Assessment of the potential use of VAL-1221 for Lafora disease: MS-based proteomics for the characterization and quantitation of the biotechnological drug in plasma and cerebrospinal fluid

BackgroundVAL-1221 is a biotechnological fusion protein that combines the Fab portion of a cell-penetrating antibody with recombinant human acid -glucosidase. Originally used for the treatment of Pompe disease, it has since attracted interest for possible repurposing in Lafora disease (LD), an ultra-rare, fatal form of progressive myoclonus epilepsy characterized by the accumulation of polyglucosan aggregates (Lafora bodies, LBs) within the central nervous system (CNS). Given its design, which includes a cell-penetrating domain, VAL-1221 has been hypothesized to cross the blood-brain barrier (BBB) and target pathogenic glycogen deposits within the CNS in LD. This study aimed to investigate the presence of VAL-1221 in plasma and cerebrospinal fluid (CSF) of LD patients and assess its potential to cross the BBB, using high-resolution mass spectrometry coupled with micro-liquid chromatography (microLC-HRMS/MS). MethodsAs part of a compassionate use program, five LD patients received intravenous VAL-1221 (20 mg/kg, every other week). LD untreated patients were included as controls. Plasma samples were collected at multiple time points up to 24 hours post-infusion, and CSF samples were obtained based on concentration profiles. Untargeted-to-targeted bottom-up proteomics were used to detect a unique peptide tag in biological fluids. Method validation included assessments of precision, accuracy, matrix effects, and analyte stability. ResultsVAL-1221 was consistently detected in plasma up to 4 hours post-infusion, while no VAL-1221 was detected in CSF samples with the methods limit of detection. The validated method showed high sensitivity, precision (RSD [≤]15%), accuracy (RE [≤]15%), and acceptable matrix effect. Recovery was optimal for CSF; it was low in plasma (Rec% > {+/-}20). ConclusionVAL-1221 was reliably detected in plasma after infusion, but no measurable levels were observed in CSF based on the validated methods sensitivity. These findings suggest that the drug, when administered intravenously, may not reach the central nervous system, indicating that this route may not be appropriate for efficacy.