[Prognostic significance of lysosomal cysteine proteases in the estimation of the effectiveness of the antitumorigenic therapy].

The influence of the untitumor drugs, cyclophosphamide (CPA) and nitrosomethylurea (NMM) on the activity of lysosomal cysteine proteases cathepsin B and L in the tumor tissue was studied. Regression or reduction in the rate of growth of LS and RLS (drug sensitive and resistant sarcomas, respectively) during injection of CPA or NMM was accompanied by the increase in the activity of cysteine proteases cathepsin B and L in the tumor tissue. The increase of cathepsin B and L activity in the tumor tissue was correlated with the therapeutic effect of the used drugs. Data obtained suggest that cathepsin B and L activity in the tumor tissue have a prognostic significance for the effectiveness of antitumor therapy.