Phenotypic expression of swallowing function in Niemann-Pick disease type C1.

BACKGROUND: Niemann-Pick disease type C1 (NPC1) is a rare autosomal recessive disease characterized by endolysosomal accumulation of unesterified cholesterol with progressive deterioration in swallowing, often leading to premature death. Although documented, the natural history of NPC1 swallowing dysfunction has yet to be delineated systematically. This manuscript aims to provide a comprehensive characterization of the phenotypic spectrum and progression of swallowing dysfunction in NPC1. METHODOLOGY: The National Institutes of Health (NIH) NPC1 natural history study (NCT00344331) enrolled 120 patients, who underwent comprehensive interpretative swallow assessments for swallowing safety, dietary modifications, and aspiration risk. Longitudinal statistical modeling accounted for all outcomes with NPC1 disease covariates (first symptom onset, age at neurological symptom onset, seizure history, duration of neurological symptoms) as well as miglustat use (a glucosylceramide synthase inhibitor) and NIH study duration (NIHSD; the length of time an individual participated in the NIH study). Probabilities for disease progression and time to swallowing decline were conducted for the entire cohort. RESULTS: Time to swallowing decline with American Speech-Language-Hearing Association National Outcome Measure (ASHA-NOMS) and the NIH-adapted Penetration Aspiration Scale (NIH-PAS) were identified: [Formula: see text] person-years and [Formula: see text] person-years, respectively. NIHSD and seizure history consistently and significantly were associated with decline (ORNIHSD = 1.34-2.10, 95% CI 1.04-3.4, p = 0.001-0.026; ORSeizure = 3.26-18.22, 1.03-167.79; p = 0.001-0.046), while miglustat use revealed protection (ORMiglustat = 0.01-0.43, 0.007-0.98; p = 0.001-0.044). The probability of decline with NPC1 neurological severity scale and annual severity increment scale were established with the aforementioned covariates, varying amongst subgroups. CONCLUSION: This study represents the most extensive collection of prospective, instrumental swallowing assessments in NPC1 to date with an interpretive analysis providing an improved understanding of NPC1 disease progression with swallowing function-serving as a foundation for clinical management and future NPC1 therapeutics.

Association of Miglustat With Swallowing Outcomes in Niemann-Pick Disease, Type C1.

Importance: Niemann-Pick disease, type C1 (NPC1) is a progressive neurovisceral disease with no US Food and Drug Administration-approved therapy. Miglustat, a drug used off-label in the United States for the treatment of NPC1, appears to stabilize neurologic disease progression. Several prospective trials suggest that miglustat stabilizes oropharyngeal swallowing function; however, its effect on dysphagia and aspiration risk has not been demonstrated instrumentally. Objective: To determine if miglustat therapy is associated with stabilized swallowing dysfunction in individuals with NPC1. Design, Setting, and Participants: Patients with confirmed NPC1 diagnoses were evaluated in a single-center cohort study of NPC1 from April 1997 to November 2019. Longitudinal data from individuals with neurologic disease onset prior to age 15 years were analyzed. The study population was divided into those with neurologic disease onset in early childhood (age <6 years) and late childhood (age ≥6 years and <15 years). Analysis began September 2019. Exposures: Oral miglustat at baseline and at follow-up. Main Outcomes and Measures: Oropharyngeal swallowing function was assessed with videofluoroscopic swallowing studies. Overall swallowing ability and aspiration risk were evaluated using the American Speech-Language-Hearing Association National Outcome Measurement System swallowing domain and an adapted Rosenbek aspiration-penetration scale, respectively. Results: Overall, 50 participants were evaluated at baseline (median [interquartile range] age, 9.4 [3.4-16.4] years; 26 [52%] female). The median (interquartile range) duration of follow-up was 3.0 (1.1-4.4) years. Miglustat use was associated with decreased odds of worse American Speech-Language-Hearing Association National Outcome Measurement System swallowing domain outcomes in all 3 subsets (overall: odds ratio [OR], 0.09 [95% CI, 0.02-0.36); P < .001; early childhood: OR, 0.17 [95% CI, 0.04-0.67]; P = .01; late childhood: OR, 0.05 [95% CI, 0.01-0.29]; P = .001). Miglustat use was associated with decreased odds of worse Rosenbek aspiration-penetration scale outcomes in the overall cohort (OR, 0.28 [95% CI, 0.08-0.95]; P = .04) but not in each subgroup (early childhood: OR, 0.27 [95% CI, 0.06-1.22]; P = .09; late childhood: OR, 0.38 [95% CI, 0.06-2.33]; P = .29). Conclusions and Relevance: These data suggest that miglustat use is associated with stabilized swallowing function and reduced aspiration risk in NPC1, thus supporting its use in this population. In addition, these data demonstrate that a quantification of swallowing dysfunction can be used as a clinically relevant, functional outcome measure in future therapeutic trials in NPC1.