Conditions: Cystinosis
Keywords: Nephropathic Cystinosis Cysteamine Delayed-release Cysteamine CTNS Protein, Human Orphan Disease
Allocation: NA | Intervention model: SINGLE_GROUP
Enrollment: 17
Healthy volunteers: no

Brief summary:
This was a long-term, open-label study of the safety, tolerability and effectiveness of RP103 in cystinosis patients who were naïve to any form of cysteamine treatment. Participants received RP103 treatment for at least 12 months. U.S. participants transitioned to the commercially approved drug PROCYSBI®. In Brazil, after at least 12 months of study participation and upon approval by the Brazilian regulatory authorities, participants were eligible to transition to a post-study drug supply program, and continue to receive the drug at no personal cost.

Detailed description:
The purpose of this study was to gather information about the safety and effectiveness (how well it works to treat cystinosis) of a new drug called RP103.

In cystinosis, the body builds up cystine. When taken regularly, the active ingredient of an older, already approved drug called Cystagon® (cysteamine bitartrate) reduces cystine in the body. RP103 has the same active ingredient as Cystagon® and is designed to reduce cystine in a similar way that Cystagon® does. RP103 is also different from Cystagon®: Instead of the cysteamine bitartrate being absorbed from the stomach, RP103 is designed to be absorbed from the small intestine. This may make the effects of the drug last longer, so that it can be taken twice a day instead of four times a day like Cystagon®.

To decide if RP103 is effective, the study used two types of blood tests. One test is pharmacodynamics (PD), which measures the amount of white blood cell (WBC) cystine after taking study drug. WBC cystine is a laboratory test used to find out if cysteamine bitartrate is reducing cystine levels in the body. The second test is pharmacokinetics (PK), which measures the amount of cysteamine in the blood after taking the drug.

Study with completed results acquired from Horizon in 2024.

Arms:
arm 1: From Day 1 and throughout the duration of participation, RP103 (Cysteamine Bitartrate Delayed-release Capsules) was administered every 12 hours (Q12H), supplied as 75 mg and 25 mg capsules.

Interventions: intervention 1: RP103
Intervention descriptions: intervention 1: Cysteamine Bitartrate Delayed-release Capsules (RP103) were administered twice daily, orally or via gastrostomy tube (G-tube), after a 2-hour fast. The starting dose was one-quarter of the RP103 targeted maintenance dose based on age, weight, and body surface area. The recommended targeted maintenance dose for children up to 6 years old was 1 gram/m²/day, in 2 divided doses given Q12H. The dose was gradually escalated, in 10% steps, based on monitoring of WBC cystine levels 30 minutes after the morning RP103 dose collected every 2 weeks, until the participant's WBC cystine level was \<1 nmol ½ cystine/mg protein.

Protocol document: