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

Unmet needs in phenylketonuria: an exploratory Italian survey among patients and caregivers

OBJECTIVE

Patients with phenylketonuria (PKU) require a strict diet to maintain phenylalanine (Phe) levels within the desired range. However, the diet can be onerous, resulting in poor adherence. We carried out the first online national survey in Italy to better understand the perceptions, knowledge, and experiences of both patients with PKU and caregivers with the goal of improving patient outcomes.

METHODS

An online survey of 35 questions to patients and 36 questions to caregivers was distributed in September 2022 through physicians and relevant Italian associations. The information collected included knowledge and impact of PKU, unmet needs, knowledge of available drugs, and satisfaction with therapy.

RESULTS

Overall, 241 questionnaires were completed by 85 patients and 156 caregivers (96.0% were parents). Knowledge of the pathogenic basis of PKU was generally high. The most common patient-reported symptoms were agitation/anxiety (48.8%), fatigue (41.1%), mood disorders (39.8%), and difficulty concentrating (33.4%). Different perspectives on adherence to a low-Phe diet were observed (22.9% of patients reported strict adherence vs. 47.0% of caregivers). Drugs that allow more freedom were needed by 49.4% of patients and 61.7% of caregivers, along with a wider range of choices of non-dietary treatments (48.2% and 60.0%, respectively). Unmet informational needs of patients included PKU and pregnancy, complications, travel, sports, and transition into adult care.

CONCLUSIONS

Our data showed that patients with PKU and their caregivers reported difficulties in adherence to diet therapy and indicated interest in new therapeutic approaches. Apparent differences between patient and caregiver perspectives were identified. More informational resources on PKU are needed.

Health-related quality of life in a european sample of adults with early-treated classical PKU

BACKGROUND

Phenylketonuria (PKU) is a rare inborn error of metabolism affecting the catabolism of phenylalanine (Phe). To date, findings regarding health-related quality of life (HRQoL) in adults with early-treated classical PKU are discrepant. Moreover, little is known about metabolic, demographic, and cognitive factors associated with HRQoL. Hence, we aimed to investigate HRQoL and its association with demographic, metabolic, and cognitive characteristics in a large European sample of adults with early-treated classical PKU.

RESULTS

This cross-sectional study included 124 adults with early-treated classical PKU from Hungary, Italy, Spain, Switzerland, and Turkey. All participants prospectively completed the PKU quality of life questionnaire (PKU-QoL), a questionnaire specifically designed to evaluate the impact of PKU and its treatment on HRQoL in individuals with PKU. In addition, information about Phe levels (concurrent and past year), demographic (age and sex), and cognitive variables (intelligence quotient, IQ) were collected. Most domains revealed little or no impact of PKU on HRQoL and more than three-quarters of the patients rated their health status as good, very good, or excellent. Nevertheless, some areas of concern for patients were identified. Patients were worried about the guilt that they experience if they do not adhere to the dietary protein restriction and they were most concerned about high Phe levels during pregnancy. Further, tiredness was the most affected symptom, and the supplements' taste was considered a main issue for individuals with PKU. The overall impact of PKU on HRQoL was higher in women (U = 1315.5, p = .012) and in adults with a lower IQ (rs = - 0.448, p = .005). The overall impact of dietary protein restriction was higher in adults with higher concurrent Phe levels (rs = 0.272, p = .007) and higher Phe levels during the past year (rs = 0.280, p = .009).

CONCLUSION

The impact of PKU on most domains assessed in the PKU-QoL was considered to be low. These results likely reflect the successful implementation of the newborn screening resulting in the prevention of severe adverse long-term outcomes. However, a particular clinical focus should be given to patients with lower IQ, higher Phe levels, and women, as these variables were associated with a lower HRQoL.

Expert Consensus on the Long-Term Effectiveness of Medical Nutrition Therapy and Its Impact on the Outcomes of Adults with Phenylketonuria

Many adults with phenylketonuria (PKU) rely on medical nutrition therapy (MNT; low phenylalanine (Phe) diet with protein substitutes/medical foods) to maintain blood Phe concentrations within recommended ranges and prevent PKU-associated comorbidities. Despite disease detection through newborn screening and introduction of MNT as early as birth, adherence to MNT often deteriorates from childhood onwards, complicating the assessment of its effectiveness in the long term. Via a modified Delphi process, consensus (≥70% agreement) was sought on 19 statements among an international, multidisciplinary 13-member expert panel. After three iterative voting rounds, the panel achieved consensus on 17 statements related to the limitations of the long-term effectiveness of MNT (7), the burden of long-term reliance on MNT (4), and its potential long-term detrimental health effects (6). According to the expert panel, the effectiveness of MNT is limited in the long term, is associated with a high treatment burden, and demonstrates that adults with PKU are often unable to achieve metabolic control through dietary management alone, creating an unmet need in the adult PKU population.

