DeLucia, Michael W.

ABSTRACT Globoid cell leukodystrophy (GLD), also known as Krabbe disease, is a devastating, degenerative neurological disorder. It is inherited as an autosomal recessive trait caused by loss‐of‐function mutations in the galactocerebrosidase (GALC) gene. Previously, we have shown that peripheral injection of recombinant GALC, administered every other day, results in a substantial improvement in early clinical phenotype in the twitcher mouse model of GLD. While we did detect active enzyme in the brain following peripheral administration, most of the administered enzyme was localized to the periphery. Given the substantial central nervous system (CNS) involvement in this disease, we were interested in determining whether or not a single‐dose administration of the recombinant enzyme directly to the CNS, which could potentially be achieved clinically, would result in any substantial improvement. Following intracerebroventricu‐lar (icv) administration of GALC we noted a significant, 16.5%, reduction in the GALC substrate psychosine, the abnormal accumulation of which is believed to play a pivotal role in the CNS pathology observed in this disease. Moreover, recombinant GALC was found not only in periventricular regions but also at sites distant to the injection such as the cerebral cortex and cerebellum. Most importantly, animals receiving a single icv dose of the enzyme at postnatal day 20 survived up to 51 days, which compares favorably to the control twitcher animals, which normally only live to postnatal day 40/42. These results indicate that even a single icv administration of the recombinant enzyme can have significant clinical impact and suggests that other lysosomal storage disorders with significant CNS involvement may similarly benefit.—Lee, W.C., Tsoi, Y.K., Troendle, F.J., DeLucia, M.W., Ahmed, Z., Dicky, C.A., Dickson, D.W., Eckman, C.B. Single dose intracerebroventricular administration of galactocerebrosidase improves survival in a mouse model of globoid cell leukodystrophy. FASEB J. 21, 2520–2527 (2007)

ABSTRACT Globoid cell leukodystrophy (GLD) or Krabbe disease is a devastating, degenerative neurological disorder caused by mutations in the galactosylceramidase (GALC) gene that severely affect enzyme activity. Currently, treatment options for this disorder are very limited. Enzyme replacement therapy (ERT) has been shown to be effective in lysosomal storage disorders with predominantly peripheral manifestations such as type I Gaucher's and Fabry's disease. Little however is known about the possible benefit of ERT in GLD, which has a substantial central nervous system component. In this study, we examined the effect of peripheral GALC injections in the twitcher mouse model of the disease. Although we were unable to block the precipitous decline that normally occurs just before death, we did observe significant early improvements in motor performance, a substantial attenuation in the initial failure to thrive, and an increase in life span. Immunohistochemical and activity analyses demonstrated GALC uptake in multiple tissues, including the brain. This was associated with a decrease in the abnormal accumulation of the GALC substrate psychosine, which is thought to play a pivotal role in disease pathology. These results indicate that peripheral ERT is likely to be beneficial in GLD.