Nephropathic cystinosis is a rare autosomal recessive
lysosomal storage disease that is characterized by accumulation of
cysteine and formation of crystals within cells of different organs and tissues causing systemic manifestations in childhood that include poor linear growth, ocular involvement,
hypothyroidism, and progressive
kidney disease. This study was a long-term, prospective open-label evaluation of twice-daily delayed release (DR)
cysteamine capsules in
cystinosis patients <6 years of age who were naïve to any form of
cysteamine treatment. Fifteen treatment-naïve patients <6 years old (mean age 2.2 ± 1.0 years, 53% male, 73% White) were enrolled and treated with DR-
cysteamine capsules for up to 18 months. Patients had clinically meaningful decreases in WBC
cysteine concentration during treatment (3.2 ± 3.0 nmol ½
cystine/mg
protein at Day 1 to 0.8 ± 0.8 nmol ½
cystine/mg
protein at study exit), and anthropometric data improvements were consistently observed in height, weight and body surface area. Additionally, estimated glomerular filtration rate increased from 55.93 ± 22.43 ml/min/1.73 m2 at baseline to 63.79 ± 21.44 ml/min/1.73 m2 at study exit. Pharmacokinetic/Pharmacodynamic results support the use of the same starting, escalation, and maintenance doses according to body surface for children aged <6 years that are currently recommended in adults and older children. All patients experienced ≥1 adverse event(s) with
vomiting (80%) and
upper respiratory tract infection (53%) most frequently reported. Based on our study, patients <6 years of age with
nephropathic cystinosis without prior treatment can safely and effectively initiate treatment with DR-
cysteamine, a delayed-release form of
cysteamine bitartrate that can be given every 12 h.