Previous experimental studies, utilizing dipeptides of L-mimosine against melanoma, suggested that the selectivity of this class of HOPO-based molecules was mainly due to their ability to inhibit and consequently down-regulate tyrosinase which causes perturbations in melanin production [62, 63] the levels of which are increasing in metastatic melanoma thereby reducing the outcome of radiotherapy. This evidence concerns the gene TYR and metastatic melanoma.