Activity of the folate analog 10-ethyl, 10-deaza-aminopterin (10-EdAM) against human head and neck cancer xenografts.

In a previous study we established a markedly increased antitumour activity of 10-ethyl, 10-deaza-aminopterin (10-EdAM) as compared to methotrexate (MTX) when tested in vitro in squamous cell carcinoma cell lines from the head and neck (HNSCC). In this paper we describe the antitumour activity of these drugs in vivo in athymic nude mice bearing HNSCC xenografts. Using a schedule of 125 mg/kg i.p. for both drugs, injected on day 0 and 7, 10-EdAM caused a significant response in 2 out of 5 tumour lines, whereas MTX was completely inactive. These two lines moderately sensitive to 10-EdAM were not affected when the drug was given daily times 5 at an equitoxic dose of 0.75 mg/kg, indicating that the effect of the drug may be schedule dependent.