An Open-label Extension Safety Study of MELAS Patients Who Completed TIS6463-203 (PRIZM)

The goal of this clinical trial is to evaluate the long-term safety and tolerability of zagociguat in patients with MELAS who completed study medication treatment in the lead-in study TIS6463-203. TIS6463-204 is evaluating zagociguat in an open-label extension study at the daily dose of 15mg. The study medication is a once daily oral table and will be provided at the clinic and/or shipped to the participant's home. Study assessments will be conducted during clinic visits which will occur at three months and then at six months. Thereafter, clinic visits will occur every six months.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

Key information

Conditions

Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-Like Episodes (MELAS Syndrome) Acid-Base Imbalance Acidosis Acidosis, Lactic Brain Diseases Brain Diseases, Metabolic Brain Diseases, Metabolic, Inborn Cardiovascular Diseases Central Nervous System Diseases Cerebral Small Vessel Diseases Cerebrovascular Disorders Congenital, Hereditary, and Neonatal Diseases and Abnormalities Genetic Diseases, Inborn MELAS Syndrome Metabolic Diseases Metabolism, Inborn Errors Mitochondrial Diseases Mitochondrial Encephalomyopathies Mitochondrial Myopathies Mitochondrial encephalopathy Muscular Diseases Musculoskeletal Diseases Nervous System Diseases Neuromuscular Diseases Nutritional and Metabolic Diseases Vascular Diseases

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

Neuroscience Research Australia, Sydney, New South Wales, Australia

About this study

On Screening Visit Day -1 (which corresponds to Period 2 Week 12 Visit from lead-in study TIS6463-203), participants will sign the informed consent form, be confirmed eligible for this open-label extension study and undergo Screening Visit assessments. Eligible participants will begin dosing the next day on Day 1 (there is no Day 0) at home. Participants will have a 3-month visit and 6-month study visit at the clinic and thereafter will have a clinic visit every 6 months. Participants should have a Follow-up Visit 4 (+1) weeks after zagociguat discontinuation.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Signed an Institutional Review Board (IRB)/Independent Ethics Committee (IEC)-approved informed consent form (ICF).
Completed TIS6463-203 treatment through the Period 2 Week 12 Visit.
Agrees to follow lifestyle restrictions.
Other criteria per the protocol.

Exclusion criteria

Any medical condition or clinical finding that, per investigator judgement, would preclude safe study participation and/or completion of all trial requirements.

Treatment and study plan

zagociguat 15mg

Drug

once daily oral tablets

Other names: IW-6463, CY6463

Primary outcomes

Incidence of Treatment-emergent Adverse Events (TEAEs)

Time frame: Day 1 through the Follow-up for treatment period 4 weeks after last dose of study medication.

TEAEs are any untoward event that may or may not be related to study medication.

Sponsors and collaborators

Lead sponsor

Tisento Therapeutics

Industry

Registry information

Official study title

An Open-label Extension Study Evaluating the Safety of Zagociguat in Participants With MELAS Who Completed TIS6463-203

Important dates

Study start: 2025
Primary completion: 2028
Study completion: 2028
First posted: May 7, 2025
Registry last updated: Jul 7, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

Completed