The shared features of both non-responsive clusters (3 and 4) included the overexpression of multiple tumor antigen genes: PAGE2, GAGE2A, GAGE13, and GAGE2E. Such tumor antigens have been described in many cancer types, and they represent cancer/testis antigens which are normally expressed in male germ cells and are repressed in cancer [59,60]. Here, GAGE2A is linked to cancer.