It did not take me long to find what I was looking for, but there it was! Superman #22 (Vol 2), Lex had been wearing a Kryptonite ring believing the radiation from it to be safe. At this point it is discovered it was not and Lex needs His hand amputated to prevent the cancer's spread, but by then it has already metastasized, and his condition is terminal.
By the time we get to Action Comics # 670 Lex has hatched a plan to save his life and fool the world in to believing he is dead. Luthor decides to fake his own death so he can remove his brain from his cancer-ridden body and then grow a cloned body around it, whereupon he passes himself off as his illegitimate 21-year-old son and heir, Lex Luthor II. His deception is benefited by a vibrant new body with a beard and full head of red hair. As Luthor II, he inherits control of LexCorp but the clone body eventually begins to deteriorate and age (and lose its hair) at a rapid rate, a side-effect of a disease that affects all clones.
The more I look at Jesse Eisenberg with the long red Hair the more it makes me wonder if this is the version of Lex he will be portraying in Batman V Superman. What do you think? Comment below and lets here your thought.