Paclitaxel is converted to its toxic form by P450/P450R, and it is effective for the treatment of metastasic melanoma by depleting MDSCs [3, 25]; Docetaxel is differently processed by P450 cytochromes and lacks efficacy against melanoma [25-27]; and Irinotecan is activated by carboxylesterases, while neutralized by P450R [28]. The gene discussed is POR; the disease is melanoma.