The Immortal (1970)

Through a genetic fluke, test driver Ben Richards was born with natural immunities to every known illness. Barring a fatal accident, Ben should live longer than anyone has ever lived. When an elderly billionaire discovers that periodic transfusions of Ben's blood can cure diseases, rejuvenate and extend life in others, the old man becomes obsessed with caging Ben, to use him as a personal fountain of youth. Ben escapes his captor, and is forced to stay on the run to avoid the billionaire's goons while also searching for his long-lost brother, Jason. Jason Richards may have the same kind of blood as Ben, and may face the same kind of danger.