Sounds like Sealab 2021... in SPACE!
"People with terminal illnesses volunteer for program Starship Earth. Altering their molecules cures them but gives them extraordinary abilities. The group orbits Earth as a doomsday Earth defense. Alien DNA is discovered on an asteroid and bred. When the bred aliens take over Earth Starship Earth is recalled to save the planet. They defeat the aliens. Alien meets the Fantastic Four."