Nutrition management of PKU with pegvaliase therapy: update of the web-based PKU nutrition management guideline recommendations

BACKGROUND

The web-based GMDI/SERN PKU Nutrition Management Guideline, published before approval of pegvaliase pharmacotherapy, offers guidance for nutrition management of individuals with phenylketonuria (PKU) treated with dietary therapy and/or sapropterin. An update of this guideline aims to provide recommendations that improve clinical outcomes and promote consistency and best practice in the nutrition management of individuals with PKU receiving pegvaliase therapy. Methodology includes: formulation of a research question; review, critical appraisal, and abstraction of peer-reviewed studies and unpublished practice literature; expert input through Delphi surveys and a Nominal Group process; and external review by metabolic experts.

RESULTS

Recommendations, summary statements, and strength of evidence are included for each of the following topics: (1) initiating a pegvaliase response trial, (2) monitoring therapy response and nutritional status, (3) managing pegvaliase treatment after response to therapy, (4) education and support for optimal nutrition with pegvaliase therapy, and (5) pegvaliase therapy during pregnancy, lactation, and adolescence. Findings, supported by evidence and consensus, provide guidance for nutrition management of individuals receiving pegvaliase therapy for PKU. Recommendations focus on nutrition management by clinicians, as well as the challenges for individuals with PKU as a result of therapy changes.

CONCLUSIONS

Successful pegvaliase therapy allows the possibility for individuals with PKU to consume an unrestricted diet while still maintaining the benefits of blood phenylalanine control. This necessitates a perspective change in education and support provided to individuals in order to achieve healthy nutrient intake that supports optimal nutritional status. The updated guideline, and companion Toolkit for practical implementation of recommendations, is web-based, allowing for utilization by health care providers, researchers, and collaborators who advocate and care for individuals with PKU. These guidelines are meant to be followed always taking into account the provider's clinical judgement and considering the individual's specific circumstances. Open access is available at the Genetic Metabolic Dietitians International ( https://GMDI.org ) and Southeast Regional Genetics Network ( https://managementguidelines.net ) websites.

Patient preference for early onset of efficacy of preventive migraine treatments

Objective

The objective of this study was to ascertain to what extent adults with migraine value an early onset of efficacy for preventive migraine treatments.

Background

In placebo‐controlled clinical trials, treatment with eptinezumab resulted in a lower proportion of adults with migraine on the first day following infusion (day 1; 14% point‐reduction for chronic migraine [CM] in PROMISE‐2 and 8% point‐reduction for episodic migraine [EM] in PROMISE‐1).

Methods

Adults with migraine completed an online preference‐elicitation thresholding exercise to ascertain to what extent they value not having a migraine on day 1 postdosing relative to a clinically relevant reduction in number of migraine days during the first month postdosing (≥2 migraine‐free days for CM and ≥1 migraine‐free days for EM).

Results

One hundred and one participants (mean age, 50.6 ± 12.4 years; 81 [80%] women) were included. In participants with CM, 29 of 50 (58%) considered the eptinezumab‐generated reduction in the likelihood of migraine on day 1 postdosing to be at least as important as a clinically relevant reduction in number of migraine days the first month postdosing, whereas 37 of 50 (74%) considered a clinically relevant reduction of migraine days the first month postdosing to have a value equivalent to the eptinezumab‐generated reduction in the likelihood of migraine on day 1 postdosing. In participants with EM, 18 of 35 (51%) considered the eptinezumab‐generated reduction in the likelihood of migraine on day 1 postdosing to be at least as important as a clinically relevant reduction in migraine days the first month postdosing, whereas 24 of 35 (69%) considered a clinically relevant reduction of migraine days the first month postdosing to have a value equivalent to the eptinezumab‐generated reduction in the likelihood of migraine on day 1 postdosing.

Conclusion

Most participants considered the reduction in the likelihood of migraine offered by eptinezumab on day 1 postdosing to be at least as important as a clinically relevant reduction in migraine days the first month postdosing.

Italian national consensus statement on management and pharmacological treatment of phenylketonuria

BACKGROUND

Phenylketonuria (PKU) is a rare inherited metabolic disorder caused by defects in the phenylalanine-hydroxylase gene (PAH), the enzyme catalyzing the conversion of phenylalanine to tyrosine. PAH impairment causes phenylalanine accumulation in the blood and brain, with a broad spectrum of pathophysiological and neurological consequences for patients. Prevalence of disease varies, with peaks in some regions and countries, including Italy. A recent expert survey described the real-life of clinical practice for PKU in Italy, revealing inhomogeneities in disease management, particularly concerning approach to pharmacotherapy with sapropterin hydrochloride, analogous of the natural PAH co-factor, allowing disease control in a subset of patients. Therefore, the purpose of this paper is to continue the work initiated with the expert survey paper, to provide national guidances aiming to harmonize and optimize patient care at a national level.

