Talazoparib and Low-Dose Temozolomide in Treating Participants With Relapsed or Refractory Extensive-Stage Small Cell Lung Cancer

Inclusion Criteria: * Able to provide informed consent. * Cytologically or histologically confirmed small cell lung cancer (SCLC) with extensive-stage disease. * Relapsed (progressed within 6 months) or refractory (progressed during or within 4 weeks of completing 1st line platinum based regimen). * Measurable disease, as per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. * Archival or fresh tissue biopsy available for exploratory analyses. * Eastern Cooperative Oncology Group (ECOG) performance status of =\< 1. * Able to swallow the study drugs, has no known intolerance to study drugs or excipients, and able to comply with study requirements. * Female participants of childbearing potential must have a negative pregnancy test at screening and must agree to use a highly effective birth control method (defined in protocol) from the time of the first study drug treatment through 45 days after the last study drug treatment. * Male participants must use a condom when having sex from the time of the first study drug treatment through 105 days after the last study drug treatment. Contraception should be considered for a non-pregnant female partner of childbearing potential. * Male and female participants must agree not to donate sperm or eggs, respectively, from the first study drug treatment through 105 days and 45 days after the last study drug treatment, respectively. * Female participants may not be breastfeeding at baseline through 45 days after the last study drug…