Pharmacokinetics, Efficacy, and Safety of Encaleret in Pediatric Participants With Autosomal Dominant Hypocalcemia Type 1 (ADH1)

NCT07080385 | Recruiting Phase 2 DMC FDA Drug

• 1 other identifier: CLTX-305-303
• Study Type: interventional
• Target: 28
• Locations: 2 countries
• Sites: 6

Brief 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.

Conditions

Autosomal Dominant Hypocalcemia Type 1 (ADH1)

Keywords

Autosomal dominant hypocalcemia type 1; ADH1; Encaleret

Outcome Measures

Primary Outcomes (3)

• Period 1: Maximum Plasma Concentration (Cmax) of Encaleret and Metabolites M1, and M3

  5 days

• Period 1: Area Under the Plasma Concentration-time Curve (AUC) of Encaleret and Metabolites M1, and M3

  5 days

• Period 3: Number of Participants with Albumin-corrected Blood Calcium (cCa) and Urinary Calcium (UCa) Excretion Response

  Week 25

Secondary Outcomes (23)

• Period 1: Change from Baseline in Blood cCa

  Baseline up to Day 5

• Period 1: Change from Baseline in Blood Intact Parathyroid Hormone (iPTH) Concentration

  Baseline up to Day 5

• Period 1: Change from Baseline in Blood Phosphate Concentration

  Baseline up to Day 5

• Period 1: Change from Baseline in Blood 1,25-(OH)2 Vitamin D Concentration

  Baseline up to Day 5

• Period 1: Change from Baseline in Blood Magnesium Concentration

  Baseline up to Day 5

Study Arms (1)

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.

Drug: Encaleret

Interventions

Encaleret DRUG

Oral tablets, age-appropriate pediatric formulation (currently under development).

Encaleret

Eligibility Criteria

• Age: 0 Years - 17 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Calcilytix Therapeutics, Inc., a BridgeBio company: lead

Study Sites (6)

Yale University

New Haven, Connecticut, 06511, United States

RECRUITING

Children's National Medical Center

Washington D.C., District of Columbia, 20010, United States

RECRUITING

Nemours Children's Health

Jacksonville, Florida, 32207, United States

RECRUITING

The Children's Hospital of Philadelphia

Philadelphia, Pennsylvania, 19104, United States

RECRUITING

Royal London Hospital

London, E1 1FR, United Kingdom

RECRUITING

Royal Manchester Children's Hospital

Manchester, M13 9WL, United Kingdom

RECRUITING

Study Officials

• Calcilytix Medical Director

  Calcilytix Therapeutics, Inc., a BridgeBio company

  STUDY DIRECTOR

Central Study Contacts

Medical Information

CONTACT

650-600-3610; MedInfo@bridgebio.com

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SEQUENTIAL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 14, 2025
• First Posted: July 23, 2025
• Study Start: January 30, 2026
• Primary Completion (Estimated): December 1, 2028
• Study Completion (Estimated): December 1, 2030
• Last Updated: April 22, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

US (4); GB (2)