Premanifest Huntington's Disease: Creatine Safety & Tolerability Extension Study (Pre-CREST-X)

• Safety [ Time Frame: 12 months ] [ Designated as safety issue: Yes ]
  Frequency of adverse events
• Tolerability [ Time Frame: 12 months ] [ Designated as safety issue: Yes ]
  Proportion of subjects completing the extension study at given dose level

• Clinical measures [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  Components of the UHDRS (Unitifed Huntington Disease Rating Scale)
• Biological Markers of Disease Progression [ Time Frame: 12 Months ] [ Designated as safety issue: No ]
  Biological indicators that creatine treatment might affect the progression of HD: plasma levels of creatine, serum levels of 8OH2'dG and 8OHG, magnetic resonance imaging (MRI), morphometric neuroimaging (biomarker of neurodegeneration), metabolomic profiling, and gene expression analysis to assess transcriptional effects of HD and creatine therapy.

The purpose of this clinical trial is to extend the Pre-Crest study (Protocol # (NCT00592995) to further assess the long-term safety and tolerability of up to 30 grams daily creatine in individuals at-risk for Huntington's Disease (HD) and to assess whether biomarkers responsive to creatine in symptomatic individuals are informative in premanifest individuals over a longer duration.

Extensive evidence exists that neurodegeneration begins many years before HD can be diagnosed clinically. Therefore, it is most desirable to begin a neuroprotective therapy before or during this premanifest period with the aim of delaying onset, as well as slowing functional decline. Cellular energy depletion is present early in HD and can be ameliorated by creatine, which helps regenerate cellular ATP. Preclinical evidence for creatine's potential neuroprotective effects in animal models of HD has been well-documented. Before the clinical efficacy of creatine can be tested in premanifest HD, its long-term safety and tolerability must be assessed in these individuals and its ability to favorably modify biomarkers of HD should also be confirmed. This extension trial will continue to follow eligible individuals who completed the PreCREST study on open-label creatine (up to 30 grams daily) for long term safety and tolerability. Additional biological and imaging biomarkers of disease progression and potential response to treatment will also be assessed.

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• Kim J, Amante DJ, Moody JP, Edgerly CK, Bordiuk OL, Smith K, Matson SA, Matson WR, Scherzer CR, Rosas HD, Hersch SM, Ferrante RJ. Reduced creatine kinase as a central and peripheral biomarker in Huntington's disease. Biochim Biophys Acta. 2010 Jul-Aug;1802(7-8):673-81. Epub 2010 May 9.
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• Borovecki F, Lovrecic L, Zhou J, Jeong H, Then F, Rosas HD, Hersch SM, Hogarth P, Bouzou B, Jensen RV, Krainc D. Genome-wide expression profiling of human blood reveals biomarkers for Huntington's disease. Proc Natl Acad Sci U S A. 2005 Aug 2;102(31):11023-8. Epub 2005 Jul 25.
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• Dedeoglu A, Kubilus JK, Yang L, Ferrante KL, Hersch SM, Beal MF, Ferrante RJ. Creatine therapy provides neuroprotection after onset of clinical symptoms in Huntington's disease transgenic mice. J Neurochem. 2003 Jun;85(6):1359-67.

Inclusion Criteria:

• Individuals who have completed the Pre-CREST Study.
• Individuals capable of providing independent informed consent and complying with trial procedures.

Exclusion Criteria:

-Clinical evidence of unstable medical or psychiatric illness in the investigator's judgment.

Additional eligibility criteria apply.