Precision Medicine in Neurodegeneration with Brain Iron Accumulation (NBIA) Disorders: An Update on Emerging...

Neurodegeneration with Brain Iron Accumulation (NBIA) is a heterogeneous group of heritable, mostly recessive, progressive neurodegenerative diseases characterized by iron deposition in the basal ganglia and brainstem. There are no solid global epidemiological data on prevalence and incidence of NBIA subtypes, but registry data and expert opinion suggest PKAN, BPAN, PLAN, and MPAN are the most common subtypes. NBIA disorders present with a wide spectrum of clinical symptoms, including movement disorders (dystonia, parkinsonism, chorea), pyramidal involvement (eg, spasticity), speech and cognitive deficits, motor and cognitive slowing, and ocular abnormalities. Treatment remains symptomatic, though several new drugs are in development.

Following our review published in 2021, this article provides an updated summary of recent developments. We discuss the rationale of new compounds, summarize clinical trials or-in their absence-preclinical studies for NBIA subtypes. The article is divided into two sections: one section on general approaches based on the shared feature of increased iron in the brain; and the second section on tailor-made, mechanistic treatments for the various NBIA subtypes targeting the specific molecular and cellular pathways of the affected enzyme including gene therapy.

In summary, randomized controlled trials in NBIA have not yet demonstrated substantial benefit, neither for iron removal, in general, which appears to be clinically ineffective in most subtypes, except aceruloplasminemia; nor for subtype-specific approaches. Several ongoing studies are exploring more dedicated compounds in this exciting field.