Humoral responses to ERp5 are associated with immune-mediated tumor destruction in diverse solid and hematologic malignancies. A longitudinal analysis of antibodies to human ERp5 was performed with serial sera samples diluted 1:50 and a secondary anti–human pan-IgG antibody. MEL15 and M37 are metastatic melanoma patients, L1 is a metastatic non-small cell lung carcinoma patient, OV65 is a metastatic ovarian carcinoma patient, and MY2 and MY5 are acute myeloid leukemia patients. denotes vaccination with irradiated, autologous, GM-CSF–secreting tumor cells. indicates the infusion of a fully human anti–CTLA-4 blocking monoclonal antibody (MDX-010; ipilumimiab).