Background: If symptomatic in infants, the autosomal recessive disease lysosomal acid lipase deficiency (LAL-D; sometimes called Wolman disease or LAL-D/Wolman phenotype) is characterized by complete loss of LAL enzyme activity. This very rare, rapidly progressive form of LAL-D results in severe manifestations leading to failure to thrive and death, usually by 6 months of age. We report results from 2 open-label studies of enzyme replacement therapy with sebelipase alfa, a recombinant human LAL, in infants with LAL-D: the phase 2/3 Survival of LAL-DInfantsTreated With SebelipaseAlfa (VITAL) study (NCT01371825) and a phase 2 dose-escalation study (LAL-CL08 [CL08]; NCT02193867). In both, infants received once-weekly intravenous infusions of sebelipase alfa.Results: The analysis population contained 19 patients (9 in VITAL; 10 in CL08). Kaplan–Meier estimates of survival to 12 months and 5 years of age were 79% and 68%, respectively, in the combined population, and the median age of surviving patients was 5.2 years in VITAL and 3.2 years in CL08. In both studies, median weight-for-age, length-for-age, and mid-upper arm circumference-for-agezscores increased from baseline to end of study. Decreases in median liver and spleen volume over time were noted in both studies. Short-term transfusion-free hemoglobin normalization was achieved by 100% of patients eligible for assessment in VITAL, in an estimated median (95% confidence interval [CI]) time of 4.6 (0.3–16.6) months. In CL08, short-term transfusion-free hemoglobin normalization was achieved by 70% of patients eligible for assessment, in an estimated median (95% CI) time of 5.5 (3.7–19.6) months. No patient discontinued treatment because of treatment-emergent adverse events. Most infusion-associated reactions (94% in VITAL and 88% in CL08) were mild or moderate in severity.Conclusions: The findings of these 2 studies of infants with rapidly progressive LAL-D demonstrated that enzyme replacement therapy with sebelipase alfa prolonged survival with normal psychomotor development, improved growth, hematologic parameters, and liver parameters, and was generally well tolerated, with an acceptable safety profile.

Sanfilippo syndrome type B (Sanfilippo B) belongs to a group of rare lysosomal storage diseases characterized by progressive cognitive decline from an early age, acute hyperactivity, and concomitant somatic symptoms. Caregivers face a unique set of challenges related to the complex nature of Sanfilippo B, but the burden and impact on quality of life (QoL) of caregivers is poorly defined and best practice guidance for clinicians is lacking. An international clinical advisors meeting was convened to discuss key aspects of caregiver burden associated with Sanfilippo B based on findings from qualitative and quantitative research undertaken to identify and quantify the nature and impact of the disease on patients and caregivers. Providing care for patients with Sanfilippo B impinges on all aspects of family life, evolving as the patient ages and the disease progresses. Important factors contributing toward caregiver burden include sleep disturbances, impulsive and hyperactive behavior, and communication difficulties. Caregiver burden remained high throughout the life of the patient and, coupled with the physical burden of daily care, had a cumulative impact that generated significant psychological stress. A Sanfilippo-specific QoL questionnaire is needed that is directed at caregiver needs and burden and best practice management of these domains.

To report interim results from the ongoing, open-label, phase 3 APHENITY Extension Study (NCT05166161), evaluating long-term treatment with sepiapterin in patients with phenylketonuria. Participants received an age-based dose of oral sepiapterin daily; those with mean blood phenylalanine (Phe) levels <360 μmol/L (<5.95 mg/dL) after 2 weeks underwent a 26-week dietary Phe tolerance assessment, wherein dietary Phe intake was adjusted and blood Phe levels monitored. Other participants continued treatment with optional diet liberalization. Primary endpoints included change from baseline to week 26 in dietary Phe intake and treatment-emergent adverse events (TEAEs). As of September 2, 2024, 169 participants received sepiapterin (median [minimum, maximum] age: 14.0 [0.2, 55.0] years, median exposure: 72.9 weeks); 102 participants underwent dietary Phe tolerance assessments. Mean (SD) dietary Phe intake increased from 27.6 (18.0) mg/kg/day at baseline to 62.5 (41.5) mg/kg/day at week 26 (least-squares mean change [SE]: 36.4 [2.8] mg/kg/day from baseline) (P < .0001 from post hoc analysis). The incidence of treatment-related TEAEs was 29.0%; 3 participants (1.8%) discontinued treatment owing to treatment-related TEAEs. There were no treatment-related serious TEAEs or deaths. Interim results support the long-term safety of sepiapterin and demonstrate the potential for diet liberalization in adults and children with phenylketonuria. NCT05166161 (https://www. gov/study/NCT05166161; date of registration, December 8, 2021).

