A Trial Investigating the Safety, Tolerability and Efficacy of TransCon PTH Administered Daily in Adults With Hypoparathyroidism (PaTHway)

January 21, 2026 updated by: Ascendis Pharma Bone Diseases A/S

PaTHway TRIAL: A Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Parallel Group Trial, With an Open-Label Extension, Investigating the Safety, Tolerability and Efficacy of TransCon PTH Administered Subcutaneously Daily in Adults With Hypoparathyroidism

During the first 26 weeks of the trial, participants were randomly assigned to one of two groups: one group received TransCon PTH and one group received placebo. All participants started with study drug at a dose of 18 mcg/day and were individually and progressively titrated to an optimal dose in dose increments of 3 mcg/day. TransCon PTH or placebo were administered as a subcutaneous injection using a pre-filled injection pen. Neither trial participants nor their doctors knew who had been assigned to each group. After the 26 weeks, participants continued in the trial as part of a long-term extension study. During the extension, all participants received TransCon PTH, with the dose adjusted to their individual needs. This was a global trial that was conducted in the United States, Canada, Germany, Denmark, Norway, Italy, and Hungary.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
84

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Nova Scotia
      • Halifax, Nova Scotia, Canada, B3H 2Y9
        • Ascendis Pharma Investigational Site
    • Ontario
      • Oakville, Ontario, Canada, L6M 1M1
        • Ascendis Pharma Investigational Site
    • Quebec
      • Québec, Quebec, Canada, G1V 4G2
        • Ascendis Pharma Investigational Site
  • Denmark
    • Capital Region
      • Copenhagen, Capital Region, Denmark, 2100
        • Ascendis Pharma Investigational Site
    • Central Jutland
      • Aarhus, Central Jutland, Denmark, 8200
        • Ascendis Pharma Investigational Site
  • Germany
    • Saxony
      • Dresden, Saxony, Germany, 01307
        • Ascendis Pharma Investigational Site
  • Hungary
      • Budapest, Hungary, 1083
        • Ascendis Pharma Investigational Site
    • Csongrád megye
      • Szeged, Csongrád megye, Hungary, 6720
        • Ascendis Pharma Investigational Site
  • Italy
    • Emilia-Romagna
      • Bologna, Emilia-Romagna, Italy, 40138
        • Ascendis Pharma Investigational Site
    • Lazio
      • Rome, Lazio, Italy, 00128
        • Ascendis Pharma Investigational Site
    • Piacenza
      • Pisa, Piacenza, Italy, 56126
        • Ascendis Pharma Investigational Site
  • Norway
      • Oslo, Norway, 0176
        • Ascendis Pharma Investigational Site
  • United States
    • California
      • San Francisco, California, United States, 94143
        • Ascendis Pharma Investigational Site
    • Illinois
      • Chicago, Illinois, United States, 60637
        • Ascendis Pharma Investigational Site
    • Minnesota
      • Rochester, Minnesota, United States, 55905
        • Ascendis Pharma Investigational Site
    • Nevada
      • Reno, Nevada, United States, 89511
        • Ascendis Pharma Investigational Site
    • New York
      • New York, New York, United States, 10032
        • Ascendis Pharma Investigational Site
    • North Carolina
      • Greenville, North Carolina, United States, 27834
        • Ascendis Pharma Investigational Site
    • Texas
      • Austin, Texas, United States, 78731
        • Ascendis Pharma Investigational Site
      • Fort Worth, Texas, United States, 76132
        • Ascendis Pharma Investigational Site
    • Washington
      • Spokane, Washington, United States, 99204
        • Ascendis Pharma Investigational Site

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Males and females, ≥18 years of age
  2. Subjects with postsurgical chronic HP, or auto-immune, genetic, or idiopathic HP for at least 26 weeks. Diagnosis of HP is established based on historic hypocalcemia in the setting of inappropriately low serum PTH levels

  3. Requirement for doses of SoC (e.g., calcitriol, alfacalcidol, calcium supplements) at or above a minimum threshold:

    • For countries other than Japan: requirement for a dose of calcitriol ≥0.5 μg/day, or alfacalcidol ≥1.0 μg/day and (elemental) calcium ≥800 mg/day (e.g., calcium citrate, calcium carbonate etc.) for at least 12 weeks prior to Screening. In addition, the dose of calcitriol, or alfacalcidol, or calcium should be stable for at least 5 weeks prior to Screening
    • For Japan: requirement for a dose of calcitriol ≥1.0 μg/day, or alfacalcidol ≥2.0 μg/day for at least 12 weeks prior to Screening. In addition, the dose of calcitriol or alfacalcidol should be stable for at least 5 weeks prior to Screening. In Japan only (due to local practice and dietary patterns), there is no requirement to exceed a minimum dose of calcium supplements

