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MBX 2109

Phase 2

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

Success Probability

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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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Recent Changes (Last 90 Days)

MEDIUMMay 21, 2026NCT06465108TRIAL_REMOVED: changed
MEDIUMMay 21, 2026NCT06465108TRIAL_REMOVED: changed

Frequently asked questions about MBX 2109

What is MBX 2109 used for?

MBX 2109 is an investigational small molecule being developed for hypoparathyroidism, a condition where the body produces insufficient parathyroid hormone. It has also been studied in healthy volunteers and in people with renal impairment to assess safety and pharmacokinetics. The drug is not yet approved and remains in clinical development.

How does MBX 2109 work?

MBX 2109 is a small molecule, but its specific molecular target has not been disclosed. The drug is being studied for its safety, tolerability, pharmacokinetics, and pharmacodynamics in healthy subjects, and for safety, pharmacokinetics, and efficacy in patients with hypoparathyroidism.

Who makes MBX 2109?

MBX 2109 is being developed by MBX Biosciences, Inc., a biopharmaceutical company. The company's stock trades under the ticker symbol MBX. MBX Biosciences is conducting clinical trials of MBX 2109 in the United States and other countries.

What phase is MBX 2109 in?

MBX 2109 has completed Phase 1 and Phase 2 clinical trials. A Phase 1 study in healthy subjects and a Phase 1 study in subjects with renal impairment have been completed, as has a Phase 2 study in patients with hypoparathyroidism. The drug is investigational and not FDA approved.

What clinical trials is MBX 2109 in?

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

Is MBX 2109 the same as other drugs?

MBX 2109 is the sole name provided for this drug; no alternative names have been disclosed. It is a distinct investigational small molecule being developed by MBX Biosciences for hypoparathyroidism and related conditions.