The Massachusetts-based biotech plans to use the funds to push its candidates into mid-stage clinical trials in a space dominated by Vertex.
Making good on plans filed in late January, cystic fibrosis-focused Sionna Therapeutics announced expected figures for its IPO on Monday.
In an SEC filing, Sionna said it is offering 8,823,529 shares priced between $16 and $18 per share, for a target total of $150 million.
Sionna’s portfolio is aimed at drugging the cystic fibrosis transmembrane conductance regulator (CFTR) protein, mutations in which are the main cause of the disease. Sionna’s drugs in development all target CFTR in different ways, including two that stabilize NBD1, a domain of CFTR that, according to the company, was previously considered undruggable.
Sionna aims to use the proceeds from the IPO to push its NBD1-targetting drugs, currently in Phase I trials, into mid-stage studies.
In March 2024, Sionna raised $182 million in a Series C round, and in June it put together a licensing deal with AbbVie for two more cystic fibrosis drugs in Phase II trials. The cash from the Series C will keep the company afloat through 2026, according to Sionna CEO Mike Cloonan.
In its SEC filing, Sionna noted that the total global market for CFTR-targeting was around $10 billion in 2023, and is expected to grow to $15 billion by 2029.
The most notable drug on the cystic fibrosis market right now is Trikafta, manufactured by Vertex Pharmaceuticals, which improves the function of CFTR proteins through a slightly different mechanism than Sionna’s drugs. In a note written in December after Trikafta received extended FDA approval, Truist analysts said that Sionna’s development pipeline was a reason for Vertex “to stay vigilant.”
Sionna is not the only company going after CFTR and its theoretically undruggable parts. Swiss biopharma company Idorsia Pharmaceuticals published research last year on a candidate targeting the same mutation as Sionna’s NBD1 drugs, though that work is still preclinical.
