ADARx, Trex, and Retension take aim at IPOs

The appetite among US biotechs for IPOs shows no signs of being satisfied, with three more companies – ADARx Pharma, TRex Bio, and Retension Pharma – joining the lunch queue.

siRNA specialist ADARx sets sights on bumper $372m raise

ADARx Pharmaceuticals, a San Diego-based biotech developing siRNA therapies for various diseases, has announced the terms for its IPO, hoping to raise up to $372 million from the sale of 21.9 million shares at a price range of $15 to $17. The startup is targeting a valuation of $1.74 billion and intends to list on the Nasdaq under the ADRX symbol.

ADARx's lead asset is onvuzosiran, an siRNA that switches off prekallikrein (PKK) production in the liver, and is in the phase 3 STOP-HAE trial for the prevention of hereditary angioedema (HAE) attacks, due to read out next year. Following after is complement factor B (CFB) inhibitor agazisiran – in mid-stage testing for IgA nephropathy (IgAN), complement 3 glomerulopathy (C3G), paroxysmal nocturnal hemoglobinuria (PNH), and immune complex membranoproliferative glomerulonephritis (IC-MPGN) – and phase 1 project ADX-626 for stroke prevention.

The company already boasts a substantial collaboration with AbbVie, worth in the region of $8 billion, including an upfront payment of $335 million, and AbbVie has agreed to buy an approximately 4.9% stake in the company in a private placement, concurrent to the IPO, that could be worth $80 to $100 million.

Lilly-backed TRex seeks funds for Treg pipeline

South San Francisco-based TRex Bio has broken cover with its IPO plans, seeking to raise cash for its pipeline of medicines based on regulatory T cell (Treg) biology, led by TRB-061, an investigational TNFR2 agonist which has generated early clinical results in moderate-to-severe atopic dermatitis and is due to report the main outcome in the middle of next year.

The company's Deep Biology platform is designed to decode Treg functionality in human tissue, mapping drivers of immune dysregulation and uncovering novel targets for drug discovery. The platform has already won the company an alliance with Eli Lilly, which licensed one Treg candidate – TRB-051 – in a $1.1 billion deal signed in 2023. The drug is being tested in a phase 2a trial for activity in lupus with cutaneous involvement.

TRex – which has a CD30-targeting candidate (TRB-071) due to start trials in inflammatory bowel disease (IBD) in the first half of 2027 – plans to list on the Nasdaq under the symbol TRXB.

Retension's spin on the PDE5 inhibitor class

Retension Pharma is resurrecting a plan to develop the PDE5 inhibitor class – known as the basis for erectile dysfunction therapies like sildenafil and tadalafil – as a treatment for serious hypertension, and needs funds to complete a phase 2a trial of its RTN-001 candidate.

Sildenafil was originally developed for high blood pressure, with lacklustre efficacy, before being repurposed as an ED drug. Falls Church, Virginia-based Retension company, which plans to list on the Nasdaq under the RTSN ticker, is testing RTN-001 as a treatment for uncontrolled and resistant hypertension. It licensed the drug, which is designed to preferentially target cardiovascular tissues, from Sanofi.