Activity of cyclophosphamide and 1-methylnitrosourea on Ehrlich carcinoma transplanted in different sites. Correlation between drug level and tumor inhibition

Previous findings show that experimental tumors of the mouse, such as Ehrlich carcinoma and Sarcoma 180, transplanted in different sites, elicit a different sensitivity to the same drug according to the site of tumor implantation. Cyclophosphamide is highly active on intraperitoneal or subcutaneous tumors, but is ineffective on intracerebral tumors. However, the opposite is true for drugs such as nitroso-derivatives, which are active only on intracerebral tumors. The studies presented in this report were performed in order to elucidate whether different concentrations of drugs at the three tumor sites are related to the different antitumoral effects. It was found that measurements of blood and tissue concentrations explain fairly well the different activities of the drugs being tested.