TRexBio and Retension Pharmaceuticals are set to debut Friday, bringing this year’s biotech IPO count to 29 as the sector’s rebound continues. City Therapeutics and Iambic Therapeutics hope to push that number even higher.
The biotech IPO frenzy is very much alive this October spooky season, with TRexBio and Retension Pharmaceuticals set to begin trading Friday with offerings totaling $161.7 million. City Therapeutics and Iambic Therapeutics are lined up behind them, outlining expected prices for their own offerings.
First up is TRexBio, hitting the Nasdaq with a $116.7 million offering. The immunoregulatory medicine developer sold 8.3 million common stock shares at $14 per share, coming in at the low end of its expected $14 to $16 range. Underwriters also have a 30-day option to buy 1.25 million more shares at the same price.
Big Pharma Eli Lilly reported direct holdings of 5.4 million TRex shares, according to a Thursday SEC filing. The biotech’s CEO is Johnston Erwin, who spent nearly 20 years at Lilly before leading TRex. In 2023, TRex and Lilly linked up in a deal worth more than $1.1 billion in biobucks to develop treatments for immune-mediated diseases.
Now, TRex will use the new funds to advance its investigational fusion protein TRB-061, currently in early-stage development for atopic dermatitis. A topline Phase 1b readout is expected in mid-2027. TRex will also put some of the money into the preclinical CD30 agonist TRB-071.
Joining TRex on the markets Friday is Retension Pharmaceuticals, which will debut with $45 million. The cardiovascular-focused company sold 3.75 million shares at $12 a piece—the midpoint of its expected price range. Underwriters also have the option to purchase up to 562,500 more shares at the IPO price over the next 30 days.
The Virginia biotech will use the proceeds to back its sole clinical candidate: RTN-001, a daily oral small-molecule PDE-5 blocker being developed for hypertension. The money will support ongoing Phase 2b development and the advancement to Phase 3, according to Retension.
Including the two newest additions, 29 biotechs have gone public in 2026, an incredible leap from 2025’s total of eight public biotech debuts. Already this year, the industry has had its most IPOs since 2021, when biopharma recorded 78 at the height of the COVID-19 pandemic.
Up next to potentially go public is RNAi biotech City Therapeutics, which filed IPO plans at the end of September and just revealed that it expects to raise around $158.3 million, according to a Friday SEC filing. That estimate is based on an expected pricing at $18 per share.
Founded in 2023 by former Alnylam leader John Maraganore, the biotech plans on divvying up the cash, with $30 million expected to bankroll the development of CITY-FXI, which is currently being evaluated in a Phase 1 trial for thrombosis, while also launching a Phase 2 trial to assess the asset’s efficacy in preventing blood clotting in knee replacement surgery.
Another $20 million will fuel clinical development of RNAi therapy CITY-RBP4 in Stargardt disease and geographic atrophy, while $40 million is intended to fund the clinical tests of CITY-TFR2 in anemia associated with myelofibrosis. The biotech has also earmarked $70 million for platform development and preclinical activities.
Lastly, AI-fueled Iambic Therapeutics has targeted a $15 to $17 per share range for an expected $135 million IPO. The Nvidia-backed cancer company has allotted $75 million of that money for its lead candidate IAM1363, an oral HER2 inhibitor designed to penetrate the brain and target several known disease-causing mutations of the protein. IAM1363 is currently being studied in a Phase 1/1b trial for HER2-altered solid tumors, with registrational studies planned for 2027.
Some of the money will also go toward moving the KIF18A blocker IAM217 for triple-negative breast cancer and the dual CDK2/4 inhibitor IAM-C1 into clinical testing.
