[Modulation of the antitumor effect of cyclophosphamide by the recombinant probiotic Subalin]

A new preparation "subalin" developed on the basis of a recombinant saprophyte strain of Bacillus subtilis 2135/105 producing human interferon alpha-2 has been tested for its ability of increasing the effectiveness of antitumor therapy. The study used Lewis lung carcinoma bearing mice C57B1/6 treated with injections of 60 mg/kg body cyclophosphamide, intraperitoneally, on days 3 and 7 of tumor growth. Subalin was administered per as on days 1-14 after tumor transplantation. Combined treatment with cyclophosphamide and subalin resulted in a significantly higher inhibition of primary tumor growth and metastatic spreading as compared with control receiving cyclophosphamide alone. Also, there were fewer animals with metastasis; the average number of these lesions per animal and the total affected area were less. Subalin proved to exert a moderate antitumor and antimetastatic effect. The cytostatic activity of peritoneal macrophages was higher in mice treated with subalin. It is suggested that the chemo-sensitizing and antitumor effects of subalin are due to its ability to induce endogenous interferon production.