Company: SION
Filing Date: 2025-01-17
Form Type: S-1
Source: 0001193125-25-008474
Chunk: 365

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-01-17
Form: S-1
Chunk 365
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 Registration Statement (or any Registration Statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933), and to file the same, with all exhibits thereto, and all documents in connection therewith, with the Securities and Exchange Commission granting unto each said attorney-in-factand agent full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as such person might or could do in person, hereby ratifying and confirming all that any said attorney-in-factand agent, or any substitute or substitutes of any of them, may lawfully do or cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement and Power of Attorney has been signed by the following person in the capacities and on the date indicated.

| Signature                        
 /s/ Michael Cloonan Michael      
 Cloonan, M.B.A.                  
 /s/ Elena Ridloff Elena Ridloff, 
 C.F.A.                           |     | Title                                                                                                                    
 President, Chief Executive Officer and Director (Principal Executive Officer)                                            
 Chief Financial Officer and Head of Corporate Development (Principal Financial Officer and Principal Accounting Officer) |     | Date             
 January 17, 2025 
 January 17, 2025 |
|:---------------------------------|:----|:-------------------------------------------------------------------------------------------------------------------------|:----|:-----------------|
| /s/ Paul Clancy                  |     | Chair of the Board of Directors                                                                                          |     | January 17, 2025 |
| Paul Clancy, M.B.A.              |     |                                                                                                                          |     |                  |
| /s/ Bruce Booth                  |     | Director                                                                                                                 |     | January 17, 2025 |
| Bruce Booth, D.Phil.             |     |                                                                                                                          |     |                  |
| /s/ H. Edward Fleming, Jr.       |     | Director                                                                                                                 |     | January 17, 2025 |
| H. Edward Fleming, Jr., M.D.     |     |                                                                                                                          |     |                  |

II-6

| Signature                    
 /s/ Lucian Iancovici         |     | Title    
 Director |     | Date             
 January 17, 2025 |
|:-----------------------------|:----|:---------|:----|:-----------------|
| Lucian Iancov