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A benefit-risk analysis of pegvaliase for the treatment of phenylketonuria: A study of patients' preferences.

ABSTRACT: Background:Phenylketonuria (PKU) leads to an accumulation of phenylalanine (Phe) in the blood and subsequent neurologic, cognitive, psychiatric, and behavioral dysfunction. Many patients report social isolation and decreased quality of life. Pegvaliase is an enzyme substitution therapy that reduces blood Phe levels in patients with PKU and is associated with a risk of hypersensitivity reactions. Objective:To define the minimum acceptable benefit (MAB) of pegvaliase, i.e., the minimum probability of achieving a blood Phe level <360??mol/L, which patients require to tolerate the risks of hypersensitivity associated with pegvaliase. Methods:Adult, pegvaliase-naïve patients with blood Phe levels >600??mol/L participated in a patient-preference web survey using two surveys: adapted swing-weighting and thresholding. Participants were asked to make ordinal choices between varying clinical benefit and severity levels for hypersensitivity. Disease effects and treatment satisfaction were also assessed. Results:Among 45 participants, the mean (standard deviation) self-reported blood Phe level was 976.9 (429.9) ?mol/L; only 28.8% reported satisfaction with their current treatment. Most (84.4%) indicated difficulty in following a PKU diet; 60% reported that the PKU diet was burdensome, and 58% reported feeling socially isolated. Most (?69%) reported their MAB to be less than the expected clinical benefit provided by pegvaliase; the mean MAB was 22.7% and 34.4% in the swing-weighting and thresholding surveys, respectively. Conclusion:Most participants felt the burden of PKU on their daily lives, were dissatisfied with current treatments, and were willing to accept the risks of hypersensitivity reactions to achieve recommended blood Phe levels with pegvaliase treatment.

SUBMITTER: SriBhashyam S

PROVIDER: S-EPMC6722251 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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A benefit-risk analysis of pegvaliase for the treatment of phenylketonuria: A study of patients' preferences.

SriBhashyam Sumitra S Marsh Kevin K Quartel Adrian A Weng Haoling H HH Gershman Ari A Longo Nicola N Thomas Janet J Zori Roberto R

Molecular genetics and metabolism reports 20190830

<h4>Background</h4>Phenylketonuria (PKU) leads to an accumulation of phenylalanine (Phe) in the blood and subsequent neurologic, cognitive, psychiatric, and behavioral dysfunction. Many patients report social isolation and decreased quality of life. Pegvaliase is an enzyme substitution therapy that reduces blood Phe levels in patients with PKU and is associated with a risk of hypersensitivity reactions.<h4>Objective</h4>To define the minimum acceptable benefit (MAB) of pegvaliase, i.e., the mini ...[more]

PMID: 31497506

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Project description:BackgroundDeficiency of phenylalanine hydroxylase causes phenylketonuria (PKU) with elevated phenylalanine (Phe) levels and associated neuropsychiatric and neurocognitive symptoms. Pegvaliase (PEGylated phenylalanine ammonia lyase) is an investigational agent to lower plasma Phe in adults with PKU. This study aimed to characterize the long-term efficacy, safety, and immunogenicity of pegvaliase in adults with PKU.MethodsPAL-003 is an ongoing, open-label, long-term extension study of the pegvaliase dose-finding parent phase 2 studies. Participants continued the dose of pegvaliase from one of three parent studies, with dose adjustments to achieve a plasma Phe concentration between 60 and 600 μmol/L.ResultsMean (standard deviation [SD]) plasma Phe at treatment-naïve baseline for 80 participants in the parent studies was 1302.4 (351.5) μmol/L. In the 68 participants who entered the extension study, plasma Phe decreased 58.9 (39)% from baseline, to 541.6 (515.5) μmol/L at Week 48 of treatment. Plasma Phe concentrations ≤120 μmol/L, ≤360 μmol/L, and ≤ 600 μmol/L were achieved by 78.7, 80.0, and 82.5% of participants, respectively. Mean (SD) protein intake at baseline was 69.4 (40.4) g/day (similar to the recommended intake for the unaffected population) and remained stable throughout the study. All participants experienced adverse events (AEs), which were limited to mild or moderate severity in most (88.8%); the most common AEs were injection-site reaction (72.5%), injection-site erythema (67.5%), headache (67.5%), and arthralgia (65.0%). The AE rate decreased from 58.3 events per person-year in the parent studies to 18.6 events per person-year in the extension study.ConclusionsPegvaliase treatment in adults with PKU produced meaningful and persistent reductions in mean plasma Phe concentration with a manageable safety profile for most subjects that continued with long-term treatment.Trial registrationClinicalTrials.gov , NCT00924703. Registered June 18, 2009, https://clinicaltrials.gov/ct2/show/NCT00924703.

