Effects of chemoimmunotherapy with and without surgery in murine MBT-2 bladder tumor

Using C3H/He JCr mice bearing the syngeneic MBT-2 bladder tumor, it was found that cyclophosphamide (CYC 100 mg/kg i.p.) treatment, 1 day before and 2 weeks after surgery, followed by postoperative autologous tumor vaccine immunization can be an effective adjuvant anticancer therapy. The short-term exogeneous addition of low dose IL-2 administration to the protocol provided no further benefit. Suppression of tumor growth was observed in a classical Winn assay when splenocytes were obtained on day 23 from mice receiving this effective adjuvant therapy with surgery on day 8. Splenocytes from tumor-bearing mice (TBM) treated with CYC were augmented in terms of their proliferative response to concanavalin A during the first 2 weeks after CYC treatment. Studies using 3-day TBM established that significant suppression of tumor growth and prolonged survivals were dependent upon CYC treatment being combined with tumor vaccine and/or interleukin-2; single agent treatments were ineffective.