DTS-201 sodium (CPI-0004Na) is a peptidic prodrug of Doxorubicin. DTS-201, comprising the tetrapeptide portion, is cleaved by endopeptidases in the tumor environment to produce metabolites that subsequently enter the cell and are converted to active Doxorubicin. DTS-201 shows antitumoral efficacy in tumor xenograft models of prostate, breast, and lung cancer.