White blood cell (WBC) cystine levels serve as the primary therapeutic target for monitoring cysteamine treatment in cystinosis, with a goal of \<1.9 nmol ½ cystine/mg protein as measured 5-6 hours post-dose when treated with immediate-release formulation, Cystagon® , or 11-12 hours post-dose when treated with delayed-release formulation, Procysbi®, using UCSD granulocyte assay. Although cysteamine dosing in cystinosis has traditionally been individualized based on WBC cystine levels, the FDA-approved Cystagon® prescribing information now includes an approximate recommended maintenance dose of 1.30 g/m²/day. When this dosing strategy is plotted against body weight, it aligns with the dosing regimen of TTI-0102 that was found effective in mitochondrial diseases, demonstrating a linear relationship between dose and weight. The main objective of this study is to demonstrate that administration of a single dose of 60 ± 5 mg/kg/day of TTI-0102 (\~26 mg/kg cysteamine base equivalent) allows maintenance of WBC cystine at \<1.9 nmol ½ cystine/mg protein over 24 hours as determined by UCSD granulocyte assay.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
6
TTI-0102 (cysteamine-pantetheine disulfide) - a prodrug of other FDA-approved forms of cysteamine
White blood cell (WBC) cystine
The primary endpoint is the change in white blood cell (WBC) cystine levels following treatment with TTI-0102. The study will evaluate whether a weight-based dose of 60 ± 5 mg/kg/day maintains WBC cystine levels below 1 nmol ½ cystine/mg protein over 24 hours.
Time frame: Comparison of baseline, Day 1-2, Day 3-4, and treatment end (Day 7)
Pharmacokinetic parameter: Cmax
cysteamine in plasma
Time frame: At specified days/timepoints during the treatment period: Day1-2, Day 3-4, Day 7
Pharmacokinetic parameter: Tmax
cysteamine in plasma
Time frame: At specified days/timepoints during the treatment period: Day1-2, Day 3-4, Day 7
Pharmacokinetic parameter: AUC
cysteamine in plasma
Time frame: At specified days/timepoints during the treatment period: Day1-2, Day 3-4, Day 7
Pharmacodynamic biomarker: lactate in plasma
Time frame: Baseline (Day 0) to treatment end (Day 7)
Pharmacodynamic biomarker: pyruvate in whole blood
Time frame: Baseline (Day 0) to treatment end (Day 7)
Pharmacodynamic biomarker: tryptophan in plasma
Time frame: Baseline (Day 0) to treatment end (Day 7)
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