Self/less (2015)

Ryan Reynolds and Ben Kingsley star in a drama where immortality has some side effects 

Damian Hale has built an empire but is dying from cancer. Using his extreme wealth, he decides to undergo a first-of-its-kind medical treatment that will transfer his consciousness into the body of a healthy young man. At first, he enjoys his newfound youth, but there is no going back to his old self. Soon, he finds himself fading and caught in the grip of a dark experiment.