Background Niemann-Pick disease, type C1 (NPC1) is a lysosomal storage disorder characterized by progressive neurodegeneration. In preclinical testing 2-hydroxypropyl-β-cyclodextrins (HPβCD) significantly delayed cerebellar Purkinje cell loss, slowed progression of neurological signs, and increased lifespan in murine and feline models of NPC1. Methods Safety and clinical efficacy of intrathecal HPβCD were evaluated in an open-label, dose- escalation phase 1/2a study. Intrathecal doses ranging from 50–1200 mg were evaluated in 14 neurologically affected NPC1 participants treated monthly for 12 to 18 months. Three additional participants were treated every two weeks for 18 months. Serum and CSF 24(S)- hydroxycholesterol, which served as a biomarker of target engagement, and CSF protein biomarkers were evaluated. NPC Neurological Severity Scores (NSS) were used to compare disease progression in HPβCD-treated participants relative to a historical comparison cohort of 21 NPC1 participants of similar age range. Findings No drug-related serious adverse events were observed. Mid- to high-frequency hearing loss, an expected adverse event, was documented. When managed with hearing aids, this did not have an appreciable impact on daily communication. Biomarker studies were consistent with improved neuronal cholesterol homeostasis and decreased neuronal pathology. The NSS score for the 14 participants treated monthly increased at a rate of 122 ± 0 34 points/year compared to 2 92 ± 0 27 points/year (p=0 0002) for the comparison group. Decreased progression was observed for NSS domains of ambulation (p=0 0622), cognition (p=0 0040) and speech (p=0 0423). Interpretation This phase 1/2a study of intrathecal HPβCD for the treatment of NPC1 demonstrated an acceptable safety profile and slowing of disease progression.

Niemann-Pick Disease, type C is a neurodegenerative, lysosomal storage disorder with a broad clinical spectrum and a variable age of onset. The absence of a universally accepted clinical outcome measure is an impediment to the design of a therapeutic trial for NPC. Thus, we developed a clinical severity scale to characterize and quantify disease progression. Clinical signs and symptoms in nine major (ambulation, cognition, eye movement, fine motor, hearing, memory, seizures, speech, swallowing,) and eight minor (auditory brainstem response, behavior, gelastic cataplexy, hyperreflexia, incontinence, narcolepsy, psychiatric, respiratory problems) domains were scored. Data were collected from 18 current NPC patients and were extracted from records of 19 patients. Both patient cohorts showed a linear increase in severity scores over time. Cross-sectional evaluation of current patients showed a linear increase in the severity score. Longitudinal chart review of historical data demonstrated that although age of onset varied significantly, the rate of progression appeared linear, independent of age of onset, and similar in all patients. Combining the data from both cohorts, disease progression could be modeled by the following equation: Ŝ t0+x = Ŝ t0 + 1.87x; where Ŝ t0 is the initial score and Ŝ t0+x is the predicted future score after x years. Our observation that disease progression is similar across patients and independent of age of onset is consistent with a biphasic pathological model for NPC. This scale may prove useful in the characterization of potential biomarkers, and as an outcome measure to monitor disease progression in NPC patients.