TRex Bio (TRXB) Eyes $125 Million IPO to Advance Immune-Restoring Therapies

TRex Bio (TRXB) is preparing to offer 8,333,334 shares on the Nasdaq Global Select Market at $14–$16 per share. At the $15 midpoint, the offering would raise approximately $125 million before expenses and value the company at approximately $411.7 million, based on 27.45 million shares outstanding after the offering, excluding the underwriters’ option. J.P. Morgan, Evercore ISI, Cantor, Stifel and Wedbush PacGrow are underwriting the transaction. The South San Francisco company is developing medicines designed to restore immune balance and promote tissue repair in autoimmune and inflammatory diseases.

TRex’s approach centers on regulatory T cells, or Tregs, which help control immune responses and maintain healthy tissue. Rather than simply blocking inflammatory signals, the company aims to strengthen the immune system’s own regulatory mechanisms in affected tissues. Its Deep Biology platform uses human tissue samples and functional testing to identify drug targets and guide development. The approach offers a potentially differentiated path in immunology, although its ability to deliver meaningful and durable benefits in patients remains to be established.

The lead wholly owned candidate, TRB-061, is a TNFR2 agonist designed to expand and activate Tregs in inflamed tissues. TRex began a Phase 1a trial in healthy volunteers in June 2025 and initiated the Phase 1b portion in patients with moderate-to-severe atopic dermatitis in April 2026. Topline Phase 1b data are expected in mid-2027. The study evaluates safety, drug exposure and biological activity, alongside exploratory measures of clinical efficacy. Atopic dermatitis is a substantial market, but TRex will need to demonstrate a compelling benefit in a field that already includes established biologic and oral treatments.

A second wholly owned candidate, TRB-071, targets CD30 and is intended to augment tissue Tregs while block