HypoparathyroidismPhase 2NCT06988670
A Phase 2 Trial Investigating the Safety, Tolerability and Efficacy of EXT608 in Adults With Hypoparathyroidism
A Phase 2 study testing EXT608 in people with Hypoparathyroidism, run by Extend Biosciences Inc. at 1 site in Argentina.
Trial summary
The goal of this clinical trial is to investigate the safety, tolerability and efficacy of EXT608 in adults with hypoparathyroidism. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Hypoparathyroidism
- What is being tested?
- EXT608
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 35 participants
- Where
- 1 siteArgentina
- Study dates
- 5 May 2025to May 2027
- Phase
- Phase 2
- Are there results?
- Not yet: the study is under way
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 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Ability to personally provide written, signed, and dated informed consent to participate in the study.
- An understanding, ability, and willingness to fully comply with study procedures and restrictions.
- Male or female between 18 and 65 years of age. Male participants with female partners of child bearing potential must agree to use barrier contraception, e.g., condoms plus spermicide, from administration of the study drug until at least 3 months after administration of the study drug. Abstinence from heterosexual intercourse from administration of study drug until at least 3 months after administration of study drug is acceptable if it is in accordance with the participant's lifestyle. Female participants should be either surgically sterile (had a bilateral tubal ligation, bilateral salpingectomy, bilateral oophorectomy, or hysterectomy), postmenopausal (defined as 12 months with no menses prior to screening and a serum follicle stimulating hormone in the postmenopausal range at screening), or, if of child bearing potential, must be non-lactating and willing to use a highly effective method of birth control for 30 days prior to administration of study drug and agree to continued use of this method until at least 3 months after administration of study drug.
- Participants have a history of hypoparathyroidism for 12 months at least, with PTH levels below the LLN with concomitant serum calcium < 9 mg/dL.
- Participants are treated with a daily dose > 750 mg elemental calcium if using > 0.25 µg/day calcitriol, or a daily dose > 1000 mg elemental calcium if not using calcitriol.
- Participants have normal blood levels of 25-hydroxyvitamin D (i.e. > 20 ng/dL or > 75 nmol/L) and not above 1.5 times the upper limit of normal.
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- Participants have normal thyroid test results for 3 months at least while taking a stable dose of thyroid medication or no medication.
- Participants have a BMI < 35 kg/m2.
- Albumin-adjusted serum calcium level should be between the lower half and the middle of the normal range upon randomization into the study.
Who cannot join
- Participants with hypoparathyroidism due to an activating mutation of the calcium sensing receptor, pseudohypoparathyroidism, any non-hypoparathyroidism disease that may affect calcium metabolism or phosphor-calcium homeostasis, or requiring parenteral calcium infusions.
- Unwillingness to use a diary deployed on a smartphone daily for recording vitamin D, active vitamin D, calcium, magnesium and study drug doses as well as periodic symptom reporting.
- Participants with a history of neoplasia (except thyroid cancer) with no sign of recurrence 5 years after diagnosis.
- Participants with a history of or active GI tract disease that may impact the absorption of calcium (e.g. malabsorption).
- Participants with a history of severe hypocalcemia leading to seizures or cardiac arrhythmias within 6 months prior to screening.
- Participants with chronic kidney disease (eGFR < 30 ml/min) or active nephrolithiasis (needing pain medication in the last 6 months).
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- Participants taking the following medications within the respective exclusion period:
- Proton pump inhibitors (4 weeks)
- Bisphosphonates (3 months)
- Parathyroid hormone, PTH analogs (6 months)
- Thiazide diuretics (14 days)
- Calcitonin or calcinet hydrochloride (3 months)
- Participant has increased CV proarrhythmic potential:
- Participant has a QT interval with Fridericia's correction method (QTcF) >450 ms or PR outside the range of 120 to 220 ms, confirmed with one repeat testing, at the Screening Visit or Inpatient Check-in (Day -1) Visit.
- A history of additional risk factors for TdP (e.g., heart failure, hypokalemia, family history of Long QT Syndrome).
- The use of concomitant medications that prolong the QT/QTc interval.
- Chronic/severe cardiac disease including, but not limited to, cardiac insufficiency, unstable angina, arrhythmias, bradycardia (resting heart rate <60 beats/minute), or hypotension (systolic and diastolic blood pressures <100 and 60 mmHg, respectively).
