Rifampin in CYP24A1-related Hypercalcemia and Hypercalciuria
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Rifampin.
- Who it may be relevant to
- Registry conditions: Idiopathic Infantile Hypercalcaemia - Severe Form, Genetic Disease, Hypercalcemia, Idiopathic, of Infancy, Hypercalciuric Hypercalcemia. Basic parameters: 6 months — 65 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- United States
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
Rifampin to Reduce Elevated Levels of Blood and Urine Calcium in Patients With Inactivating Mutations in the CYP24A1 Gene
Overview
This study evaluates the efficacy of rifampin in the treatment of hypercalcemia and/or hypercalciuria in participants with at least one inactivating mutation of the CYP24A1 gene. Eligible subjects will receive rifampin for a total of 16 weeks during this study.
Detailed description
Idiopathic infantile hypercalcemia (IIH; omim 143880) is a genetic disorder of mineral metabolism characterized by severe hypercalcemia and/or hypercalciuria, suppressed serum levels of parathyroid hormone (PTH) and elevated levels of the active vitamin D metabolite, 1,25(OH)2D. Biallelic inactivating mutations of CYP24A1, the gene encoding the 24-hydroxylase enzyme that represents the principal pathway for inactivation of vitamin D metabolites, cause the most common and severe form of IIH.
Investigators have preliminary data supporting a novel therapeutic approach to repurpose rifampin as an agent to induce over-expression of CYP3A4 and CYP3A5, enzymes that are expressed in the liver and intestine. When these enzymes are induced, the increased enzyme activity provides an alternative catabolic pathway for inactivation of vitamin D metabolites. The purpose of this study is to obtain support for an open label, escalating dose study to assess the effect, safety, and tolerability of once daily oral rifampin in participants with IIH due to inactivating mutations in CYP24A1.
In this study, Investigators will recruit 60 patients with at least one inactivating mutation of CYP24A1. Participants will be observed for 8-weeks before a 16-week treatment phase of rifampin and 8 further weeks of observation. In addition to following the effect of treatment on calcium homeostasis, Investigators will also study the pharmacokinetics of rifampin in this condition and the effect on intestinal calcium absorption.
Interventions
- Drug Rifampin
Rifampin 5 mg/kg (max 300 mg) daily for 8 weeks, followed by rifampin 10 mg/kg (max 600 mg) daily for 8 weeks.
Primary outcome measures
- Serum albumin-adjusted calcium [Time frame: up to 32 weeks]
- Serum parathyroid hormone [Time frame: up to 32 weeks]
- Urinary calcium excretion [Time frame: up to 32 weeks]
Secondary outcome measures (3)
- Intestinal calcium absorption [Time frame: baseline, 8, 16, 24 and 32 weeks post-dose]
- Nephrocalcinosis [Time frame: Baseline and week 32]
- Rifampin pharmacokinetics [Time frame: 8, 16 and 24 weeks post-dose]
Eligibility criteria
Inclusion criteria
- Males or females age 6 months to 65 years.
- at least one mutations of CYP24A1
- Serum and/or urinary calcium above the normal reference range for age
- Serum PTH concentration <20 pg/ml
- Elevated or normal serum concentration of 1,25-dihydroxyvitamin D3.
Exclusion criteria
- Parents/guardians or subjects who, in the opinion of the Investigator, may be non-compliant with study schedules or procedures.
- Allergy to rifampin or related medications
- Current therapies with medications that have significant drug-drug interactions with rifampin, defined as a medication considered to interact with CYP3A4 or CYP3A5 and either induce or inhibit expression or function of these P450 enzymes. By "drug-drug" interactions we are looking for medications that will affect metabolism or action of rifampin as exclusionary, not medications that will be affected by rifampin.
- Pregnancy or breastfeeding
- Laboratory abnormalities that indicate clinically significant hepatic, or renal disease:
- Aspartate Aminotransferase (AST/SGOT) > 2.0 times the upper limit of normal Alanine aminotransferase (ALT/SGPT) > 2.0 times the upper limit of normal Total bilirubin > 2.0 times the upper limit of normal Creatinine > 2.0 times the upper limit of normal
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Allocation
- N/A
- Model
- Single group
- Masking
- Open label
- Primary purpose
- Treatment
Study locations
United States · 1 center
- Children's Hospital of Philadelphia — Philadelphia
Publications
- Hawkes CP, Li D, Hakonarson H, Meyers KE, Thummel KE, Levine MA. CYP3A4 Induction by Rifampin: An Alternative Pathway for Vitamin D Inactivation in Patients With CYP24A1 Mutations. J Clin Endocrinol Metab. 2017 May 1;102(5):1440-1446. doi: 10.1210/jc.2016-4048. PMID 28324001
- Dauber A, Nguyen TT, Sochett E, Cole DE, Horst R, Abrams SA, Carpenter TO, Hirschhorn JN. Genetic defect in CYP24A1, the vitamin D 24-hydroxylase gene, in a patient with severe infantile hypercalcemia. J Clin Endocrinol Metab. 2012 Feb;97(2):E268-74. doi: 10.1210/jc.2011-1972. Epub 2011 Nov 23. PMID 22112808
- Schlingmann KP, Kaufmann M, Weber S, Irwin A, Goos C, John U, Misselwitz J, Klaus G, Kuwertz-Broking E, Fehrenbach H, Wingen AM, Guran T, Hoenderop JG, Bindels RJ, Prosser DE, Jones G, Konrad M. Mutations in CYP24A1 and idiopathic infantile hypercalcemia. N Engl J Med. 2011 Aug 4;365(5):410-21. doi: 10.1056/NEJMoa1103864. Epub 2011 Jun 15. PMID 21675912
Identifiers
NCT: NCT03301038 · 16-013429 · R01DK112955