Abstract: The invention is based on the observation that certain phenols, monophenols or benzenediols, can be metabolized into reactive quinones, in particular ortho-quinones and related reactive intermediates, which is brought about by oxidation of monophenols and benzenediols by proteins exhibiting tyrosinase activity, such as human tyrosinase and the related proteins TRP1 and TRP2. Although the substances and the produced reactive intermediates are toxic and can induce cell death, it is more relevant according to this invention that they function as haptens that become covalently bound to the tyrosinase enzymes, in particular to histidine moieties, in or near the catalytic site of proteins exhibiting tyrosinase activity, such as tyrosinase, TRP1 and TRP2. An immune response is then to be mounted against these haptenized auto-antigens, in order to treat melanocytic malignancies, in particular melanomas.