Compositions containing epidithiodioxopiprazines and methods of their use are provided. Epidithiodioxopiprazines can be isolated from natural resources or synthesized de novo. Moreover, epidithiodioxopiprazines, including Verticillin A, are shown to effectively sensitize multiple types of tumor cells to TRAIL-induced apoptosis. In addition, epidithiodioxopiprazines, including Verticillin A, are shown to effectively overcome cancer cell resistance to existing drugs (i.e. Etoposide, Cisplatin, 5-FU and Doxorubicin). Therefore, compositions and methods are provided for use in sensitizing target cancer cells to death receptor- and other anticancer drugs-induced apoptosis. Methods of treating cancer in a subject in need thereof are also provided.