- Any condition or disease that, in the opinion of the investigator, may interfere with a participant's participation or may confound the interpretation of safety or efficacy in the study.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Argentina1 site, 1 recruiting
- Recruiting
Trial Site
Buenos Aires, Buenos Aires F.D., 1180AAX
Sponsor Representative, 7325998581, info@extendbio.com
About this study
Official title: A Phase 2, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Multiple Ascending Dose Trial Investigating the Safety, Tolerability and Efficacy of EXT608 in Adults With Hypoparathyroidism
The goal of this clinical trial is to investigate the safety, tolerability and efficacy of EXT608 in adults with hypoparathyroidism.
- Conditions
- Hypoparathyroidism
- Being tested
- EXT608, Placebo
- Keywords
- hypopara
- Medical subject headings
- Hypoparathyroidism
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
EXT608Drug
Modified version of parathyroid hormone attached to vitamin D to extend half-life
PlaceboOther
Placebo for injection
| Study group | Role | What they receive |
|---|---|---|
| Active | Experimental | EXT608 solution for injection, administered subcutaneously once-weekly, with multiple ascending doses (MAD) with a starting dose of 50 ug for 4 weeks, continuing to individualized dosing for 8 weeks Receives: Drug: EXT608 |
| Placebo | Placebo comparator | Placebo solution, administered subcutaneously once-weekly, with multiple ascending doses (MAD) with a fixed dose for 4 weeks, continuing to variable dosing for 8 weeks Receives: Other: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Assess the safety and tolerability of multiple subcutaneous (SC) escalating dose levels of EXT608 in participants with hypoparathyroidism by determining frequency and severity of treatment emergent adverse events and post-dose change in lab results
Frequency and severity of treatment emergent adverse events; frequency and severity of post-dose change from baseline in laboratory analyses; percentage of participants with injection site reactions
Measured: From enrollment until the end of treatment at 12 weeks
Secondary outcomes (4)
Assess the pharmacokinetics (PK) of multiple SC doses of EXT608 given over 4 weeks in participants with hypoparathyroidism by determining Area Under the Curve (AUC)
Determine Area Under the Curve (AUC)
Measured: From enrollment until 4 weeks
Assess the pharmacokinetics (PK) of multiple SC doses of EXT608 given over 4 weeks in participants with hypoparathyroidism by determining drug half-life
Determine drug half-life
Measured: From enrollment until 4 weeks
Assess the clinical efficacy of multiple fixed SC doses of EXT608 given over 4 weeks (at week 4), and individualized dosing after an additional 8 weeks (at week 12) in participants with hypoparathyroidism by assessing serum calcium
Proportion of participants with normal serum calcium
Measured: From enrollment until the end of treatment at 12 weeks
Assess the clinical efficacy of multiple fixed SC doses of EXT608 given over 4 weeks (at week 4), and individualized dosing after an additional 8 weeks (at week 12) in participants with hypoparathyroidism by assessing supplementation
Assess change from baseline of daily ingested amount of oral calcium, vitamin D supplements
Measured: From enrollment until the end of treatment at 12 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 May 2025
- Study start5 May 2025
- Primary completionMay 2027 (estimated)
- Study completionMay 2027 (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 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Care provider, Investigator
- Enrolment
- 35 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Extend Biosciences Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06988670
- Sponsor's protocol ID
- EXT608-201
- Other IDs
- R01FD007824, R44DK138647
- Status last verified
- May 2025
- First submitted
- 30 Apr 2025
- Last updated
- 25 May 2025
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Undecided: Will be determined upon completion of the study.
Study at a glance
From the registry record, last updated by the sponsor on 25 May 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Multiple Ascending Dose Trial Investigating the Safety, Tolerability and Efficacy of EXT608 in Adults With Hypoparathyroidism
- ClinicalTrials.gov ID
- NCT06988670
- Acronym / sponsor ID
- EXT608-201
- Conditions
- Hypoparathyroidism
- Keywords
- hypopara
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 35 participants (estimated)
- Lead sponsor
- Extend Biosciences Inc.Industry (pharma, biotech, devices)
- Study start
- 5 May 2025 (actual)
- Primary completion
- May 2027 (estimated)
- Study completion
- May 2027 (estimated)
- First posted
- 25 May 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this clinical trial is to investigate the safety, tolerability and efficacy of EXT608 in adults with hypoparathyroidism.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, care provider, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Active | Experimental | Drug: EXT608EXT608 solution for injection, administered subcutaneously once-weekly, with multiple ascending doses (MAD) with a starting dose of 50 ug for 4 weeks, continuing to individualized dosing for 8 weeks |
| Placebo | Placebo comparator | Other: PlaceboPlacebo solution, administered subcutaneously once-weekly, with multiple ascending doses (MAD) with a fixed dose for 4 weeks, continuing to variable dosing for 8 weeks |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (9 listed)
- Ability to personally provide written, signed, and dated informed consent to participate in the study.
