PhenylketonuriaPKUNCT01428258
Phase 2 Study of Glycomacropeptide Versus Amino Acid Diet for Management of Phenylketonuria
A study testing GMP Diet/GMP Medical Foods and AA Diet/AA Medical Foods in people with Phenylketonuria, run by University of Wisconsin, Madison at 2 sites in United States.
Trial summary
For individuals with Phenylketonuria (PKU), the investigators hypothesize that glycomacropeptide will provide an acceptable form of low-phenylalanine dietary protein that will improve dietary compliance, blood phenylalanine levels, cognitive function, and ultimately quality of life compared with the usual amino acid… Read more about this study
- Who is it for?
- Ages 12 to 45 years
- Conditions the study is for
- Phenylketonuria
- What is being tested?
- GMP Diet/GMP Medical Foods and AA Diet/AA Medical Foods
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 32 participants
- Where
- 2 sitesUnited States
- Study dates
- Sep 2011to May 2016
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 12 to 45 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- Identified PKU by newborn screening; started diet treatment before 1 mo age
- Diagnosis of classical or variant PKU with documented phenylalanine level of greater than 600 umol/L at 7-10d of age
- Follows or willing to follow PKU diet and consume amino acid medical formula providing more than 50% of protein needs
- Acceptance of glycomacropeptide foods determined prior to enrollment
Who cannot join
- Females who are pregnant or planning pregnancy
- Individuals with mental deficits due to untreated or poorly controlled PKU
- Individuals with any health condition deemed to interfere with participation
Trial locations and contacts
2 sites in 1 country.
United States2 sites
Children's Hospital of Boston
Boston, Massachusetts, 02115
University of Wisconsin-Madison
Madison, Wisconsin, 53706
About this study
Official title: Phase 2 Study of Glycomacropeptide vs. Amino Acid Diet for the Management of PKU
For individuals with Phenylketonuria (PKU), the investigators hypothesize that glycomacropeptide will provide an acceptable form of low-phenylalanine dietary protein that will improve dietary compliance, blood phenylalanine levels, cognitive function, and ultimately quality of life compared with the usual amino acid based diet. The study is funded by the Food and Drug Administration (FDA) Office of Orphan Products Development Grants Program, R01 FD003711.
Read the detailed description
Individuals with phenylketonuria (PKU) lack the enzyme phenylalanine hydroxylase that is needed to metabolize the essential amino acid phenylalanine (phe). When eating a normal diet they show an elevated level of phe in blood that is toxic to the brain. In order to prevent brain damage and cognitive impairment, individuals with PKU must follow a lifelong, low-phe diet that is restricted in natural foods and requires ingestion of a phe-free amino acid (AA) formula. Most adolescents and adults with PKU find the AA formula unpalatable and go off the diet resulting in elevated blood phe levels and neuropsychological deterioration. Glycomacropeptide (GMP), an intact protein produced during cheese making, is uniquely suited to a low-phe diet because it is the only known dietary protein that contains minimal phe. Foods and beverages made with GMP are a palatable alternative to AA formula. The long term goal is to assess the safety, efficacy and acceptability of GMP for the nutritional management of PKU. The specific aim is to conduct a randomized, two-stage, 11-wk, crossover trial comparing the GMP diet with the AA diet in 30 subjects with PKU ≥12 years of age treated since birth with a low-phe AA diet. The sites are: University of Wisconsin-Madison, Waisman Center (primary) and Harvard University, Children's Hospital Boston. Subjects will be recruited and randomized to begin the first 3-wk of the study with either a low-phe diet in which the majority of dietary protein is provided by GMP or AA medical foods and then, after a 3-wk washout with intake of their usual diet, begin the second diet for 3-wk. Dietary education will be provided in a 1-wk base period preceding initiation of each diet.
