**1.4. Previous treatments employed**

**1. Introduction**

96 Cyclodextrin - A Versatile Ingredient

Niemann-Pick disease type C (NPD-C) is a rare autosomal recessive disorder characterized by lysosomal lipid storage in which faulty intracellular lipid transport leads to accumulation of

NPD-C is caused by mutations in either the *NPC1* or *NPC2* genes. The *NPC1* gene, located on the long arm of chromosome 18 (18q11.2), encodes a large (142 kDa) membrane glycoprotein placed in endosomes and lysosomes. This protein mediates intracellular cholesterol trafficking via binding of cholesterol to its N-terminal domain. *NPC2* gene, located on the long arm of chromosome 14 (14q24.3), encodes a small (16 kDa) lysosomal protein that binds to cholesterol. NPC1 and NPC2 proteins seem to act in the cooperative transportation of molecules within cells. Recently, it has been shown, the N-terminal domain of NPC1 protein may interact with NPC2 protein to facilitate cholesterol efflux from the late endosome and lysosomes [3, 4]. The majority of patients show mutations in the *NPC1* gene (95%), whereas a much smaller number suffer mutations in the *NPC2* gene, but the resulting phenotypes are clinically indistinguishable. Loss of function of either of these proteins results in an accumulation of cholesterol and other lipids, including sphingomyelin, sphingosine, and gangliosides (GM2 and

The diagnosis of NPD-C requires a combination of clinical, cellular, and molecular criteria. NPD-C is suspected on the basis of the clinical features. Systemic manifestations such as hepatosplenomegaly neonatal, cholestatic jaundice, or splenomegaly can lead to diagnosis, but, due to the heterogeneous clinical phenotype, diagnosis is often delayed for many years or missed altogether [4]. A Suspicion Index tool might be useful as a screen for NPD-C, a risk prediction score ≥70 indicates a strong suspicion for NPD-C [5]. The diagnosis of NPD-C is confirmed by biochemical testing that demonstrates impaired cholesterol esterification and positive filipin staining in cultured fibroblasts obtained from a skin biopsy. Filipin staining demonstrates intense punctate pattern of fluorescence concentrated around the nucleus, consistent with unesterified cholesterol. Molecular genetic testing of *NPC1* and *NPC2* are commercially available and they detect pathogenic variants in approximately 94% of individuals

The filipin assay is unable to provide a firm diagnosis in fibroblasts with "variant" phenotypes that represent one-third of NPD-C cases. Moreover, the assay is invasive and the results can delay for 3 months. Genetic analysis is an important diagnostic tool, though, due to cost considerations, generally applied as a confirmatory rather than screening test. In recent years have been identified promising NPD-C biomarkers. One of these markers, cholestane-3β,5α,6β-triol, which is a cholesterol oxidation product, has emerged as a sensitive diagnostic

unesterified cholesterol and glycosphingolipids in several neurovisceral tissues [1, 2].

GM3), within the endosomes and lysosome [3, 4].

**1.1. Etiology**

**1.2. Diagnosis**

with NPD-C [4].

for NPD-C [6, 7].

There is no curative treatment for NPD-C. The disease management is individualized and it consists mainly of symptomatic treatment. Seizures, dystonia, and cataplexy can respond to drugs. Other symptomatic measures like physiotherapy in spasticity, gastrostomy tube placement to prevent aspiration and/or inadequate nutrition in patients with progressive dysphagia, and bronchoalveolar lavage to improve pulmonary function are useful in the disease management. Combination of drug regimens have been shown to lower hepatic and plasma cholesterol but there is no evidence that these results affect the progression of the disease in humans or murine models. Behavioral and speech problems or schooling difficulties should be referred to as psychiatric team and special schooling [8, 9].

To date, miglustat is the only disease-specific drug approved in Europe, Canada, and Japan. The drug works by inhibiting the glucosylceramide synthase enzyme that is responsible for the first step in the synthesis of most glycosphingolipids. Miglustat has shown to stabilize key parameters of neurological disease progression in patients of all ages, but it has no effect on the systemic manifestations or intracellular cholesterol accumulation associated with this disorder [10].

There is a persistent search for new treatments to prevent or slow down the progression of NPD-C. Investigational therapies in course are 2-hydroxypropyl-beta-cyclodextrin (HP-β-CD) or hematopoietic stem cell transplantation.

