Eladocagene exuparvovec 280 giga vector genomes/0.5ml solution for infusion vials

IntroductionAromatic L-amino acid decarboxylase (AADC) deficiency is a rare disease with symptoms including movement disorders, developmental delays, and autonomic symptoms starting from birth; further, patients with AADC deficiency are at a high risk of death in the first decade of life. Limited information on the impact of treatment with gene therapy on patients' disease trajectories and survival, quality-of-life, and resource usage benefits are available.MethodA cohort-based model with a lifetime horizon has been developed, based on motor milestones, to estimate the long-term benefits for patients after treatment with eladocagene exuparvovec compared to best supportive care (BSC). The model takes a National Health Service (NHS) perspective using a UK setting. The model comprises two parts: the developmental phase, in which patients with initially no motor function can progress to other motor milestone states, and a long-term projection phase. Efficacy for eladocagene exuparvovec is derived from clinical trial data with a duration up to 120 months. As the incidence of AADC deficiency is low, data for key model inputs is lacking; therefore estimates of survival by motor milestone were based on proxy diseases. A disease-specific utility study provided quality of life inputs and a burden of illness study informed inputs for disease management.ResultsThe model indicates survival (25.25 undiscounted life years gained) and quality-of-life benefits (20.21 undiscounted quality-adjusted life years [QALYs] gained) for patients treated with eladocagene exuparvovec compared to BSC. Resource usage costs are greater for patients treated with eladocagene exuparvovec, mainly due to the increased life expectancy during which patients accrue additional healthcare resource usage. Scenario analyses indicate robust results.ConclusionThis study assessed long-term outcomes for patients with AADC deficiency. Patients treated with eladocagene exuparvovec were found to have improved survival and quality of life benefits compared to patients treated with BSC.

Abstract licence: CC BY-NC 4.0

BackgroundAromatic l-amino acid decarboxylase deficiency (AADCD) is a rare, early-onset, dyskinetic encephalopathy mostly reflecting a defective synthesis of brain dopamine and serotonin. Intracerebral gene delivery (GD) provided a significant improvement among AADCD patients (mean age, ≤6 years).ObjectiveWe describe the clinical, biological, and imaging evolution of two AADCD patients ages >10 years after GD.MethodsEladocagene exuparvovec, a recombinant adeno-associated virus containing the human complimentary DNA encoding the AADC enzyme, was administered into bilateral putamen by stereotactic surgery.ResultsEighteen months after GD, patients showed improvement in motor, cognitive and behavioral function, and in quality of life. Cerebral l-6-[18F] fluoro-3, 4-dihydroxyphenylalanine uptake was increased at 1 month, persisting at 1 year compared to baseline.ConclusionTwo patients with a severe form of AADCD had an objective motor and non-motor benefit from eladocagene exuparvovec injection even when treated after the age of 10 years, as in the seminal study.

Abstract licence: CC BY

Aromatic l-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive disorder that results in a lack of the monoamine neurotransmitters dopamine, serotonin, norepinephrine, and epinephrine. Patients present with a wide spectrum of symptoms, including motor and autonomic dysfunction, hypotonia, and developmental delay, often before the age of one. Until recently, treatment options were limited to symptom control, but the recent approval of the first gene therapy for AADC deficiency in Europe and the UK has provided an alternative to treating symptoms for this disease. Eladocagene exuparvovec is a one-time gene therapy, administered bilaterally to the putamen by magnetic resonance imaging-guided stereotactic neurosurgery. While administration of the gene therapy itself is minimally invasive, the anesthetic management of patients with AADC deficiency is challenging due to the absence of sympathetic regulation secondary to the lack of adrenergic neurotransmitters. Optimal anesthetic management requires an understanding of the complex and heterogeneous nature of the disease. Hemodynamic instability, temperature dysregulation, and hypoglycemia are of primary concern, but there are also challenges regarding intravenous access and airway management. A thorough preoperative assessment is essential and should be guided by the patient's history. Advanced planning is necessary regarding the timing of the procedure schedule and operative plan; meticulous preparation, simulation for the operating room, as well as communication with all perioperative staff members, are crucial. Intraoperatively, utmost care must be taken to protect the skin, maintain body temperature, and to prepare for inotropic and/or glycemic support as needed. Postoperative intensive care management is necessary for consideration of postoperative extubation and provision of supportive care. With careful planning, preparation, and vigilance, patients with AADC deficiency can safely undergo anesthesia.

Abstract licence: CC BY

ABSTRACT Aromatic ʟ‐amino acid decarboxylase (AADC) deficiency is a rare pediatric neurotransmitter disorder that typically necessitates lifelong care, and that carries a risk of childhood mortality. Eladocagene exuparvovec gene therapy is designed to restore AADC production. Study GT‐002 (NCT04903288) is a phase 2, multicenter, open‐label trial assessing the pharmacodynamics, safety, and efficacy of eladocagene exuparvovec administered to the putamen bilaterally in pediatric patients with AADC deficiency using a magnetic resonance (MR)‐compatible cannula. Patients received eladocagene exuparvovec at 1.8 × 10 11 vector genomes via the SmartFlow MR‐compatible cannula in a single operative session. Endpoints include the change from baseline in cerebrospinal fluid homovanillic acid levels, motor milestone achievement, and safety. Here we report results from 48 weeks of follow‐up. Mean (SD) cerebrospinal fluid homovanillic acid levels increased from baseline (22.5 [32.3] nmol/L; n  = 13) to week 48 (55.3 [45.6] nmol/L; change from baseline: 28.3 [13.7] nmol/L; p  = 0.0003; n  = 9), indicating de novo dopamine production. At baseline ( n  = 13), all patients showed severe motor developmental delay; at week 48 ( n  = 12), nine achieved full head control, four could sit unassisted, two could stand with support, and two could walk independently to a toy. Overall, 260 treatment‐emergent adverse events were reported in 13 patients; 259 were deemed unrelated and one likely unrelated to the MR‐compatible cannula. No treatment‐emergent adverse events led to study withdrawal and no deaths occurred. This study provides further evidence of the favorable pharmacodynamic, efficacy, and safety profile of eladocagene exuparvovec in children with AADC deficiency; intraputaminal administration using an MR‐compatible cannula was well tolerated. Study GT‐002 (NCT04903288) provides further evidence of the favourable pharmacodynamic, efficacy and safety profile of eladocagene exuparvovec gene therapy in children with AADC deficiency over 48 weeks and demonstrates that intraputaminal administration using an MR‐compatible cannula was well tolerated, allowing for real‐time MRI confirmation of cannula placement and infusate coverage, and for accurate dosing to the putamen.

Abstract licence: CC BY 4.0