Irinotecan is an analog of camptothecin that is used clinically to treat colon and ovarian cancers, among others. Irinotecan exhibits anticancer chemotherapeutic, anti-angiogenic, and immunosuppressive activities. Irinotecan inhibits DNA topoisomerase I and sensitizes tumors to the effects of radiation. In glioma models, irinotecan decreases the number of tumor vessels and decreases expression of VEGF and HIF-1α, inhibiting tumor growth. Irinotecan also moderates inhibition of dendritic cell differentiation and may produce cholinergic side effects, suggesting potential inhibition of acetylcholinesterase (AChE) as well.