Effect of two antiproteinases on the growth of transplantable tumors and the proliferation of untransformed and transformed cells in culture

Experiments were carried out for the evaluation of the effect of two antiproteinases, aprotinin, and epsilon-amino caproic acid (EACA), on several transplantable tumors and cells in culture. It was demonstrated that aprotinin has a preferential therapeutic effect on the solid form of L1210, in comparison with its ascitic form. Treatment with aprotinin of Lewis lung carcinoma, melanoma B16, and hepatoma 22, in a limited chronic time schedule 1-9, and 1-11 brought no significant increase in survival; positive therapeutic effects had been shown for the first and the last of the tumors mentioned with life-time injections of the drug. Moreover, aprotinin treatment increased the number of lung nodules for the Lewis lung carcinoma inoculated either subcutaneously or intravenously. EACA applied with the same schedule had no effect on the survival of tumor-bearing animals. These data are discussed in terms of their relevance to anti-proteinase therapy in human cancer. No selective inhibition of proliferation for more tumorigenic cell culture lines of spontaneous and viral origin was demonstrated after treatment with both compounds.