Antitumor Efficacy and Toxicity of 5-Fluorouracil-Loaded Poly(Lactide Co-glycolide) Pellets

The aim of this study was to formulate a biodegradable implant capable of imparting local antitumor activity through the sustained release of the chemotherapeutic agent, 5-fluorouracil (5-FU). Thus, injectable pellets (<1.2 mm diameter) made from poly(lactide co-glycolide) (PLGA) and loaded with 5-FU at varying drug:polymer ratios were fabricated using hot-melt extrusion and tested for their ability to provide sustained release of 5-FU in in vitro and in vivo settings. In addition, these formulations were compared against soluble 5-FU for their antitumor activity in vivo as well as for their toxicity. It was demonstrated that the release rate of 5-FU from PLGA pellets was directly related to the percentage of 5-FU in the pellets. PLGA pellets loaded with 50% w/w 5-FU exhibited comparable, and significantly enhanced, antitumor activity (as measured by tumor volumes and survival) in vivo in a thymoma and colon cancer model, respectively, when compared to an equivalent bolus dose (120 mg/kg) of soluble 5-FU. We concluded that 5-FU-loaded PLGA pellets were more effective and specifically less erythrotoxic than 5-FU bolus injections and therefore may prove to be of benefit as an intraoperative adjunct therapy for patients with cancers that are sensitive to 5-FU and who are undergoing tumor resection.