It should be noted that back on April 4, 2008 Inovio reported positive Phase I/II (human) results from a different vaccine targeting prostate cancer, but did not follow up on those results. That vaccine had targeted CD4 and CD8. While that specific vaccine no longer appears to be under development, Inovio continues to work on CD4/CD8 targets as shown by its January 23, 2014 IL-33 immune activator study press release ; that study was pre-clinical, using mice. Apparently by 2011 it had become apparent that INO-5150 was a better candidate for development.