Humoral immune response against tumor antigens after treatment with a cancer antigen specific active immunotherapy and its association with improved clinical outcome

A method of treating a prostate cancer patient who is responsive to cancer antigen specific active immunotherapy (CASAI) using prostatic acid phosphatase as a target cancer antigen where the method comprises the steps of:

• i. selecting a prostate cancer patient with white blood cells who has been treated with a cancer antigen specific active immunotherapy (CASAI) using prostatic acid phosphatase fused to granulocyte macrophage colony-stimulating factor as a target cancer antigen to activate the patient's white blood cells under ex vivo conditions and who has an increase in reactive antibody levels in two or more non-target predetermined biomarker antigens of prostate cancer where the increase in reactive antibody levels is determined using an immunoassay that detects reactive antibody levels for at least four of the following predetermined biomarker antigens of prostate cancer:
• PSA, KLK2, KRAS, ERAS, LGALS8, and LGALS3 compared to a baseline antibody level from before CASAI treatment;
• and,
• ii. treating the prostate cancer patient with CASAI using a target cancer antigen comprising prostatic acid phosphatase fused to granulocyte macrophage colony-stimulating factor to activate the patient's white blood cells under ex vivo conditions.