The SPARKLE registry: a multicenter, multinational, noninterventional, prospective cohort registry study in patients with alpha-mannosidosis

Background Alpha-mannosidosis is a lysosomal storage disorder caused by reduced enzymatic activity of alpha-mannosidase. Intracellular accumulation of mannose-rich oligosaccharides leads to a continuum of various heterogeneous clinical symptoms. Velmanase alfa (Lamzede®) is a human recombinant alpha-mannosidase approved in Europe in 2018 as the first enzyme replacement therapy for the treatment of non-neurologic manifestations in patients with mild-to-moderate alpha-mannosidosis. SPARKLE is an alpha-mannosidosis registry study intended to obtain long-term safety and effectiveness data on the use of velmanase alfa during routine clinical care in patients with alpha-mannosidosis and is a post-approval commitment to European marketing authorization. In addition, SPARKLE will expand the current understanding of alpha-mannosidosis by collecting data on the clinical manifestations, progression, and natural history of the disease in treated and untreated patients, respectively. Results SPARKLE is a post-authorization safety and efficacy registry designed as a multicenter, multinational, noninterventional, prospective cohort study of patients with alpha-mannosidosis, starting in 2020. Patients will be followed for up to 15 years. Safety and effectiveness outcomes under routine clinical care will be evaluated. The primary safety outcomes are the rate of adverse events (anti-velmanase alfa-immunoglobulin G antibody development, infusion-related reactions, and hypersensitivity). Secondary safety outcomes include the evaluation of medical events, change in vital signs, laboratory tests, physical examination, and electrocardiogram results. The primary effectiveness outcome is a global treatment response rate, evaluated as the individual aggregate of single endpoints from pharmacodynamic, functional, and quality of life effectiveness outcomes; secondary effectiveness outcomes are to characterize the population of patients with alpha-mannosidosis with regard to clinical manifestation, progression, and natural history of the disease. Any patient in the European Union with a diagnosis of alpha-mannosidosis who is willing to participate will likely be eligible for inclusion in the registry. Publications to disseminate scientific insights from the registry are planned. Conclusion This study will provide real-world data on the long-term safety and effectiveness of velmanase alfa in patients with alpha-mannosidosis during routine clinical care and increase the understanding of the natural course, clinical manifestations, and progression of this ultra-rare disease.