This is a Phase I, dose escalation study of EM-1421 administered by intravenous infusion (IV) for five consecutive days every 28 days to patients with solid tumors refractory to current therapies. There have been no previous human studies of intravenous (into one's vein) EM-1421 treatment; however, lab research (research in test tubes and/or animals) suggests that EM-1421 has shown some activity against tumors in animals. This activity in animal models suggests that EM-1421 may be a useful chemotherapy for human cancer.