# EDGAR Filing Document

**Accession Number:** 0001776111
**File Stem:** 0001193125-26-097611
**Filing Date:** 2026-3
**Character Count:** 19872
**Document Hash:** e13f49e46812d706189d9eb0f373e16c
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-097611.hdr.sgml**: 20260309

**ACCESSION NUMBER**: 0001193125-26-097611

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 12

**CONFORMED PERIOD OF REPORT**: 20260309

**ITEM INFORMATION**: Regulation FD Disclosure

**ITEM INFORMATION**: Other Events

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20260309

**DATE AS OF CHANGE**: 20260309

**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:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-42272
- **FILM NUMBER:** 26733254

**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

?xml version='1.0' encoding='ASCII'? 8-K

**UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549**

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## FORM 8-K

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**CURRENT REPORT**

**Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934**

**Date of Report (Date of earliest event reported):** March 09, 2026<br>

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MBX Biosciences, Inc.

**(Exact name of Registrant as Specified in Its Charter)**

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| | | |
|:---|:---|:---|
| Delaware | 001-42272 | 84-1882872 |
| **(State or Other Jurisdiction<br>of Incorporation)** | **(Commission File Number)** | **(IRS Employer<br>Identification No.)** |
| 11711 N. Meridian Street<br>Suite 300 |  |  |
| Carmel**,** Indiana |  | 46032 |
| **(Address of Principal Executive Offices)** |  | **(Zip Code)** |

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**Registrant's Telephone Number, Including Area Code:** (317) 659-0200<br>

Not Applicable

**(Former Name or Former Address, if Changed Since Last Report)**

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Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

**Securities registered pursuant to Section 12(b) of the Act:**

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| | | |
|:---|:---|:---|
| **<br>Title of each class** | **Trading<br>Symbol(s)** | **<br>Name of each exchange on which registered** |
| Common Stock, $0.0001 par value per share | MBX | Nasdaq Global Select Market |

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Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

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## Item 7.01 Regulation FD Disclosure.
On March 9, 2026, MBX Biosciences, Inc. (the "Company") issued a press release titled "MBX Biosciences Announces Successful End-of-Phase 2 FDA Meeting and Provides Phase 3 Development Plan for Once-Weekly Canvuparatide for Hypoparathyroidism." A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K.

The information in Item 7.01 of this Current Report on Form 8-K, including Exhibit 99.1, is being furnished and shall not be deemed "filed" for the purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that Section, nor shall it be deemed subject to the requirements of amended Item 10 of Regulation S-K, nor shall it be deemed incorporated by reference into any filing of the Company under the Securities Act of 1933, as amended, or the Exchange Act, whether made before or after the date hereof, regardless of any general incorporation language in such filing. The furnishing of this information hereby shall not be deemed an admission as to the materiality of any such information.

## Item 8.01 Other Events.
On March 9, 2026, the Company announced completion of an End-of-Phase 2 ("EOP2") meeting with the U.S. Food and Drug Administration ("FDA"). Based on feedback from the FDA, the Company plans to advance once-weekly canvuparatide into a Phase 3 trial for the treatment of chronic hypoparathyroidism ("HP") in the third quarter of 2026.

The Phase 3 double-blind placebo-controlled trial will enroll approximately 160 patients randomized in a 3:1 ratio to receive canvuparatide or placebo. Following randomization, there will be a four-week fixed dose period of 600 ug canvuparatide (or placebo), followed by an eighteen-week dose-titration period, and a four-week maintenance period. The Phase 3 trial will evaluate the primary endpoint, proportion of participants who achieve normal serum calcium and independence from conventional therapy, as well as certain secondary endpoints, including normalization of urinary calcium. The primary endpoint will be assessed at week 26, followed by an open label extension.

The Company also announced that once-weekly canvuparatide has been granted Orphan Drug Designation by the European Medicines Agency for the treatment of chronic HP, supporting its continued clinical development in Europe.

*This Current Report on Form 8-K contains "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, each as amended. The words "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "plan," "potential," "predict," "project," "should," "target," "would" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These forward-looking statements include, but are not limited to, express or implied statements regarding: MBX Biosciences' expectations regarding the design of a Phase 3 trial; expectations regarding timing, including plans to initiate a Phase 3 clinical trial in Q3 2026; the potential for canvuparatide to be a new standard of care for HP; the potential market opportunity in HP; orphan drug designation and the intended benefits of such designation; and the unmet need for a new treatment option.*

