Company: SION
Filing Date: 2025-02-03
Form Type: S-1/A
Source: 0001193125-25-018825
Chunk: 325

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-03
Form: S-1/A
Chunk 325
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     |                         |         |   |     |      |         |   |
| Cash and cash equivalents                                                             |     | $                       |  38,521 |   |     | $    |  54,837 |   |
| Restricted cash                                                                       |     |                         |     962 |   |     |      |     962 |   |
| Total cash, cash equivalents, and restricted cash                                     |     | $                       |  39,483 |   |     | $    |  55,799 |   |

The accompanying notes are an integral part of these consolidated financial statements. F-6

SIONNA THERAPEUTICS, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1. Nature of the Business

Organization

Sionna
Therapeutics, Inc. (the “Company”), formerly known as Sling Therapeutics, Inc., is a clinical-stage biopharmaceutical company dedicated to researching and developing novel medicines for cystic fibrosis. The Company was
incorporated in Delaware in August 2019 and is headquartered in Waltham, Massachusetts.

Risks and Uncertainties

The Company is subject to a number of risks common to other companies in the biotechnology industry, including but not limited to, development by
competitors of new technological innovations, risks of failure of preclinical studies and clinical trials, development and manufacturing of product candidates, obtaining regulatory approval for product candidates, competition from substitute
products, the need to successfully commercialize and gain market acceptance of its product candidates, protection of proprietary technology, dependence on key personnel, the ability to attract and retain qualified employees, reliance on third party
organizations compliance with government regulations, and the need to obtain additional financing. Product candidates currently under development will require significant additional research and development efforts, including extensive clinical
testing and regulatory approval, prior to commercialization. These efforts will require significant amounts of additional capital, adequate personnel infrastructure, and extensive compliance-reporting capabilities. Even if the Company’s
development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

Liquidity and Going Concern

The Company has funded its operations primarily with proceeds from the sale of convertible preferred stock and has not generated
revenue from product sales or other sources. As of December 31, 2023, the Company has raised an aggregate of $149.0 million in net proceeds through the sale of convertible preferred stock. In March 2024, the