Autosomal Dominant Hypocalcemia Type 1 (ADH1)Phase 2/3CALIBRATE-PEDSNCT07080385
Pharmacokinetics, Efficacy, and Safety of Encaleret in Pediatric Participants With Autosomal Dominant Hypocalcemia Type 1 (ADH1)
A Phase 2/3 study testing Encaleret in people with Autosomal Dominant Hypocalcemia Type 1 (ADH1), run by Calcilytix Therapeutics, Inc., a BridgeBio company at 6 sites in 2 countries.
Trial summary
The overall objective of this study is to evaluate the pharmacokinetics (PK), efficacy, and safety of encaleret in pediatric participants from birth to 17 years of age with ADH1. Read more about this study
- Who is it for?
- Ages 0 to 17 years
- Conditions the study is for
- Autosomal Dominant Hypocalcemia Type 1 (ADH1)
- What is being tested?
- Encaleret
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 28 participants
- Where
- 6 sitesin 2 countries
- Study dates
- 30 Jan 2026to Dec 2030
- Phase
- Phase 2/3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 0 to 17 years
- All sexes
- No healthy volunteers
- Child
Who may be able to join
- Provide written informed consent (if legally permitted), or have written informed consent from a parent/legal guardian and provide assent (where required and as appropriate per local requirements)
- Have a documented pathogenic or likely pathogenic activating variant, or variant of uncertain significance of the calcium-sensing receptor (CASR), associated with biochemical findings of hypoparathyroidism at screening or a documented history of hypoparathyroidism as manifested by hypocalcemia and intact parathyroid hormone (PTH) <40 picogram per milliliter (pg/mL) (4.2 picomoles per liter [pmol/L])
- Have at least 1 symptom or sign of hypoparathyroidism at screening or a documented history of symptoms or signs of hypoparathyroidism
- Be on ADH1 treatment for at least 6 months before screening for cohorts 1 to 3, or for at least 3 months before screening for cohort 4
Who cannot join
- History of thyroid or parathyroid surgery
- History of renal transplantation
- History of cancer (except thyroid cancer, basal cell skin cancer, or squamous cell skin cancer), skeletal malignancies, bone metastases, irradiation (radiotherapy) to the skeleton, chemotherapy with alkylating agents, Paget disease, fibrous dysplasia, chronic osteomyelitis, bone infarcts, benign bone tumors with curettage and bone grafts, retinoblastoma, or Li-Fraumeni syndrome within 5 years before screening
- Received any investigational medicinal product within 30 days or 5 half-lives before Day 1, whichever is longer, or is in follow-up for another interventional clinical study during screening
- Treatment with a strong P-glycoprotein (P-gp) inhibitor within 300 days before screening for amiodarone or within 30 days before screening for any other strong P-gp inhibitor
- Treatment with cardiac glycosides, or is being breastfed while the participant's nursing mother is treated with cardiac glycosides, within 30 days before screening
- Presence or history of any disease or condition (eg, drug or alcohol dependence) that would affect the participant's safety, treatment compliance, or ability to complete the study, in the opinion of the investigator
- Other protocol defined inclusion/exclusion criteria apply.
Trial locations and contacts
6 sites in 2 countries. Contact the study team or a site near you to ask about taking part.
6 sites in 2 countries
United States4 sites, 4 recruiting
- Recruiting
Nemours Children's Health
Jacksonville, Florida, 32207
- Recruiting
Yale University
New Haven, Connecticut, 06511
- Recruiting
The Children's Hospital of Philadelphia
Philadelphia, Pennsylvania, 19104
- Recruiting
Children's National Medical Center
Washington D.C., District of Columbia, 20010
United Kingdom2 sites, 2 recruiting
- Recruiting
Royal London Hospital
London, E1 1FR
- Recruiting
Royal Manchester Children's Hospital
Manchester, M13 9WL
About this study
Official title: A Phase 2/3, Multicenter, Single-Arm, Open-Label Study Evaluating the Pharmacokinetics, Efficacy, and Safety of Encaleret in Pediatric Participants With Autosomal Dominant Hypocalcemia Type 1 (ADH1)
The overall objective of this study is to evaluate the pharmacokinetics (PK), efficacy, and safety of encaleret in pediatric participants from birth to 17 years of age with ADH1.