- Conditions
- Phenylketonuria
- Being tested
- GMP Diet/GMP Medical Foods, AA Diet/AA Medical Foods
- Keywords
- Diet therapy, Low phenylalanine diet, Attention, Executive function
- Medical subject headings
- Phenylketonurias
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
GMP Diet/GMP Medical FoodsOther
Also called GMP Medical Foods, Glytactin trademark of Cambrooke Therapeutics,LLC
The intervention consists of a low-phenylalanine (Phe) diet in combination with medical foods made with the peptide GMP supplemented with limiting indispensable amino acids, as provided by Cambrooke Therapeutics, LLC. The diet is formulated to replace the protein equivalents provided by AA medical foods with GMP medical foods, keeping other dietary components constant. The GMP dietary treatment period consists of all subjects following the GMP diet for 3-wks at home. The GMP diet intervention is administered in differing orders, GMP Diet/AA Diet or AA diet/GMP Diet.
AA Diet/AA Medical FoodsOther
Also called AA Medical Foods
The intervention consists of a low-Phe diet in combination with commercial AA medical foods as consumed in each subject's usual diet. A total of 15 different commercial AA medical foods were consumed by subjects in the study. The diet is formulated to provide each subject with their typical daily intake of protein equivalents from AA medical foods. The AA dietary treatment period consists of all subjects following the AA diet for 3-wks at home. The AA Diet comparator intervention is administered in differing orders, GMP Diet/AA Diet or AA diet/GMP Diet.
| Study group | Role | What they receive |
|---|---|---|
| GMP Diet/GMP Medical Foods | Experimental | The experimental intervention is the GMP diet followed at home for 3-wk. In this randomized crossover study, half of subjects (n=15) were randomized to receive the GMP diet as the first arm, and half of the subjects (n=15) were randomized to receive the GMP diet as the second arm. Receives: Other: AA Diet/AA Medical Foods |
| AA Diet/AA Medical Foods | Active comparator | The experimental intervention is the AA diet followed at home for 3-wk. In this randomized crossover study, half of subjects (n=15) were randomized to receive the AA diet as the first arm, and half of the subjects (n=15) were randomized to receive the AA diet as the second arm. Receives: Other: GMP Diet/GMP Medical Foods |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in the Plasma Phenylalanine Concentration of PKU Subjects Fed the Glycomacropeptide Diet Compared With the Change When Fed the Amino Acid Diet
Plasma will be collected at each base week and after 3 weeks on each of the dietary treatments, glycomacropeptide and amino acid, following an overnight fast. Plasma phenylalanine concentration (along with the complete profile of free amino acids) will be determined with an amino acid analyzer in the Wisconsin State Lab of Hygiene. Statistical analysis to determine the significance of the change in plasma phe concentration when comparing the 2 diets will consist of ANCOVA with covariates for baseline Phe and dietary Phe intake. The change in plasma Phe concentration from day 22 (final) to day 1 (baseline) was determined after adjusting for baseline Phe level and dietary Phe intake.
Measured: baseline to day 22 on each diet
Secondary outcomes (6)
Dietary Compliance
Compliance with the glycomacropeptide and amino acid dietary treatments will be assessed by comparison of the intake of medical food in grams of protein from medical food per day based on subject completion of 3-day food records prior to the final study visit on day 22. Statistical analysis for a dietary treatment effect will consist of ANOVA.
Measured: 3 week dietary treatment
Executive Function Assessed by BRIEF
Completion of a standardized test, the Behavior Rating Inventory of Executive Function (BRIEF), by each subject for the GMP diet and the AA diet. Values are T-scores which have a mean of 50 points and a SD of 10 points. A T score of <50 is considered within the normative range. Data are analyzed with a paired t-test.
Measured: day 22 of each dietary treatment
Vitamin D (25-OH) Plasma Concentration at Day 22
Vitamin D was measured as a measure of the capacity for calcium absorption. Higher levels of plasma vitamin D are consistent with higher calcium absorption.
Measured: day 22 of each dietary treatment
Comparison of Phe Concentrations in Plasma With Concentrations in Dried Blood Spots
Concentrations of Phe in plasma and in dried blood spots collected simultaneously by subjects will be compared using 2 methodologies, regardless of intervention. At each of the 4 study visits (baseline and final for each dietary treatment): 1) venipuncture was used to collect blood and plasma was isolated and analyzed for Phe with ion exchange chromatography and 2) subjects were asked right after the venipuncture to spot their blood on filter paper for analysis of Phe with tandem mass spectroscopy (MS/MS). The discrepancy in Phe concentrations with these 2 methods was compared for each sample pair using Bland-Altman statistical analysis. Each subject should have had 4 sample pairs, 29 x 4 = 116, but we ended up with only 110 sample pairs, as explained below.
