That abstract was from 2005. It's impressive since it has both lab dish as well as mouse study with oral route. probably helpful to know how much orally. Here's what pubmed lists currently:
http://www.ncbi.nlm.nih.gov/pubmed?t...opein%20cancer
Unfortunately not much outside of petri dish analysis. maybe this wasn't patentable and they couldn't come up with a synthetic version. That seems to be the usual method for cashing in on/propelling forward natural compounds.