- Being tested
- Encaleret
- Keywords
- Autosomal dominant hypocalcemia type 1, ADH1, Encaleret
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
EncaleretDrug
Oral tablets, age-appropriate pediatric formulation (currently under development).
| Study group | Role | What they receive |
|---|---|---|
| Encaleret | Experimental | Participants will receive encaleret dosing in Period 1 (6 days), Period 2 (20 weeks) and Period 3 (4 weeks). Following completion of Period 3, participants will have the option to enter a long-term extension (LTE) to continue encaleret for an additional approximately 24 months or until the sponsor decides to end the study, whichever occurs first. Receives: Drug: Encaleret |
What is being measured
The primary outcome is the main question the study is designed to answer.
Period 1: Maximum Plasma Concentration (Cmax) of Encaleret and Metabolites M1, and M3
Measured: 5 days
Period 1: Area Under the Plasma Concentration-time Curve (AUC) of Encaleret and Metabolites M1, and M3
Measured: 5 days
Period 3: Number of Participants with Albumin-corrected Blood Calcium (cCa) and Urinary Calcium (UCa) Excretion Response
Measured: Week 25
Secondary outcomes (23)
Period 1: Change from Baseline in Blood cCa
Measured: Baseline up to Day 5
Period 1: Change from Baseline in Blood Intact Parathyroid Hormone (iPTH) Concentration
Measured: Baseline up to Day 5
Period 1: Change from Baseline in Blood Phosphate Concentration
Measured: Baseline up to Day 5
Period 1: Change from Baseline in Blood 1,25-(OH)2 Vitamin D Concentration
Measured: Baseline up to Day 5
Period 1: Change from Baseline in Blood Magnesium Concentration
Measured: Baseline up to Day 5
Period 1: Change from Baseline in 24-hour UCa in Toilet Trained Participants
Measured: Baseline up to Day 5
Period 1: Change from Baseline in Spot Ratio of UCa/Urinary Creatinine (UCr) In Non-toilet Trained Participants
Measured: Baseline up to Day 5
Period 3: Number of Participants with Blood iPTH Within the Reference Range
Measured: Week 25 (post-dose)
Period 3: Number of Participants with Blood Phosphate Within the Reference Range
Measured: Week 25
Period 3: Number of Participants with Blood Magnesium Within the Reference Range
Measured: Week 25
Period 3: Number of Participants with Blood 1,25-(OH)2 Vitamin D Within the Reference Range
Measured: Week 25
Periods 1, 2, and 3: Change from Baseline in Short Form-10 Health Survey for Children (SF-10) in Participants Aged ≥6 Years
Measured: Baseline up to Week 25
Periods 1, 2, and 3: Dose of Calcium Supplements and/or Active Vitamin D Analogs Used as Rescue Therapy
Measured: 25 weeks
Periods 1, 2, and 3: Dosing Frequency of Calcium Supplements and/or Active Vitamin D Analogs Used as Rescue Therapy
Measured: 25 weeks
Periods 1, 2, 3, and LTE: Number of Participants with Adverse Events (AEs) and Serious AEs (SAEs)
Measured: 145 weeks
LTE: Change from Baseline in Blood cCa
Measured: Baseline up to 145 weeks
LTE: Change from Baseline in Blood iPTH Concentration
Measured: Baseline up to 145 weeks
LTE: Change from Baseline in Blood Phosphate Concentration
Measured: Baseline up to 145 weeks
LTE: Change from Baseline in Blood 1,25-(OH)2 Vitamin D Concentration
Measured: Baseline up to 145 weeks
LTE: Change from Baseline in Blood Magnesium Concentration
Measured: Baseline up to 145 weeks
LTE: Change from Baseline in 24-hour UCa In Toilet Trained Participants
Measured: Baseline up to 145 weeks
LTE: Change from Baseline in Spot Ratio of UCa/UCr In Non-toilet Trained Participants
Measured: Baseline up to 145 weeks
LTE: Change from Baseline in SF-10 in Participants Aged ≥6 Years
Measured: Baseline up to 145 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Jul 2025
- Study start30 Jan 2026
- Primary completionDec 2028 (estimated)
- Study completionDec 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Autosomal Dominant Hypocalcemia Type 1 (ADH1)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2/3
