A Study to Assess TTI-0102 vs Placebo in MELAS Patients

This is a randomized, double-blind, placebo-controlled study. Prior to treatment, patients will undergo a screening visit. If eligible, each subject will return for a Day 1 visit and will receive their first dose of investigational product (TTI-0102 or placebo). At the end of the first week of treatment, subjects will return for a Week 1/Day 8 study visit to assess study drug dosing/tolerance and instruct on dosing for the upcoming second week of treatment. For the first 8 weeks of treatment, subjects will alternate between returning to the clinic for detailed assessments (Weeks 4 and 8) and receiving a telephone call from the Investigator team to assess safety and TTI-0102 dose (Weeks 2 and 6) and the potential need for an immediate unscheduled study visit. After the first 8 weeks of treatment, subjects will continue to return to the clinic for monthly assessments at Weeks 12, 16, 20. The Study Exit visit will occur at Week 24, and subjects will be offered to continue on an open-label extension study of TTI-0102. If a subject does not complete the study, they will be asked to return for a Study Exit visit 4 weeks after last study drug dose. Primary Objective The primary objective of this study is to assess the efficacy, safety and tolerability of oral TTI 0102 compared to placebo, for up to 6 months in patients with MELAS. Secondary Objective The secondary objectives of this study are to assess the efficacy, pharmacokinetics (PK) and pharmacodynamics (PD) of cysteamine after oral administration of TTI-0102 at steady state, in patients with MELAS on a stable dose of TTI-0102. This is a randomized, double-blind, placebo-controlled study. Prior to treatment, patients will undergo a screening visit. If eligible, each subject will return for a Day 1 visit and will receive their first dose of investigational product (TTI-0102 or placebo). At the end of the first week of treatment, subjects will return for a Week 1/Day 8 study visit to assess study drug dosing/tolerance and instruct on dosing for the upcoming second week of treatment. For the first 8 weeks of treatment, subjects will alternate between returning to the clinic for detailed assessments (Weeks 4 and 8) and receiving a telephone call from the Investigator team to assess safety and TTI-0102 dose (Weeks 2 and 6) and the potential need for an immediate unscheduled study visit. After the first 8 weeks of treatment, subjects will continue to return to the clinic for monthly assessments at Weeks 12, 16, 20. The Study Exit visit will occur at Week 24, and subjects will be offered to continue on an open-label extension study of TTI-0102. If a subject does not complete the study, they will be asked to return for a Study Exit visit 4 weeks after last study drug dose. Study Drug Dosing To prevent any manifestation of intolerance at the initiation of drug treatment, only half a dose (2.75 grams) will be given once a day for the first week of treatment. During the following weeks of treatment, patients will be given a full dose of 5.5 grams once a day. Interim Data Review After nine (9) patients have completed three months of treatment (the Week 12 visit) an interim data cut will take place to assess safety and potential efficacy signals. Even if no indications of efficacy are detected at this early stage, the trial itself will not be terminated unless there is a serious safety concern (i.e., protocol-defined Stopping Criteria are met).