Andrew Niccol (imdb) wrote the screenplay and may be tapped to helm the film which is being produced by Inferno. (imdb)
Meyer's The Host is a science fiction romance in which humans are being erased by The Souls, a parasitic race that subsumes a human body and replaces their consciousness. Melanie Stryder is one of the small number of remaining humans fighting for the survival of their race. She is captured by The Souls and implanted with The Wanderer but she fights to preserve her mind, fights because she is in love. The Wanderer is so impacted by Melanie's memories and feelings of her life and her love that it reconnects with her old life and her old lover, building a love triangle in two bodies.