Encaleret for Hypocalcemia

(CALIBRATE Trial)

Not currently recruiting at 32 trial locations
MI
Overseen ByMedical Information
Age: Any Age
Sex: Any
Trial Phase: Phase 3
Sponsor: Calcilytix Therapeutics, Inc., a BridgeBio company
No Placebo GroupAll trial participants will receive the active study treatment (no placebo)
Pivotal Trial (Near Approval)This treatment is in the last trial phase before FDA approval
Prior Safety DataThis treatment has passed at least one previous human trial

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests a new treatment called encaleret for individuals with Autosomal Dominant Hypocalcemia Type 1 (ADH1), a condition that lowers calcium levels in the blood. Researchers aim to evaluate the effectiveness and safety of encaleret compared to the usual care, which includes calcium supplements and active Vitamin D. Participants with specific gene changes related to ADH1 who have experienced its symptoms may be suitable candidates. The goal is to determine if encaleret can better manage calcium levels in these patients. As a Phase 3 trial, this study represents the final step before FDA approval, offering participants a chance to contribute to potentially groundbreaking treatment advancements.

Will I have to stop taking my current medications?

Yes, you may need to stop taking certain medications. If you are on thiazide diuretics, phosphate binders, magnesium or potassium supplements, or potassium-sparing diuretics, you will need to discontinue them before starting the trial. There are specific timeframes for stopping these medications, such as at least 14 days for thiazides and at least one day for phosphate binders.

Will I have to stop taking my current medications?

Yes, you may need to stop taking certain medications. If you are on thiazide diuretics, you must stop them at least 14 days before a specific visit. You also need to stop phosphate binders (except calcium salts), magnesium or potassium supplements, and potassium-sparing diuretics before starting the trial.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research shows that encaleret is generally safe for people. Studies have found that encaleret helps maintain balanced calcium levels in individuals with Autosomal Dominant Hypocalcemia Type 1 (ADH1). In earlier research, participants used encaleret for up to 18 months without major problems. No serious side effects were reported, indicating its safety for long-term use. These findings provide promising evidence about the safety of encaleret for those considering participation in a clinical trial.12345

Why do researchers think this study treatment might be promising for hypocalcemia?

Unlike the standard of care for hypocalcemia, which involves calcium supplements and active Vitamin D, encaleret offers a unique approach by directly adjusting calcium levels in the body. Researchers are excited about encaleret because it targets the underlying regulation of calcium, potentially allowing for more precise control of calcium levels. This could lead to more effective management of hypocalcemia symptoms with fewer side effects compared to traditional treatments.

What evidence suggests that this trial's treatments could be effective for hypocalcemia?

Research has shown that encaleret, which participants in this trial may receive, may help treat Autosomal Dominant Hypocalcemia Type 1 (ADH1). In one study, encaleret helped maintain stable calcium levels in patients over time. This stability suggests it could be a reliable way to manage the condition. Reports noted that patients taking encaleret experienced significant improvements in their mineral balance. Overall, these findings support the idea that encaleret can be effective for people with ADH1.12678

Who Is on the Research Team?

CM

Calcilytix Medical Director

Principal Investigator

Calcilytix Therapeutics, Inc., a BridgeBio company

Are You a Good Fit for This Trial?

This trial is for people with a genetic variant causing hypoparathyroidism (ADH1), aged 16-18 with closed growth plates, not on certain diuretics or supplements, and meeting specific treatment criteria. Excluded are those recently on PTH treatments, had seizures or thyroid surgery, pregnant/nursing women, low Vitamin D levels, certain viral infections, or severely reduced kidney function.

Inclusion Criteria

I am 16-17 years old and my growth plates are closed.
I have shown symptoms or signs of ADH1.
Participants must meet SoC Optimization criteria as defined in the protocol
See 5 more

Exclusion Criteria

Pregnant or nursing (lactating) women, where pregnancy is confirmed by a positive beta-human chorionic gonadotropin (β-hCG) laboratory test
I have had surgery on my thyroid or parathyroid.
My kidney function is low, with an eGFR below 30 mL/min/1.73 m^2.
See 5 more

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

Up to 6 weeks

SoC Optimization

Participants undergo a standard of care optimization phase to confirm eligibility for the main study

Up to 15 weeks

SoC Maintenance

Participants maintain their standard of care dose, adjusted only for safety concerns

4 weeks

Randomized Treatment

Participants are randomized to receive either encaleret or SoC treatment, with doses adjusted based on blood calcium levels

20 weeks

Dose Maintenance

Participants maintain their dose of encaleret or SoC

4 weeks

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

Long-Term Extension (optional)

Participants may opt into continuation of encaleret treatment long-term

Up to 48 months

What Are the Treatments Tested in This Trial?