Measured: 4 times total, 2 per treatment
Bone-specific Alkaline Phosphatase (BSAP) Plasma Concentration at Day 22
Plasma concentration of BSAP was determined as a measure of bone turnover.
Measured: day 22 of each dietary treatment
N-terminal Telopeptide (NTX) Plasma Concentration at Day 22
Plasma concentration of NTX was determined as a measure of bone resorption; higher levels indicate greater bone breakdown
Measured: day 22 of each dietary treatment
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Sep 2011 (estimated)
- Study startSep 2011
- Primary completionNov 2015
- Study completionMay 2016
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (13)Papers the sponsor has linked to this study.
- Other trials for PhenylketonuriaStudies of the same condition, open and under way.
- More trials run by University of Wisconsin, MadisonThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- The study is a randomized, two-arm, crossover trial comparing the GMP diet and the AA diet in 30 subjects with PKU \> 12 years of age. Subjects were randomized to start with either the GMP diet or the AA diet which they followed for 3-wk at home, followed by a 3-wk washout period when they resumed their usual AA diet, and then 3-wk of either the GMP diet or the AA diet whichever they did not consume first. Each subject served as their own control; there was no control group. We studied medical foods - either AA or GMP medical foods which are not drugs. The FDA did not require that we have an IND.
- Masking
- None (open label)
- Enrolment
- 32 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Wisconsin, Madison
- Sponsor type
- University, hospital or other
- Collaborators
- Boston Children's Hospital
- Responsible party
- Sponsor
- Investigators
- Denise M Ney, PhD, RD, Study director, Professor of Nutritional Sciences, University of Wisconsin-Madison
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT01428258
- Sponsor's protocol ID
- H-2010-0165
- Other IDs
- 1R01FD003711-01A1
- Acronym
- PKU
- Status last verified
- Jul 2018
- First submitted
- 31 Aug 2011
- Last updated
- 24 Aug 2018
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- Individual data sharing
- No
Publications
van Calcar SC, MacLeod EL, Gleason ST, Etzel MR, Clayton MK, Wolff JA, Ney DM. Improved nutritional management of phenylketonuria by using a diet containing glycomacropeptide compared with amino acids. Am J Clin Nutr. 2009 Apr;89(4):1068-77. doi: 10.3945/ajcn.2008.27280. Epub 2009 Feb 25.
PubMed 19244369Ney DM, Gleason ST, van Calcar SC, MacLeod EL, Nelson KL, Etzel MR, Rice GM, Wolff JA. Nutritional management of PKU with glycomacropeptide from cheese whey. J Inherit Metab Dis. 2009 Feb;32(1):32-9. doi: 10.1007/s10545-008-0952-4. Epub 2008 Oct 29.
PubMed 18956251Ney DM, Hull AK, van Calcar SC, Liu X, Etzel MR. Dietary glycomacropeptide supports growth and reduces the concentrations of phenylalanine in plasma and brain in a murine model of phenylketonuria. J Nutr. 2008 Feb;138(2):316-22. doi: 10.1093/jn/138.2.316.
PubMed 18203898MacLeod EL, Clayton MK, van Calcar SC, Ney DM. Breakfast with glycomacropeptide compared with amino acids suppresses plasma ghrelin levels in individuals with phenylketonuria. Mol Genet Metab. 2010 Aug;100(4):303-8. doi: 10.1016/j.ymgme.2010.04.003. Epub 2010 Apr 14.
PubMed 20466571Laclair CE, Ney DM, MacLeod EL, Etzel MR. Purification and use of glycomacropeptide for nutritional management of phenylketonuria. J Food Sci. 2009 May-Jul;74(4):E199-206. doi: 10.1111/j.1750-3841.2009.01134.x.
