Food or medicine? A European regulatory perspective on nutritional therapy products to treat inborn errors of metabolism

Mapping challenges in the accessibility of treatment products for urea cycle disorders: A survey of European healthcare professionals

Current management guidelines for urea cycle disorders (UCDs) offer clear strategies, incorporating both authorized and non-authorized medicinal products (including intravenous formulations and products regulated as food). These varying product categories are subject to specific accessibility challenges related to availability, reimbursement, and pricing. The aim of this study is to identify potential obstacles to optimal UCD treatment implementation in European clinical practice. A survey aimed at metabolic healthcare professionals (HCPs) managing patients with UCDs in Europe was disseminated through the European Reference Network for Hereditary Metabolic Disorders and the European registry and network for intoxication type metabolic diseases. Forty-eight survey responses were collected from 21 European countries. In 16 of these countries, at least one metabolic HCP reported challenges in accessing UCD products. Reimbursement issues were reported for most products (8/10), including both authorized and non-authorized products. Availability-related challenges were also reported for 8/10 products, although unavailability was limited to non-authorized products. Prices impacted accessibility for all authorized products (3/3) and one non-authorized IV product. The accessibility of UCD treatment products varied across Europe, although no clear regional variations could be discerned. Survey data revealed that metabolic HCPs experience challenges in accessing both authorized and non-authorized products for UCD management in the majority of European countries. This indicates that registering unauthorized products may not resolve all issues. Improved reimbursement policies and fair pricing models, as well as (adjusted) authorization procedures may help address these concerns, thereby optimizing treatment access for UCD patients.

3D Printing of Dietary Products for the Management of Inborn Errors of Intermediary Metabolism in Pediatric Populations

The incidence of Inborn Error of Intermediary Metabolism (IEiM) diseases may be low, yet collectively, they impact approximately 6-10% of the global population, primarily affecting children. Precise treatment doses and strict adherence to prescribed diet and pharmacological treatment regimens are imperative to avert metabolic disturbances in patients. However, the existing dietary and pharmacological products suffer from poor palatability, posing challenges to patient adherence. Furthermore, frequent dose adjustments contingent on age and drug blood levels further complicate treatment. Semi-solid extrusion (SSE) 3D printing technology is currently under assessment as a pioneering method for crafting customized chewable dosage forms, surmounting the primary limitations prevalent in present therapies. This method offers a spectrum of advantages, including the flexibility to tailor patient-specific doses, excipients, and organoleptic properties. These elements are pivotal in ensuring the treatment's efficacy, safety, and adherence. This comprehensive review presents the current landscape of available dietary products, diagnostic methods, therapeutic monitoring, and the latest advancements in SSE technology. It highlights the rationale underpinning their adoption while addressing regulatory aspects imperative for their seamless integration into clinical practice.

Effectiveness of L-serine supplementation in children with a GRIN2B loss-of-function mutation: Rationale and protocol for single patient (n-of-1) multiple cross-over trials

Rationale

Loss-of-function (LoF) mutations in GRIN2B result in neurologic abnormalities due to N-methyl-D-aspartate receptor (NMDAR) dysfunction. Affected persons present with various symptoms, including intellectual developmental disability (IDD), hypotonia, communication deficits, motor impairment, complex behavior, seizures, sleep disorders and gastrointestinal disturbance. Recently, in vitro experiments showed that D-serine mitigates function to GluN2B (mutation)-containing NMDARs. 11 previous case reports are published on (experimental) L-serine treatment of patients between 1.5 and 12 years old with GRIN2B missense or null mutations, some of whom showed notable improvement in motor and cognitive performance, communication, behavior and abnormalities on electro encephalography (EEG). Our objective is to further evaluate the effectiveness of L-serine for GRIN2B-related neurodevelopmental disorder (GRIN2B-NDD), using an n-of-1 trial design, increasing the level of evidence.

Methods/design

These n-of-1 trials, consisting of 2 cycles of 6 months, will be performed to evaluate the effect of L-serine compared to placebo in 4 patients with a GRIN2B LoF mutation. The aggregation of multiple n-of-1 trials will provide an estimate of the average treatment effects.The primary outcome is the Perceive-Recall-Plan-Perform of Task Analysis, assessing developmental skills. Secondary outcomes include Goal Attainment Scaling, seizure log books, EEGs, sleep log books, the irritability subscale of the Aberrant Behavior Checklist, the Bristol Stool Scale and the Pediatric Quality of Life Inventory.

Conclusion

This study employs an innovative methodological approach to evaluate the effectiveness of L-serine for patients with a GRIN2B LoF mutation. The results will establish a foundation for implementing L-serine as a disease-modifying treatment in GRIN2B-NDD.