Temozolomide With or Without Veliparib in Treating Patients With Relapsed or Refractory Small Cell Lung Cancer

This randomized phase II trial studies how well temozolomide with or without veliparib works in treating patients with small cell lung cancer that has returned or does not respond to treatment. Temozolomide works by damaging molecules inside the cancer cells, such as deoxyribonucleic acid (DNA), that are needed for cancer survival and growth. Veliparib may stop the growth of tumor cells by blocking proteins that are needed for repairing the damaged DNA and it may also help temozolomide to kill more cancer cells. It is not yet know whether temozolomide is more effective with or without veliparib in treating patients with relapsed or refractory small cell lung cancer.