The Keto and Zytiga thing, they both target an enzyme called CPY17, they both use Prednisone (usually), I think Zytiga is re=engineered and new patent thingy therefore obtained and it might be more potent and it should be look at the price comparison:
Keto (www.northdrugstore.com) 1+ months worth for under $100 (U.S. dollars) (drug was used on PCa in like 1981-2)
Zytiga (part of Johnson & Johnson) 1 month worth for $5,300 (U.S.- slam your insurance company for it)
In clinical trial of Zytiga, they barred anyone whom used Keto prior (clue- that it works similarly or would effect the same control mechanisms?)
Anything new today will cost plenty because of the clincial trials FDA processes, how wonderful for everyone.