Abstract: The invention relates to compositions comprising therapeutic antibodies, and uses and methods for increasing the potency of therapeutic antibodies. In particular, the invention provides a composition comprising (i) an agent which reduces Fc receptor binding of endogenous serum antibodies, and (ii) a therapeutic antibody, preferably a therapeutic antibody which is resistant to the agent. The therapeutic antibody may be administered to the subject after a set time interval, or the blood of the subject may be treated with the agent prior to administration of the therapeutic antibody.