A new drug called RP103 (Cysteamine Bitartrate) is currently being developed by a US based pharmaceutical company called Raptor Pharmaceuticals.
This drug is able to increase production of a naturally occurring protein Glutathione which works as a super antioxidant and protects against reactive oxygen species which can cause mitochondrial damage.
Raptor started a clinical trial in 2014 which was extended in early 2016. The extended trial is looking at children aged 2-17 with genetically confirmed mitochondrial disease.
The trial will asses the safety, tolerability and efficacy of this drug across a wide range of syndromes including Leigh's, LHON, MERFF, MELAS, MNGIE, Kearn-Sayre Syndrome and POLG-related disorders. This study is expected to complete in May 2018.
Edison Pharmaceuticals are currently also developing a similar Glutathione precursor called EPI-589, however at present this is only in clinical trials for ALS and Parkinson's Disease, not mitochondrial disease.