DFT383 in Pediatric Participants With Nephropathic Cystinosis

This study is an open-label, multi-center, phase I/II study to assess the safety, tolerability, and efficacy of DFT383 in participants aged 2 to 5 years with nephropathic cystinosis, followed by a long-term extension phase. The study includes two Treatment Groups (Cohort 1 and Cohort 0) and consists of a Core Phase and a long-term Extension Phase. Participants in Cohort 1 will receive DFT383 and participate in both the Core and Extension Phase. Participants in Cohort 0 will not receive study treatment and will participate in the Core Phase only. The two cohorts will be run in parallel. Investigational sites may participate in one or both cohorts. Cohort 1 Approximately 15 participants will receive treatment with DFT383 in 3 (sub) cohorts (1A, 1B and 1C) dosed in a staggered approach. The total study duration for a participant in Cohort 1 will be up to 32 months in the core phase and up to 13 years for the long-term extension phase. Cohort 0 Approximately 15 participants meeting similar inclusion/exclusion criteria and receiving SoC will be enrolled. The Schedule of Activities will be reduced for this Cohort. This cohort 0 is not a direct control but will provide essential context for interpreting the results observed in the participants receiving DFT383. The total study duration for a participant in Cohort 0 will be up to 24 months.