Influence of trypsin on cytostatic effects of cyclophosphamide in rats with Guerin tumours.

Trypsin in a dose of 5 mg/kg had no significant effect on tumour growth. Given simultaneously with cyclophosphamide the enzyme was found to reduce considerably the weight of tumours and to decrease the levels of DNA and RNA as compared with the group of animals receiving only cyclosphosphamide. These effects were correlated with histological examinations of tumour tissue. Trypsin was also shown to prevent the development of toxic effects of cyclophosphamide on the haemopoetic system. Probable mechanisms of the observed changes are discussed.