PGP and colorectal carcinoma: For example, DOX-loaded gold nanorods coated with mesoporous silica (mSiO2) used in CRC photothermal therapy (PTT) and chemotherapy have been improved by using pH-responsive polyhistidine (PHIS) and D-α-tocopherol PEG 1000 succinate (TPGS) to induce endocytic pathway escape and to inhibit P-GP, respectively [28].