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A Trial Investigating the Safety, Tolerability and Efficacy of TransCon PTH in Adults With Hypoparathyroidism

PaTH Forward: A Phase 2, 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

Status
Completed
Phases
Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04009291
Acronym
PaTH Forward
Enrollment
59
Registered
2019-07-05
Start date
2019-08-27
Completion date
2025-04-17
Last updated
2026-06-18

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Endocrine System Diseases, Hypoparathyroidism, Parathyroid Diseases

Keywords

Hypoparathyroidism, Parathyroid Hormone, PTH(1-34), Prodrug, Sustained Release, TransCon PTH, Parathyroid Hormone Replacement Therapy

Brief summary

During the first four weeks of the trial, participants were randomly assigned to one of four groups: three groups received fixed doses of TransCon PTH and one group received placebo. TransCon PTH or placebo were administered as a subcutaneous injection using a pre-filled injection pen. Neither trial participants nor their doctors know who has been assigned to each group. After the four weeks, participants continued in the trial as part of a long-term extension period. 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, Italy and Norway.

Interventions

COMBINATION_PRODUCTTransCon PTH

TransCon PTH drug product is supplied as a clear solution containing TransCon PTH with a nominal PTH(1-34) content of 0.3 mg/mL in a pre-filled pen intended for subcutaneous injection.

COMBINATION_PRODUCTPlacebo for TransCon PTH

Placebo is supplied as a clear solution containing the formulation buffer for TransCon PTH in a pre-filled pen intended for subcutaneous injection.

Sponsors

Ascendis Pharma A/S
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Intervention model description

Double-blind, placebo controlled, parallel group with subjects randomized into 4 treatment groups (1:1:1:1): TransCon PTH 15 mcg/day, TransCon PTH 18 mcg/day, TransCon PTH 21 mcg/day, placebo

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

1. Males and females aged ≥18 years. 2. Subjects with postsurgical chronic HP or auto-immune, genetic, or idiopathic HP for at least 26 weeks. 3. On a stable dose for at least 12 weeks (or 4 weeks if on Natpara as of September 2019) prior to Screening of: * ≥0.25 μg BID of calcitriol (active vitamin D) or ≥0.5 μg BID or ≥1.0 μg daily of alfacalcidol (active vitamin D), and * ≥400 mg BID calcium citrate or carbonate. 4. Optimization of supplements prior to randomization to achieve the target levels of: * 25(OH) vitamin D levels of 30-70 ng/mL (75-175 pmol/mL) and * Magnesium level within the normal range and * Albumin-adjusted or ionized serum calcium (sCa) level in the lower half of the normal range. 5. BMI 17-40 kg/m2 at Visit 1. 6. If ≤25 years of age, radiological evidence of epiphyseal closure based on x-ray of non-dominant wrist and hand. 7. eGFR \>30 mL/min/1.73m2 during Screening. 8. Thyroid-stimulating hormone (TSH) within normal laboratory limits within the 12 weeks prior to Visit 1; if on suppressive therapy for thyroid cancer, TSH level must be ≥0.2 μIU/mL. 9. If treated with thyroid hormone replacement therapy, the dose must be stable for at least 12 weeks prior to Visit 1. 10. Able to perform daily subcutaneous self-injections of study drug (or have a designee perform injection) via a pre-filled injection pen. 11. Written, signed, informed consent of the subject.

Exclusion criteria

1. Known activating mutation in the calcium-sensing receptor (CaSR) gene. 2. Impaired responsiveness to PTH (pseudohypoparathyroidism) which is characterized as PTH-resistance, with elevated PTH Levels in the setting of hypocalcemia. 3. Any disease that might affect calcium metabolism or calcium-phosphate homeostasis or PTH levels other than HP, such as active hyperthyroidism; Paget's disease; hypomagnesemia; type 1 diabetes mellitus or poorly controlled type 2 diabetes mellitus; severe and chronic cardiac, liver, or renal disease; Cushing syndrome; rheumatoid arthritis; multiple myeloma; active pancreatitis; malnutrition; rickets; recent prolonged immobility; active malignancy (other than low-risk well differentiated thyroid cancer or basal cell skin cancer); parathyroid carcinoma within 5 years prior to Screening; acromegaly; multiple endocrine neoplasia types 1 and 2. 4. Use of loop diuretics, phosphate binders (other than calcium carbonate/calcium citrate), digoxin, lithium, methotrexate, or systemic corticosteroids (other than replacement therapy). 5. Use of thiazide diuretic within 4 weeks prior to the Screening 24-hour urine collection or the first dose adjustment of SOC during Screening. 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 5 weeks prior to Visit 1. 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 Visit 1. 8. Use of bisphosphonates (oral or IV) or denosumab within 2 years prior to Visit 1. 9. Non-hypocalcemic seizure disorder with a history of a seizure within 26 weeks prior to Visit 1. 10. Increased risk for osteosarcoma, such as those with Paget's disease of bone or unexplained elevations of alkaline phosphatase, open epiphyses, 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. Note: Highly effective contraception (see Appendix 7) is required for sexually active women of childbearing potential during the trial and for 2 weeks after the last dose of study drug, and pregnancy testing will be performed throughout the trial. Sexually active women of childbearing potential who are unwilling to use highly effective contraception are excluded from the trial. 12. Diagnosis of drug or alcohol dependence within 3 years prior to Visit 1. 13. Disease processes that may adversely affect gastrointestinal absorption including but not limited to short bowel syndrome, bowel resection, gastric bypass, tropical sprue, active celiac disease, active ulcerative colitis, gastroparesis, AIRE gene mutations with malabsorption, and active Crohn's disease. 14. Chronic or severe cardiac disease within 26 weeks prior to Visit 1 including but not limited to congestive heart failure, myocardial infarction, QTcF \>430 msec (males) or \>450 msec (females), severe or uncontrolled arrhythmias, bradycardia (resting heart rate \<50 beats/minute), symptomatic hypotension, systolic BP \<80 mm Hg or diastolic \<40 mm Hg, or poorly controlled hypertension (systolic BP \>150 mm Hg or diastolic \>95 mm Hg). 15. Cerebrovascular accident within 5 years prior to Visit 1. 16. History of renal colic or acute gout within 52 weeks prior to Visit 1. 17. Any disease or condition that, in the opinion of the investigator, may 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 1-year duration of the trial. 18. Known allergy or sensitivity to PTH or any of the excipients. 19. Participation in another clinical trial in which receipt of investigational drug or device occurred within 8 weeks (or at least 5.5 times the half-life of the investigational drug) prior to Visit 1. 20. Likely to be non-compliant with respect to trial conduct.