PubMed 19490325Ney DM, Stroup BM, Clayton MK, Murali SG, Rice GM, Rohr F, Levy HL. Glycomacropeptide for nutritional management of phenylketonuria: a randomized, controlled, crossover trial. Am J Clin Nutr. 2016 Aug;104(2):334-45. doi: 10.3945/ajcn.116.135293. Epub 2016 Jul 13.
PubMed 27413125Stroup BM, Held PK, Williams P, Clayton MK, Murali SG, Rice GM, Ney DM. Clinical relevance of the discrepancy in phenylalanine concentrations analyzed using tandem mass spectrometry compared with ion-exchange chromatography in phenylketonuria. Mol Genet Metab Rep. 2016 Jan 16;6:21-6. doi: 10.1016/j.ymgmr.2016.01.001. eCollection 2016 Mar.
PubMed 27014575Ney DM, Murali SG, Stroup BM, Nair N, Sawin EA, Rohr F, Levy HL. Metabolomic changes demonstrate reduced bioavailability of tyrosine and altered metabolism of tryptophan via the kynurenine pathway with ingestion of medical foods in phenylketonuria. Mol Genet Metab. 2017 Jun;121(2):96-103. doi: 10.1016/j.ymgme.2017.04.003. Epub 2017 Apr 6.
PubMed 28400091Stroup BM, Murali SG, Nair N, Sawin EA, Rohr F, Levy HL, Ney DM. Dietary amino acid intakes associated with a low-phenylalanine diet combined with amino acid medical foods and glycomacropeptide medical foods and neuropsychological outcomes in subjects with phenylketonuria. Data Brief. 2017 Jun 7;13:377-384. doi: 10.1016/j.dib.2017.06.004. eCollection 2017 Aug.
PubMed 28664173Stroup BM, Sawin EA, Murali SG, Binkley N, Hansen KE, Ney DM. Amino Acid Medical Foods Provide a High Dietary Acid Load and Increase Urinary Excretion of Renal Net Acid, Calcium, and Magnesium Compared with Glycomacropeptide Medical Foods in Phenylketonuria. J Nutr Metab. 2017;2017:1909101. doi: 10.1155/2017/1909101. Epub 2017 May 4.
PubMed 28546877Stroup BM, Ney DM, Murali SG, Rohr F, Gleason ST, van Calcar SC, Levy HL. Metabolomic Insights into the Nutritional Status of Adults and Adolescents with Phenylketonuria Consuming a Low-Phenylalanine Diet in Combination with Amino Acid and Glycomacropeptide Medical Foods. J Nutr Metab. 2017;2017:6859820. doi: 10.1155/2017/6859820. Epub 2017 Dec 31.
PubMed 29464117Stroup BM, Nair N, Murali SG, Broniowska K, Rohr F, Levy HL, Ney DM. Metabolomic Markers of Essential Fatty Acids, Carnitine, and Cholesterol Metabolism in Adults and Adolescents with Phenylketonuria. J Nutr. 2018 Feb 1;148(2):194-201. doi: 10.1093/jn/nxx039.
PubMed 29490096Stroup BM, Hansen KE, Krueger D, Binkley N, Ney DM. Sex differences in body composition and bone mineral density in phenylketonuria: A cross-sectional study. Mol Genet Metab Rep. 2018 Feb 3;15:30-35. doi: 10.1016/j.ymgmr.2018.01.004. eCollection 2018 Jun.
PubMed 30023287
Study at a glance
From the registry record, last updated by the sponsor on 24 Aug 2018. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Phase 2 Study of Glycomacropeptide vs. Amino Acid Diet for the Management of PKU
- ClinicalTrials.gov ID
- NCT01428258
- Acronym / sponsor ID
- PKU / H-2010-0165
- Conditions
- Phenylketonuria
- Keywords
- Diet therapy, Low phenylalanine diet, Attention, Executive function
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 32 participants (actual)
- Lead sponsor
- University of Wisconsin, MadisonUniversity, hospital or other
- Collaborators
- Boston Children's Hospital
- Study start
- Sep 2011
- Primary completion
- Nov 2015 (actual)
- Study completion
- May 2016 (actual)
- First posted
- 2 Sep 2011 (estimated)
- Results
- Posted 3 Mar 2017
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
For individuals with Phenylketonuria (PKU), the investigators hypothesize that glycomacropeptide will provide an acceptable form of low-phenylalanine dietary protein that will improve dietary compliance, blood phenylalanine levels, cognitive function, and ultimately quality of life compared with the usual amino acid based diet. The study is funded by the Food and Drug Administration (FDA) Office of Orphan Products Development Grants Program, R01 FD003711.
