Eli Lilly-backed TRex Bio and hypertension-focused Retension Pharmaceuticals brought in $116.7 million and $45 million from their respective IPOs. The pair of biotechs went public on the same morning that RNA-focused City Therapeutics mapped out plans for its own $158 million listing.
TRex’s share price of $14 came in at the bottom end of its predicted range of $14 to $16. By offering its expected amount of 8.3 million shares, the biotech brought in $116.7 million of gross proceeds—although this could rise by around $17.5 million if underwriters fully take up their option to buy an additional 1.3 million shares at the same price.
Should the final price fall in the middle of this range, TRex estimates the IPO will bring $111.3 million in net proceeds—rising to $128.7 million if underwriters fully take up their option to buy an additional 1.3 million shares at the same price.
TRex—whose stock is due to list on the Nasdaq under the ticker “TRXB” Friday morning—first broke cover in 2021 with a $59 million series A. The South San Francisco-based biotech has since attracted attention on the strength of a platform for discovering ways to modulate regulatory T cells (Tregs), which play a key role in tissue inflammation.
The biotech penned a collaboration with Johnson & Johnson a year later, and in 2023 Lilly paid $55 million to take up its option to license an immune effector cell modulator that has since entered the clinic. In fact, Lilly already expressed an interest in participating in the IPO, according to TRex.
The biotech’s CEO Johnston Erwin, a long-time Lilly veteran, currently oversees a workforce of 60 full-time employees. TRex had around $91 million sitting in the bank following an $84 million series B in 2024 and a $50 million financing at the start of this year.
The company said earlier this week that it expects to spend $90 million on bankrolling phase 2 trials for its tumor necrosis factor receptor 2 (TNFR2) agonist TRB-061 in atopic dermatitis (AD), as well as moving the therapy into other autoimmune and inflammatory diseases, including alopecia areata. Topline data from an ongoing phase 1 trial in AD is due to read out in mid-2027.
An additional $10 million is expected to be spent on taking a CD30 agonist dubbed TRB-071 into the clinic in a phase 1 trial of healthy volunteers. By triggering both the activation and expansion of Tregs, the biotech hopes that TRB-071 has the potential to address underlying immune dysregulation in immune-mediated diseases such as inflammatory bowel disease.
Retension secures upsized offering
Retension’s IPO may be comparatively more modest, but the company exceeded its original expectations. The biotech is offering 3.8 million shares—above the 3.3 million it had anticipated earlier this week—priced at the middle of the $11 to $13 range it had previously set out.
This is due to bring Retension $45 million in gross proceeds, compared to the $33.8 million net proceeds the company suggested on Monday. This haul could rise by around $6.8 million if underwriters take up their option to buy an additional 562,500 shares at the same price.
The biotech—whose stock is set to list on the Nasdaq under the ticker “RTSN”—has previously said that it expects to spend $18 million on completing a phase 2b study of RTN-001 in patients with uncontrolled hypertension (uHTN). Retension has been testing the once-daily, oral, small-molecule phosphodiesterase-5 (PDE-5) inhibitor as a way to reduce blood pressure by potentiating nitric oxide signalling.
A further $10 million will be needed for a phase 3 study in uHTN, according to a Monday filing.
Retension is hoping that RTN-001 will differentiate itself from first-generation PDE-5 inhibitors like Viagra—which never lived up to their early promise to reduce blood pressure—because the next-gen drug has been engineered to have increased bioavailability and an increased distribution to the muscular arteries.
RTN-001 has already demonstrated a clinically meaningful reduction in systolic blood pressure and diastolic blood pressure in pilot phase 2 studies, the biotech has previously said.
City cements IPO plans
City is aiming to exceed both TRex and Retension by planning to raise $158.3 million by offering 9.7 million shares priced between $17 and $19 apiece. This haul could rise to $182.7 million if underwriters take up their option to buy an additional 1.5 million shares at the same estimated price of $18, the biotech said.
In a Friday filing, the company said that $30 million has been earmarked to fund the Factor XI-targeting RNA interference (RNAi) therapeutic CITY-FXI through an ongoing phase 1 study and into a mid-stage trial for patients who’ve undergone knee surgery, a setting where thrombosis is common.
Another $20 million will be set aside for a phase 1 study of a GalNAc-conjugated siRNA therapeutic called CITY-RBP4 and prepare to evaluate it for Stargardt disease and geographic atrophy.
An additional $40 million is also needed for another GalNAc-conjugated asset dubbed CITY-TFR2, which is due to enter a trial in China later this year as a potential treatment for anemia. City has plans to expand into other chronic conditions where anemia is prevalent, like chronic kidney disease and inflammatory diseases, including inflammatory bowel disease.
The raft of IPOs and announcements this morning comes a day after AI biotech Iambic Therapeutics mapped out plans for a $135 million listing. So far, 2026 has seen record-breaking IPOs from the likes of Kailera Therapeutics and Parabilis Medicines.
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