Laura Dern and Jared Leto have signed on to star alongside James Gandolfini, John Travolta and Salma Hayek in Millennium Films’ “Lonely Hearts.”Now in production, pic is based on the true story of a detective who tracked down and arrested a pair of serial killers who entrapped their victims by answering lonelyhearts personals. Holly Wiersma and Boaz Davidson produce the pic. Avi Lerner, Danny Dimbort, Trevor Short and John Thompson of Millennium serve as exec producers along with Randall Emmett and George Furla of Emmett/Furla Prods. Anson Downes and Linda Favila of Travolta’s JTP Films are associate producers. Dern will next be seen in Lions Gate’s “Happy Endings.” Leto recently wrapped “Awake” opposite Helen Mirren.