Detailed description
Individuals with phenylketonuria (PKU) lack the enzyme phenylalanine hydroxylase that is needed to metabolize the essential amino acid phenylalanine (phe). When eating a normal diet they show an elevated level of phe in blood that is toxic to the brain. In order to prevent brain damage and cognitive impairment, individuals with PKU must follow a lifelong, low-phe diet that is restricted in natural foods and requires ingestion of a phe-free amino acid (AA) formula. Most adolescents and adults with PKU find the AA formula unpalatable and go off the diet resulting in elevated blood phe levels and neuropsychological deterioration. Glycomacropeptide (GMP), an intact protein produced during cheese making, is uniquely suited to a low-phe diet because it is the only known dietary protein that contains minimal phe. Foods and beverages made with GMP are a palatable alternative to AA formula. The long term goal is to assess the safety, efficacy and acceptability of GMP for the nutritional management of PKU. The specific aim is to conduct a randomized, two-stage, 11-wk, crossover trial comparing the GMP diet with the AA diet in 30 subjects with PKU ≥12 years of age treated since birth with a low-phe AA diet. The sites are: University of Wisconsin-Madison, Waisman Center (primary) and Harvard University, Children's Hospital Boston. Subjects will be recruited and randomized to begin the first 3-wk of the study with either a low-phe diet in which the majority of dietary protein is provided by GMP or AA medical foods and then, after a 3-wk washout with intake of their usual diet, begin the second diet for 3-wk. Dietary education will be provided in a 1-wk base period preceding initiation of each diet.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- The study is a randomized, two-arm, crossover trial comparing the GMP diet and the AA diet in 30 subjects with PKU > 12 years of age. Subjects were randomized to start with either the GMP diet or the AA diet which they followed for 3-wk at home, followed by a 3-wk washout period when they resumed their usual AA diet, and then 3-wk of either the GMP diet or the AA diet whichever they did not consume first. Each subject served as their own control; there was no control group. We studied medical foods - either AA or GMP medical foods which are not drugs. The FDA did not require that we have an IND.
| Arm | Type | Receives |
|---|---|---|
| GMP Diet/GMP Medical Foods | Experimental | Other: AA Diet/AA Medical FoodsThe experimental intervention is the GMP diet followed at home for 3-wk. In this randomized crossover study, half of subjects (n=15) were randomized to receive the GMP diet as the first arm, and half of the subjects (n=15) were randomized to receive the GMP diet as the second arm. |
| AA Diet/AA Medical Foods | Active comparator | Other: GMP Diet/GMP Medical FoodsThe experimental intervention is the AA diet followed at home for 3-wk. In this randomized crossover study, half of subjects (n=15) were randomized to receive the AA diet as the first arm, and half of the subjects (n=15) were randomized to receive the AA diet as the second arm. |
Who may qualify
- Ages
- 12 to 45 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult
Key inclusion criteria (4 listed)
- Identified PKU by newborn screening; started diet treatment before 1 mo age
- Diagnosis of classical or variant PKU with documented phenylalanine level of greater than 600 umol/L at 7-10d of age
- Follows or willing to follow PKU diet and consume amino acid medical formula providing more than 50% of protein needs
- Acceptance of glycomacropeptide foods determined prior to enrollment
Key exclusion criteria (3 listed)
- Females who are pregnant or planning pregnancy
- Individuals with mental deficits due to untreated or poorly controlled PKU
- Individuals with any health condition deemed to interfere with participation
