Investigators propose to study the single agent activity of pazopanib in a Phase II trial of patients with relapsed or refractory small cell lung cancer. Because these patients have very limited treatment options, use of an investigational agent in this patient population is supported by current National Comprehensive Cancer Network guidelines. Using correlative biologic studies to evaluate the anti angiogenic activity of pazopanib in the absence of concomitant chemotherapy will allow us to delineate the responses due to this drug and the effect on angiogenesis.