Treatment of head and neck and esophageal xenografts employing Alimta (R) and concurrent ionizing radiation

We examined the interaction between Alimta((R)) and ionizing radiation (IR) as a potential strategy to enhance the therapeutic ratio of combined-modal ity cancer treatment. Mice bearing human esophageal adenocarcinoma xenograf ts (Seg-1) or squamous cell carcinoma xenografts (SQ-20B) were treated with Alimta and IR employing a fractionated treatment schedule. Treatment with Alimta alone slowed the growth of Seg-1 but not SQ-20B tumors compared with control tumors. In Seg-1 xenografts combined treatment with Alimta and IR produced significant tumor growth inhibition compared with Alimta alone or IR alone. In SQ-20B xenografts, treatment with Alimta did not enhance IR-me diated tumor growth inhibition suggesting that sensitivity to Alimta is nec essary for an interactive cytotoxic effect with IR. The present data sugges t the potential clinical efficacy of combining Alimta administration with r adiotherapy for Alimta-sensitive cells and indicate that further testing ne eds to be conducted to optimize the dosing schedule to enhance the interact ion between the therapeutic agents.