Additional Study Information: This is a research study to test the effectiveness of Toca 511/Toca FC, an experimental drug, for treatment of recurring brain tumors compared to current standard of care. The study will enroll 370 subjects age 18-85 years who choose to undergo removal of the tumor a second time. At the time of surgery patients will be randomly assigned in a 1:1 ratio to receive either the experimental drug or the standard of care. Treatment will begin approximately 6 weeks after surgery. Blood, tumor, and cerebrospinal fluid will be collected to determine the effectiveness of the new drug. Given the tendency of malignant brain tumors to recur and and the limited success of the current standard of care, Toca 511/Toca FG has the potential for improving the outcome of patients with recurring brain tumors.