Niemann-Pick type C1 (NPC) disease is a lysosomal storage disease caused by mutations in the NPC1 gene, leading to an increase in unesterified cholesterol and several sphingolipids, and resulting in hepatic disease and progressive neurological disease. We show that subcutaneous administration of the pharmaceutical excipient 2-hydroxypropyl-β-cyclodextrin (HPβCD) to cats with NPC disease ameliorated hepatic disease, but doses sufficient to reduce neurological disease resulted in pulmonary toxicity. However, direct administration of HPβCD into the cisterna magna of presymptomatic cats with NPC disease prevented the onset of cerebellar dysfunction for greater than a year and resulted in a reduction in Purkinje cell loss and near-normal concentrations of cholesterol and sphingolipids. Moreover, administration of intracisternal HPβCD to NPC cats with ongoing cerebellar dysfunction slowed disease progression, increased survival time, and decreased the accumulation of brain gangliosides. An increase in hearing threshold was identified as a potential adverse effect. These studies in a feline animal model have provided critical data on efficacy and safety of drug administration directly into the central nervous system that will be important for advancing HPβCD into clinical trials.

2-hydroxypropyl-β-cyclodextrin (HPβCD) is a promising experimental therapy for Niemann-Pick type C disease that improved intracellular cholesterol transport, substantially reduced neurodegeneration and hepatic disease, and increased lifespan in npc1−/− mice. On the basis of favorable treatment outcome in mice, HPβCD is being evaluated as a therapy in children with Niemann-Pick type C (NPC) disease. We evaluated the efficacy of HPβCD in the feline model of NPC disease and recognized a dose-dependent increase in hearing threshold associated with therapy as determined by brain stem auditory evoked response (BAER) testing. To further assess the effect of HPβCD on hearing threshold, normal cats were administered the drug s.c. at either 4000 mg/kg or 8000 mg/kg body weight, or intrathecally at a dose of 4000 mg/kg brain weight. HPβCD caused a significant increase in hearing threshold following one dose of 8000 mg/kg s.c. or 120 mg intrathecally, and the effect was maintained for at least 12 weeks. Repeated weekly s.c. administration of 4000 mg/kg HPβCD resulted in a similar increase in hearing threshold. These studies are the first to describe a specific negative effect of HPβCD on the auditory system and suggest the need for auditory testing in patients receiving similar doses of HPβCD.

Niemann-Pick disease type C (NPC disease) is an incurable cellular lipid-trafficking disorder characterized by neurodegeneration and intralysosomal ac

Globoid cell leukodystrophy (GLD), or Krabbe disease, is an inherited, neurologic disorder that results from deficiency of a lysosomal enzyme, galactosylceramidase (GALC). Most commonly, deficits of GALC result in widespread central and peripheral nervous system (CNS, PNS) demyelination and death in affected infants typically by 2 years of age. Hematopoietic stem cell transplantation is the current standard of care in children diagnosed prior to symptom onset; however, disease correction is incomplete. Herein we present the first adeno-associated virus (AAV) gene therapy experiments in a naturally occurring canine model of GLD that closely recapitulates the clinical disease progression, neuropathological alterations, and biochemical abnormalities observed in human patients. Adapted from studies in the twitcher mice, GLD dogs were treated by combination intravenous (IV) and intracerebroventricular (ICV) injections of AAVrh10 to target both PNS and CNS. Combination of IV and ICV AAV gene therapy had a clear dose response and resulted in delayed onset of clinical signs, extended lifespan, correction of biochemical defects, and attenuation of neuropathology. For the first time we have established therapeutic effect in the canine model of GLD by targeting both peripheral and central nervous system impairments with potential clinical implications for GLD patients.

Globoid cell leukodystrophy (GLD; Krabbe disease) is a progressive, incurable neurodegenerative disease caused by deficient activity of the hydrolytic enzyme galactosylceramidase (GALC). The ensuing cytotoxic accumulation of psychosine results in diffuse central and peripheral nervous system (CNS, PNS) demyelination. Presymptomatic hematopoietic stem cell transplantation (HSCT) is the only treatment for infantile-onset GLD; however, clinical outcomes of HSCT recipients often remain poor, and procedure-related morbidity is high. There are no effective therapies for symptomatic patients. Herein, we demonstrate in the naturally occurring canine model of GLD that presymptomatic monotherapy with intrathecal AAV9 encoding canine GALC administered into the cisterna magna increased GALC enzyme activity, normalized psychosine concentration, improved myelination, and attenuated inflammation in both the CNS and PNS. Moreover, AAV-mediated therapy successfully prevented clinical neurological dysfunction, allowing treated dogs to live beyond 2.5 years of age, more than 7 times longer than untreated dogs. Furthermore, we found that a 5-fold lower dose resulted in an attenuated form of disease, indicating that sufficient dosing is critical. Finally, postsymptomatic therapy with high-dose AAV9 also significantly extended lifespan, signifying a treatment option for patients for whom HSCT is not applicable. If translatable to patients, these findings would improve the outcomes of patients treated either pre- or postsymptomatically.