Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 140

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 140
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 of:

| • |     | $4.3 million increase in complementary modulator programs cost due to the initiation of the SION-109 Phase 1 clinical trial in 2024 offset by a $7.0 million decrease in NBD1 program costs due to a decrease in manufacturing expenses; and |

| • |     | unallocated research and development expenses increased by $15.0 million due to                                                                                                          
 in-process research and development (“IPR&D”) costs incurred in connection with the AbbVie License Agreement of $13.6 million and other unallocated research and development expenses of 
 $1.4 million due to increased professional services and external research and development spend.                                                                                         |

100

General and Administrative Expenses The following table summarizes our general and administrative expenses (in thousands):

|                                                        | 2024 | Nine Months         
 Ended September 30, |       |     | 2023 |   |       |     | Change |       |
|:-------------------------------------------------------|:-----|:--------------------|------:|:----|:-----|:--|------:|:----|:-------|------:|
| Personnel-related (including stock-based compensation) |      | $                   | 5,608 |     |      | $ | 4,452 |     | $      | 1,156 |
| Professional services & fees                           |      |                     | 2,636 |     |      |   | 1,499 |     |        | 1,137 |
| Facility expenses                                      |      |                     | 1,144 |     |      |   | 1,051 |     |        |    93 |
| Total general and administrative expenses              |      | $                   | 9,388 |     |      | $ | 7,002 |     | $      | 2,386 |

General and administrative expenses increased by $2.4 million to $9.4 million for the nine months ended September 30, 2024, from $7.0 million for the nine months ended September 30, 2023. The increase in general and administrative expenses was primarily due to:

| • |     | $1.2 million increase in personnel-related (including stock-based compensation) primarily due to an increase in 
 stock-based compensation; and                                                                                   |

| • |     | $1.1 million increase in fees related to increased use of consultants and professional service organizations. |

Interest Income Interest income increased by $3.9 million