Interventions

  • Calcium supplements and active Vitamin D
  • Encaleret
Trial Overview The study aims to compare the effectiveness and safety of encaleret against standard care in treating ADH1. Participants will receive either encaleret or the usual treatment without knowing which one they're getting to measure differences in health outcomes.
How Is the Trial Designed?
2Treatment groups
Experimental Treatment
Group I: Standard of Care (SoC)Experimental Treatment1 Intervention
Group II: EncaleretExperimental Treatment1 Intervention

Find a Clinic Near You

Who Is Running the Clinical Trial?

Calcilytix Therapeutics, Inc., a BridgeBio company

Lead Sponsor

Trials
3
Recruited
180+

Published Research Related to This Trial

WR-2721, a compound used to protect normal tissues during radio- and chemotherapy, causes hypocalcemia by reducing plasma calcium levels and inhibiting parathyroid hormone (PTH) secretion, as shown in studies with rats.
The hypocalcemic effect of WR-2721 is not dependent on phosphate presence or hypomagnesemia, indicating it has unique mechanisms that inhibit renal calcium reabsorption independently of PTH.
Inhibition of parathyroid hormone secretion and parathyroid hormone-independent diminution of tubular calcium reabsorption by WR-2721, a unique hypocalcemic agent.Hirschel-Scholz, S., Caverzasio, J., Bonjour, JP.[2018]
In a phase 1 study involving 11 pediatric hemodialysis patients aged 2 to 18 years, a single dose of etelcalcetide (0.035 mg/kg) was well tolerated, with adverse events consistent with known safety profiles in adults, and no serious adverse events reported.
Etelcalcetide effectively reduced serum intact parathyroid hormone (iPTH) levels, with significant decreases observed within 4 hours post-dose, indicating its potential efficacy in managing secondary hyperparathyroidism in children.
Phase 1, single-dose study to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of etelcalcetide in pediatric patients with secondary hyperparathyroidism receiving hemodialysis.Sohn, W., Salusky, IB., Schmitt, CP., et al.[2021]
Cinacalcet effectively lowers serum calcium and parathyroid hormone (PTH) levels in patients with Primary Hyperparathyroidism (PHPT), with a significant normalization of serum calcium observed in 76% of patients across 17 cohort studies and 4 randomized controlled trials (RCTs) involving a total of 940 participants.
The treatment is considered safe, showing no significant difference in overall adverse events compared to placebo, and it is particularly beneficial for patients who cannot undergo parathyroidectomy.
The efficacy and safety of cinacalcet in primary hyperparathyroidism: a systematic review and meta-analysis of randomized controlled trials and cohort studies.Chandran, M., Bilezikian, JP., Lau, J., et al.[2022]

Citations

News DetailsBridgeBio Reports Positive Phase 3 Topline Results for Encaleret in Patients with Autosomal Dominant Hypocalcemia Type 1. October 29, 2025.
NCT05680818 | Efficacy and Safety of Encaleret ...The primary purpose of the study is to understand the effectiveness, safety, and tolerability of encaleret when compared to standard of care (SoC) treatment ...
Results From A Phase 2 Study Over 18 Months Of Encaleret ...The consistent and sustained results from over 18 months of outpatient encaleret treatment are clinically meaningful and support Phase 3 ...
OR36-06 Sustained Normalization of Mineral Homeostasis ...The mean±SD encaleret sulfate dose at the end of P3, Week 24 (P3W24) was 86±70mg BID, remaining stable at LTE Month 12 (LTEM12) (n=11) (71±62mg ...
A Phase 2B, Open-Label, Dose-Ranging Study of ...This Phase 2b, open-label, dose-ranging study will evaluate the safety, tolerability, pharmacodynamics, and pharmacokinetics of the calcilytic encaleret (CLTX- ...
Safety, Tolerability, and Efficacy of Encaleret in Participants ...The primary purpose of this study is to evaluate the safety, tolerability and effectiveness of encaleret in participants with Autosomal Dominant Hypocalcemia ...
Encaleret for ADH1 – ENDO 2022 Ph2b dataEncaleret is currently under clinical development, and its safety and efficacy ... Periods 2 and 3 Results (n=13): BID Encaleret restored and maintained.
Encaleret (CLTX-305) sustained normalization of mineral ...Encaleret (CLTX-305) sustained normalization of mineral homeostasis in patients with autosomal dominant hypocalcemia type 1 over 18 months in a phase 2 study [ ...
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