It was reported that THOP1 secreted by tumor cells was a very likely candidate for the extracellular activation of CPI-0004Na which was a prodrug of doxorubicin, and the improved therapeutic index of CPI-0004Na compared with free doxorubicin was confirmed in three tumor xenograft models of prostate, breast, and lung cancer [10], [25]. This evidence concerns the gene THOP1 and lung cancer.