Atopic dermatitis is, on paper, a solved problem.
Dupixent grossed over $14 billion in 2024.
Rinvoq picked up the JAK end of the market. Tralokinumab, lebrikizumab, nemolizumab.
The IL-4/IL-13/IL-31 menu has more options than most clinicians can keep straight.
So why is anyone still building a new immunology asset for moderate-to-severe AD?
Because none of those drugs work for everyone. And none of them try to fix the underlying immune dysregulation. They suppress symptoms, sometimes durably, sometimes not.
TRex Bio, the South San Francisco company built around tissue-resident regulatory T cell biology, this week dosed the first patient in the Phase 1b portion of TRB-061, a TNFR2-selective agonist designed to do the opposite of suppression. It expands and activates the regulatory T cells that should be quieting inflammation in skin tissue but aren’t.
Proof-of-concept data is expected in 2027.
The mechanism is the part to slow down on.
TNF receptor 2 is a TNF receptor with a very specific expression pattern. It’s enriched on Tregs in barrier tissues, and its activation selectively expands the Treg population without triggering TNFR1-driven pro-inflammatory signaling.
TNFR2 = expand.
TNFR1 = promote inflammation.
Most TNF biology in the clinic has been about blocking TNF entirely (Humira and friends).
Agonizing one specific TNF receptor on one specific cell type to drive immunoregulation is a different bet, and it’s one that biology has flirted with for years without anyone landing it in a clean clinical asset.
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So if everyone’s been trying to do it, and nobody has succeeded, what’s “novel” about TRex’s approach?
Well, they claim to have figured out which Treg subsets matter in lesional AD skin, and built TRB-061 against the receptor that activates that exact population.
Their proprietary platform combines computational biology with high-throughput omics on actual human disease tissue, instead of mouse models. The molecule was identified through transcriptomic mapping of TNFR2-driven Treg activity in atopic dermatitis lesions, with ex vivo validation.
Preclinical data showed effector Treg expansion in blood and tissue without unwanted broader immune activation, which is the safety story regulators will care about most.
Cool idea, and they’ve some money to see if it’ll work.
They closed an oversubscribed $84 million Series B in November 2024 led by Delos Capital, with Eli Lilly, SV Health Investors, Pfizer Ventures, J&J via JJDC, Polaris Partners, and Alexandria all participating. Total raised stands at $172 million.
Lilly licensed three of TRex’s preclinical programs in 2023 and has TRB-051 in Phase 1 under their banner.
J&J exercised an option in 2024 for tissue-targeted immune disease drugs.
So, yeah. Two of the most disciplined immunology buyers in pharma are already on the cap table and on the partnership rolodex.
The Phase 1a/1b trial (NCT06934252) is enrolling 115 patients across healthy volunteers and AD patients, with the Phase 1b portion now active. If TRB-061 shows clear Treg expansion biomarkers and an early efficacy signal in AD by 2027, the question becomes whether you’d rather block IL-13 forever, or restart the immune balance the patient was supposed to have in the first place.
Different question, different answer.
A Treg-restoring approach in barrier-tissue autoimmune disease has been a long-held thesis.
TRex Bio is the company carrying it into late-stage Phase 1.
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