The goal of this clinical trial is to investigate the safety, tolerability and efficacy of EXT608 in adults with hypoparathyroidism.
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 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).
Parallel
EXT608
DrugModified version of parathyroid hormone attached to vitamin D to extend half-life
Placebo
Other interventionPlacebo for injection
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
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)
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
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
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
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