- An understanding, ability, and willingness to fully comply with study procedures and restrictions.
- Male or female between 18 and 65 years of age. Male participants with female partners of child bearing potential must agree to use barrier contraception, e.g., condoms plus spermicide, from administration of the study drug until at least 3 months after administration of the study drug. Abstinence from heterosexual intercourse from administration of study drug until at least 3 months after administration of study drug is acceptable if it is in accordance with the participant's lifestyle. Female participants should be either surgically sterile (had a bilateral tubal ligation, bilateral salpingectomy, bilateral oophorectomy, or hysterectomy), postmenopausal (defined as 12 months with no menses prior to screening and a serum follicle stimulating hormone in the postmenopausal range at screening), or, if of child bearing potential, must be non-lactating and willing to use a highly effective method of birth control for 30 days prior to administration of study drug and agree to continued use of this method until at least 3 months after administration of study drug.
- Participants have a history of hypoparathyroidism for 12 months at least, with PTH levels below the LLN with concomitant serum calcium < 9 mg/dL.
- Participants are treated with a daily dose > 750 mg elemental calcium if using > 0.25 µg/day calcitriol, or a daily dose > 1000 mg elemental calcium if not using calcitriol.
Key exclusion criteria (18 listed)
- Participants with hypoparathyroidism due to an activating mutation of the calcium sensing receptor, pseudohypoparathyroidism, any non-hypoparathyroidism disease that may affect calcium metabolism or phosphor-calcium homeostasis, or requiring parenteral calcium infusions.
- Unwillingness to use a diary deployed on a smartphone daily for recording vitamin D, active vitamin D, calcium, magnesium and study drug doses as well as periodic symptom reporting.
- Participants with a history of neoplasia (except thyroid cancer) with no sign of recurrence 5 years after diagnosis.
- Participants with a history of or active GI tract disease that may impact the absorption of calcium (e.g. malabsorption).
- Participants with a history of severe hypocalcemia leading to seizures or cardiac arrhythmias within 6 months prior to screening.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| EXT608Modified version of parathyroid hormone attached to vitamin D to extend half-life | Drug | Active |
| PlaceboPlacebo for injection | Other | Placebo |
Primary outcome
Assess the safety and tolerability of multiple subcutaneous (SC) escalating dose levels of EXT608 in participants with hypoparathyroidism by determining frequency and severity of treatment emergent adverse events and post-dose change in lab results
Time frame: From enrollment until the end of treatment at 12 weeks
Frequency and severity of treatment emergent adverse events; frequency and severity of post-dose change from baseline in laboratory analyses; percentage of participants with injection site reactions
4 secondary outcomes
Assess the pharmacokinetics (PK) of multiple SC doses of EXT608 given over 4 weeks in participants with hypoparathyroidism by determining Area Under the Curve (AUC)
Time frame: From enrollment until 4 weeks
Assess the pharmacokinetics (PK) of multiple SC doses of EXT608 given over 4 weeks in participants with hypoparathyroidism by determining drug half-life
Time frame: From enrollment until 4 weeks
Assess the clinical efficacy of multiple fixed SC doses of EXT608 given over 4 weeks (at week 4), and individualized dosing after an additional 8 weeks (at week 12) in participants with hypoparathyroidism by assessing serum calcium
Time frame: From enrollment until the end of treatment at 12 weeks
Assess the clinical efficacy of multiple fixed SC doses of EXT608 given over 4 weeks (at week 4), and individualized dosing after an additional 8 weeks (at week 12) in participants with hypoparathyroidism by assessing supplementation
Time frame: From enrollment until the end of treatment at 12 weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 25 May 2025.
- Individual participant dataSharing planned: Undecided. Will be determined upon completion of the study.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing EXT608 in people with Hypoparathyroidism, run by Extend Biosciences Inc. at 1 site in Argentina.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 9 inclusion and 18 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 25 May 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Argentina. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Each site lists its own contact: choose the nearest one under Trial locations. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Assess the safety and tolerability of multiple subcutaneous (SC) escalating dose levels of EXT608 in participants with hypoparathyroidism by determining frequency and severity of treatment emergent adverse events and post-dose change in lab results (time frame: From enrollment until the end of treatment at 12 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 25 May 2025.