Phase 3 Study of Cysteamine Bitartrate Delayed-release (RP103) Compared to Cystagon® in Patients With Cystinosis

Inclusion Criteria: * Male and female subjects must have nephropathic cystinosis. * Subjects must be on a stable dose of Cystagon® sufficient to maintain their white blood cell (WBC) cystine level at ≤ 1.0 nmol/half-cystine/mg protein. * Subjects must be able to swallow their typically administered Cystagon® capsule with the capsule intact. * Within the last 6 months, no clinically significant change in liver function \[i.e., ALT, AST, total bilirubin\] and renal function \[i.e., estimated GFR\] at Screening as determined by the Investigator. * Subjects with an estimated GFR (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 or their parent or guardian must provide written informed consent and assent (where applicable) prior to participation in the study. Exclusion Criteria: * Subject's age \< 6 years old or subject's weight \< 21 kg. * 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, 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 receiving any form of cysteamine medication through a gastric tube. * Subjects who are receiving maintenance dialysis or who have had a kidney transplant. * Subjects who are on an active kidney transplant list or who are planning to receive a kidney transplant within 3 months of Screening. * 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 have a made a blood donation within 30 days of Screening. * Subjects who, in the opinion of the Investigator, are not able or willing to comply with the protocol.