PARTICIPANTS

The Consensus Group, convened by 10 Steering Committee members, consisted of a multidisciplinary crowd of 46 experts in the management of PKU in Italy.

CONSENSUS PROCESS

The Steering Committee met in a series of virtual meeting in order to discuss on clinical focuses to be developed and analyzed in guidance statements, on the basis of expert practice based evidence, large systematic literature review previously performed in the expert survey paper, and evidence based consensus published. Statements were re-discussed and refined during consensus conferences in the widest audience of experts, and finally submitted to the whole consensus group for a modified-Delphi voting.

RESULTS

Seventy three statements, divided in two main clinical areas, PKU management and Pharmacotherapy, achieved large consensus in a multidisciplinary group of expert in different aspects of disease. Importantly, these statements involve guidances for the use of sapropterin dihydrochloride, still not sufficiently implemented in Italy, and a set of good practice to approach the use of novel enzyme replacement treatment pegvaliase.

CONCLUSIONS

This evidence-based consensus provides a minimum set of guidances for disease management to be implemented in all PKU centers. Moreover, these guidances represent the first statement for sapropterin dihydrochloride use, implementation and standardization in Italy, and a guide for approaching pegvaliase treatment at a national level on a consistent basis.

Assessing Patient Preferences in Rare Diseases: Direct Preference Elicitation in the Rare Chronic Kidney Disease, Immunoglobulin A Nephropathy

Background

Patient preference information is increasingly being used to inform decision making; however, further work is required to support the collection of preference information in rare diseases. This study illustrates the use of direct preference elicitation methods to collect preference data from small samples in the context of early decision making to inform the development of a product for the treatment of immunoglobulin A nephropathy.

Method

An interview-based swing weighting approach was used to elicit preferences from 40 patients in the US and China. Attributes were identified through a background review, expert engagement and patient focus groups. Participants completed a series of tasks that involved ranking, rating and scoring improvements in the attributes to obtain attribute swing weights and partial value functions. The preference results were then incorporated into a benefit-risk assessment simulation tool.

Results

Participants placed the greatest value on avoiding end-stage renal/kidney disease. Similar weight was given to short-term quality-of-life improvements and avoiding infections. Treatment burden (number of vaccinations) received the least weight. Heterogeneity in preferences was also observed. Consistency tests did not identify statistically significant variation in preferences, and qualitative data suggested that the elicitation exercise was sensitive to participants’ interpretation of attributes and that participants were able to express their preferences.

Conclusion

Direct preference elicitation methods can be used to collect preference data from small samples. Further work should continue to test the validity of the estimate generated by such methods.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40271-021-00521-3.

Case-control study about the acceptance of Pegvaliase in Phenylketonuria

Introduction

Pegvaliase is a novel enzyme substitution therapy approved by the European Drug Administration (EDA) in May 2019 for the treatment of Phenylketonuria (PKU) in adults and children ≥16 years of age. The pegylated phenylalanine ammonia lyase is isolated from bacteria and therefore provokes multifarious immunogenic reactions. Thus, the selection of the right patient for a potential harmful treatment is essential for patient's contentedness and long-term therapy compliance.

Methods and results

101 patients with PKU were screened for eligibility for an additional treatment with Pegvaliase. 51 patients were included in the study, 26 received a structural information about the new treatment for in mean 43 ± 12 min and clinical data and plasma Phe-levels were assessed. After 4 weeks of consideration the willing of treatment initiation as well as reasons for denial are registered. 7 patients (27%) concluded in beginning of treatment. Phe-level in this (acceptance) group were higher (1180 ± 231 μmol/l) compared to the denial group (930 ± 278 μmol/l, p = .01). After 4 weeks Phe-levels in the acceptance group remained stable (1264 ± 311 μmol/l, p = .26) while Phe-levels in the denial group decreased (779 ± 226 μmol/l, p < .01). Main reasons for denial of therapy were fear of adverse effects (47%), no need for additional treatment (26%) and the subcutaneous way of application (21%).

Conclusion

PKU patients have reservations against an invasive subcutaneous treatment for their disease. This is mainly caused by the form of application by syringe and the potential harmful side effects. Only less than one-third of the patients in our cohort are willing to start treatment. Besides that, most PKU patients seem to have untapped potential for self-contained reduction of Phe-levels only by being focused on their diet.