Clinical trial NCT00730080: Sapropterin in Individuals With Phenylketonuria
Official title: Effects of Sapropterin on Brain and Cognition in Individuals With Phenylketonuria
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Phenylketonuria
Keywords: phenylketonuria
sapropterin
Kuvan
cognition
executive abilities
brain
Lead sponsor: Washington University School of Medicine
Sponsor class: OTHER
Collaborators: name: BioMarin Pharmaceutical
name: University of Missouri-Columbia
First posted: 2008-08-08
Enrollment: 45
Sex: ALL
Minimum age (years): 6
Maximum age (years): 50
Standard ages: CHILD
ADULT
Accepts healthy volunteers: yes
Observational model: CASE_CONTROL
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Primary care clinic for phenylketonuria. St. Louis community for control.

Brief summary: Investigators at Washington University will examine the effects of sapropterin (Kuvan) on brain and cognition in individuals with phenylketonuria (PKU) using neuropsychological and neuroimaging procedures. Sapropterin is a medication developed by BioMarin Pharmaceutical Inc. that is approved by the FDA for treatment of patients with PKU to reduce phenylalanine (Phe) levels. Patients beginning treatment with sapropterin as standard clinical care will be enrolled in the study. As a first step, patients with PKU will receive baseline neuropsychological and neuroimaging evaluations 1 day prior to beginning treatment with sapropterin. Screening for response to sapropterin will occur over 4 weeks. At the end of 4 weeks, response to sapropterin will be reviewed. Patients with a reduction of ≥ 20% in blood Phe (i.e., responders) will receive follow-up neuropsychological and neuroimaging evaluations after 6 months of treatment with sapropterin. Patients (both responders and nonresponders) will receive long-term follow-up neuropsychological and neuroimaging evaluations 3 to 5 years after initial enrollment in the study.

The focus of neuropsychological testing will be executive abilities, as these abilities are particularly susceptible to disruption in individuals with PKU. We hypothesize that improvements in these abilities will occur following treatment with sapropterin. For neuroimaging assessments, structural magnetic resonance imaging (MRI) will permit evaluation of changes in the structure and volume of the gray and white matter of the brain, whereas diffusion tensor imaging (DTI) will permit evaluation of microstructural white matter integrity.

Detailed description: Investigators at Washington University will examine the effects of sapropterin (Kuvan) on brain and cognition in individuals with phenylketonuria (PKU) using neuropsychological and neuroimaging procedures. Sapropterin is a medication developed by BioMarin Pharmaceutical Inc. that is approved by the FDA for treatment of patients with PKU to reduce phenylalanine (Phe) levels. Patients beginning treatment with sapropterin as standard clinical care will be enrolled. As a first step, patients with PKU who are ≥ 6 years of age will receive baseline neuropsychological and neuroimaging evaluations 1 day prior to beginning their treatment with sapropterin. Screening for response to sapropterin (20mg/kg/day) will then occur over 4 weeks as standard care for enrolled patients. At the end of 4 weeks, response to sapropterin will be reviewed. Patients with a reduction of ≥ 20% in blood Phe (i.e., responders) will receive follow-up neuropsychological and neuroimaging evaluations after 6 months of treatment with sapropterin. Patients (both responders and nonresponders) will receive long-term follow-up neuropsychological and neuroimaging evaluations 3 to 5 years after initial enrollment in the study.

A matched control group of healthy individuals without PKU will receive baseline and follow-up neuropsychological and neuroimaging evaluations for comparison purposes and to control for possible practice effects in repeated neuropsychological testing.

The focus of neuropsychological testing will be executive abilities, as these abilities are particularly susceptible to disruption in individuals with PKU. Specifically, the focus of neuropsychological assessment will be working memory, strategic processing, and inhibitory control, as our research group has shown that each of these executive abilities is impaired in individuals with PKU. (White, D. 2001 Neuropsychol.)(White, D. 2002 J. Int. Neuropsychol. Soc.)(Christ, S. 2006 Dev. Neuropsychol.) We hypothesize that improvements in these abilities will occur following treatment with sapropterin.

For neuroimaging assessments, both structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI; mean diffusivity and fractional anisotropy) will be used. Structural MRI will permit evaluation of changes in the structure and volume of the gray and white matter of the brain. DTI will permit evaluation of microstructural white matter integrity. Brain abnormalities have been noted in individuals with PKU, and using DTI our research group recently identified abnormalities in the integrity of white matter in early and continuously treated individuals with PKU.

The primary objectives of the proposed study are two-fold. First, we will determine whether cognition (particularly executive abilities) improves in patients with PKU who have been treated with sapropterin. Second, we will determine whether the integrity of the brain improves in patients with PKU who have been treated with sapropterin. In addition, the interrelationships between changes in cognition and brain will be examined.

Eligibility criteria: Inclusion Criteria:

* Willing and able to provide informed consent or assent.
* Willing and able to comply with study procedures.
* Greater than or equal to 6 years of age.
* For phenylketonuria,intention of physician to prescribe sapropoterin.
* For phenylketonuria,phenylalanine level greater than or equal to 450μmol/L.
* For phenylketonuria, negative pregnancy test if of childbearing potential.
* For phenylketonuria, willing to use contraception if sexually active.

