A review [0] found that only 37% of research on mice translate in humans. But as someone interested in neurodegenerative diseases I can only recall that there were ~2500 clinical trials done on Alzheimer because of interesting results in mice and ... not a single one was effective in humans.

For less investigated diseases such as ALS or Parkinson it's about 700 trials without any success.

An excellent article discussing why mice studies are not applicable to humans, at least for ALS, is this one: https://www.nature.com/articles/nrneurol.2015.65

[0] http://jamanetwork.com/journals/jama/article-abstract/203577