This drug delivery system consists of ELP–elastin-like polypeptide, CPP–cell penetrating peptide, a cleavable linker to enable doxorubicin release in the targeted low pH microenvironment of the tumor, and a derivative of the anticancer agent doxorubicin modified by a 6-maleimidocaproyl moiety for conjugation to a terminal cysteine residue on ELP. This evidence concerns the gene NR5A1 and neoplasm.