Kristen Stewart is shifting from vampires to rockers.The “Twilight” star is set to topline in “The Runaways,” a rock biopic of the ’70s all-girl band. Thesp will star as Joan Jett. Film will follow the early beginnings of the Runaways, whose members include Jett, Lita Ford and Cherri Currie. Best known for their hit song “Cherry Bomb,” the teen band was highly influential in the music scene of the late ’70s and early ’80s. Shooting will begin in early 2009 and will accommodate Stewart’s commitment to the “Twilight” sequel, “New Moon,” also slated to begin lensing at that time.