Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 318

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 318
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  10,275 |   |
| Cash, cash equivalents and restricted cash at end of period                           |     | $                       |  39,483 |   |     | $    |  55,799 |   |
| Supplemental disclosure of non-cash investing and financing                           
 activities:                                                                           |     |                         |         |   |     |      |         |   |
| Fixed asset additions included in accounts payable and accrued expenses               |     | $                       |       — |   |     | $    |     427 |   |
| Supplemental cash flow information:                                                   |     |                         |         |   |     |      |         |   |
| Right-of use asset obtained in exchange for new operating lease                       
 liability                                                                             |     | $                       |   9,516 |   |     | $    |       — |   |
| Reconciliation of cash and restricted cash:                                           |     |                         |         |   |     |      |         |   |
| 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