GMP Case Studies of Tolerance, Safety and Acceptability in PKU and TYR

Evaluating the Tolerance, Safety and Acceptability of GMP-based Protein Substitutes for the Dietary Management of Phenylketonuria and Tyrosinaemia in Children and Adults: a Case Study Series

Three new protein substitutes have been developed to help with compliance in PKU and TYR patients, which are powdered protein substitutes, low in Phe and, low in Phe and Tyr respectively, with a mixed balance of glycomacropeptide (GMP), essential and non-essential amino acids, carbohydrates, fats and micronutrients for the dietary management of PKU and TYR.

This series of case-studies will evaluate the acceptability, compliance, gastrointestinal tolerance and safety of the three GMP-based products for PKU and TYR in 45 patients with PKU and TYR, in both adults and children over 3 years (15 patients per product). The case study will last 29 days in total, including a 1-day baseline period followed by a 28-day intervention period. The case studies will be conducted across multiple specialist metabolic centres in the UK, to meet the UK ACBS and GMS requirements for acceptability studies. A series of case studies is undertaken due to the rarity of these conditions and the difficulty in recruiting these patients to trials.

Study Overview

• Status: Completed
• Conditions: PKU; Tyrosinemias
• Intervention / Treatment: Dietary supplement: PKU/TYR GMP Protein Substitute

Detailed Description

Phenylketonuria (PKU) and Tyrosinaemia (TYR) are rare inherited metabolic disorders of amino acid metabolism requiring dietary management. PKU is characterised by an inability to metabolise the essential dietary amino acid phenylalanine (Phe) into tyrosine (Tyr). As such, without appropriate management, PKU can lead to extremely elevated levels of Phe within the blood and brain, which can be detrimental to neurological health. The dietary management of PKU involves restricting dietary sources of Phe. Tyrosinaemia (TYR) is characterised by the inability to metabolise the dietary amino acid Tyr. If left uncontrolled, TYR can lead to serious hepatic, renal and neurological complications. The dietary management of TYR involves restriction of dietary sources of Tyr and Phe (as Phe is converted into Tyr). The dietary management of PKU and TYR involves restricting dietary protein intake to promote optimal metabolic control, whilst meeting all other amino acid and nutrient requirements. As Phe and Tyr are present in significant quantities in nearly all dietary proteins, this usually requires a very low protein diet from food, supplemented with a Phe-free (for PKU) or Phe- and Tyr-free (for TYR) amino acid-based protein substitute. However, compliance with the diet is often poor, with patients commonly going "off diet" during adolescence and in adulthood. This can lead to entirely preventable, lifelong mental and physiological impairments. Reasons for non-compliance often revolve around the strong taste of amino acid-based protein substitutes, alongside the inability to conform to the normal eating habits of peers.

Three new protein substitutes have been developed to help with compliance in PKU and TYR patients, which are powdered protein substitutes, low in Phe and, low in Phe and Tyr respectively, with a mixed balance of glycomacropeptide (GMP), essential and non-essential amino acids, carbohydrates, fats and micronutrients for the dietary management of PKU and TYR. The protein in GMP-based products for PKU and TYR are based on GMP, a peptide isolated from milk during cheese manufacturing and the only known naturally derived protein source low in Phe and Tyr. The GMP is supplemented with appropriate quantities of other amino acids which are naturally low or not present in GMP, as well as carbohydrates and fats. This differs from traditional formulae which are based wholly on individual, synthetically produced amino acids to provide the source of dietary nitrogen, supplemented with vitamins and minerals. Studies to date have illustrated that PKU patients who replace their regular Phe-free amino acid-based formula with GMP-based foods may have better diet compliance, prefer the taste and may have improved blood Phe control.

This series of case-studies will evaluate the acceptability, compliance, gastrointestinal tolerance and safety of the three GMP-based products for PKU and TYR in 45 patients with PKU and TYR, in both adults and children over 3 years (15 patients per product). The case study will last 29 days in total, including a 1-day baseline period followed by a 28-day intervention period. The case studies will be conducted across multiple specialist metabolic centres in the UK, to meet the UK ACBS and GMS requirements for acceptability studies. A series of case studies is undertaken due to the rarity of these conditions and the difficulty in recruiting these patients to trials.

• Study Type: Interventional
• Enrollment (Actual): 45
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Bristol, United Kingdom
    • Bristol University Hospitals

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 3 years and older (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Male or female
• Over 3 years of age
• Diagnosed with classical or variant type phenylketonuria, or tyrosinaemia (as appropriate)
• Have been compliant in taking at least one protein substitute, providing at least 10g protein equivalents, for at least 1 month prior to trial commencement
• Have a prescribed daily Phe or Phe and Tyr allowance for PKU or TYR respectively
• Written or electronic informed consent from patient, and/or from parent/caregiver if applicable

Exclusion Criteria:

• Currently prescribed Sapropterin or similar tetrahydrobiopterin based medication
• Pregnant or lactating
• Requiring parenteral nutrition
• Major hepatic or renal dysfunction
• Participation in other studies within 1 month prior to entry of this study
• Allergy to any of the study product ingredients, including milk and soy
• Investigator concern around willingness/ability of patient or parent/caregiver to comply with protocol requirements

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: GMP-based products; GMP-based nutritional protein substitutes for the dietary management of PKU and TYR	Dietary supplement: PKU/TYR GMP Protein Substitute; After a 1-day baseline period during which patients will consume their usual protein substitute, each patient will receive one the case study product for 4 weeks (28 days).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Acceptability	Acceptability of the patients' usual protein substitute and the study product assessed by the Dietitian with a series of questions posed to the patient and/or parent/caregiver on on all attributes which included appearance, smell, taste, texture (mouthfeel), ease of mixing, ease of taking, after taste and smell of breath after taking, assessed on a 5-point likert scale (Great; Good; OK; Bad; Terrible).	Baseline (Day 1) - End of case studies (Day 29)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Compliance	Compliance (% intake compared to that prescribed) with the recommended intake of the patients' usual protein substitute (during baseline) and with the case study product (during the case study period) will be assessed by the Dietitian.	Baseline (Day 1) - End of case studies (Day 29)
Gastro-intestinal (GI) tolerance	Gastro-intestinal (GI) tolerance symptoms will be recorded by the Dietitian.	Baseline (Day 1) - End of case studies (Day 29)
Anthropometry	Body weight (kg) and height (m) will be measured where possible using standard methods to calculate body mass index (BMI)	Baseline (Day 1) - End of case studies (Day 29)

Collaborators and Investigators

• Sponsor: Nutricia UK Ltd
• Investigators: Study Chair: Rebecca Stratton, Nutricia UK Ltd

Study record dates

Study Major Dates

• Study Start (Actual): September 16, 2020
• Primary Completion (Actual): August 30, 2023
• Study Completion (Actual): November 24, 2023

Study Registration Dates

• First Submitted: September 6, 2021
• First Submitted That Met QC Criteria: September 29, 2021
• First Posted (Actual): September 30, 2021

Study Record Updates

• Last Update Posted (Actual): November 27, 2023
• Last Update Submitted That Met QC Criteria: November 24, 2023
• Last Verified: November 1, 2023

More Information

Terms related to this study

• Keywords: PKU; TYR
• Additional Relevant MeSH Terms: Metabolic Diseases; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Genetic Diseases, Inborn; Metabolism, Inborn Errors; Brain Diseases, Metabolic; Brain Diseases, Metabolic, Inborn; Amino Acid Metabolism, Inborn Errors; Tyrosinemias
• Other Study ID Numbers: GMP2020

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No