Design outcomes

Primary

MeasureTime frameDescription
Efficacy - Primary Endpoint During the Blinded PeriodWeek 4The percentage of subjects with albumin-adjusted serum calcium within the normal range, and spot morning fractional excretion of calcium (spot AM FECa) within normal range (≤2%) or a reduction by at least 50% from baseline, and not taking active vitamin D supplements, and taking ≤1000 mg/day of calcium supplements

Secondary

MeasureTime frameDescription
Efficacy - Key Secondary Endpoint During the Blinded PeriodWeek 4The percentage of subjects with albumin-adjusted serum calcium within the normal range, and spot AM FECa within the normal range (≤2%) or a reduction by at least 50% from baseline, and not taking active vitamin D supplements, and taking ≤ 500 mg/day of calcium supplements

Countries

Canada, Denmark, Germany, Italy, Norway, United States

Contacts

STUDY_DIRECTORMedical Director, MD

Ascendis Pharma A/S

Participant flow

Pre-assignment details

A total of 104 subjects were screened and 59 of these met eligibility criteria and were enrolled into the study. All participants who completed the 4-week double-blind period entered the open-label extension (OLE) period, where they received TransCon PTH.

Participants by arm

ArmCount
TransCon PTH 15 mcg
TransCon PTH 15 mcg delivered once daily by subcutaneous injection TransCon PTH: TransCon PTH drug product is supplied as a clear solution containing TransCon PTH with a nominal PTH(1-34) content of 0.3 mg/mL in a pre-filled pen intended for subcutaneous injection.
14
TransCon PTH 18 mcg
TransCon PTH 18 mcg delivered once daily by subcutaneous injection TransCon PTH: TransCon PTH drug product is supplied as a clear solution containing TransCon PTH with a nominal PTH(1-34) content of 0.3 mg/mL in a pre-filled pen intended for subcutaneous injection.
15
TransCon PTH 21 mcg
TransCon PTH 21 mcg delivered once daily by subcutaneous injection TransCon PTH: TransCon PTH drug product is supplied as a clear solution containing TransCon PTH with a nominal PTH(1-34) content of 0.3 mg/mL in a pre-filled pen intended for subcutaneous injection.
15
Placebo
Placebo mimicking 15, 18, or 21 mcg of TransCon PTH delivered once daily by subcutaneous injection Placebo for TransCon PTH: Placebo is supplied as a clear solution containing the formulation buffer for TransCon PTH in a pre-filled pen intended for subcutaneous injection.
15
Total59

