Lilly-backed TRex Bio raises $116.7 million in Nasdaq IPO priced at $14 a share

TRex Bio has priced its initial public offering, selling 8,333,334 shares at $14 each to raise $116.7 million in gross proceeds, with trading on the Nasdaq under the ticker TRXB due to start on Friday ¹². Eli Lilly, which held about 24% of the South San Francisco company before the listing, had indicated interest in buying part of the offering ¹².

What the offering raised and where it goes

The $14 price sat at the bottom of the $14 to $16 range TRex had set earlier in the week ¹². Underwriters hold an option on roughly 1.3 million more shares, which would add around $17.5 million if taken up in full ². TRex has raised $220 million in venture money to date, including an $84 million series B in 2024 and a $50 million financing at the start of 2026, and had around $91 million in the bank before the listing ¹².

The company builds drugs that switch on regulatory T cells, or Tregs, the immune cells that stop the body attacking itself ¹. Its lead candidate, TRB-061, is a fusion protein that targets tumour necrosis factor receptor 2 on Tregs and is in a Phase 1 trial in atopic dermatitis ¹². TRex told investors it expects to spend $90 million taking TRB-061 into Phase 2 in atopic dermatitis and into other immune diseases, alopecia areata among them ². A further $10 million is set aside for a Phase 1 study in healthy volunteers of TRB-071, which targets a second Treg receptor, CD30, and is aimed at inflammatory bowel disease ¹².

Lilly and Johnson & Johnson are both partners. Each has licensed or exercised options on experimental treatments TRex discovered, and Lilly paid $55 million in 2023 to exercise its option on an immune cell modulator that has since reached the clinic ¹². Chief executive Johnston Erwin, a long-time Lilly employee, runs a staff of 60 ².

What it means for the market

The pricing adds to a busy year for biotech listings. TRex is one of 23 drug developers to go public in 2026, and six of them, a little over 25%, work on immune diseases, according to BioPharma Dive's count ¹. Investment firm William Blair said in a report this week that public investment in biotech had sped up sharply in 2026, a trend BioPharma Dive tied to IPOs, a similar number of reverse mergers and several SPAC deals ¹.

The same morning brought two more listings in the queue. Retension Pharmaceuticals, which is testing an oral PDE-5 inhibitor in uncontrolled hypertension, raised $45 million from an upsized offering of 3.8 million shares, up from 3.3 million planned ¹². RNA company City Therapeutics set terms to raise $158.3 million by selling 9.7 million shares at $17 to $19 each, a day after AI drug developer Iambic Therapeutics laid out plans for a $135 million listing ².

For pharma business development teams, the TRex structure is the point to watch: a large drugmaker that is already a licensee, an option holder and the largest shareholder, now also signalling it will buy into the float. The deal still priced at the bottom of its range rather than above it ¹².

Caveats

TRex's clinical evidence is early. TRB-061 has yet to report human data, and topline results from the ongoing Phase 1 trial in atopic dermatitis are due in mid-2027 ².