Despite undergoing potentially curative surgical resection or combination therapy, a significant number of patients with cancer will have their cancer recur. Patients with recurrent cancer have a significantly lower survival rate and incur much higher medical costs compared to those whose disease does not recur. Multiple clinical studies have demonstrated that additional courses of chemotherapy or radiation in the adjuvant setting do not or only minimally improve outcomes for these patient groups. Thus, in the majority of cases, the current standard of care following treatment of metastatic disease and the achievement of disease-free status is watchful waiting. With recurrence rates of 95% and 85% in stage IV sarcoma and small cell lung cancer respectively and 70% for ovarian cancer, there is a clear unmet medical need for new treatments for recurrent disease.