• By selectively augmenting regulatory T cells (“Tregs”), TRB-061 is designed to restore immune balance and promote repair in skin and other barrier tissues
• Sixteen-week Phase 1b data anticipated in the first half of 2027

TRex Bio, Inc. (“TRexBio”), a clinical-stage biotechnology company discovering and developing immunoregulatory medicines based on tissue Treg biology, today announced that the first patient has been dosed in the Phase 1b portion of its ongoing clinical trial of TRB-061, a novel TNFR2 agonist in development for the treatment of moderate-to-severe atopic dermatitis (“AD”). This milestone represents progress toward a differentiated therapeutic approach to immune modulation for the treatment of autoimmune and inflammatory diseases built on restoring balance and repair in inflamed tissues.

“We believe TRB-061 has the potential to be a differentiated approach to treating atopic dermatitis, and dosing the first patient in our Phase 1b study marks an important step toward generating proof-of-concept data,” said Johnston Erwin, Chief Executive Officer of TRexBio. “While currently approved treatments have made great strides, significant unmet need remains in AD, underscoring the importance of advancing new therapeutics with novel mechanisms of action.”

TRB-061, TRexBio’s lead wholly owned program, is designed to selectively agonize TNFR2 to expand and activate tissue Tregs, without activating other immune cells involved in inflammation. In AD, where local immune dysregulation plays a central role, TRB-061 may offer a differentiated approach to restoring immune homeostasis via a dual anti-inflammatory and skin repair response. This approach has the potential to address significant unmet medical need by supporting more durable disease control.

“Atopic dermatitis is a widespread skin disease that remains a significant burden for patients, and Treg mediated immune dysregulation plays a central role in ongoing skin inflammation,” said Ariella Kelman, M.D., Chief Medical Officer of TRexBio. “TRB-061 is designed to selectively engage TNFR2, augment tissue Tregs, and promote barrier tissue repair. This portion of our Phase 1 trial will help us evaluate that biology directly in patients with moderate-to-severe AD.”

The Phase 1b portion of the clinical trial is a randomized, double-blind, placebo-controlled study designed to evaluate TRB-061 subcutaneously administered in patients with moderate-to-severe AD. The study will assess safety and tolerability as primary endpoints, with pharmacokinetics and immunogenicity as secondary endpoints. Exploratory endpoints include pharmacodynamic measures, including Treg expansion in blood and skin, and clinical assessments of disease activity. The study is expected to enroll approximately 50 participants with data anticipated in the first half of 2027.

About TRB-061

TRB-061 is a novel, selective TNFR2 agonist designed to restore immune balance by activating and expanding effector Tregs in tissue. TNFR2 is a crucial regulator of immune homeostasis, supporting tissue repair and counteracting inflammation. Defects in TNFR2 signaling are linked to multiple autoimmune and inflammatory diseases. Selective agonism of TNFR2 by TRB-061 may represent a new therapeutic pillar for long-term inflammatory disease control. TRB-061 is currently in a Phase 1 clinical trial for moderate-to-severe atopic dermatitis.

About Atopic Dermatitis

Atopic dermatitis (“AD”) is a chronic inflammatory skin disease characterized by rash, itching, and skin barrier dysfunction. AD affects up to 20% of children and 10% of adults, affecting approximately 204 million people worldwide. In moderate-to-severe cases, AD is associated with systemic immune activation, extensive body surface area involvement, and substantial quality-of-life impairment. While approved biologics have improved outcomes for some patients, more than half discontinue current therapies within two years due to ineffectiveness and long-term side effects.

About TRexBio

TRexBio is a clinical-stage biotechnology company developing novel therapeutics designed to modulate tissue regulatory T cell biology and restore immune balance in autoimmune and inflammatory diseases. The company’s Deep Biology Platform maps human tissue Treg behavior to disease processes to identify and characterize novel targets for therapeutic intervention in autoimmune and inflammatory diseases. This platform has yielded multiple development candidates for potential first-in-class and best-in-class medicines across TRexBio’s own pipeline, as well as with top pharma partners. TRexBio is led by an experienced management team and headquartered in South San Francisco, California. For more information, visit www.trex.bio.

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“We believe TRB-061 has the potential to be a differentiated approach to treating atopic dermatitis, and dosing the first patient in our Phase 1b study marks an important step toward generating proof-of-concept data,” said Johnston Erwin, CEO of TRexBio.