Polymer chemotherapy for head and neck cancer.

OBJECTIVES

To study a new method of delivery of chemotherapy for the treatment of squamous cell carcinomas (SCCs) of the head and neck, to evaluate the pharmacokinetics of four anticancer agents (cisplatin, fluorouracil [5-FU], methotrexate [MTX], and paclitaxel) loaded into the biodegradable polymer, polyanhydride polymer poly(FAD:SA), and to evaluate the effectiveness and toxicity of the drug-polymer combination against human SCCs, both in vitro and in vivo.

STUDY DESIGN

Poly(FAD:SA) was loaded with different chemotherapeutic drugs and its in vitro and in vivo drug release and tissue penetration characteristics were studied. The biocompatibility and toxicity of the polymer-drug combination were determined. The effectiveness of the drug-polymer was evaluated against three different human SCCs (larynx O11, pharynx FADU, and floor of mouth UM- SCC1) cultured in vitro and in nude mice carrying human SCC xenografts.

METHODS

The in vitro drug release pharmacokinetics of the drugs were performed using atomic absorption spectrometry for cisplatin and high-pressure liquid chromatography for the 5-FU, MTX, and paclitaxel studies. In vitro tumor cytotoxicity was assessed by growth assay. In vivo cytotoxicity was assessed by growth rate inhibition in a nude mouse model.

RESULTS

All four chemotherapy drugs demonstrated a continuous release that followed first-order kinetics from the polymer. More than 95% of the MTX and 5-FU, 70% of the cisplatin, and 20% of the paclitaxel was released within the 10 days of the assay. Tumor cytotoxicity revealed that the polymer was very effective against the human SCCs O11, FADU, and UM- SCC1 in vitro. When a small amount of polymer (1-2 g) was added to the cell culture and left for 7 days, 96.6% of the UM-SCC1 cells, 86.9% of the FADU cells, and 94.6% of the O11 cells were killed. When the culture medium was then changed every 2 days to remove the effect of nutrient depletion or chemicals released by the degrading polymer, 74% of the UM-SCC1 cells, 94.5% of the FADU cells, and 66.1% of the O11 cells were killed at 7 days. The tumor animal model was the nude mouse carrying human floor of mouth SCC xenografts. Different amounts of cisplatin were incorporated into the polymers (5% and 7% drug/polymer at a weight/weight [wt/wt] load). Thirty-five days after implantation of the polymer in nude mice, the mean treated tumor size was 65.5% of controls in the 5% group and 31.8% in the 7% group. Seventy days after implantation the mean treated tumor size was 41.4% of controls in the 5% group and 38.1% in the 7% group, indicating a statistically significant delay of tumor growth compared with controls or with intraperitoneally injected cisplatin. The blank polymer was well tolerated by the mouse and had no effect on tumor growth.

CONCLUSIONS

The study results indicate that polymer chemotherapy is effective against a variety of SCCs of the head and neck, both in vitro and in vivo, and may become a useful therapeutic option for head and neck cancer.