[Effects of IgG-Fc-mitomycin C conjugate on cancer cells]

The binding of IgF Fc was studied in cultured tumor cells and antitumor effects of Fc-mitomycin C conjugate (Fc-MMC) on cultured tumor cells and tumor bearing mice were examined. 125I-labeled Fc bound to tumor cells Colon26, HLE, MKN28 and MKN74, and its binding was inhibited by the addition of non-labeled Fc. The binding increased in the course of exposure time up to 60 minutes and reached a value of more than 90% within 30 minutes. The cytotoxicity to the cultured tumor cells were not different in the 60 minutes incubation, but in the 30 minutes incubation, Fc-MMC showed more than two times as strong cytotoxicity as MMC (p<0.005). 2.5 mg/kg of MMC and 2.5 mg/kg of Fc-MMC equivalent to free MMC concentration were administered to Colon26 bearing BALB/c mice. The tumor growth in Fc-MMC-administered mice was lower than that in MMC-administered mice. 1.25 mg/kg and 2.5 mg/kg of agents were given to P-388 bearing mice, and the survival time in 1.25 mg/kg of Fc-MMC-administered mice was significantly longer than that in MMC-administered mice (p < 0.005). The body weight was reduced in MMC 2.5 mg/kg administered mice, but these reduction was not observed in Fc-MMC group. These observation suggest that Fc-MMC may be a promising anticancer agent on clinical applications.