Baseline characteristics

CharacteristicTransCon PTH 15 mcgTotalPlaceboTransCon PTH 21 mcgTransCon PTH 18 mcg
Age, Continuous47.03 years
STANDARD_DEVIATION 13.23
49.82 years
STANDARD_DEVIATION 12.094
51.80 years
STANDARD_DEVIATION 12.345
53.67 years
STANDARD_DEVIATION 11.287
46.58 years
STANDARD_DEVIATION 11.157
Body Mass Index27.08 kg/m^2
STANDARD_DEVIATION 5.723
27.57 kg/m^2
STANDARD_DEVIATION 4.415
28.30 kg/m^2
STANDARD_DEVIATION 3.775
26.12 kg/m^2
STANDARD_DEVIATION 4.647
28.76 kg/m^2
STANDARD_DEVIATION 3.148
Ethnicity (NIH/OMB)
Hispanic or Latino
0 Participants1 Participants0 Participants1 Participants0 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
14 Participants58 Participants15 Participants14 Participants15 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
0 Participants0 Participants0 Participants0 Participants0 Participants
Height166.92 cm
STANDARD_DEVIATION 8.806
165.75 cm
STANDARD_DEVIATION 9.52
164.07 cm
STANDARD_DEVIATION 10.368
165.37 cm
STANDARD_DEVIATION 10.961
166.71 cm
STANDARD_DEVIATION 8.385
Race/Ethnicity, Customized
American Indian or Alaska Native
0 Participants0 Participants0 Participants0 Participants0 Participants
Race/Ethnicity, Customized
Asian
0 Participants2 Participants0 Participants2 Participants0 Participants
Race/Ethnicity, Customized
Black or African American
0 Participants0 Participants0 Participants0 Participants0 Participants
Race/Ethnicity, Customized
Native Hawaiian or Other Pacific Islander
0 Participants0 Participants0 Participants0 Participants0 Participants
Race/Ethnicity, Customized
Other
0 Participants3 Participants0 Participants0 Participants3 Participants
Race/Ethnicity, Customized
Unknown
0 Participants0 Participants0 Participants0 Participants0 Participants
Race/Ethnicity, Customized
White
14 Participants54 Participants15 Participants13 Participants12 Participants
Sex: Female, Male
Female
12 Participants48 Participants12 Participants12 Participants12 Participants
Sex: Female, Male
Male
2 Participants11 Participants3 Participants3 Participants3 Participants
Weight76.58 kg
STANDARD_DEVIATION 22.479
76.32 kg
STANDARD_DEVIATION 16.869
76.43 kg
STANDARD_DEVIATION 14.256
72.26 kg
STANDARD_DEVIATION 18.621
80.04 kg
STANDARD_DEVIATION 11.279

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
EG002
affected / at risk
EG003
affected / at risk
EG004
affected / at risk
deaths
Total, all-cause mortality
0 / 140 / 150 / 150 / 150 / 59
other
Total, other adverse events
6 / 145 / 157 / 156 / 1557 / 59
serious
Total, serious adverse events
0 / 140 / 150 / 150 / 158 / 59

Outcome results

Primary

Efficacy - Primary Endpoint During the Blinded Period

The percentage of subjects with albumin-adjusted serum calcium within the normal range, and spot morning fractional excretion of calcium (spot AM FECa) within normal range (≤2%) or a reduction by at least 50% from baseline, and not taking active vitamin D supplements, and taking ≤1000 mg/day of calcium supplements

Time frame: Week 4

ArmMeasureValue (NUMBER)
TransCon PTH 15 mcgEfficacy - Primary Endpoint During the Blinded Period50.0 Percentage of participants
TransCon PTH 18 mcgEfficacy - Primary Endpoint During the Blinded Period40.0 Percentage of participants
TransCon PTH 21 mcgEfficacy - Primary Endpoint During the Blinded Period60.0 Percentage of participants
PlaceboEfficacy - Primary Endpoint During the Blinded Period26.7 Percentage of participants
Comparison: Fisher's exact test is used to compare differences in the proportion of subjects meeting the composite primary endpoint in the TransCon PTH versus pooled placebo groupp-value: =0.2635t-test, 2 sided
Comparison: Fisher's exact test is used to compare differences in the proportion of subjects meeting the composite primary endpoint in the TransCon PTH versus pooled placebo groupp-value: =0.6999t-test, 2 sided
Comparison: Fisher's exact test is used to compare differences in the proportion of subjects meeting the composite primary endpoint in the TransCon PTH versus pooled placebo groupp-value: =0.1394t-test, 2 sided
Secondary

Efficacy - Key Secondary Endpoint During the Blinded Period

The percentage of subjects with albumin-adjusted serum calcium within the normal range, and spot AM FECa within the normal range (≤2%) or a reduction by at least 50% from baseline, and not taking active vitamin D supplements, and taking ≤ 500 mg/day of calcium supplements

Time frame: Week 4

ArmMeasureValue (NUMBER)
TransCon PTH 15 mcgEfficacy - Key Secondary Endpoint During the Blinded Period50.0 Percentage of participants
TransCon PTH 18 mcgEfficacy - Key Secondary Endpoint During the Blinded Period26.7 Percentage of participants
TransCon PTH 21 mcgEfficacy - Key Secondary Endpoint During the Blinded Period60.0 Percentage of participants
PlaceboEfficacy - Key Secondary Endpoint During the Blinded Period20.0 Percentage of participants
Comparison: Fisher's exact test is used to compare differences in the proportion of subjects meeting the composite primary endpoint in the TransCon PTH versus pooled placebo groupp-value: =0.1281t-test, 2 sided
Comparison: Fisher's exact test is used to compare differences in the proportion of subjects meeting the composite primary endpoint in the TransCon PTH versus pooled placebo groupp-value: >0.9999t-test, 2 sided
Comparison: Fisher's exact test is used to compare differences in the proportion of subjects meeting the composite primary endpoint in the TransCon PTH versus pooled placebo groupp-value: =0.0604t-test, 2 sided

Source: ClinicalTrials.gov · Data processed: Jun 19, 2026