Ex vivo determination of increased tumor immunogenicity of a tumor biopsy is used as a guide to identify immunotherapy of a tumor in a patient. Most preferably, the ex vivo tests will include exposureof biopsy samples to stress conditions to produce pretreated tumor cells that are then assayed with immune competent cells for increased activation or activity. Test conditions include exposure of the biopsy samples to immune stimulatory compositions, antibodies against neoepitopes, and/or modified cells, and an increase of immunogenicity is preferably determined by their exposure to T cells and/or NK cells.