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| GMP Diet/GMP Medical FoodsAlso: GMP Medical Foods, Glytactin trademark of Cambrooke Therapeutics,LLCThe intervention consists of a low-phenylalanine (Phe) diet in combination with medical foods made with the peptide GMP supplemented with limiting indispensable amino acids, as provided by Cambrooke Therapeutics, LLC. The diet is formulated to replace the protein equivalents provided by AA medical foods with GMP medical foods, keeping other dietary components constant. The GMP dietary treatment period consists of all subjects following the GMP diet for 3-wks at home. The GMP diet intervention is administered in differing orders, GMP Diet/AA Diet or AA diet/GMP Diet. | Other | AA Diet/AA Medical Foods |
| AA Diet/AA Medical FoodsAlso: AA Medical FoodsThe intervention consists of a low-Phe diet in combination with commercial AA medical foods as consumed in each subject's usual diet. A total of 15 different commercial AA medical foods were consumed by subjects in the study. The diet is formulated to provide each subject with their typical daily intake of protein equivalents from AA medical foods. The AA dietary treatment period consists of all subjects following the AA diet for 3-wks at home. The AA Diet comparator intervention is administered in differing orders, GMP Diet/AA Diet or AA diet/GMP Diet. | Other | GMP Diet/GMP Medical Foods |
Primary outcome
Change in the Plasma Phenylalanine Concentration of PKU Subjects Fed the Glycomacropeptide Diet Compared With the Change When Fed the Amino Acid Diet
Time frame: baseline to day 22 on each diet
Plasma will be collected at each base week and after 3 weeks on each of the dietary treatments, glycomacropeptide and amino acid, following an overnight fast. Plasma phenylalanine concentration (along with the complete profile of free amino acids) will be determined with an amino acid analyzer in the Wisconsin State Lab of Hygiene. Statistical analysis to determine the significance of the change in plasma phe concentration when comparing the 2 diets will consist of ANCOVA with covariates for baseline Phe and dietary Phe intake. The change in plasma Phe concentration from day 22 (final) to day 1 (baseline) was determined after adjusting for baseline Phe level and dietary Phe intake.
6 secondary outcomes
Dietary Compliance
Time frame: 3 week dietary treatment
Executive Function Assessed by BRIEF
Time frame: day 22 of each dietary treatment
Vitamin D (25-OH) Plasma Concentration at Day 22
Time frame: day 22 of each dietary treatment
Comparison of Phe Concentrations in Plasma With Concentrations in Dried Blood Spots
Time frame: 4 times total, 2 per treatment
Bone-specific Alkaline Phosphatase (BSAP) Plasma Concentration at Day 22
Time frame: day 22 of each dietary treatment
N-terminal Telopeptide (NTX) Plasma Concentration at Day 22
Time frame: day 22 of each dietary treatment
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Aug 2018.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Background: PubMed 19244369van Calcar SC, MacLeod EL, Gleason ST, Etzel MR, Clayton MK, Wolff JA, Ney DM. Improved nutritional management of phenylketonuria by using a diet containing glycomacropeptide compared with amino acids. Am J Clin Nutr. 2009 Apr;89(4):1068-77. doi: 10.3945/ajcn.2008.27280. Epub 2009 Feb 25.
- Background: PubMed 18956251Ney DM, Gleason ST, van Calcar SC, MacLeod EL, Nelson KL, Etzel MR, Rice GM, Wolff JA. Nutritional management of PKU with glycomacropeptide from cheese whey. J Inherit Metab Dis. 2009 Feb;32(1):32-9. doi: 10.1007/s10545-008-0952-4. Epub 2008 Oct 29.
- Background: PubMed 18203898Ney DM, Hull AK, van Calcar SC, Liu X, Etzel MR. Dietary glycomacropeptide supports growth and reduces the concentrations of phenylalanine in plasma and brain in a murine model of phenylketonuria. J Nutr. 2008 Feb;138(2):316-22. doi: 10.1093/jn/138.2.316.
- Background: PubMed 20466571MacLeod EL, Clayton MK, van Calcar SC, Ney DM. Breakfast with glycomacropeptide compared with amino acids suppresses plasma ghrelin levels in individuals with phenylketonuria. Mol Genet Metab. 2010 Aug;100(4):303-8. doi: 10.1016/j.ymgme.2010.04.003. Epub 2010 Apr 14.
