Clinical Trial Details
— Status: Terminated
Administrative data
| NCT number |
NCT04450212 |
| Other study ID # |
STUDY00001593 |
| Secondary ID |
P01GM116691-02S1 |
| Status |
Terminated |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
August 25, 2017 |
| Est. completion date |
July 31, 2023 |
Study information
| Verified date |
December 2023 |
| Source |
University of Washington |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
The overall purpose of this study is to determine how variation in the CYP4F2 gene modulates
the synthesis of vitamin K-dependent clotting factors. We propose that the CYP4F2*3 gene
variant increases short- and long-term vitamin K concentrations in the liver by reducing the
efficiency of vitamin K metabolism. The investigators will study the effect of vitamin K
supplementation on two biomarkers of hepatic vitamin K concentration in groups with defined
CYP4F2*3 genotype. Specifically, the investigators will test for an association between our
novel biomarkers of long-term (plasma Factor II proteoforms) and short-term (urinary K-Acid
catabolites) hepatic vitamin K concentration and CYP4F2*3 following a 10-day period of
vitamin K supplementation in healthy volunteers.
Description:
The investigators will study the effect of vitamin K supplementation on two biomarkers of
hepatic vitamin K concentration in groups with defined CYP4F2*3 genotype. Specifically, the
investigators will test for an association between our novel biomarkers of long-term (plasma
Factor II proteoforms) and short-term (urinary K-Acid catabolites) hepatic vitamin K
concentration and CYP4F2*3 following a 10-day period of vitamin K supplementation in healthy
volunteers.
The investigators will recruit, by posted advertisements at UWMC, male and female healthy
volunteers. A two-step selection process will be employed. Subjects will self-select by
responding to flyers, and contact the research coordinator. The research coordinator will
screen them for eligibility over the phone and if eligible, make an appointment for the first
study visit. For the first phase, the Research Coordinator will collect a buccal swab of DNA
from ~ 200 eligible candidates; the DNA will be tested for absence or presence of the
CYP4F2*3 variant allele. The PI and Research Coordinator will review the genotyping results
and then select 14 individuals with either a homozygous CYP4F2*3 genotype or a heterozygous
CYP4F2*1/*3 genotype, and a demographically matched group of 14 with a homozygous CYP4F2*1
genotype at the diagnostic locus for the supplementation phase of the study. The study
coordinator will then contact these subjects by phone for Phase II participation.
Procedures - Phase I, Buccal Swab Collection for DNA Isolation.
Demographic Questionnaire: Self-reported heritage, age, and sex will be collected through a
brief demographic questionnaire.
Buccal Swab: We will collect cheek cells with a cotton swab and isolate DNA and test for the
CYP4F2*1 and CYP4F2*3 alleles.
Genotyping: CYP4F2 genotype will be determined by a validated TaqMan assay (ABI/ThermoFisher
Scientific), using commercially available DNA hybridization probes to test for the absence or
presence of the CYP4F2*3 allele. Subjects who are either a homozygous CYP4F2*3 genotype or a
heterozygous CYP4F2*1/*3 genotype, and CYP4F2*3 alleles will be eligible for Phase II.
Procedures - Phase II, Vitamin K Supplementation.
Vitamin K Supplementation: Research participants selected for the supplementation study based
on CYP4F2 genotype will be given 1-mg/day phylloquinone (Vitacost; Natures Life K-1
Phylloquinone) for 10 consecutive days. Each dose will be taken in the morning (~ 8 am), with
one half pint of 2% milk to facilitate absorption.
Sample Collection: For the supplementation study, a venous blood sample (10 mL EDTA tube) and
a spot urine sample will be collected after an overnight fast from d1 through d5 and on d8
and d10 of Vitamin K supplementation for 10 days. Plasma will be isolated and both samples
will be stored at -70°C until analysis. Women of child-bearing potential will have a urine
pregnancy test of d1 and if positive, will be withdrawn from the study, and all samples and
data will be destroyed.
Measurement of Plasma Factor II Proteoforms: Plasma concentration of the 11 individual
proteoforms of Factor II will be measured byLC-MS/MS. This data will be used to calculate
three metrics of long-term vitamin K status, unFII, ucFII:iFII and inFII:aFII. These
represent different mathematical measures of the degree of Factor II undercarboxylation.
Prospective analysis of plasma vitamin K1, PIVKA II and ucOC is not planned, but will be held
in reserve should the need for that data arise.
Measurement of Urinary K-Acid I and II: Quantitation of K-Acid I and II, and creatinine (Cr)
in spot urine samples will be performed, using a validated LC-MS/MS assay that the
investigators have recently developed. The total and individual urinary K-Acid/Cr ratio will
be computed.
Statistical Analysis Plan: The investigators will conduct an unpaired t-test to compare the
mean response to vitamin K supplementation in the two CYP4F2 genotype groups. Response is
defined as the area under the vitamin K status value x time curve, corrected for baseline,
for the 10-day intervention period. A secondary metric will be the absolute peak change in
the vitamin K status ratio. Both short (urinary K-Acid/Cr ratio) and long-term (ucFII:iFII
and inFII:aFII) biomarkers will tested separately. Based on pilot data, a sample size of 14
in each genotype group will provide a power of at least 80% to detect a significant effect at
the significance 0.05 level, when there is a two-fold difference in the response to
supplementation.
