Lilly-Backed TRex Bio and Retension Join Nasdaq IPO Class, Disclose Use of Proceeds

Eli Lilly-backed TRex Bio and hypertension drug developer Retension Pharmaceuticals have joined the initial public offering (IPO) class this year.

According to filings with the U.S. Securities and Exchange Commission (SEC) and a report by Fierce Biotech on the 19th (local time), the two companies have not yet disclosed the number or price of shares to be offered but have revealed plans for using the IPO proceeds.

TRex Bio plans to prioritize funding for a phase 2 clinical trial of the tumor necrosis factor receptor 2 (TNFR2) agonist TRB-061 in atopic dermatitis. Key data from the ongoing phase 1 trial are expected in mid-2027.

The company said in its filing that it plans to expand development of the Fc fusion protein into other autoimmune and inflammatory diseases, including alopecia areata.

Another priority is the CD30 agonist TRB-071. TRex Bio plans to enter a phase 1 clinical trial in healthy volunteers and said the drug could address the underlying immune dysregulation of immune-mediated diseases, including inflammatory bowel disease, by inducing the activation and proliferation of regulatory T cells (Tregs).

TRex Bio emerged in 2021 with a $59 million series A financing and drew attention for its platform for modulating Tregs, a T-cell subset that plays a key role in tissue inflammation. The following year, it entered into a collaboration agreement with Johnson & Johnson, and in 2023, Lilly paid $55 million to exercise a license option for immune effector cell modulators.

TRex Bio said Lilly has already expressed its intention to participate in the IPO. CEO Johnston Irwin is a Lilly alumnus and currently leads 60 employees. The company has approximately $91 million in cash following an $84 million series B financing in 2024 and a $50 million financing early this year.

Retension will prioritize using the IPO proceeds to complete the phase 2b trial of RTN-001 in patients with uncontrolled hypertension (uHTN). RTN-001 is an oral, once-daily small-molecule phosphodiesterase 5 (PDE-5) inhibitor that lowers blood pressure by enhancing nitric oxide signaling.

Retension said RTN-001 was designed to improve bioavailability and muscular arterial distribution compared with first-generation PDE-5 inhibitors such as Viagra. The drug was shown to clinically significantly reduce systolic and diastolic blood pressure in a pilot phase 2 trial.

Some of the IPO proceeds will also be used to initiate a phase 3 trial in uHTN. Retension CSO Paul Sweetnam and three other members of the development team participated in the invention of RTN-001 while at Surface Logix. Following licensing agreements and acquisitions, Cadmen and Sanofi, among others, held ownership of the drug before Retension was established and secured the license.

Retension currently has 12 full-time employees and held $13.5 million in cash as of the end of June. The two companies are pursuing Nasdaq listings amid a 2026 IPO boom that included the record-setting listings of Parabilis Medicines and Kylera Therapeutics.