A New Viscous Cysteamine Eye Drops Treatment for Ophthalmic Cystinosis: An Open-Label Randomized Comparative Phase...

Area of Science:

• Ophthalmology
• Pharmacology
• Genetics

Background:

• Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in various tissues, including the cornea.
• Corneal cystine crystal deposition can lead to photophobia and vision impairment.
• Cysteamine hydrochloride (CH) is a standard treatment, but its efficacy and convenience can be improved.

Purpose of the Study:

• To evaluate the efficacy of new viscous cysteamine hydrochloride (vCH) 0.55% eye drops compared to standard CH 0.10% eye drops.
• To assess the superiority of vCH 0.55% in reducing corneal cystine crystal density.
• To evaluate improvements in photophobia, corneal cystine crystal scores, and cystine crystal depth.

Main Methods:

• An open-label, phase III, randomized, two-arm multicenter trial was conducted.
• Patients aged ≥2 years with cystinosis received either vCH 0.55% or CH 0.10% eye drops four times daily for 90 days.
• Corneal cystine crystal density was measured using in vivo confocal microscopy (IVCM); photophobia, corneal cystine crystal scores (CCCSs), and cystine crystal depth were also assessed.

Main Results:

• The mean absolute change in IVCM total score at day 90 was significantly greater in the vCH 0.55% group (-4.6 ± 3.1) compared to the CH 0.10% group (-0.46 ± 3.38; P < 0.0001).
• vCH 0.55% treatment resulted in significantly greater improvements in photophobia, CCCSs, and corneal cystine crystal depth.
• The most common local adverse drug reactions in both groups included stinging, burning, redness, and blurred vision.

Conclusions:

• Viscous cysteamine hydrochloride (vCH) 0.55% eye drops are effective in reducing corneal cystine crystal density.
• vCH 0.55% demonstrates superiority over standard CH 0.10% drops.
• The vCH formulation offers advantages in convenience and preference over hospital pharmacy preparations.