Therapeutic potential of pyruvate therapy for patients with mitochondrial diseases: a systematic review

Background: Mitochondrial disease is a term used to describe a set of heterogeneous genetic diseases caused by impaired structure or function of mitochondria. Pyruvate therapy for mitochondrial disease is promising from a clinical point of view. Methods: According to PRISMA guidelines, the following databases were searched to identify studies regarding pyruvate therapy for mitochondrial disease: PubMed, EMBASE, Cochrane Library, and Clinicaltrials. The search was up to April 2019. The endpoints were specific biomarkers (plasma level of lactate, plasma level of pyruvate, L/P ratio) and clinical rating scales [Japanese mitochondrial disease-rating scale (JMDRS), Newcastle Mitochondrial Disease Adult Scale (NMDAS), and others]. Two researchers independently screened articles, extracted data, and assessed the quality of the studies. Results: A total of six studies were included. Considerable differences were noted between studies in terms of study design, patient information, and outcome measures. The collected evidence may indicate an effective potential of pyruvate therapy on the improvement of mitochondrial disease. The majority of the common adverse events of pyruvate therapy were diarrhea and short irritation of the stomach. Conclusion: Pyruvate therapy with no serious adverse events may be a potential therapeutic candidate for patients with incurable mitochondrial diseases, such as Leigh syndrome. However, recent evidence taken from case series and case reports, and theoretical supports of basic research are not sufficient. The use of global registries to collect patient data and more adaptive trial designs with larger numbers of participants are necessary to clarify the efficacy of pyruvate therapy.