TRexBio Advances Novel Atopic Dermatitis Drug Aiming to Reset Immune System

SOUTH SAN FRANCISCO, CA – April 29, 2026 – TRex Bio, Inc., a clinical-stage biotechnology company, has officially dosed the first patient in a pivotal Phase 1b study of its novel drug, TRB-061, for moderate-to-severe atopic dermatitis. The move signals a critical step forward for a therapeutic that aims not just to suppress symptoms, but to fundamentally restore immune balance in the skin, offering a new dimension of hope for millions suffering from the chronic inflammatory disease.

Atopic dermatitis (AD), commonly known as eczema, is a relentless condition characterized by itchy, inflamed skin that affects up to 10% of adults and 20% of children worldwide. While recent years have brought a wave of advanced biologic and small molecule drugs, a significant unmet need persists. TRexBio's candidate, TRB-061, enters this competitive landscape with a unique mechanism of action designed to provide a more durable and restorative treatment.

“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, in a company statement. “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.”

A Differentiated Approach in a Crowded Market

The global market for atopic dermatitis treatments is substantial, valued at approximately $17 billion in 2024 and projected to nearly double to over $32 billion by 2032. This growth is fueled by the rising prevalence of the disease and the commercial success of targeted therapies.

The current treatment paradigm is dominated by drugs that block specific inflammatory pathways. Biologics like Sanofi’s Dupixent (dupilumab), which targets the IL-4 and IL-13 cytokines, have become blockbuster therapies. They are joined by other biologics and a class of oral medications known as JAK inhibitors, including Pfizer’s Cibinqo (abrocitinib) and AbbVie’s Rinvoq (upadacitinib), which offer rapid relief by tamping down the inflammatory cascade.

Despite their effectiveness for many, these treatments are not a panacea. The press release from TRexBio highlights a stark reality: more than half of patients discontinue their current therapies within two years, often due to a lack of efficacy or long-term side effects. This creates a significant opportunity for a drug with a fundamentally different approach. TRB-061 is not designed to simply block an inflammatory signal; it is engineered to actively promote immune resolution and tissue repair, a strategy that could lead to more lasting disease control.

The Science of an Immune Reset

At the heart of TRexBio's strategy is a sophisticated understanding of tissue regulatory T cells, or Tregs. These specialized immune cells act as the body's peacekeepers, responsible for maintaining balance and preventing the immune system from attacking its own tissues. In autoimmune and inflammatory conditions like atopic dermatitis, the function of these Tregs is often impaired, allowing pro-inflammatory cells to run rampant.

TRB-061 is designed to selectively activate a receptor known as TNFR2 (Tumor Necrosis Factor Receptor 2). This receptor is a crucial regulator of immune homeostasis and is found in high concentrations on the most potent and effective Tregs, particularly those residing in tissues like the skin. By agonizing, or activating, TNFR2, TRB-061 aims to expand the population and enhance the function of these tissue-specific Tregs directly at the site of inflammation.

“TRB-061 is designed to selectively engage TNFR2, augment tissue Tregs, and promote barrier tissue repair,” noted Ariella Kelman, M.D., Chief Medical Officer of TRexBio. “This portion of our Phase 1 trial will help us evaluate that biology directly in patients with moderate-to-severe AD.”

This approach represents a paradigm shift. Instead of a broad blockade of inflammation, it is a precision tool designed to empower the body's own regulatory mechanisms. The goal is a dual benefit: an anti-inflammatory response coupled with active skin repair, potentially breaking the chronic cycle of flare-ups that defines the disease.

Clinical Pathway and Patient Impact

The newly initiated Phase 1b trial is a randomized, double-blind, placebo-controlled study that will enroll approximately 50 participants with moderate-to-severe atopic dermatitis. The primary goals are to assess the safety and tolerability of TRB-061, which is administered via subcutaneous injection.

Beyond safety, the trial includes critical exploratory endpoints that will provide the first human data on the drug's unique mechanism. Researchers will be closely monitoring pharmacodynamic measures, including the expansion of Tregs in both the blood and skin biopsies of patients. These results will be crucial for validating that TRB-061 is working as intended and for establishing a potential therapeutic dose for future, larger trials. The company anticipates having data from this study in the first half of 2027.

For patients, the burden of atopic dermatitis extends far beyond the physical itch. The disease is associated with significant impairments to quality of life, including sleep disturbances, anxiety, depression, and reduced productivity. The prospect of a therapy that could offer more durable control with a novel safety profile is a source of considerable hope for those who have cycled through existing treatments without finding lasting relief.

TRexBio’s Strategic Vision and Big Pharma Backing

The TRB-061 trial is not just a test of a single drug; it is a validation of TRexBio's entire scientific platform. The company's 'Deep Biology Platform' is designed to map Treg biology across different tissues to identify novel therapeutic targets. The success of TRB-061 would provide powerful proof-of-concept for this approach, paving the way for other programs in the company's pipeline.

Investors and pharmaceutical giants have already taken note. TRexBio has raised a total of $219 million, including a recent $50 million Series B financing that attracted prominent investors like Janus Henderson Investors and Balyasny Asset Management. This financial backing is bolstered by major strategic partnerships with two of the world's largest pharmaceutical companies.

TRexBio has a multi-year research collaboration and licensing agreement with Janssen (a Johnson & Johnson company) and a separate, highly productive partnership with Eli Lilly and Company. The collaboration with Lilly has already yielded a candidate, TRB-051, which entered a Phase 1 study in 2024, and provides TRexBio with the potential to earn over $1.1 billion in milestone payments plus royalties. These alliances provide not only capital but also significant external validation of the company's science and its potential to generate a new class of medicines.

While the path to regulatory approval is long and data from the current trial are still years away, the initiation of patient dosing for TRB-061 marks a tangible advancement. It represents a deliberate step toward a new frontier in immunology, where the goal is not simply to manage a disease, but to teach the body how to heal itself.