There was no significant correlation between serum IgG levels of gp100 and its antigen expression in the tumor (r [9] = − .2974, p = 0.4370) or MelanA/MART1 and its antigen expression (r [9] = − .3167, p = 0.4101) before the start of treatment, which further supports the independent character of the association between the presence of these antibodies in the serum of metastatic melanoma patients and their better overall survival (Additional file 2: Figure S7A-F). Here, PMEL is linked to metastatic melanoma.