Immunotherapy of murine bladder cancer by irradiated tumor vaccine

This investigation explored the efficacy of irradiated autologous mouse bladder tumor (Ir-MBT2) as an active specific immunotherapeutic agent and as adjuvant therapy with Bacillus Calmette-Guerin (BCG) against a subcutaneously transplanted murine bladder tumor. Tumor incidence was significantly reduced in groups receiving BCG (27%, p less than 0.005) or Ir-MBT2 with BCG (53%, p less than 0.025), compared to control (93%). Survival was significantly improved in groups treated with BCG (100%, p less than 0.005), 10(5) Ir-MBT2 with BCG (53%, p less than 0.01), or 10(7) Ir-MBT2 with BCG (47%, p less than 0.025) compared with control (13%). Surprisingly, Ir-MBT2 consistently reduced the efficacy of BCG alone. Ir-MBT2 alone (10(7)) appeared to enhance tumor growth. Autologous irradiated bladder tumor vaccine, alone or in combination with BCG, displayed no immunotherapeutic advantage. The use of irradiated tumor cell vaccine for bladder cancer therapy may reduce the results achievable with BCG alone.