Project description:BackgroundRare disease patients and caregivers face uncommon, serious, debilitating conditions often characterised by poor prognosis and limited treatment options. This study aimed to explore what they consider of value when choosing between hypothetical therapeutic options and to quantify both their benefit-risk preferences and the influence of disease context.MethodsA mixed-methods survey with patients and caregivers was conducted in the United Kingdom across a range of rare diseases. Discrete-choice experiments that compared hypothetical treatment profiles of benefits and risks were used to measure respondent preferences across a set of seven attributes related to health outcomes, safety, and process of care. Bespoke questions on current disease management and the joint use of the 12-item WHODAS 2.0 questionnaire and of two Likert scales capturing self- and proxy-assessed disease-induced threat to life and impairment were implemented to describe disease context. Additionally, qualitative insights on the definitions of value and risk were collected from respondents.ResultsFinal study sample included 721 patients and 152 informal caregivers, across 52 rare diseases. When choosing between hypothetical novel treatments for rare diseases, respondents attributed most importance to drug response, risk of serious side effects, and the ability to conduct usual activities while on treatment. In contrast, attributes related to treatment modalities were the least important. Respondents expressed a willingness to accept risks in hopes of finding some benefit, such as a higher chance of drug response or greater health improvement potential. Increasing disease severity, impairment or disability, and the lack of effective therapeutic options were shown to raise significantly the willingness to gain benefit through increased risk.ConclusionsThis is the first study performing a quantitative discrete choice experiment amongst patients and caregivers across 52 rare conditions. It enables a more detailed understanding of the relationship between disease context, treatment attributes and the degree of risk respondents are willing to take to gain a specific degree of benefit. Researchers of novel therapeutics for rare diseases should be encouraged to invest in preference elicitation studies to generate rigorous patient evidence and specific regulatory guidance should be issued to acknowledge their importance and their use in marketing authorisations.

Project description:ObjectiveTo present a case series that illustrates real-world use of pegvaliase based on the initial experiences of US healthcare providers.MethodsSixteen healthcare providers from 14 centers across the US with substantial clinical experience in treating patients with phenylketonuria (PKU) with pegvaliase in the two-plus years since FDA approval (May 2018) provided cases that exemplified important lessons from their initial experiences treating patients with pegvaliase. Key lessons from each case and takeaway points were discussed in both live and virtual meetings.ResultsFifteen cases of adults with PKU (eight males, seven females), representing a spectrum of age (18 to 53 years), previous PKU care, comorbidities, and socioeconomic situations were reviewed and discussed. Full extended case reports are included in the Supplement. The cases showed that treating patients with a daily injectable can be challenging due to a patient's financial problems, treatment challenges, and neuropsychological and psychiatric comorbidities, which can be identified before starting pegvaliase, but do not prohibit successful treatment. The authors agreed that patient education on adverse events (AEs), time to efficacy, dietary changes, and food preparation is an ongoing process that should start prior to initiating pegvaliase treatment. Treatment goals and planned dietary changes once efficacy is reached should be defined prior to treatment initiation and re-evaluated throughout the course of therapy. Each patient's titration schedule and dietary adjustments are unique, depending on occurrence of AEs and individual goals of treatment. Despite the AE profile of pegvaliase, all but two patients remained motivated to continue treatment and achieved efficacy (except one patient in whom titration was still ongoing). AEs occurring early in the treatment pathway may require prolongation of the titration phase and/or concomitant medication use, but do not seem indicative of future tolerability or eventual efficacy. Close follow-up of patients during titration and maintenance to help with dietary changes is important.ConclusionThis case series provides real-world experience on the use of pegvaliase. Until data from registries and independent research become available, the data presented herein can support appropriate management of patients receiving pegvaliase in clinical practice.

Dataset Information

A benefit-risk analysis of pegvaliase for the treatment of phenylketonuria: A study of patients' preferences.

Publications

A benefit-risk analysis of pegvaliase for the treatment of phenylketonuria: A study of patients' preferences.

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