Two more biotechs join IPO waiting list

Odyssey Therapeutics and Sionna Therapeutics have filed to carry out initial public offerings (IPOs) on the Nasdaq, taking the number in the newly-filed queue to four since the start of the year.

The two filings – both for companies based in Massachusetts and reported by Renaissance Capital – have the usual $100 million placeholder value, but both the number of shares on offer and their price range remain confidential for now.

Odyssey is a specialist in autoimmune and inflammatory diseases. In its provisional prospectus, the start-up says the proceeds of the IPO will go towards phase 2a trials of OD-07656, its small molecule RIPK2 inhibitor. To date, most effort by the pharma industry in this area has focused on RIPK1, so far with little success.

A monotherapy trial in ulcerative colitis is scheduled to start in the next few weeks, while a combination study with Takeda's blockbuster inflammatory bowel disease (IBD) therapy Entyvio (vedolizumab), an alpha-4 beta-7 integrin antagonist that made more than $5 billion in sales in 2023, is slated for 2026.

Some of the cash raised in the IPO is also set aside for advancing two preclinical-stage programmes targeting IRAK4 and TNFR2, while Odyssey said it may also look to in-license "businesses, technology, or assets."

The biotech is still well-funded, ending the third quarter of 2024 with more than $154 million in cash after completing a $101 million Series C at the end of 2023 and having raised around $487 million since it was formed in 2021. It plans to list on the Nasdaq under the ODTX ticker.

Turning to Sionna, the biotech is focused on the development of novel therapies for cystic fibrosis (CF) that normalise the function of the CFTR protein, whose gene is defective or missing in patients with the genetic disorder.

Its prospectus says that the IPO will fund phase 1 and phase 2a proof-of-concept testing of a pair of compounds that regulate CFTR by stabilising a nucleotide-binding domain for the protein (NBD1), which work in a different way to current treatments based on exon-skipping therapies pioneered by Vertex Pharma.

The proceeds are also earmarked for a phase 2b trial and to build manufacturing capacity and to continue clinical testing of compounds, three of which have been licensed from AbbVie, that work in complementary ways. Leading those is galicaftor, which targets CFTR's transmembrane domain 1 (TMD1) and has completed a phase 2 study.

Formed in 2019, Sionna's most recent financing was a $182 million third round that closed last year, which followed a $111 million Series B in 2022. It ended the third quarter of 2024 with just under $181 million in cash, and plans to list on the Nasdaq under the symbol SION.

The two filings follow in the footsteps of obesity drug developer Metsera and genetic medicines developer Maze Therapeutics, which filed to list on the Nasdaq earlier this month.

After hitting a record high in 2021, the number of biotech IPOs have fallen to a yearly average in the 20s, with most successful entries in the last few quarters involving companies with mid- to late-stage clinical projects. At the same time, the number of $100 million-plus private rounds has increased steadily, which may have pegged back the incentive to take on the additional administration and oversight required with a public listing.