Gefitinib, a drug approved to treat advanced non–small-cell lung cancer in patients who have received chemotherapy, also may be useful in treating oral cancer, reported researchers in the Dec. 20 issue of International Journal of Cancer.
Gefitinib inhibits epidermal growth factor receptor, or EGFR, which is overactive in several types of cancer. Researchers at Ehime University in Japan conducted a study to investigate whether treating oral cancer cells with gefitinib could improve response to radiotherapy in oropharyngeal squamous cell carcinoma, or OSCC, cells.
They observed cell growth inhibition in vitro when the cells were treated with radiation or gefitinib. When cancer cells were treated with radiation followed by gefitinib, researchers noted a cooperative antiproliferative effect. The combination treatment of gefitinib and radiation completely inhibited the downstream signaling of EGFR.
Researchers found that after radiation, gefitinib had a strong inhibitory effect on tumor cell mechanisms that repair DNA damage. They also found that the combination of gefitinib and radiation caused growth inhibition and regression of well-established OSCC tumors in athymic mice; tumor volume was reduced from 1,008.2 to 231.4 cubic millimeters in HSC2 cells and from 284.2 to 12.4 mm3 in HSC3 cells.
Immunohistochemical analysis of OSCC cells grafted into mice revealed that gefitinib caused a striking decrease in tumor cell proliferation when combined with radiotherapy.
Researchers concluded that gefitinib enhances tumors’ response to radiation by multiple mechanisms that may involve growth inhibition and effects on DNA repair after exposure to radiation.