  4. Optimization of supplements prior to randomization to achieve the target serum levels of:

    • 25(OH) vitamin D levels of 20-80 ng/mL (49-200 nmol/L) and
    • Magnesium level in the normal range, or just below the normal range and
    • Albumin-adjusted or ionized sCa level in the normal range, or just below the normal range
  5. The subject demonstrates a 24-hour uCa excretion of ≥125 mg/24h (on a sample collected within 52 weeks prior to Screening or during the Screening Period)
  6. BMI 17- 40 kg/m2 at Screening
  7. If ≤25 years of age, radiological evidence of epiphyseal closure based on X-ray of nondominant wrist and hand
  8. Thyroid-stimulating hormone (TSH) within normal laboratory limits within the 6 weeks prior to Visit 1; if on suppressive therapy for a history of thyroid cancer, TSH level must be ≥0.2 mIU/mL
  9. If treated with thyroid hormone replacement therapy, the dose must have been stable for at least 5 weeks prior to Screening
  10. eGFR ≥30 mL/min/1.73 m2 during Screening
  11. Able to perform daily subcutaneous self-injections of study drug (or have a designee to perform injections) via a pre-filled injection pen
  12. Able and willing to provide written and signed informed consent in accordance with GCP

Exclusion Criteria:

  1. Impaired responsiveness to PTH (pseudohypoparathyroidism) which is characterized as PTH-resistance, with elevated PTH levels in the setting of hypocalcemia
  2. Any disease that might affect calcium metabolism or calcium-phosphate homeostasis or PTH levels other than HP, such as active hyperthyroidism; Paget disease of bone; severe hypomagnesemia; type 1 diabetes mellitus or poorly controlled type 2 diabetes mellitus (HbA1C >9%, documented HbA1C result drawn within 12 weeks prior to Screening is acceptable); severe and chronic liver, or renal disease; Cushing syndrome; multiple myeloma; active pancreatitis; malnutrition; rickets; recent prolonged immobility; active malignancy (other than low-risk well differentiated thyroid cancer or basal cell skin cancer); active hyperparathyroidism; parathyroid carcinoma within 5 years prior to Screening; acromegaly; or multiple endocrine neoplasia types 1 and 2
  3. High risk thyroid cancer within 2 years, requiring suppression of TSH <0.2 mIU/mL
  4. Use of loop diuretics, phosphate binders (other than calcium supplements), digoxin, lithium, methotrexate, biotin >30 μg/day, or systemic corticosteroids (other than as replacement therapy)
  5. Use of thiazide diuretic within 4 weeks prior to the 24-hour urine collection scheduled to occur within 1 week prior to Visit 1
  6. Use of PTH-like drugs (whether commercially available or through participation in an investigational trial), including PTH(1-84), PTH(1-34), or other N-terminal fragments or analogs of PTH or PTH-related protein, within 4 weeks prior to Screening
  7. Use of other drugs known to influence calcium and bone metabolism, such as calcitonin, fluoride tablets (>0.5 mg/day), strontium, or cinacalcet hydrochloride, within 12 weeks prior to Screening
  8. Use of osteoporosis therapies known to influence calcium and bone metabolism, i.e., bisphosphonate (oral or intravenous [IV]), denosumab, raloxifene, or romosozumab therapies within 2 years prior to Screening
  9. Non-hypocalcemic seizure disorder with a history of a seizure within 26 weeks prior to Screening
  10. Increased risk for osteosarcoma, such as those with Paget's disease of bone or unexplained elevations of alkaline phosphatase, hereditary disorders predisposing to osteosarcoma, or with a prior history of substantial external beam or implant radiation therapy involving the skeleton
  11. Pregnant or lactating women
  12. Male who has a female partner who intends to become pregnant or is of childbearing potential and is unwilling to use adequate contraceptive methods during the trial
  13. Diagnosed drug or alcohol dependence within 3 years prior to Screening
  14. Disease processes that adversely affect gastrointestinal absorption, including but not limited to short bowel syndrome, significant small bowel resection, gastric bypass, tropical sprue, active celiac disease, active ulcerative colitis, active Crohn's disease, gastroparesis and AIRE gene mutations with malabsorption
  15. Chronic or severe cardiac disease within 26 weeks prior to Screening including but not limited to congestive heart failure, myocardial infarction, severe or uncontrolled arrhythmias, bradycardia (resting heart rate <48 beats/minute, unless chronic and asymptomatic), symptomatic hypotension or systolic BP <80 mm Hg or diastolic <40 mm Hg or poorly controlled hypertension (systolic BP >165 mm Hg or diastolic >95 mm Hg). In the absence of a prior history of hypertension, an isolated BP >165/95 in the setting of white coat hypertension/anxiety may not be exclusionary and a measurement can be repeated prior to randomization
  16. Cerebrovascular accident within 5 years prior to Screening
  17. Within 26 weeks prior to Screening: acute colic due to nephrolithiasis, or acute gout. Subjects with asymptomatic renal stones are permitted
  18. Participation in any other interventional trial in which receipt of investigational drug or device occurred within 8 weeks (or within 5.5 times the half-life of the investigational drug (whichever comes first) prior to Screening
  19. Any disease or condition that, in the opinion of the investigator, may require treatment or make the subject unlikely to fully complete the trial, or any condition that presents undue risk from the investigational product or procedures, including treated malignancies that are likely to recur within the approximate 3.5-year duration of the trial
  20. Known allergy or sensitivity to PTH or any of the excipients [metacresol, mannitol, succinic acid, NaOH/(HCl)]
  21. Likely to be non-compliant with respect to trial conduct
  22. Any other reason that in the opinion of the investigator would prevent the subject from completing participation or following the trial schedule

