Described are methods of treatment of a small cell lung cancer subject expressing Schlafen-11 (SLFN 11) with a Poly (ADP-ribose) polymerases (PARP) inhibitor or a pharmaceutically acceptable salt thereof. Specifically, the method comprising detecting SLFN 11 in a tumor cell sample from the subject, and administering effective amount of a PARP inhibitor, such as talazoparib or the tosylate salt of talazoparib, to the subject.
