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MBX 2109

Phase 2

Hypoparathyroidism | Small molecule | Endocrine |MBX Biosciences, Inc.|Last Updated: Mar 20, 2026

Target and mechanism

ModalitySmall molecule

Also known as MBX 2109 (Part A)

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLED
Total Trials1
Total Enrollment64

FDA Designations

No designations recorded

Clinical trial landscape

MBX 2109 · 3 trials · 3 indications

Phase 2 1Phase 1 2
NCT06465108Safety, Pharmacokinetics and Efficacy of MBX 2109 in Patients With HypoparathyroidismHypoparathyroidism
COMPLETED64 Analytics
PHASE2COMPLETED
Safety, Pharmacokinetics and Efficacy of MBX 2109 in Patients With Hypoparathyroidism
HypoparathyroidismUnlock trial analytics

Study Endpoints

Primary Endpoints

To evaluate the effect of pooled weekly doses of MBX 2109 on the proportion of responder patients defined by serum calcium levels and treatment with active vitamin D and calcium supplements at Week 12/Visit 15
Week 12

Proportion of patients pooled across MBX 2109 doses meeting the composite criteria at week 12/Visit 15 * Independence from active vitamin D supplements * Oral elemental calcium doses of ≤600 mg/day * Serum albumin-adjusted calcium (AdjCa) values of 8.2 to 10.6 mg/dL

Area under the plasma concentration-time curve from time 0 extrapolated to infinity (AUC0-∞)
Baseline through Day 36

Assess the plasma pharmacokinetics (PK) of MBX 2109 and MBX 2099 following a single 900 µg subcutaneous (SC) dose

Maximum observed concentration (Cmax)
Baseline through Day 36

Assess the plasma pharmacokinetics (PK) of MBX 2109 and MBX 2099 following a single 900 µg subcutaneous (SC) dose

Area under the plasma concentration-time curve from time 0 to time of last quantifiable sample (AUC0-T)
Baseline through Day 36

Assess the plasma pharmacokinetics (PK) of MBX 2109 and MBX 2099 following a single 900 µg subcutaneous (SC) dose

Apparent clearance (CL/F) (MBX 2109 only)
Baseline through Day 36

Assess the plasma pharmacokinetics (PK) of MBX 2109 and MBX 2099 following a single 900 µg subcutaneous (SC) dose

Time to maximum concentration (Tmax)
Baseline through Day 36

Assess the plasma pharmacokinetics (PK) of MBX 2109 and MBX 2099 following a single 900 µg subcutaneous (SC) dose

Terminal elimination half-life (t1/2)
Baseline through Day 36

Assess the plasma pharmacokinetics (PK) of MBX 2109 and MBX 2099 following a single 900 µg subcutaneous (SC) dose

Apparent volume of distribution (Vz/F) (MBX 2109 only)
Baseline through Day 36

Assess the plasma pharmacokinetics (PK) of MBX 2109 and MBX 2099 following a single 900 µg subcutaneous (SC) dose

Primary Outcome Measures
Baseline through Day 40 (part A) or Day 60 (Part B)

Number of participants with adverse events (AEs) or Serious Adverse Events (SAEs)

Secondary Endpoints

Secondary Outcome Measures 1
Baseline through Day 40 (part A) or Day 60 (Part B)
Secondary Outcome Measures 2
Baseline through Day 40 (part A) or Day 60 (Part B)
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Study Design & Arms

AllocationRANDOMIZED
MaskingDOUBLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Starting dose of 400 µg once-weekly by subcutaneous injectionEXPERIMENTAL -
Starting dose of 600 µg once-weekly by subcutaneous injectionEXPERIMENTAL -
Starting dose of 800 µg once-weekly by subcutaneous injectionEXPERIMENTAL -
Placebo - once-weekly by subcutaneous injectionPLACEBO_COMPARATOR -
Single 900 µg dose of MBX 2109EXPERIMENTALA single, 900 µg dose of MBX 2109 will be administered subcutaneously in the abdomen
MBX 2109 (Part A)EXPERIMENTALSingle ascending SC doses
MBX 2109 (Part B)EXPERIMENTALRepeated ascending SC doses
PlaceboPLACEBO_COMPARATOR -

Interventions

NameTypeDescription
MBX 2109DRUGSupplied as 1.5 mg per vial reconstituted in 1.4 mL water for injection to a concentration of 1.0 mg/mL
PlaceboOTHERSupplied in 1.4 mL water for injection
MBX 2109 (Part A)DRUGSingle ascending SC dose of MBX 2109: 50 µg, 150 µg, 300 µg, 460 µg, 600 µg
MBX 2109 (Part B)DRUGRepeated ascending SC doses of MBX 2109: 200 µg, 300 µg, 460 µg, 600 µg, 900 µg
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Eligibility Criteria

Age Range18 Years to 100 Years
SexALL
Healthy VolunteersNo
Study Sites33

Inclusion Criteria: 1. Is an adult ≥18 years of age at the time of the Screening visit. a. If ≤25 years of age, radiological evidence of epiphyseal closure based on X-ray of non-dominant wrist and hand 2. Has a diagnosis of one of the following types of hypoparathyroidism for at least 26 weeks ...

Countries:United StatesArgentinaTurkey (Türkiye)
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Competitive Landscape -Hypoparathyroidism 5 trials

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Frequently asked questions about MBX 2109

What is MBX 2109?

MBX 2109 is an investigational small molecule developed by MBX Biosciences, Inc. It has been studied in healthy adult volunteers, in patients with hypoparathyroidism, and in adults with impaired renal function. It is not approved and remains in clinical development.

What is MBX 2109 used for in hypoparathyroidism?

MBX 2109 has been studied as a potential treatment for hypoparathyroidism, a condition in which the body produces insufficient parathyroid hormone. A completed Phase 2 trial, NCT06465108, evaluated its safety, pharmacokinetics, and efficacy in 64 patients with hypoparathyroidism across the United States, Argentina, and Turkey.

Who makes MBX 2109?

MBX 2109 is developed by MBX Biosciences, Inc., which trades under the ticker MBX. The company has sponsored the clinical program for the drug, including studies in healthy volunteers, patients with hypoparathyroidism, and adults with impaired renal function.

What phase is MBX 2109 in?

MBX 2109 is in clinical development and is not FDA approved. Its program includes completed Phase 1 studies and a completed Phase 2 trial in hypoparathyroidism. No active trials are currently listed for the drug.

What clinical trials is MBX 2109 in?

MBX 2109 has been evaluated in three completed trials. NCT05158335 was a Phase 1 study in 76 healthy adults. NCT06496217 was a Phase 1 study in 25 adults with normal and impaired renal function. NCT06465108 was a Phase 2 study in 64 patients with hypoparathyroidism.

Is MBX 2109 the same as MBX 2109 (Part A)?

Yes, MBX 2109 (Part A) refers to the same investigational drug as MBX 2109, developed by MBX Biosciences, Inc. The parenthetical label distinguishes a portion of the clinical program rather than a separate compound.