Company: SION
Filing Date: 2025-02-04
Form Type: CORRESP
Source: 0001193125-25-020012
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Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-04
Form: CORRESP
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VIA EDGAR February 4, 2025 U.S. Securities and Exchange Commission Division of Corporation Finance Office of Life Sciences 100 F Street N.E. Washington, D.C. 20549 Attention: Tamika Sheppard, Laura Crotty, Jenn Do and Angela Connell

| Re: | Sionna Therapeutics, Inc. |

Acceleration Request for Registration Statement on Form S-1 File No. 333-284352 Dear Ladies and Gentlemen, Pursuant to Rule 461 under the Securities Act of 1933, as amended (the “ Act”), Sionna Therapeutics, Inc. (the “ Company”) hereby requests that the effective date of the above-referenced registration statement (the “ Registration Statement”) be accelerated to February 6, 2025 at 4:01 p.m. Eastern Time, or as soon thereafter as practicable, unless we or our outside counsel, Goodwin Procter LLP, request by telephone that such Registration Statement be declared effective at some other time. In making this acceleration request, the Company acknowledges that it is aware of its responsibilities under the Act. Once the Registration Statement is effective, please orally confirm the event with our counsel, Goodwin Procter LLP, by calling Gabriela Morales-Rivera at (617) 570-1329. If you have any questions regarding this request, please contact Gabriela Morales-Rivera of Goodwin Procter LLP at (617) 570-1329. Sincerely, SIONNA THERAPEUTICS, INC.

| /s/ Michael Cloonan                   |
| Michael Cloonan                       |
| President and Chief Executive Officer |

| cc: | Elena Ridloff, Sionna Therapeutics, Inc. |

Jennifer Fitzpatrick, Sionna Therapeutics, Inc. Gabriela Morales-Rivera, Goodwin Procter LLP William D. Collins, Goodwin Procter LLP Janet Hsueh, Goodwin Procter LLP