Metachromatic leukodystrophy (MLD) is a fatal inherited lysosomal storage disease that can be detected through newborn bloodspot screening. The feasibility of the screening assay and the clinical rationale for screening for MLD have been previously demonstrated, so the aim of this study is to determine whether the addition of screening for MLD to the routine newborn screening program in the UK is a cost-effective use of National Health Service (NHS) resources. A health economic analysis from the perspective of the NHS and Personal Social Services was developed based on a decision-tree framework for each MLD subtype using long-term outcomes derived from a previously presented partitioned survival and Markov economic model. Modelling inputs for parameters related to epidemiology, test characteristics, screening and treatment costs were based on data from three major UK specialist MLD hospitals, structured expert opinion and published literature. Lifetime costs and quality-adjusted life years (QALYs) were discounted at 1.5% to account for time preference. Uncertainty associated with the parameter inputs was explored using sensitivity analyses. This health economic analysis demonstrates that newborn screening for MLD is a cost-effective use of NHS resources using a willingness-to-pay threshold appropriate to the severity of the disease; and supports the inclusion of MLD into the routine newborn screening programme in the UK.

Background: In phenylketonuria (PKU) patients, dried blood spot (DBS) sampling remains the standard method for monitoring phenylalanine (Phe) levels. However, delays in reporting results can hinder timely dietary adjustments. Patients and caregivers have expressed a preference for point-of-care testing (POCT) devices that enable home-based monitoring. Objectives: Our aim was to compare blood Phe measurements in PKU patients and caregiver usability of a POCT system with DBS, which is the standard practice monitoring method. Methods: Twenty participants (eighteen children with PKU and two healthy controls) were recruited. Caregivers of children with PKU were asked to perform blood Phe measurements at home under the supervision of a researcher, using both the POCT device (Egoo Phe system) and DBS sampling. Healthy controls collected the same number of samples using both methods in a hospital setting. The POCT system required 40 µL of blood and used an enzymatic, bioluminescent detection system. DBS samples were analyzed by tandem mass spectrometry (TMS) and required two blood spots (approximately 100 µL of blood). The Egoo Connect App, linked via Bluetooth to the POCT device, displayed results after 29 min. Caregiver usability of the POCT system was assessed using questionnaires at each visit. Results: A total of 100 paired samples were collected. Median values were 274 μmol/L (range: 30–1039) for POCT and 270 μmol/L (range: 20–1190) for DBS. POCT readings were a mean of 4.6% higher than DBS with a noticeable strong correlation observed (y = 1.017x; R² = 0.8450; p < 0.0001). The usability of the POCT system improved with caregiver practice, and all caregivers expressed a preference for POCT over DBS. Conclusions: The POCT system for blood Phe demonstrated strong concordance with DBS and high caregiver acceptance, highlighting its potential to transform PKU care through faster, patient-driven monitoring and more timely clinical decision-making.

In patients with phenylketonuria (PKU), sapropterin dihydrochloride (sapropterin) lowers blood phenylalanine (Phe) and may enhance Phe tolerance in sapropterin responsive patients. Attention to its administration, particularly the timing, and giving it with food with appropriate macronutrient composition, is important. We describe two boys with PKU who improved their Phe tolerance and metabolic control when they adjusted their method of sapropterin administration. Case 1: aged 7.25 years with mild PKU experienced a 40 % reduction in blood Phe after a 30-day sapropterin trial (20 mg/kg). Initially, he took sapropterin once daily dissolved in water. This increased his protein tolerance from 26 g to 50 g/day and reduced his protein equivalent from protein substitute to 20 g/day. His blood Phe was a median of 230 μmol/L (range: 130-300). After six months, twice-daily dosing further improved his protein tolerance to 60 g/day, with a lower median blood Phe (130 μmol/L, range: 80-220). By age 8 years, he swallowed tablets intact with meals, ate an unrestricted protein intake (∼80 g/day), stopped protein substitute, maintained excellent metabolic control with perceived cognitive improvement. Case 2: a boy who aged 4.992 years with mild PKU had a 33 % reduction in blood Phe after a 30-day sapropterin (20 mg/kg) trial. Initially, he took sapropterin once daily dissolved in water, increasing his protein tolerance from 14 g to 55 g/day, and reducing protein equivalent from protein substitute to 20 g/day. Median blood Phe was 240 μmol/L (range: 120-320). At age 6.92 years, twice-daily dosing and swallowing intact tablets further lowered his blood Phe, to a mean of 130 μmol/L (range: 100-130). He stopped dietary protein restriction and protein substitute intake. These case studies showed clinical and dietary benefits with adjustment of sapropterin administration. It was unclear if the improvements observed were associated with twice daily sapropterin administration, attention to taking it with fat containing meals, swallowing the tablets intact, or a combination of these. Further research to monitor the efficacy and safety of administration change is necessary.