Looks like institutional interest is increasing.
Bank of America has increased its' stake with 9.200 shares since March 31 2013, before they held 300 shares. Whitebox Advisors from 50.000 shares to 478,000 shares since March 31 2013/
IMO others like Goldman Sachs, Allianz Asset Management, UBS, Wells Fargo, Barclays, ... will follow and increase their position as time passes and milestones are getting nearer and getting reached.
Maybe they send some analyst to the American Brain Tumor Association family day on July 26 as Northwest Biotherapeutics is sponsoring this event.