Abstract: Methods for producing an anti-tumor effect in a subject suffering from a cancer or a tumor are disclosed. The methods comprise administering to the patient a Vascular Disrupting Agent (VDA) that a combretastatin agent and one or more antibodies selected from the group consisting of: a CTLA-4 antibody, a PD-1 antibody, a PD-L1 antibody, and a PD-L2 antibody in amounts effective therefor. Examples of combretastatin include CA1P, CA4P, and their corresponding salts and prodrugs. The combination of the VDA and one or more of the antibodies produced a synergistic anti-tumor effect.