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Sequential
- Masking
- None (open label)
- Enrolment
- 28 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Calcilytix Therapeutics, Inc., a BridgeBio company
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Calcilytix Medical Director, Study director, Calcilytix Therapeutics, Inc., a BridgeBio company
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07080385
- Sponsor's protocol ID
- CLTX-305-303
- Acronym
- CALIBRATE-PEDS
- Status last verified
- Mar 2026
- First submitted
- 14 Jul 2025
- Last updated
- 22 Apr 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 22 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2/3, Multicenter, Single-Arm, Open-Label Study Evaluating the Pharmacokinetics, Efficacy, and Safety of Encaleret in Pediatric Participants With Autosomal Dominant Hypocalcemia Type 1 (ADH1)
- ClinicalTrials.gov ID
- NCT07080385
- Acronym / sponsor ID
- CALIBRATE-PEDS / CLTX-305-303
- Keywords
- Autosomal dominant hypocalcemia type 1, ADH1, Encaleret
- Phase
- Phase 2/3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 28 participants (estimated)
- Lead sponsor
- Calcilytix Therapeutics, Inc., a BridgeBio companyIndustry (pharma, biotech, devices)
- Study start
- 30 Jan 2026 (actual)
- Primary completion
- Dec 2028 (estimated)
- Study completion
- Dec 2030 (estimated)
- First posted
- 23 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The overall objective of this study is to evaluate the pharmacokinetics (PK), efficacy, and safety of encaleret in pediatric participants from birth to 17 years of age with ADH1.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Sequential
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Encaleret | Experimental | Drug: EncaleretParticipants will receive encaleret dosing in Period 1 (6 days), Period 2 (20 weeks) and Period 3 (4 weeks). Following completion of Period 3, participants will have the option to enter a long-term extension (LTE) to continue encaleret for an additional approximately 24 months or until the sponsor decides to end the study, whichever occurs first. |
Who may qualify
- Ages
- 0 to 17 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child
Key inclusion criteria (4 listed)
- Provide written informed consent (if legally permitted), or have written informed consent from a parent/legal guardian and provide assent (where required and as appropriate per local requirements)
- Have a documented pathogenic or likely pathogenic activating variant, or variant of uncertain significance of the calcium-sensing receptor (CASR), associated with biochemical findings of hypoparathyroidism at screening or a documented history of hypoparathyroidism as manifested by hypocalcemia and intact parathyroid hormone (PTH) <40 picogram per milliliter (pg/mL) (4.2 picomoles per liter [pmol/L])
- Have at least 1 symptom or sign of hypoparathyroidism at screening or a documented history of symptoms or signs of hypoparathyroidism
- Be on ADH1 treatment for at least 6 months before screening for cohorts 1 to 3, or for at least 3 months before screening for cohort 4
Key exclusion criteria (8 listed)
- History of thyroid or parathyroid surgery
- History of renal transplantation
- History of cancer (except thyroid cancer, basal cell skin cancer, or squamous cell skin cancer), skeletal malignancies, bone metastases, irradiation (radiotherapy) to the skeleton, chemotherapy with alkylating agents, Paget disease, fibrous dysplasia, chronic osteomyelitis, bone infarcts, benign bone tumors with curettage and bone grafts, retinoblastoma, or Li-Fraumeni syndrome within 5 years before screening
- Received any investigational medicinal product within 30 days or 5 half-lives before Day 1, whichever is longer, or is in follow-up for another interventional clinical study during screening
- Treatment with a strong P-glycoprotein (P-gp) inhibitor within 300 days before screening for amiodarone or within 30 days before screening for any other strong P-gp inhibitor
