His White BLood Cell Count is amazing as Lara has stated. Thats why he has not been killed after being shot so many times. But After he finds out aboout the disease, there are two things that happen in the comics. 1 is that SUperman gives him the cure on terms that he does a ton of charity work, etc. etc. the other is that Lex fakes his death and Cadmus Labs basically "regrows" a body fo him but he still has his own brain and he calls him self ALexander the Son of Lex Luthor. Like he was the long lost son of the Original Lex and at first he is all nice and stuff but he later turns evil after he thinks that Superman has been killed by Doomsday.