VTS-270 (Kleptose® HPB, Roquette Pharma, France) and Trappsol® Cyclo™ (CTD Holdings, Inc., Alachua, FL) are HP-β-CD products under investigation as novel treatments for NPD-C. Differences between these two products have been studied based on ion distribution and abundance profiles using mass spectrometry methodology as a means to assess key molecular distinctions between products. Trappsol® Cyclo™ was found to have a higher degree of substitution compared with VTS-270, with a greater number of hydroxypropyl groups and increased levels of dimeric ions. Additional differences in ion mobility profiles were found, there is a much greater level of non-specific chemical "noise" associated with Trappsol® Cyclo™.

at lower concentrations [14].There are several theories about the mechanism by which cyclo-

Use of 2-Hydroxypropyl-Beta-Cyclodextrin for Niemann-Pick Type C Disease

http://dx.doi.org/10.5772/intechopen.71970

99

*In vitro* beta-cyclodextrins showed a high affinity for sterols as compared to other lipid and, because of the relatively high specificity of this substance for cholesterol, it was suggested that

The unexpected discovery of the utility of cyclodextrin in NPD-C was observed in a study in Npc1−/− mice treated with a combination therapy of two drugs, one of them (allopregnanolone) formulated in a cyclodextrin complex [15]. A later study showed the same cholesterol intraneuronal storage reduction and longevity increase with the combination of allopregnanolone and cyclodextrin than with the control arm, treated only with the cyclodextrin [16]. These results led researchers to perform studies to address the role of cyclodextrin as a possible treatment. The Npc1−/− mice receiving subcutaneous (SC) or intraperitoneal cyclodextrin every other day for 2 weeks revealed a slight decrease of intraneuronal accumulation of either cholesterol or gangliosides. Both routes showed similar outcome, but SC administration seemed to be a slightly more efficacious [16]. In another study, Npc1−/− mice treated with a single SC injection at 7 days of age of HP-β-CD (4000 mg/kg body weight) prolonged the average life (108 days). Treatment with cyclodextrin improved hepatic dysfunction and decreased neurodegeneration, increasing the number of Purkinje cells surviving at 49 days of age nearly threefold respect to untreated mice [16]. In previous studies, no significant toxicity was observed following the administration of HP-β-CD except for increased macrophage infiltration of the lungs found at post mortem examination [16, 17]. Other studies in Npc1−/− mice showed that 1500 mg/kg HP-BC-D administered weekly caused a decrease in hepatic unesterified cholesterol concentrations without substantial effect on neurological signs The slight effects of the HP-β-CD on neurological symptoms at low doses may be partially due to their apparent non-

The efficacy of HP-β-CD was also tested in a feline model of NPD-C. Cats affected with NPD-C were first administered the drug at 3 weeks of age, prior to the onset of clinical signs of disease, and continued to receive the drug weekly. Cats were placed into one of five groups: received no HP-β-CD; received a weekly dose of 1000 mg/kg; 4000 mg/kg; 8000 mg/ kg body weight HP-β-CD subcutaneously; or 4000 mg/kg brain weight (120 mg for a 30 g brain weight) HP-β-CD intrathecally every 2 weeks. The preliminary data suggested a similar requirement for doses equal to or greater than 4000 mg/kg to positively affect neurological disease. Nevertheless, doses of 4000 mg/kg body weight resulted in an increase in hearing threshold only after repeated dosing and doses of 8000 mg/kg body weight resulted in significant increases in hearing threshold in both normal cats and cats with NPD-C following the

Studies in mouse models have shown that systemic administration of HP-β-CD, starting in early neonatal life, diminishes unesterified cholesterol accumulation in most organs, slows

beta-cyclodextrins might be effective in modifying cholesterol metabolism in vivo.

dextrins affect cholesterol homeostasis but none have been confirmed.

permeation of the blood-brain barrier (BBB) [18].

administration of a single dose [19].

**2.2. Animal studies**

These two products are not chemically equivalent and therefore may not be biochemically equivalent or lead to comparable formulations from a clinical development perspective. The data suggest that biological and potential therapeutic equivalence should not be assumed. Further studies are needed to examine potential differences in biological and therapeutic effects of Trappsol® Cyclo™ and VTS-270 [11].