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Placebo Comparator: Placebo
Placebo for TransCon PTH delivered once daily by subcutaneous injection
Combination product: Placebo
Placebo is supplied as a solution containing the formulation buffer for TransCon PTH in a single-patient-use prefilled pen intended for subcutaneous injection.
Experimental: TransCon PTH
TransCon PTH at a starting dose of 18 mcg delivered once daily by subcutaneous injection and titrated to an optimal dose
Combination product: TransCon PTH
TransCon PTH drug product is supplied as a solution with a concentration of 0.3 mg PTH(1-34)/mL in a single-patient-use prefilled pen intended for subcutaneous injection.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Efficacy - Primary Endpoint During the Blinded Period
Time Frame: 26 weeks
The primary endpoint was a multi-component endpoint that included the percentage of participants who met the following criteria at 26 weeks of blinded treatment: 1) albumin-adjusted serum calcium measured within 4 weeks prior to and on Week 26 visit within the normal range (8.3 to 10.6 mg/dL), and 2) independence from active vitamin D within 4 weeks prior to Week 26 visit (i.e., all daily standing dose of active vitamin D equal to zero AND use of PRN ≤7 days during the 4 weeks), and 3) independence from therapeutic doses of calcium within 4 weeks prior to Week 26 visit (i.e., average daily standing dose of elemental calcium ≤600 mg AND use of PRN doses on ≤7 days during the 4 weeks), and 4) no increase in prescribed study drug within 4 weeks prior to Week 26 visit.
26 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change From Baseline to Week 26 in HPES Symptom - Physical Domain Score
Time Frame: 26 weeks
Change from baseline in Hypoparathyroidism Patient Experience Scale (HPES) Symptom - Physical Domain score, a disease-specific patient reported outcome, at 26 weeks of treatment. The measure uses a scale of 0-100 and values represent the change in scores from baseline. A decrease in HPES score denotes an improvement in hypoparathyroidism disease related physical symptoms.
26 weeks
Change From Baseline to Week 26 in HPES Symptom - Cognitive Domain Score
Time Frame: 26 weeks
Change from baseline in Hypoparathyroidism Patient Experience Scale (HPES) Symptom - Cognitive Domain score, a disease-specific patient reported outcome, at 26 weeks of treatment. The measure uses a scale of 0-100 and values represent the change in scores from baseline. A decrease in HPES score denotes an improvement in hypoparathyroidism disease related cognitive symptoms.
26 weeks
Change From Baseline to Week 26 in HPES Impact - Physical Functioning Domain Score
Time Frame: 26 weeks
Change from baseline in Hypoparathyroidism Patient Experience Scale (HPES) Impact - Physical Functioning Domain score, a disease-specific patient reported outcome, at 26 weeks of treatment. The measure uses a scale of 0-100 and values represent the change in scores from baseline. A decrease in HPES score denotes an improvement in physical functioning health-related quality of life.
26 weeks
Change From Baseline to Week 26 in HPES Impact - Daily Life Domain Score
Time Frame: 26 weeks
Change from baseline in Hypoparathyroidism Patient Experience Scale (HPES) Impact - Daily Life Domain score, a disease-specific patient reported outcome, at 26 weeks of treatment. The measure uses a scale of 0-100 and values represent the change in scores from baseline. A decrease in HPES score denotes an improvement in daily health-related quality of life.
26 weeks
Change From Baseline to Week 26 in SF-36 Physical Functioning Subscale Score
Time Frame: 26 weeks
Change from baseline in the 36-item Short Form Survey (SF-36) Physical Functioning subscale score, a generic health survey, at 26 weeks of treatment. The Physical Functioning subscale uses a range of 19-57.6 and values represent the change in scores from baseline. An increase in SF-36 score denotes an improvement in physical functioning health-related quality of life.
26 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Ascendis Pharma Bone Diseases A/S

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Aimee D Shu, MD, Ascendis Pharma A/S Medical Monitor/Medical Expert

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
February 16, 2021

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 12, 2022

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 21, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 6, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 6, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 8, 2021

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 9, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 21, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • TCP-304
  • 2020-003380-26 (EudraCT Number)

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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