*Forward-looking statements are based on management's current expectations and are subject to risks and uncertainties that could negatively affect MBX Biosciences' business, operating results, financial condition and stock value. Factors that could cause actual results to differ materially from those currently anticipated include: risks relating to the Company's research and development activities; MBX Biosciences' ability to execute on its strategy including obtaining the requisite regulatory approvals on the expected timeline, if at all; uncertainties relating to preclinical and clinical development activities; the Company's dependence on third parties to conduct clinical trials, manufacture its product candidates and develop and commercialize its product candidates, if approved; MBX Biosciences' ability to attract, integrate and retain key personnel; risks related to the Company's financial condition and need for substantial additional funds in order to complete development activities and commercialize a product candidate, if approved; risks related to regulatory developments and approval processes of the U.S. Food and Drug Administration and comparable foreign regulatory authorities; risks related to establishing and maintaining MBX Biosciences' intellectual property protections; risks related to the competitive landscape for MBX Biosciences' product candidates; and final audit adjustments and other developments that may arise that would cause MBX Biosciences' expectations with respect to the estimate of cash, cash equivalents and marketable securities as of December 31, 2025 to differ, perhaps materially, from the financial results that will be reflected in MBX Biosciences' audited consolidated financial statements for the fiscal year ended December 31, 2025; as well as other risks described in "Risk Factors," in MBX Biosciences' Quarterly Report on Form 10-Q for the three months ended September 30, 2025, Annual Report on Form 10-K for the year ended December 31, 2024 filed with the Securities and Exchange Commission (SEC), as well as subsequent filings with the SEC. MBX Biosciences expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in its expectations or any changes in events, conditions or circumstances on which any such statement is based, except as required by law, and claims the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995.*

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## Item 9.01 Financial Statements and Exhibits.
(d) Exhibits.

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| | |
|:---|:---|
| <u>Exhibit No.</u> | <u>Description</u> |
| 99.1 | [<u>Press Release Issued by MBX Biosciences, Inc. on March 9, 2026</u>](mbx-ex99_1.htm) |
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document) |

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**SIGNATURES**

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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| | | | |
|:---|:---|:---|:---|
|  |  |  | MBX BIOSCIENCES, INC. |
| Date: | March 9, 2026 | By:  | /s/ P. Kent Hawryluk |
|  |  |  | President and Chief Executive Officer (Principal Executive Officer) |

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## Exhibit 99.1

**EXHIBIT 99.1**

![img258572290_0.gif](img258572290_0.gif)

**MBX Biosciences Announces Successful End-of-Phase 2 FDA Meeting and Provides Phase 3 Development Plan for Once-Weekly Canvuparatide for Hypoparathyroidism**

*Following End-of-Phase 2 meeting, MBX remains on track to initiate Phase 3 in Q3 2026*

CARMEL, Ind., March 9, 2026 (GLOBE NEWSWIRE) -- MBX Biosciences, Inc. (Nasdaq: MBX), a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of novel precision peptide therapies for the treatment of endocrine and metabolic disorders, today announced the successful completion of an End-of-Phase 2 (EOP2) meeting with the U.S. Food and Drug Administration (FDA) to discuss the overall Phase 3 trial design for once-weekly canvuparatide for the treatment of chronic hypoparathyroidism (HP).

"We are very encouraged by the outcome of our End-of-Phase 2 meeting and the constructive feedback supporting our planned Phase 3 trial for canvuparatide," said Sam Azoulay, M.D., Chief Medical Officer of MBX Biosciences. "We believe canvuparatide has the potential to establish a new standard of care in hypoparathyroidism by restoring physiologic PTH activity and maintaining normocalcemia with the convenience of a patient-centric once-weekly dosing regimen. Feedback from physicians and patients has reinforced strong interest in a less burdensome treatment option, which we believe should translate into enthusiastic enrollment in the Phase 3 trial, and we look forward to enrolling the first patient in Q3 2026 now that we have confirmed the regulatory path toward an NDA submission."

Based on feedback from the FDA, MBX plans to advance once-weekly canvuparatide into a Phase 3 trial in the third quarter of 2026. Phase 3 trial design elements have now been selected, including the number of patients, primary endpoint (including proportion of participants who achieve normal serum calcium and independence from conventional therapy) and key secondary endpoints (including normalization of urinary calcium), as well as dose selection, titration schedule and duration of the study.

The Phase 3 double-blind placebo-controlled trial will enroll approximately 160 patients, randomized in a 3:1 ratio to receive canvuparatide or placebo. Following randomization, there will be a 4-week fixed dose period of 600 mg canvuparatide (or placebo), followed by an 18-week dose-titration period, and a 4-week maintenance period. The primary efficacy analysis will be assessed at Week 26, followed by a transition to an open label extension to assess both long-term safety and durability of effect.

The Company also announced today that once-weekly canvuparatide has been granted orphan

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drug designation by the European Medicines Agency for the treatment of chronic hypoparathyroidism, supporting its continued clinical development in Europe.

