Long-Term Safety Follow-up Study of Cysteamine Bitartrate Delayed-release Capsules (RP103)

A Long-Term, Open-Label, Safety and Efficacy Study of Cysteamine Bitartrate Delayed-release Capsules (RP103) in Patients With Cystinosis

Cystinosis is an inherited disease that if untreated, results in kidney failure as early as the first decade of life. The current marketed therapy is Cystagon® (cysteamine bitartrate immediate release) which must be taken every six hours for the rest of the patient's life to prevent complications of cystinosis. Cysteamine bitartrate delayed-release capsules (RP103) is a formulation of cysteamine bitartrate that is being studied to see if it can be given less frequently, once every 12 hours, and have similar results to four times a day Cystagon®.

This is a long-term, open-label, study to determine the safety and tolerability of twice a day treatment with cysteamine bitartrate delayed-release capsules (RP103). It will involve 6-9 monthly clinic visits followed by quarterly clinic visits for the duration of the study and home use of cysteamine bitartrate delayed-release capsules.

Initially, enrollment was open to those patients who had completed the previous Phase 3 Study (RP103-03, NCT01000961). Subsequently enrollment in Study RP103-04 was opened to additional participants, including children aged 1 to 6 years and renal transplant recipients, who had previously been on a stable dose of Cystagon® for at least 21 days.

Study with completed results acquired from Horizon in 2024.

Inclusion Criteria:

• Male and female subjects must have completed the last visit of Study RP103-03 and be willing to continue with RP103 treatment.

OR for patients who did not complete the RP103-03 study:

• Male and female subjects must have cystinosis.
• Subjects must be on a stable dose of Cystagon® at least 21 days prior to Screening.
• Within the last 6 months, no clinically significant change from normal in liver function tests (i.e., alanine aminotransferase [ALT], aspartate aminotransferase [AST], total bilirubin) and renal function (i.e., estimated glomerular filtration rate [eGFR]) at Screening as determined by the Investigator.
• Subjects with an eGFR corrected for body surface area > 30 mL/min/1.73m².
• Sexually active female subjects of childbearing potential (i.e., not surgically sterile [tubal ligation, hysterectomy, or bilateral oophorectomy] or at least 2 years naturally postmenopausal) must agree to utilize the same acceptable form of contraception from Screening through completion of the study.
• Subjects must be willing and able to comply with the study restrictions and requirements.
• Subjects or their parent or guardian must provide written informed consent and assent (where applicable) prior to participation in the study.

Exclusion Criteria:

• Patients enrolled in the previous Study RP103-03 who did not complete their last scheduled Study visit or who do not wish to continue on treatment with RP103.

AND for patients who did not complete the RP103-03 study:

• Subjects less than 1 year old
• Subjects with a known history, currently of the following conditions or other health issues that make it, in the opinion of the investigator, unsafe for them to participate: inflammatory bowel disease (if currently active) or have had prior resection of small intestine; Heart disease (e.g., myocardial infarction, heart failure, unstable arrhythmias or poorly controlled hypertension) 90 days prior to Screening; Active bleeding disorder 90 days prior to Screening; Malignant disease within the last 2 years.
• Patients with a hemoglobin level < 10 g/dL at Screening or a level that, in the opinion of the investigator, makes it unsafe for the subject to participate.
• Subjects with known hypersensitivity to cysteamine or penicillamine.
• Female subjects who are nursing, planning a pregnancy, known or suspected to be pregnant, or have a positive serum pregnancy screen.
• Subjects who, in the opinion of the Investigator, are not able or willing to comply with the protocol.