Efficacy of KL1333 in Adult Patients With Primary Mitochondrial Disease

Primary mitochondrial disease with predominant neurodegenerative phenotypes, such as, but not limited to, Leigh syndrome, Leber hereditary optic neuropathy (LHON) and Neuropathy ataxia-retinitis pigmentosa syndrome (NARP).

Primary mitochondrial disease nuclear DNA mutations or mutations causing mtDNA destabilisation. Genetic mtDNA variants of uncertain significance, likely pathogenic, or pathogenic mutations with degrees of heteroplasmy below what can be considered to definitely cause PMD.

General fatigue or muscle weakness due to causes other than mitochondrial disease, in the opinion of the investigator.

Significant cardiovascular disease (e.g., sustained or symptomatic arrhythmia; dilated heart chambers or reduced function; Mobitz II atrioventricular block or greater) OR abnormal ECG that is clinically significant, as determined by the investigator. Any QTcF > 450 msec for male patients and > 470 msec for female patients is exclusionary. In the case of an exclusionary QTcF, the ECG can be repeated twice and the average of 3 QTcF intervals should be used to determine the QTcF eligibility.