Theophylline Treatment for Pseudohypoparathyroidism

Phase 2Active Not RecruitingNCT03029429

Vanderbilt University Medical Center29 enrolled

Overview

Pseudohypoparathyroidism is a genetic disorder with limited treatment options. Patients have early-onset obesity, short stature and increased risk of type 2 diabetes. This phase 2 clinical trial will test the efficacy of theophylline, a phosphodiesterase inhibitor, in pseudohypoparathyroidism. The investigators hypothesize that theophylline will cause weight loss, improve glucose tolerance and slow growth plate closure in children and young adults.

Pseudohypoparathyroidism (PHP) is a rare, genetic disorder caused by impaired stimulatory G protein (Gsα) signaling through downregulation of the gene, GNAS. The resultant hormone abnormalities can be treated with hormone replacement therapy, but other aspects of the disorder such as early-onset obesity and premature epiphyseal closure are without effective treatment options. Gsα signaling is essential for the normal hormonal function of the pituitary, thyroid, gonads, renal proximal tubules and hypothalamus. While many of the resulting hormone deficiencies can be treated with hormone replacement therapy (HRT), HRT is not an effective therapy for the severe early-onset obesity and short stature which are major features of the PHP phenotype. Therefore, the goal of this proposal is to test the efficacy of upstream therapy aimed at correcting the function of two Gsα-dependent receptors responsible for the obesity (melanocortin-4 receptor, MC4R) and short stature (parathyroid hormone, PTH, receptor) phenotype in children with PHP. Gsα-coupled receptor signaling cascade begins with an increase in cyclic adenosine monophosphate (cAMP) which is rapidly degraded by the enzyme phosphodiesterase (PDE). PDE inhibitors act by prolonging cAMP signaling by decreasing the rate of degradation. Given that patients with PHP have reduced, but not completely absent, cAMP production, the investigators seek to test the hypothesis that the PDE inhibitor theophylline will reduce BMI, glucose intolerance, and hormone resistance in children and young adults with PHP through improved Gsα-coupled receptor signaling. The investigators will conduct a 52-week randomized, placebo controlled clinical trial of theophylline in children and young adults with PHP. Theophylline is a non-selective PDE inhibitor that is generically available and has a long history of use in pediatric patients, making it an ideal drug for re-purposing in youth with PHP. Furthermore, the pharmacokinetics of theophylline are well understood and serum drug levels are easily measured. The investigators primary outcome is change in body mass index. Secondary outcome measures include change in glucose tolerance and HRT dose. Anticipating a 10% dropout rate, the investigators will enroll 34 patients and expect that 30 patients will complete the study.

Study Type

Conditions

Pseudohypoparathyroidism Albright Hereditary Osteodystrophy

Interventions

TheophyllineDRUG

oral theophylline

PlacebosDRUG

oral placebo

Eligibility

Sex: ALLMin age: 13 YearsMax age: 99 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Age 13 years and above 2. Clinical diagnosis of PHP (per the EuroPHP network classification guidelines1): Presence of PTH resistance or ectopic classification OR brachydactyly type E plus 2 minor criteria (TSH resistance, other hormonal resistance, developmental delay, intrauterine or post-natal growth retardation, obesity/overweight, specific facial features) 3. Obesity (BMI \>95th percentile for age/gender and/or ≥30 kg/m2) Exclusion Criteria: 1. Use of a PDE inhibitor in the past 30 days 2. History of a seizure disorder unrelated to hypocalcemia 3. History of a cardiac arrhythmia (not including bradycardia) 4. Hepatic insufficiency including cirrhosis and acute hepatitis (AST or ALT \>3x upper limit of normal) 5. Congestive heart failure 6. Current cigarette use or alcohol abuse 7. Pregnancy or intention to become pregnant during the next year 8. Untreated hypothyroidism (defined as free thyroxine below the lower limit of normal) 9. Active peptic ulcer disease 10. Current use of medications known to effect theophylline levels 11. History of hypersensitivity to theophylline or other medication components 12. History of Major Depressive Disorder in the past 2 years, lifetime history of suicide attempt, history of any suicidal behavior in the past month, history of other sever psychiatric disorders (e.g. schizophrenia, bipolar disorder) 13. PHQ-9 score is ≥15 or suicidal ideation of type 4 or 5 (C-SSR) in the past month 14. Unable to comply with study procedures in the opinion of the investigator

Locations (1)

Ashley Shoemaker

Nashville, Tennessee, United States

Outcomes

Primary Outcomes

Change in body mass index

BMI will be expressed a percent of the 95th percentile

Time frame: baseline and 52 weeks

Secondary Outcomes

Change in insulinogenic index

Insulinogenic index measured during a 75g oral glucose tolerance test

Time frame: baseline and 52 weeks

change in levothyroxine dose

levothyroxine dose (mcg/kg/day)

Time frame: baseline and 52 weeks

change in calcitriol dose

calcitriol dose (mcg/kg/day)

Time frame: baseline and 52 weeks

Data from ClinicalTrials.gov

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