Tumor therapy of neoplastic diseases with tumor cells and neuraminidase: Experimental studies on chessboard vaccination in transplantation tumors

Abstract

The therapeutic effect of intradermal (i.d.) injection of tumor cells mixed with VCN on growth of spontaneous metastases in transplantable tumors in mice (3-Lewis lung adenocarcinoma; B16-melanoma) and rats (R-3230 mammary adenocarcinoma) was investigated. Intradermal injection was done in a chessboard-like manner: increasing numbers (10 5, 10 6 and 10 7) of Mitomycin-treated tumor cells (M-TC) were each mixed with increasing amounts (10, 50 and 100 mU) of Vibrio cholerae Neuraminidase (VCN). These different mixtures were injected i.d. at different sites one day after resection of the primary tumor graft to mice and rats, suffering from minimal residual disease. The therapeutic effect of this so-called chessboard vaccination on minimal residual disease was compared to that of the subcutaneous or i.d. injection of VCN-treated M-TC (10 5, 10 6, 10 7 or 10 8 cells) or of single mixtures of M-TC and VCN. The results show that compared to VCN-treated M-TC or single mixtures of M-TC and VCN, chessboard vaccination is the only procedure that is therapeutically effective on metastasation of Lewis lung adenocarcinoma. The therapeutic effect could be abrogated by heat-inactivation of VCN. Incomplete chessboard vaccinations (10 5, 10 6, 10 7 tumor cells, each mixed with 5 mU VCN only) were likewise ineffective. However, treatment with incomplete chessboard vaccinations in combination with a low dose of cyclophosphamid (which is not immunosuppressive, but partly inhibits tumor growth) had a synergistic therapeutic effect on minimal residual disease of Lewis lung adenocarcinoma. In contrast, growth of metastases of B16-melanoma and R-3230 adenocarcinoma could not significantly be influenced by any of those treatments. The DTH response of tumor bearing animals against i.d. applied tumor cells was neither significantly enhanced by the admixture of enzymatically active VCN nor did the DTH response seem to be predictive for a tumor-therapeutic effect. Thomsen-Friedenreich antigens could serologically be detected on untreated cells of Lewis lung adenocarcinoma, B16-melanoma and R-3230 adenocarcinoma. Exposure of Thomsen-Friedenreich antigens after treatment with VCN was enhanced on cells of all tumors except Lewis lung adenocarcinoma. As chessboard vaccination only proved to be successful in Lewis lung adenocarcinoma, but not in the other tumors, it can be concluded that the exposure of Thomsen-Friedenreich antigen plays no decisive role in tumor therapy with tumor cells and VCN. Chessboard vaccination was tolerated without any side effects. Tumor enhancement was not observed. The mechanism underlying the therapeutic effect of chessboard vaccination is unknown. However, the experiments in combination with cyclophosphamid may indicate that by chessboard vaccination suppressor cells may be less stimulated.