Therapeutic potential of biological response modifiers against transplantable mouse tumors of spontaneous origin. I. Characterization of biological properties of tumor lines and preliminary data on response to cytostatic drugs and biomodulators.

Several transplantable lines were derived from spontaneous tumors of mouse strains of low and high cancer incidence (CBA, BALB/c and DBA/2), and eight of them were used for an evaluation of the therapeutic potential of BRM. The lowest number of cells inducing tumors was in most cases around 10(4) cells. In transplantation tests, tumors of CBA and DBA/2 mice were non-immunogenic, while tumors of BALB/c mice showed different level of immunogenicity. Transplantation of a small number of tumor cells in admixture with BCG resulted in no tumor growth of the immunogenic line X6 and no effect on take rate of non-immunogenic line X1. Sensitivity of studied tumor lines to BCNU, CY and ADR was moderate. Therapy of the tumors with postulan and CMA, two biomodulators already shown to be active against various experimental tumors, failed. The significant therapeutic response was observed in DBA/2 mice bearing i.p. transplant of lymphosarcoma X19 and treated with i.p. injections of CMA.