# EDGAR Filing Document

**Accession Number:** 0001776111
**File Stem:** 0001193125-25-211387
**Filing Date:** 2025-9
**Character Count:** 2575
**Document Hash:** 8f93461e6b12b51dee34fa5701fe23eb
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-211387.hdr.sgml**: 20260127

**ACCESSION NUMBER**: 0001193125-25-211387

**CONFORMED SUBMISSION TYPE**: CORRESP

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250922

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MBX Biosciences, Inc.
- **CENTRAL INDEX KEY:** 0001776111
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** CORRESP

**BUSINESS ADDRESS:**
- **STREET 1:** 11711 N. MERIDIAN STREET
- **STREET 2:** SUITE 300
- **CITY:** CARMEL
- **STATE:** IN
- **ZIP:** 46032
- **BUSINESS PHONE:** 3179893100

**MAIL ADDRESS:**
- **STREET 1:** 11711 N. MERIDIAN STREET
- **STREET 2:** SUITE 300
- **CITY:** CARMEL
- **STATE:** IN
- **ZIP:** 46032

**VIA EDGAR**

September 22, 2025

<br>United States Securities and Exchange Commission

Division of Corporation Finance

Office of Life Sciences

100 F. Street, N.E.

Washington, D.C. 20549

Attention: Tyler Howes

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| | |
|:---|:---|
| **Re:** | **MBX Biosciences, Inc.** |
|  | **Acceleration Request for Registration Statement on Form S-1** |
|  | **File No. 333-290447** |

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Dear Ladies and Gentlemen,

Pursuant to Rule 461 under the Securities Act of 1933, as amended (the "**Act**"), MBX Biosciences, Inc. (the "**Company**") hereby requests that the effective date of the above-referenced registration statement (the "**Registration Statement**") be accelerated to September 24, 2024 at 4:00 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 Edwin M. O'Connor at (212) 813-8853.

If you have any questions regarding this request, please contact Edwin M. O'Connor of Goodwin Procter LLP at (212) 813-8853.

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| |
|:---|
| Sincerely,<br>|
| MBX BIOSCIENCES, INC. |
| <br><u>/s/ P. Kent Hawryluk</u><br>P. Kent Hawryluk  |
| Chief Executive Officer |

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| | |
|:---|:---|
| cc: | Richard Bartram, *MBX Biosciences, Inc.* |
|  | Mitchell S. Bloom, Esq., *Goodwin Procter LLP* |
|  | Edwin M. O'Connor, Esq., *Goodwin Procter LLP*<br>|

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