 agonist with the potential to address a range of immune-mediated diseases
  • Unblinded single- and multiple-dose results in healthy participants showed consistent pharmacokinetics and reproducible activation and expansion of immunoregulatory Tregs, supporting proof of mechanism for TRB-061
  • TRB-061 was generally well tolerated across all dose levels, with no treatment-related serious adverse events or dose-limiting toxicities observed
  • Results support dose selection for the ongoing Phase 1b trial in patients with moderate-to-severe atopic dermatitis, with topline data expected in mid-2027

SOUTH SAN FRANCISCO, Calif., August 26, 2026 – TRex Bio, Inc. (“TRexBio”), a clinical-stage biotechnology company focused on tissue Treg biology for the discovery and development of immunoregulatory medicines, today announced unblinded topline results from the first-in-human Phase 1a portion of its ongoing Phase 1a/b clinical trial of TRB-061. Across the single (“SAD”) and multiple (“MAD”) ascending dose cohorts, TRB-061 was generally well tolerated and showed consistent pharmacokinetics. In addition, following single and multiple dose administration of TRB-061, selective, reproducible activation and expansion of exploratory biomarkers including regulatory T cells (“Tregs”) was observed, supporting proof of mechanism and dose selection for the ongoing Phase 1b trial in patients with moderate-to-severe atopic dermatitis.

“This is an important milestone for TRexBio, and we are pleased to report these Phauperfamily receptor highly enriched on tissue Tregs. TRB-071 is designed to activate and expand Tregs, which may increase their immune-regulatory capacity, while modulating the inflammatory pathway of the CD30-associated ligand (“CD30L”). Human genetic studies associate variants in CD30 and CD30L with inflammatory bowel disease susceptibility.

Preclinical data demonstrate that CD30 agonism via TRB-071 induces Treg activation and expansion, potentially enhancing immune-regulatory capacity and reducing inflammation in colitis models. In non-human primate studies, TRB-071 induced activation and expansion of Tregs with minimal effects on other immune cell populations. TRexBio believes these findings support the potential of TRB-071 as a differentiated approach to restoring immune balance. The company is currently conducting a three-month GLP toxicology study of TRB-071 in cynomolgus monkeys.

TRexBio also announced that its collaboration partner Lilly intends to initiate a Phase 2a clinical trial of TRB-051 in lupus with cutaneous involvement in the second half of 2026. TRB-051, an investigational modulator of immune effector cells, was first identified and advanced under a multiyear discovery collaboration between TRexBio and Lilly, leveraging TRexBio’s Deep Biology platform. TRexBio previously announced that Lilly initiated a first-in-human Phase 1 study for TRB-051 in 2024.

“TRexBio was founded on the idea that a deeper understanding of tissue Treg biology could lead to a new generation of therapeutics for autoimmune and inflammatory diseases,” said Johnston Erwin, Chief Executive Officer of TRexBio. “The progress of TRB-071, together with the continued advancement of our partnered clinical program, reflects our ability to generate and advance multiple differentiated programs toward the clinic. We believe this growing pipeline underscores the productivity of our platform and positions TRexBio to address significant unmet therapeutic needs across inflammatory and autoimmune diseases, where many patients continue to need more durable and disease-modifying treatment options.”

About TRexBio

TRexBio is a clinical-stage biotechnology company focused on tissue Treg biology for the discovery and development of immunoregulatory medicines designed to restore immune balance and promote tissue repair to address unmet needs of patients with autoimmune and inflammatory diseases. The Company’s Deep Biology platform decodes Treg functionality in human tissue, mapping key drivers of immune dysregulation and uncovering novel targets and insights that inform drug discovery and translational efforts. This platform has generated multiple therapeutic development candidates across TRexBio’s wholly owned pipeline and through collaborations with leading pharma partners. TRexBio is led by an experienced management team and headquartered in South San Francisco, California. For more information, visit www.trex.bio.  

Contacts

Investors: Laura Berner, Chief Operating Officer, TRex Bio, Inc., info@trex.bio

Media: Jessica Yingling, Ph.D., Little Dog Communications Inc., jessica@litldog.com