Abstract: Embodiments provide for anti-GPC3 antibodies compositions comprising the same, and methods of using such antibodies and compositions for the prevention, diagnosis, and treatment of cancer. In one embodiment, a method for predicting a therapeutic effect of an anti-GPC3 immunotherapy on a cancer characterized in that cells of the cancer express GPC3, comprises detecting the presence of said cells in a subject via an immunohistochemical methodology, and wherein when the presence of said cells is detected, the anti-GPC3 immunotherapy is predicted to have a therapeutic effect on the cancer in the subject.