aibioSionna Therapeutics files for IPO of common stock, seeks Nasdaq listing as SION
Tickers SION
Sionna Therapeutics filed a preliminary S-1 on January 17, 2025 for an IPO of common stock on the Nasdaq Global Market under SION. The filing leaves the share count, price range and net proceeds blank, and lists Goldman Sachs & Co. LLC, TD Cowen, Stifel and Guggenheim Securities as underwriters without marking a lead.
Key facts
- Company
- Sionna Therapeutics, Inc. (NASDAQ: SION)
- News type
- Financings
- Primary source
- Sionna Therapeutics, Inc. S-1 (2025-01-17)
Sionna Therapeutics, Inc. filed a registration statement on Form S-1 with the SEC on January 17, 2025 for an initial public offering of its common stock. The preliminary prospectus is marked subject to completion, and it leaves the number of shares, the price range and the net proceeds blank. The company has applied to list its common stock on The Nasdaq Global Market under the symbol SION,. The company is based in Waltham, Massachusetts, and its chief executive officer is Michael Cloonan.
The underwriters
The back cover of the prospectus lists Goldman Sachs & Co. LLC, TD Cowen, Stifel and Guggenheim Securities as underwriters. The filing does not say which of them is the lead or sole book-runner, and it does not give the underwriting discount. The underwriters hold an option to buy additional shares from the company, but the number is blank.
The S-1 lists Goodwin Procter LLP and Ropes & Gray LLP among the firms to receive copies of communications. It does not say which firm represents the company and which represents the underwriters.
The offering and the share count
The filing says the net proceeds would be used, together with existing cash and marketable securities, to complete ongoing Phase 1 trials, to run a planned Phase 2a proof-of-concept trial, and to carry out preclinical and early clinical work toward a dual combination of an NBD1 stabilizer and a complementary modulator. The number of shares outstanding after the offering is based on 46,656,571 shares outstanding as of September 30, 2024, after the automatic conversion of the company's preferred stock.
The company's losses and financing
The prospectus says the company's net losses were $47.3 million in 2023 and $40.2 million in 2022. Its accumulated deficit was $165.2 million as of September 30, 2024, up from $119.4 million at December 31, 2023. Since its inception the company says it has raised approximately $330 million from investors, including RA Capital, TPG's The Rise Fund, Atlas Venture, OrbiMed and Enavate Sciences.
In March 2024 the company sold 18,628,970 shares of Series C convertible preferred stock for gross proceeds of $181.9 million. Its financial statements say cash and cash equivalents were $38.5 million at December 31, 2023. The company's going-concern analysis states that this cash, together with the Series C proceeds, is expected to fund operations beyond twelve months. The prospectus also says the company will need substantial additional funding even if the offering is successful.
The CF programs
Sionna describes itself as a clinical-stage biopharmaceutical company developing medicines for cystic fibrosis that aim to normalize the function of the CFTR protein. The prospectus estimates that about 106,000 people have been diagnosed with CF in 94 countries, including about 33,000 in the United States.
The company's main programs are SION-719 and SION-451, which are being tested in Phase 1 trials in healthy subjects. Interim data as of a January 14, 2025 cutoff show both were generally well tolerated. The prospectus says SION-719 was generally well tolerated at all dose levels given, with no serious adverse events and mostly mild or moderate treatment-emergent adverse events. Topline Phase 1 results are expected in the first half of 2025.
The target exposure levels for both drugs come from a preclinical cystic fibrosis human bronchial epithelial model, and the company says it reached those target concentrations with single and multiple doses in healthy subjects. Those are exposure results, not patient outcomes.
Sionna also cites galicaftor, a TMD1-directed corrector it in-licensed from AbbVie in July 2024. The company says galicaftor completed Phase 1 and Phase 2 trials in approximately 400 subjects, with sweat chloride improvements as a single agent, in trials run by AbbVie or Galapagos NV, not by Sionna. SION-2851 has completed a Phase 1 single ascending dose trial, and a Phase 1 trial of SION-109 was recently completed.
What the filing leaves open
The price, the number of shares and the proceeds are all blank, so the size of the offering cannot be determined from this filing. The planned Phase 2a trial would enroll up to 20 CF patients on Vertex's Trikafta, with safety as the primary endpoint, starting in the second half of 2025.