Karaman O.M., Fedosova N.I., Chumak A.V., Cheremshenko N.L., Koval E.V., Todor I.N., Symchych T.V., Voyeykova І.М., Kruts’ O.O., Didenko G.V.

Aim: to investigate anti-tumor efficacy of extracellular B. subtilis IMV B-7724 lectin alone or in combination with cisplatin in rats bearing cisplatin-sensitive or cisplatin-resistant Guérin’s carcinoma. Object and methods: in the experiments, Wistar rats were used. Cisplatin-sensitive (CIS) and -resistant strains of Guérin’s carcinoma (GC) were used as models of tumor growth. The treatment of the tumor-bearing animals began on day 7 of tumor growth and included immunotherapy or a combination of immunotherapy with subsequent (on day 14 of tumor growth) chemotherapy. The lectin of B. subtilis IMV B-7724 was applied as means of immunotherapy; cisplatin was used in the schemes including chemotherapy. The antitumor effect of the applied therapeutic schemes was evaluated according to standard parameters of tumor growth: tumor volume, survival rate, tumor growth inhibition (TGI), tumor volume doubling time (TVDT), frequency of animals with tumor regression (FTR). The statistical analysis of the results was conducted according to the generally accepted methods of variation statistics. The survival rate of the animals was estimated by the Kaplan — Meier method. The difference was considered as significant at p < 0.05. Results: regardless of the sensitivity of the tumor strain to cisplatin, immunotherapy had a pronounced antitumor effect. It is worth mentioning that in the rats bearing cisplatin-sensitive GC, the most notable antitumor efficacy was registered in the group which underwent the combined treatment (immunotherapy followed by chemotherapy): TGI = 99.9%; TVDT21-29; 29-36 = -0.91; -3.57; FTR36 ≥55.6%. On the contrary, in the rats bearing cisplatin-resistant GC the most significant results were in the group receiving immunotherapy only: TGI = 100.0%; TVDT21-29; 29-36 = 0; 0; FTR36 ≥66.7%. Conclusions: applied as a means of immunotherapy to rats bearing cisplatin-resistant experimental tumor, B. subtilis IMV B-7724 lectin demonstrated a pronounced antitumor effect. In the case of cisplatin-sensitive experimental tumor, it is preferable to combine immunotherapy with cisplatin.

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