TRex Bio and Retension Pharmaceuticals have joined the 2026 biotech IPO queue, extending a year that has already produced a run of new listings. Neither company disclosed how many shares it plans to sell or at what price, but both used Securities and Exchange Commission filings to lay out what public-market capital would fund.
The contrast between the two filings is part of the signal. TRex is pitching a broader immunology platform with multiple programs and existing pharma ties, while Retension is effectively a single-asset story built around one late-clinical hypertension candidate. That both are testing the market now suggests investors are again being presented with different risk profiles, provided the proceeds map to visible development milestones.
The Pipeline Use Of Proceeds
TRex’s top spending priority is a phase 2 program for its tumor necrosis factor receptor 2 agonist TRB-061 in atopic dermatitis. Topline data from an ongoing phase 1 trial are due in mid-2027. The company also plans to extend the Fc-fusion protein into other autoimmune and inflammatory diseases, including alopecia areata.
Its other key priority is TRB-071, a CD30 agonist that TRex wants to move into a phase 1 trial in healthy volunteers. According to the filing, the biotech believes TRB-071 could address underlying immune dysregulation in immune-mediated diseases such as inflammatory bowel disease by triggering both activation and expansion of regulatory T cells.
Retension’s filing is narrower. The first call on IPO proceeds would be completing a phase 2b study of RTN-001 in patients with uncontrolled hypertension. Part of the proceeds would also go toward launching a phase 3 study in the same setting.
RTN-001 is a once-daily, oral, small molecule phosphodiesterase-5 inhibitor intended to reduce blood pressure by potentiating nitric oxide signaling. Retension argues the drug may separate itself from first-generation PDE-5 inhibitors such as Viagra, which did not fulfill their early promise in blood pressure reduction, because RTN-001 was engineered for increased bioavailability and increased distribution to the muscular arteries. The company said RTN-001 has already shown a clinically meaningful reduction in systolic blood pressure and diastolic blood pressure in pilot phase 2 studies.
The Financing Setup
TRex has been a more heavily financed private company to date. Since emerging in 2021 with a $59 million series A, it added an $84 million series B in 2024 and a $50 million financing at the start of this year. The company had about $91 million in the bank and 60 full-time employees at the time of the filing.
The biotech has also accumulated notable partners. It signed a collaboration with Johnson & Johnson in 2022, and in 2023 Eli Lilly paid $55 million to exercise an option for an immune effector cell modulator that has since entered the clinic. TRex said Lilly has already expressed interest in participating in the IPO.
Retension enters the market as a much smaller organization. It had $13.5 million in the bank as of the end of June and 12 full-time employees. Its scientific roots go back to Surface Logix, where Retension Chief Scientific Officer Paul Sweetnam and three other members of the development team were involved with inventing RTN-001. Through licensing deals and acquisitions, the asset later sat under companies including Kadmon and Sanofi before Retension was created and granted the license.
The backdrop for both filings is an IPO market that has become materially more receptive in 2026. FierceBiotech points to record-breaking listings from Parabilis Medicines and Kailera Therapeutics, while ADARx Pharmaceuticals is separately seeking $397.1 million, or up to $445.9 million if underwriters fully exercise their option for additional shares. In that context, TRex and Retension look less like isolated filings than evidence that public investors are again being asked to finance clinical execution rather than just private crossover rounds.