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| EncaleretOral tablets, age-appropriate pediatric formulation (currently under development). | Drug | Encaleret |
Primary outcome
Period 1: Maximum Plasma Concentration (Cmax) of Encaleret and Metabolites M1, and M3
Time frame: 5 days
Period 1: Area Under the Plasma Concentration-time Curve (AUC) of Encaleret and Metabolites M1, and M3
Time frame: 5 days
Period 3: Number of Participants with Albumin-corrected Blood Calcium (cCa) and Urinary Calcium (UCa) Excretion Response
Time frame: Week 25
23 secondary outcomes
Period 1: Change from Baseline in Blood cCa
Time frame: Baseline up to Day 5
Period 1: Change from Baseline in Blood Intact Parathyroid Hormone (iPTH) Concentration
Time frame: Baseline up to Day 5
Period 1: Change from Baseline in Blood Phosphate Concentration
Time frame: Baseline up to Day 5
Period 1: Change from Baseline in Blood 1,25-(OH)2 Vitamin D Concentration
Time frame: Baseline up to Day 5
Period 1: Change from Baseline in Blood Magnesium Concentration
Time frame: Baseline up to Day 5
Period 1: Change from Baseline in 24-hour UCa in Toilet Trained Participants
Time frame: Baseline up to Day 5
Period 1: Change from Baseline in Spot Ratio of UCa/Urinary Creatinine (UCr) In Non-toilet Trained Participants
Time frame: Baseline up to Day 5
Period 3: Number of Participants with Blood iPTH Within the Reference Range
Time frame: Week 25 (post-dose)
Period 3: Number of Participants with Blood Phosphate Within the Reference Range
Time frame: Week 25
Period 3: Number of Participants with Blood Magnesium Within the Reference Range
Time frame: Week 25
Period 3: Number of Participants with Blood 1,25-(OH)2 Vitamin D Within the Reference Range
Time frame: Week 25
Periods 1, 2, and 3: Change from Baseline in Short Form-10 Health Survey for Children (SF-10) in Participants Aged ≥6 Years
Time frame: Baseline up to Week 25
Periods 1, 2, and 3: Dose of Calcium Supplements and/or Active Vitamin D Analogs Used as Rescue Therapy
Time frame: 25 weeks
Periods 1, 2, and 3: Dosing Frequency of Calcium Supplements and/or Active Vitamin D Analogs Used as Rescue Therapy
Time frame: 25 weeks
Periods 1, 2, 3, and LTE: Number of Participants with Adverse Events (AEs) and Serious AEs (SAEs)
Time frame: 145 weeks
LTE: Change from Baseline in Blood cCa
Time frame: Baseline up to 145 weeks
LTE: Change from Baseline in Blood iPTH Concentration
Time frame: Baseline up to 145 weeks
LTE: Change from Baseline in Blood Phosphate Concentration
Time frame: Baseline up to 145 weeks
LTE: Change from Baseline in Blood 1,25-(OH)2 Vitamin D Concentration
Time frame: Baseline up to 145 weeks
LTE: Change from Baseline in Blood Magnesium Concentration
Time frame: Baseline up to 145 weeks
LTE: Change from Baseline in 24-hour UCa In Toilet Trained Participants
Time frame: Baseline up to 145 weeks
LTE: Change from Baseline in Spot Ratio of UCa/UCr In Non-toilet Trained Participants
Time frame: Baseline up to 145 weeks
LTE: Change from Baseline in SF-10 in Participants Aged ≥6 Years
Time frame: Baseline up to 145 weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Apr 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Calcilytix Medical Director study director
Calcilytix Therapeutics, Inc., a BridgeBio company
6 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2/3 study testing Encaleret in people with Autosomal Dominant Hypocalcemia Type 1 (ADH1), run by Calcilytix Therapeutics, Inc., a BridgeBio company at 6 sites in 2 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 22 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 6 sites in United States, United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Medical Information (650-600-3610, MedInfo@bridgebio.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Period 1: Maximum Plasma Concentration (Cmax) of Encaleret and Metabolites M1, and M3 (time frame: 5 days). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 Apr 2026.