secwatch.observer — SEC 8-K summary
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Issuer:     MBX Biosciences, Inc. (MBX)
CIK:        0001776111
Form:       8-K
Filed at:   2026-08-27T12:34:34+00:00
Accession:  0001193125-26-369674
Event type: other_material
Sentiment:  positive
Materiality: 0.70
Item codes: 7.01, 8.01, 9.01
LLM model:  deepseek-v4-flash:cloud@v2

MBX Biosciences doses first patient in Phase 3 oPTimize trial of canvuparatide for hypoparathyroidism
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- First patient dosed in pivotal Phase 3 oPTimize trial (NCT07699471) of once-weekly canvuparatide in chronic hypoparathyroidism.
- Trial enrolls ~160 adults, randomized 3:1 canvuparatide vs placebo over 26-week double-blind period, then 78-week open-label extension.
- Primary endpoint: composite responder at Week 26 (normal serum calcium, no active vitamin D, calcium ≤600 mg/day, no dose increase).
- Builds on positive Phase 2 Avail results showing normalized serum calcium, reduced urinary calcium, restored bone metabolism, increased eGFR.
- Canvuparatide administered once weekly using commercial-intent device; CEO cites potential as new standard of care.

Source:
  EDGAR index:    https://www.sec.gov/Archives/edgar/data/1776111/000119312526369674/0001193125-26-369674-index.htm
  Primary doc:    https://www.sec.gov/Archives/edgar/data/1776111/000119312526369674/mbx-20260827.htm
  HTML page:      https://secwatch.observer/filing/0001193125-26-369674

License: Source filings: public domain (SEC EDGAR). Summaries (headline + bullets): CC-BY-4.0; attribute https://secwatch.observer