Exclusion Criteria:

* Pregnant, breastfeeding, or planning to become pregnant during study.
* Use of investigational product less than 30 days prior to or during study.
* Concurrent condition that could interfere with participation or safety.
* Any condition creating high risk of poor compliance with study.
* Perceived to be unreliable or unavailable for study.
* Use of L-Dopa, methotrexate, or other drugs that inhibit folate metabolism.
* For phenylketonuria, known hypersensitivity to sapropterin or excipients.

Primary outcomes:
measure: diffusion tensor imaging of the brain
timeFrame: baseline & follow-ups
Secondary outcomes:
measure: n-back task
timeFrame: baseline & follow-ups
measure: recognition span task
timeFrame: baseline & follow-ups
measure: list learning task
timeFrame: baseline & follow-ups
measure: verbal fluency task
timeFrame: baseline & follow-ups
measure: go/no-go task
timeFrame: baseline & follow-ups
measure: stimulus-response compatibility task
timeFrame: baseline & follow-ups
measure: structural magnetic resonance imaging of the brain
timeFrame: baseline & follow-ups
measure: Wechsler Abbreviated Scale of Intelligence
timeFrame: baseline & follow-ups
Other outcomes:
Locations:
city: Saint Louis
country: United States
facility: Washington University
state: Missouri
Study officials:
affiliation: Washington University School of Medicine
name: Desiree White, Ph.D.
role: PRINCIPAL_INVESTIGATOR
affiliation: Washington University School of Medicine
name: Dorothy K. Grange, M.D.
role: PRINCIPAL_INVESTIGATOR
References:
citation: White DA, Nortz MJ, Mandernach T, Huntington K, Steiner RD. Deficits in memory strategy use related to prefrontal dysfunction during early development: evidence from children with phenylketonuria. Neuropsychology. 2001 Apr;15(2):221-9. doi: 10.1037//0894-4105.15.2.221.
citation: White DA, Nortz MJ, Mandernach T, Huntington K, Steiner RD. Age-related working memory impairments in children with prefrontal dysfunction associated with phenylketonuria. J Int Neuropsychol Soc. 2002 Jan;8(1):1-11.
citation: Christ SE, Steiner RD, Grange DK, Abrams RA, White DA. Inhibitory control in children with phenylketonuria. Dev Neuropsychol. 2006;30(3):845-64. doi: 10.1207/s15326942dn3003_5.
citation: Araujo GC, Christ SE, Steiner RD, Grange DK, Nardos B, McKinstry RC, White DA. Response monitoring in children with phenylketonuria. Neuropsychology. 2009 Jan;23(1):130-4. doi: 10.1037/a0013488.
citation: Christ SE, Huijbregts SC, de Sonneville LM, White DA. Executive function in early-treated phenylketonuria: profile and underlying mechanisms. Mol Genet Metab. 2010;99 Suppl 1:S22-32. doi: 10.1016/j.ymgme.2009.10.007.
citation: White DA, Connor LT, Nardos B, Shimony JS, Archer R, Snyder AZ, Moinuddin A, Grange DK, Steiner RD, McKinstry RC. Age-related decline in the microstructural integrity of white matter in children with early- and continuously-treated PKU: a DTI study of the corpus callosum. Mol Genet Metab. 2010;99 Suppl 1(0 1):S41-6. doi: 10.1016/j.ymgme.2009.09.016.
citation: Banerjee P, Grange DK, Steiner RD, White DA. Executive strategic processing during verbal fluency performance in children with phenylketonuria. Child Neuropsychol. 2011;17(2):105-17. doi: 10.1080/09297049.2010.525502. Epub 2010 Dec 7.
citation: Janos AL, Grange DK, Steiner RD, White DA. Processing speed and executive abilities in children with phenylketonuria. Neuropsychology. 2012 Nov;26(6):735-43. doi: 10.1037/a0029419. Epub 2012 Aug 6.
citation: Bodner KE, Aldridge K, Moffitt AJ, Peck D, White DA, Christ SE. A volumetric study of basal ganglia structures in individuals with early-treated phenylketonuria. Mol Genet Metab. 2012 Nov;107(3):302-7. doi: 10.1016/j.ymgme.2012.08.007. Epub 2012 Aug 18.
citation: Antenor-Dorsey JA, Hershey T, Rutlin J, Shimony JS, McKinstry RC, Grange DK, Christ SE, White DA. White matter integrity and executive abilities in individuals with phenylketonuria. Mol Genet Metab. 2013 Jun;109(2):125-31. doi: 10.1016/j.ymgme.2013.03.020. Epub 2013 Apr 6.
citation: Peng H, Peck D, White DA, Christ SE. Tract-based evaluation of white matter damage in individuals with early-treated phenylketonuria. J Inherit Metab Dis. 2014 Mar;37(2):237-43. doi: 10.1007/s10545-013-9650-y. Epub 2013 Sep 17.
citation: White DA, Antenor-Dorsey JA, Grange DK, Hershey T, Rutlin J, Shimony JS, McKinstry RC, Christ SE. White matter integrity and executive abilities following treatment with tetrahydrobiopterin (BH4) in individuals with phenylketonuria. Mol Genet Metab. 2013 Nov;110(3):213-7. doi: 10.1016/j.ymgme.2013.07.010. Epub 2013 Jul 19.