The sensitivity testing of Wilms' tumors to cytostatic agents with an autoradiographic in vitro short-term test.

Sensitivity of 15 Wilm's tumors in children was tested towards cytostatic agents in vitro by means of an autoradiographic short-term test. Sensitivity was measured as a magnitude of the inhibition of 3H-thymidine, resp. 3H-uridine incorporation. The test was performed with Adriamycin, Actinomycin D. Daunomycin, Bleomycin, Cyclophosphamide, Ifosfamide, Trenimon, and Arabinosylcytosine. None of the tumors is resistant to all substances, they are responsive against 2 or more drugs. The most effective drugs tested are Adriamycin, Actinomycin D and Cyclophosphamide. The tumors show a marked individual sensitivity pattern. This behavior is explained mainly by the usually high proliferative activity of Wilms' tumors. The possibilities and limits of long-term and short-term methods for sensitivity testing are discussed critically. For the evaluation of the results of in vitro testing and in vivo effectiveness the close correlation should be considered between the type of cytostatic agent and proliferation kinetics of the tumor, cytostatic agent and effect on tumor metabolism as well as the effect of the cytostatics and the nucleic acid precursors used for the short-term test. Despite the methodological limitations preclinical testing should be preferred to unselected chemotherapy.