**About Canvuparatide**

Canvuparatide is a parathyroid hormone peptide prodrug that is designed as a potential long-acting hormone replacement therapy for the treatment of HP. Leveraging the company's proprietary Precision Endocrine Peptide™ (PEP™) platform technology, canvuparatide was designed to provide convenient, once-weekly administration and a continuous, infusion-like PTH exposure with lower daily peak-to-trough ratios than observed with daily PTH dosing regimens. Canvuparatide received orphan drug designation from the U.S. Food and Drug Administration for the treatment of HP.

**About Hypoparathyroidism (HP)**

HP is a rare endocrine disease caused by a deficiency of parathyroid hormone (PTH) released by the parathyroid glands that results in decreased calcium levels in the blood, leading to hypocalcemia. Hypocalcemia can cause a variety of symptoms, such as muscle cramping or spasm, tingling, and neurological symptoms such as depression, confusion, and cognitive impairment. More serious complications can occur, including seizures and cardiac arrhythmia. HP can interfere with daily activities, negatively impacting the quality of life for patients. We estimate that HP affects more than 250,000 individuals in the U.S. and Europe. The current standard of care for HP does not address the underlying cause of the disease, PTH deficiency, and consists primarily of high doses of oral calcium and active vitamin D supplements.

**About MBX Biosciences**<br> MBX Biosciences is a biopharmaceutical company focused on the discovery, development and commercialization of novel precision peptide therapies based on its proprietary PEP™ platform, for the treatment of endocrine and metabolic disorders. The Company is advancing a pipeline of novel candidates for endocrine and metabolic disorders with clinically validated targets, established endpoints for regulatory approval, significant unmet medical needs and large potential market opportunities. The Company's pipeline includes canvuparatide (MBX 2109) for the treatment of chronic hypoparathyroidism (HP) preparing for Phase 3 development; an obesity portfolio that includes MBX 4291 in Phase 1 development, as well as multiple discovery and pre-clinical obesity candidates; and imapextide (MBX 1416) for the treatment of post-bariatric hypoglycemia (PBH) in Phase 2 development. The Company is based in Carmel, Indiana. To learn more, please visit the Company website at www.mbxbio.com and follow it on LinkedIn.

**Forward-Looking Statements**

This press release contains "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, each as amended. The words "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "plan," "potential," "predict," "project," "should," "target," "would" and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These forward-looking statements include, but are not limited

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to, express or implied statements regarding: MBX Biosciences' expectations regarding the design of a Phase 3 trial; expectations regarding timing, including plans to initiate a Phase 3 clinical trial in Q3 2026; the potential for canvuparatide to be a new standard of care for HP; the potential market opportunity in HP; orphan drug designation and the intended benefits of such designation; and the unmet need for a new treatment option.

Forward-looking statements are based on management's current expectations and are subject to risks and uncertainties that could negatively affect MBX Biosciences' business, operating results, financial condition and stock value. Factors that could cause actual results to differ materially from those currently anticipated include: risks relating to the Company's research and development activities; MBX Biosciences' ability to execute on its strategy including obtaining the requisite regulatory approvals on the expected timeline, if at all; uncertainties relating to preclinical and clinical development activities; the Company's dependence on third parties to conduct clinical trials, manufacture its product candidates and develop and commercialize its product candidates, if approved; MBX Biosciences' ability to attract, integrate and retain key personnel; risks related to the Company's financial condition and need for substantial additional funds in order to complete development activities and commercialize a product candidate, if approved; risks related to regulatory developments and approval processes of the U.S. Food and Drug Administration and comparable foreign regulatory authorities; risks related to establishing and maintaining MBX Biosciences' intellectual property protections; risks related to the competitive landscape for MBX Biosciences' product candidates; and final audit adjustments and other developments that may arise that would cause MBX Biosciences' expectations with respect to the estimate of cash, cash equivalents and marketable securities as of December 31, 2025 to differ, perhaps materially, from the financial results that will be reflected in MBX Biosciences' audited consolidated financial statements for the fiscal year ended December 31, 2025; as well as other risks described in "Risk Factors," in MBX Biosciences' Quarterly Report on Form 10-Q for the three months ended September 30, 2025, Annual Report on Form 10-K for the year ended December 31, 2024 filed with the Securities and Exchange Commission (SEC), as well as subsequent filings with the SEC. MBX Biosciences expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in its expectations or any changes in events, conditions or circumstances on which any such statement is based, except as required by law, and claims the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995.

MBX Biosciences uses and intends to continue to use its Investor Relations website as a means of disclosing material nonpublic information and for complying with its disclosure obligations under Regulation FD. Accordingly, investors should monitor the Company's Investor Relations website, in addition to following the Company's press releases, SEC filings, public conference calls, presentations, and webcasts.

**Media Contact:**

George Shea

We. Communications

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gshea@wecommunications.com

**Investor Contact:**

Jim DeNike

MBX Biosciences

jdenike@mbxbio.com

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