bar for success for pbt2 in hd is very low

It is a bit disingenuous to relate clinical trials in one disease to another. For cardiology registration trials the number of patients recruited can be in the range of 10-20k. To recruit that many patients for Huntington’s disease you would be testing 12-25% of people with the disease.

In that sense >100 patients for a phase 2 trial in Huntington’s disease is pretty big in the scheme of Huntington’s trials

Trials do not need to be that big for drugs to come into use. Sirtex one Australians should be familiar with only tested 74 patients to get sir-spheres approved.
http://www.ncbi.nlm.nih.gov/pubmed/11843249

In Huntington’s disease tetrabenzine is the only treatment approved and it did not clear safety hurdles.
The FDA approved it when its main registration trial recruited 84 patients in a trial lasting 12 weeks. That was 7 weeks of dose adjustment and 5 weeks of maintenance and follow up for a week after coming off the drug.

Tetrabenzine reduced chorea (the wavy movements people with Huntington’s disease exhibit) after testing 84 (in case people don’t realize prana tested 109 which is more than 84) for 12 weeks (again prana tested for 26 weeks which again is more than 12 weeks) and the chorea got worse after the drug was stopped in the washout period (like prana where one of the adverse events was a worsening of huntington’s disease after PBT 2 was ceased).

In terms of safety PBT2 beats tetrabenzine hands down as there is a known increased risk of adverse neurological events. Again in lay terms people tend to kill themselves if they are given tetrabenzine.

There were five study withdrawals in the TBZ group and five serious adverse events (SAEs) in four subjects (drowning suicide, complicated fall, restlessness/suicidal ideation, and breast cancer) compared with one withdrawal and no SAEs in the placebo group

http://www.ncbi.nlm.nih.gov/pubmed/16476934

http://www.fda.gov/ohrms/dockets/ac/07/briefing/2007-4328b1-02-Prestwick.pdf

http://www.centerwatch.com/drug-information/fda-approved-drugs/drug/992/xenazine-tetrabenazine

What does this mean for PRANA and PBT2 for Huntington’s disease? It hardly needs to have any benefit to be approved and has already shown it may have some benefit in cognition

In lay terms, the only approved drug was already available on the market tetrabenazine and has sales of $100-200 million for the drug company that tested it (it was subsequently sold).

Its benefit was to decrease chorea (distressing for patients) but had the potential to make them kill themselves.

I am not a neurologist like trader but I don’t think the bar for success and approval for PBT2 in Huntingon’s disease will be that high.