- Background: PubMed 19490325Laclair CE, Ney DM, MacLeod EL, Etzel MR. Purification and use of glycomacropeptide for nutritional management of phenylketonuria. J Food Sci. 2009 May-Jul;74(4):E199-206. doi: 10.1111/j.1750-3841.2009.01134.x.
- Results publication: PubMed 27413125Ney DM, Stroup BM, Clayton MK, Murali SG, Rice GM, Rohr F, Levy HL. Glycomacropeptide for nutritional management of phenylketonuria: a randomized, controlled, crossover trial. Am J Clin Nutr. 2016 Aug;104(2):334-45. doi: 10.3945/ajcn.116.135293. Epub 2016 Jul 13.
- Results publication: PubMed 27014575Stroup BM, Held PK, Williams P, Clayton MK, Murali SG, Rice GM, Ney DM. Clinical relevance of the discrepancy in phenylalanine concentrations analyzed using tandem mass spectrometry compared with ion-exchange chromatography in phenylketonuria. Mol Genet Metab Rep. 2016 Jan 16;6:21-6. doi: 10.1016/j.ymgmr.2016.01.001. eCollection 2016 Mar.
- Results publication: PubMed 28400091Ney DM, Murali SG, Stroup BM, Nair N, Sawin EA, Rohr F, Levy HL. Metabolomic changes demonstrate reduced bioavailability of tyrosine and altered metabolism of tryptophan via the kynurenine pathway with ingestion of medical foods in phenylketonuria. Mol Genet Metab. 2017 Jun;121(2):96-103. doi: 10.1016/j.ymgme.2017.04.003. Epub 2017 Apr 6.
- Results publication: PubMed 28664173Stroup BM, Murali SG, Nair N, Sawin EA, Rohr F, Levy HL, Ney DM. Dietary amino acid intakes associated with a low-phenylalanine diet combined with amino acid medical foods and glycomacropeptide medical foods and neuropsychological outcomes in subjects with phenylketonuria. Data Brief. 2017 Jun 7;13:377-384. doi: 10.1016/j.dib.2017.06.004. eCollection 2017 Aug.
- Results publication: PubMed 28546877Stroup BM, Sawin EA, Murali SG, Binkley N, Hansen KE, Ney DM. Amino Acid Medical Foods Provide a High Dietary Acid Load and Increase Urinary Excretion of Renal Net Acid, Calcium, and Magnesium Compared with Glycomacropeptide Medical Foods in Phenylketonuria. J Nutr Metab. 2017;2017:1909101. doi: 10.1155/2017/1909101. Epub 2017 May 4.
- Results publication: PubMed 29464117Stroup BM, Ney DM, Murali SG, Rohr F, Gleason ST, van Calcar SC, Levy HL. Metabolomic Insights into the Nutritional Status of Adults and Adolescents with Phenylketonuria Consuming a Low-Phenylalanine Diet in Combination with Amino Acid and Glycomacropeptide Medical Foods. J Nutr Metab. 2017;2017:6859820. doi: 10.1155/2017/6859820. Epub 2017 Dec 31.
- Results publication: PubMed 29490096Stroup BM, Nair N, Murali SG, Broniowska K, Rohr F, Levy HL, Ney DM. Metabolomic Markers of Essential Fatty Acids, Carnitine, and Cholesterol Metabolism in Adults and Adolescents with Phenylketonuria. J Nutr. 2018 Feb 1;148(2):194-201. doi: 10.1093/jn/nxx039.
- National PKU AllianceLink provided by the sponsor.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Denise M Ney, PhD, RD study director
Professor of Nutritional Sciences, University of Wisconsin-Madison
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing GMP Diet/GMP Medical Foods and AA Diet/AA Medical Foods in people with Phenylketonuria, run by University of Wisconsin, Madison at 2 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 24 Aug 2018. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Yes. Results are posted in the registry (first posted 3 Mar 2017). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in the Plasma Phenylalanine Concentration of PKU Subjects Fed the Glycomacropeptide Diet Compared With the Change When Fed the Amino Acid Diet (time frame: baseline to day 22 on each diet). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT01428258, which also lists 13 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Aug 2018; AzTrials last refreshed its copy on 7 Nov 2026.