EZN-2208 (Pegylated SN-38) in Combination With Bevacizumab in Refractory Solid Tumors

Background: \- The anticancer drug bevacizumab works by reducing the formation of new blood vessels in tumors, which can slow or stop the growth of cancer cells and supporting blood vessels. The experimental drug EZN-2208 works by limiting how well cancer cells can divide. Drugs similar to EZN-2208 also work by turning off the production of the HIF protein, which otherwise can help cancer cells to grow even when blood supply is limited. Researchers are interested in determining if EZN-2208 turns off HIF in patient tumors, and whether combining it with bevacizumab is an effective treatment for cancers that have not responded to standard treatment. Objectives: \- To assess the safety and effectiveness of the combination of EZN-2208 and bevacizumab for solid tumors that have not responded to standard treatment. Eligibility: \- Individuals at least 18 years of age who have solid tumors that have not responded to standard treatment. Design: * Participants will be screened with a full physical examination and medical history, blood and urine samples, and tumor imaging studies. * Participants will receive EZN-2208 and bevacizumab intravenously on an outpatient basis in 4-week cycles (with the exception of the first cycle, which will be 5 weeks). * Cycle 1: Participants will receive EZN-2208 once a week for 3 weeks in a row (days 1, 8, and 15), followed by 1 week without the drug. Participants will receive bevacizumab 1 week before EZN-2208 (day - 7) and then 3 weeks later (day 15). * Subsequent cycles: Participants will receive EZN-2208 once a week for 3 weeks in a row (days 1, 8, and 15), followed by 1 week without the drug. Participants will receive bevacizumab every 2 weeks (days 1 and 15). * Participants will have clinic visits with physical examinations and blood tests in the first 3 weeks of each cycle. Clinic visits may also include tumor imaging studies and tumor biopsies as directed by the study researchers. * Participants will continue to take the study dr