Immunoprophylaxis of a murine bladder cancer with high dose BCG immunizations

The immunoprophylactic effect of Mycobacterium bovis, strain Bacillus Calmette-Guerin (BCG) was studied in a syngeneic bladder tumor system. Injection of a high dose of viable BCG 10 days before tumor cell challenge induced a 46 per cent reduction in tumor take. On the other hand, no protection against tumor take was afforded by the simultaneous administration of BCG and tumor cells. Complete tumor regression, however, was observed in a number of animals of the 2 groups receiving BCG: 90 per cent in the group receiving the vaccine and the tumor simultaneously and 50 per cent in those being immunized 10 days before tumor challenge. These findings indicate that high dose, viable BCG immunization favorably alters the course of this experimental tumor.