Limited tissue penetration of taxanes: a mechanism for resistance in solid tumors.

Purpose: Limited drug penetration in solid tumors is a potential mechanism of resistance for many anticancer drugs. Taxanes represent a class of drugs that are currently undergoing a new round of development, but with little known of their ability to penetrate and distribute relative to blood vessels within solid tumors.

Experimental Design: We assessed the tissue penetration of paclitaxel and docetaxel in HCT-116 tumor xenografts and in multilayered cell culture (MCC), a three-dimensional cell culture model of the tumor extravascular compartment.