Recruiting

Phase 3

EncaleretEfficacy, Safety, and Tolerability of Encaleret in Participants With Chronic Hypoparathyroidism

Sponsor:

Calcilytix Therapeutics, Inc., a BridgeBio company

Code:

NCT07805356

Conditions

Hypoparathyroidism

Chronic Hypoparathyroidism

Eligibility Criteria

Sex: All

Age: 16+

Healthy Volunteers: Not accepted

Interventions

Encaleret

Placebo

Study Details

Brief summary:

The aim of the study is to evaluate the efficacy, safety, and tolerability of orally administered encaleret tablets in participants with chronic hypoparathyroidism (HP).

Conditions

Hypoparathyroidism

Chronic Hypoparathyroidism

Study ID

NCT07805356

Start date

Aug 31, 2026

Status verified date

Sep, 2026

Completion date

Jan, 2033

Anticipated

Primary completion date

Jan, 2028

Anticipated

Eligibility Criteria

Sex: All

Age: 16+

Healthy Volunteers: Not accepted

Key Inclusion Criteria:

Participants must have had a clinically confirmed diagnosis of chronic HP, with disease duration of at least 26 weeks prior to screening. Cause of chronic HP can be postsurgical, autoimmune or idiopathic.
For participants with nonsurgical chronic HP etiology, sufficient documentation that the participant does not harbor any variants in calcium-sensing receptor (CASR) or GNA11 that are classified as pathogenic, likely pathogenic, or of uncertain significance, with the exception of benign common polymorphisms (CASR A986S and R990G) is needed.
Participants must be on stable doses of calcium and active vitamin D supplementation at or above the following minimum thresholds for at least 6 weeks prior to screening.

For participants enrolled in study sites outside Japan:

1. Calcitriol ≥0.5 micrograms (μg)/day or alfacalcidol ≥1.0 μg/day
2. Elemental calcium ≥800 milligrams (mg)/day (for example, calcium citrate, calcium carbonate)

Participants must meet the following criteria during screening: cCa within 7.8 to 9.5 mg/deciliter (dL) and 24-hour UCa ≥300 mg/day (males) or ≥250 mg/day (females).
Participants have serum 25-hydroxy (OH) vitamin D concentration of 20 to 80 nanograms (ng)/milliliter (mL) (50-200 nanomoles \[nmol\]/liter \[L\]).
Participants have serum magnesium concentration within the reference range.
Participants on thiazide or loop diuretics must be able to discontinue them during the first 24 weeks of study (treatment).
Participants must be capable of giving signed informed consent or assent, which includes compliance with the requirements and restrictions listed in the informed consent form and in this protocol.

Key Exclusion Criteria:

Genetically confirmed diagnosis of autosomal dominant hypocalcemia type 1 (ADH1) or autosomal dominant hypocalcemia type 2 (ADH2) due to activating variants in CASR or GNA11, respectively.
History of hypocalcemic seizure in the 3 months prior to screening.
History of cancer (except non-melanoma skin cancer) or bone metastases in the 5 years prior to screening.
Prior skeletal irradiation, chemotherapy with alkylating agents, or diagnosis of Paget's disease, fibrous dysplasia, chronic osteomyelitis, bone infarcts, benign bone tumors with curettage and grafting, retinoblastoma, or Li-Fraumeni syndrome.
Presence or history of any disease or condition (for example, drug or alcohol dependence) that, in the view of the investigator, would affect the participant's safety or places the participant at high risk of poor treatment compliance or of not completing the study.

Other protocol-defined inclusion/exclusion criteria apply.

Study Design

Enrollment

160 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Encaleret

Participants will receive encaleret during the 24-week double-blind treatment period. Participants will then have the option to enter an open-label long-term extension (LTE) period to continue receiving encaleret for up to 192 weeks.

placebo comparator: Placebo

Participants will receive placebo during the 24-week double-blind treatment period. Participants will then have the option to enter an open-label LTE period to receive encaleret for up to 192 weeks.

Interventions

Encaleret

Oral tablets

Placebo

Oral tablets

Primary outcome measure

Number of Responders who Achieve Both Albumin-Corrected Blood Calcium (cCa) and 24-hour Urine Calcium (UCa) Within the Protocol-defined Target Range [ Time Frame: Week 24 ]

Central Contacts and Locations

Central contacts

Medical Information

650-600-3610 MedInfo@bridgebio.com

Locations