---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-25-086546"
form_type: "8-K"
ticker: "MBX"
cik: "0001776111"
company_name: "MBX Biosciences, Inc."
filed_at: "2025-06-16T23:59:59+00:00"
generated_at: "2026-05-19T06:39:46.537963+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# MBX Biosciences submits IND for MBX 4291, once-monthly GLP-1/GIP obesity prodrug

## Summary
- IND submitted to FDA for MBX 4291, a long-acting GLP-1/GIP receptor co-agonist prodrug for obesity.
- Designed for once-monthly administration to potentially improve adherence and GI tolerability.
- Phase 1 trial expected to start Q3 2025 in healthy overweight volunteers.
- Candidate developed using MBX's proprietary PEP platform technology.

## SEC filing metadata
- accession: 0000950170-25-086546
- form_type: 8-K
- ticker: MBX
- cik: 0001776111
- company_name: MBX Biosciences, Inc.
- filed_at: 2025-06-16T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.65
- calibrated_materiality_score: 0.65
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1776111/000095017025086546/0000950170-25-086546-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1776111/000095017025086546/mbx-20250616.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-25-086546
- JSON: https://secwatch.observer/filing/0000950170-25-086546.json
- Plain text: https://secwatch.observer/filing/0000950170-25-086546.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.