Interesting question. Since HLA G seems to be involved in immune tolerance, for example during pregnancy, where new, or immunologically completeley foreign antigens develop without immune rejection of the embryo, similar mechanisms may occure during cancer development and progression: the cancer often has many new antigens, but can escape the otherwise functioning immune system. I think a better understanding and active basic research of such mysteries and blocking of the tolerance induction could serve as target for new anticancer therapies.