Biotechs Sionna and Odyssey announce IPO plans

USA – Two Massachusetts-based biotech companies, Sionna Therapeutics and Odyssey Therapeutics, have filed for initial public offerings (IPOs) on Nasdaq, marking an ambitious start to 2025.

Both companies announced their plans following the J.P. Morgan Healthcare Conference but have not disclosed fundraising targets or IPO timelines.

Sionna will trade under the ticker symbol $SION, while Odyssey will use $ODTX.

Sionna Therapeutics: Advancing cystic fibrosis treatments

Sionna is focused on developing therapies for cystic fibrosis by targeting the NBD1 domain of the CFTR protein, which becomes dysfunctional due to genetic mutations.

The company’s two lead drug candidates are in Phase I trials, and IPO proceeds are expected to fund their progression into mid-stage clinical studies.

Additional funds will support research and development initiatives and general corporate expenses.

In March 2024, Sionna raised US $182 million in a Series C funding round to advance its programs and secure operations through 2026.

The company also struck a licensing deal with AbbVie, granting it global rights to two cystic fibrosis drugs.

Per its SEC filing, AbbVie received US $5 million upfront, US $8.6 million in Sionna stock, and is eligible for up to US $490 million in development, commercial, and sales milestones.

Sionna, led by CEO Mike Cloonan, a former Biogen and Sage Therapeutics executive, has raised approximately US $330 million since its founding in 2019.

Its top investors include RA Capital (29.2%), TPG Growth (17.4%), and Atlas Venture (11.4%).

Odyssey Therapeutics: Tackling autoimmune and inflammatory diseases

Odyssey Therapeutics is targeting autoimmune and inflammatory conditions with its lead candidate, OD-07656, a small-molecule therapy currently in development for ulcerative colitis.

The drug is set to enter Phase IIa trials in 2025. IPO proceeds will also fund two preclinical programs, including a small molecule and a protein therapeutic, through IND-enabling studies.

Odyssey’s broad pipeline spans treatments for Crohn’s disease, atopic dermatitis, systemic sclerosis, vitiligo, type 1 diabetes, and systemic lupus erythematosus. Its preclinical asthma program aligns with growing interest in TSLP-targeted therapies.

Founded in 2021 by chemistry professor and serial entrepreneur Gary Glick, Odyssey has raised over $300 million across three financing rounds, including a US $101 million Series C in December 2023. Major stakeholders include SR One (16.2%), OrbiMed (14.3%), Fidelity (6.7%), Foresite Capital (6%), according to Odyssey’s S-1 filing.

IPO climate and outlook

The IPO announcements from Sionna and Odyssey follow a quiet market in recent years but indicate renewed momentum in biotech.

If successful, the two companies will join other IPO hopefuls like obesity drug developer Metsera and kidney disease startup Maze.

Despite this activity, analysts remain cautious. Jefferies noted in a recent investor note that many companies are delaying IPO timelines due to market uncertainty.

Conversely, William Blair analysts predict approximately 30 biotech IPOs in 2025, highlighting a robust pipeline of high-quality private companies.