Ann: Bisantrene Shows Broad Anti-Cancer Activity in Cancer Cells, page-43

nM stands for nano molar, a measure of the concentration of bisantrene in this case. This is really just an arbitrary, but conservative, cut-off. What matters is if this level is above or below what can be achieved in the patient. The good news is this is well below the maximum concentration that we know patients can tolerate.

Bisantrene kills brain cancer cells, but as you rightly notice, for it to be useful bisantrene needs to cross the blood brain barrier (BBB). All the data we have suggests bisantrene doesn't do this, but if you have a formulation that won't immediately precipitate when you inject, it it may be possible to inject the drug intrathecally and bypass the BBB that way. If you want to know more about this have a look at this wiki article.

https://en.wikipedia.org/wiki/Intrathecal_administration