This is a Phase I study with the drug β-Phenethyl Isothiocyanate (PEITC) to be used in patients with Previously Treated Hematologic Malignancies or Advanced Cancer PEITC is a natural compound found in cruciferous vegetables that could increase reactive oxygen species (ROS) generation and induce apoptosis in cancer cell lines. The abnormal increase in ROS can cause oxidative mitochondrial damage, inactivation of redox-sensitive molecules, and massive cell death. PEITC has also shown to be effective in killing primary leukemia cells isolated from patients with chronic lymphocytic leukemia (CLL) and overcoming drug resistance. The study by Trachootham et al demonstrated that it is possible to take advantage of the ROS generation in cancer and use ROS-mediated mechanisms (induced by PEITC) to preferentially kill malignant cells. Thus, ROS stress associated with malignant transformation may serve as a biochemical basis for developing cancer therapeutics.