Injectable intratumoral hydrogel as 5-fluorouracil drug depot

The effectiveness of systemically administered anticancer treatments is limited by difficulties in achieving therapeutic doses within tumors, a problem that is complicated by dose-limiting side effects to normal tissue. To increase the efficacy and reduce the toxicity of systemically administered anticancer 5-fluorouracil (5-Fu) treatments in patients, intratumoral administration of an injectable hydrogel has been evaluated in the current work. The MPEG-b-(PCL-ran-PLLA) diblock copolymer (MCL) containing 5-Fu existed in an emulsion-sol state at room temperature and rapidly gelled in vivo at the body temperature. MCL acted as in vivo biodegradable drug depot over a defined experimental period. A single injection of 5-Fu-loaded MCL solution resulted in significant suppression of tumor growth, compared with repeated injection of free 5-Fu as well as saline and MCL alone. For both repeated injections of free 5-Fu and single injection of 5-Fu-loaded MCL, most of the 5-Fu was found in the tumor, indicating the maintenance of therapeutic concentrations of 5-Fu within the target tumor tissue and the prevention of systemic toxicity associated with 5-Fu in healthy normal tissues. In conclusion, this work demonstrated that intratumoral injection of 5-Fu-loaded MCL may induce significant suppression of tumor growth through effective accumulation of 5-Fu in the tumor.