HypoparathyroidismPhase 3RECLAIM-HPNCT07805356
Efficacy, Safety, and Tolerability of Encaleret in Participants With Chronic Hypoparathyroidism
A Phase 3 study testing Encaleret in people with Hypoparathyroidism and Chronic Hypoparathyroidism, run by Calcilytix Therapeutics, Inc., a BridgeBio company at 5 sites in 2 countries.
Trial 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). Read more about this study
- Who is it for?
- Ages 16 years and older
- Conditions the study is for
- Hypoparathyroidism, Chronic Hypoparathyroidism
- What is being tested?
- Encaleret
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 160 participants
- Where
- 5 sitesin 2 countries
- Study dates
- 31 Aug 2026to Jan 2033
- Phase
- Phase 3
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 16 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- 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:
- Calcitriol ≥0.5 micrograms (μg)/day or alfacalcidol ≥1.0 μg/day
- Elemental calcium ≥800 milligrams (mg)/day (for example, calcium citrate, calcium carbonate)
Show all 11Show fewer
- 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.
Who cannot join
- 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.
Trial locations and contacts
5 sites in 2 countries. Contact the study team or a site near you to ask about taking part.
5 sites in 2 countries
United States4 sites, 4 recruiting
- Recruiting
Calcilytix Therapeutics, Inc., a BridgeBio Company, Investigational Site
El Paso, Texas, 79935
- Recruiting
Calcilytix Therapeutics, Inc., a BridgeBio Company, Investigational Site
Greenville, North Carolina, 27834
- Recruiting
Calcilytix Therapeutics, Inc., a BridgeBio Company, Investigational Site
Morehead City, North Carolina, 28557
- Recruiting
Calcilytix Therapeutics, Inc., a BridgeBio Company, Investigational Site
Reno, Nevada, 89511
Canada1 site, 1 recruiting
- Recruiting
Calcilytix Therapeutics, Inc., a BridgeBio Company, Investigational Site
Oakville, Ontario, L6M 1M1
About this study
Official title: A Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study With an Open-Label Extension Investigating Efficacy, Safety, and Tolerability of Encaleret in Participants With Chronic Hypoparathyroidism
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
- Being tested
- Encaleret, Placebo
- Keywords
- Chronic Hypoparathyroidism, Hypoparathyroidism, Encaleret
- Medical subject headings
- Hypoparathyroidism
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
EncaleretDrug
Oral tablets
PlaceboDrug
Oral tablets
| Study group | Role | What they receive |
|---|---|---|
| Encaleret | Experimental | 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. Receives: Drug: Encaleret |
| Placebo | Placebo comparator | 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. Receives: Drug: Encaleret; Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of Responders who Achieve Both Albumin-Corrected Blood Calcium (cCa) and 24-hour Urine Calcium (UCa) Within the Protocol-defined Target Range
Measured: Week 24
Secondary outcomes (14)
Number of Participants With cCa Within Protocol-defined Range
Measured: Week 24
Change From Baseline to Week 24 in cCa
Measured: Baseline, Week 24
Absolute Value of cCa at Week 24
Measured: Week 24
Number of Participants With 24-hour UCa Below the Sex-specific Upper Reference Limits (Protocol-defined Range)
Measured: Week 24
Change from Baseline to Week 24 in 24-hour UCa
Measured: Baseline, Week 24
Absolute Value of 24-hour UCa at Week 24
Measured: Week 24
Number of Participants Who Meet the Primary Endpoint (Biochemical Response) and Have a Reduction From Baseline in Calcium Supplements Dose
Measured: Baseline up to Week 24
Percent Change From Baseline to Week 24 in Daily Intake of Calcium Supplements Among the Participants Who Meet the Primary Endpoint (Biochemical Response)
Measured: Baseline, Week 24
Number of Participants With Calcium Independence
Measured: Week 20 to Week 24
Change from Baseline in Signs and Symptoms of Hypoparathyroidism, Based on Participants' Responses
Measured: Baseline, Week 24
Number of Participants Who Meet the Primary Endpoint (Biochemical Response) and Have a Reduction From Baseline in Active Vitamin D Dose
Measured: Week 24
Percent Change From Baseline in Daily Intake of Active Vitamin D Among the Participants Who Meet the Primary Endpoint (Biochemical Response)
Measured: Baseline, Week 24
Number of Participants Who Meet the Primary Endpoint (Biochemical Response) and Has Active Vitamin D Independence
Measured: Week 24
Number of Participants Who Meet Specific Protocol-defined Criteria or Calcium and Vitamin D Analysis
Protocol-defined criteria which include the following: cCa within protocol-defined range, 24-hour UCa below the sex-specific upper reference limits (protocol-defined range), independence from conventional therapy, no increase in the study drug dose, and no missing active vitamin D and calcium supplementation data.
Measured: Week 20 to Week 24
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 Sep 2026
- Study start31 Aug 2026 (estimated)
- Primary completionJan 2028 (estimated)
- Study completionJan 2033 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for HypoparathyroidismStudies 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 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 160 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
- NCT07805356
- Sponsor's protocol ID
- CLTX-305-304
- Other IDs
- 2026-526140-13, U1111-1341-6994
- Acronym
- RECLAIM-HP
- Status last verified
- Sep 2026
- First submitted
- 1 Sep 2026
- Last updated
- 16 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No