Effects of acetylic salicylic acid and pentoxifylline on the efficacy of intravesical BCG therapy in orthotopic murine bladder cancer (MB49).

OBJECTIVE

Intravesical immunotherapy with bacillus Calmette-Guerin (BCG), which has become the gold standard in the adjuvant treatment of superficial bladder cancer, is hampered by local side effects. Anti-inflammatory drugs may be helpful, but as an undesired side effect, therapeutic efficacy of BCG might be impaired. Therefore, we investigated the effects of anti-inflammatory drugs on the efficacy of intravesical BCG in an animal model.

METHODS

Syngenic tumor cells were implanted into the bladders of 75 mice according to our modification of the method. Mice were randomized to 5 groups with 15 animals each and treated with phosphate buffered saline (PBS), group 1; BCG, group 2; BCG + acetylic salicylic acid (ASA), group 3; BCG + pentoxifylline (POF), group 4; autoclaved BCG (aBCG), group 5. Intravesical instillation of 1.35 mg. BCG was initiated one day after tumor inoculation and repeated in weekly intervals for 4 instillations altogether. ASA and POF in doses of 200 mg./kg. and 150 mg./kg., respectively, were given continuously with the drinking water starting at the first instillation. Autoclaved BCG served as control for the importance of viability and was given at the same dose as viable BCG. Mice were monitored for survival, gross hematuria and body weight and after 28 days evaluated for bladder weight and tumor occurrence.

RESULTS

Autoclaved BCG and PBS had no effect on tumor growth, whereas animals treated with viable BCG alone and in combination with POF and ASA, respectively, showed a significant reduction in bladder weight: PBS, 248 mg.; BCG, 140 mg. (p = 0.0009); BCG + ASA, 123 mg. (p = 0.0001); BCG + POF, 145 mg. (p = 0.0004); autoclaved BCG, 283 mg. (p = 0.21). Mice treated with BCG, BCG + ASA and BCG + POF showed a significantly higher proportion of survival until day 28 as compared to PBS alone. Autoclaved BCG had no therapeutic efficacy (Kaplan-Meier method/log rank test: BCG, p = 0.0053; BCG + ASA, p = 0.0044; BCG + POF, p = 0.0027; aBCG, p = 0.33). No significant differences among the 3 groups treated with viable BCG, with or without anti-inflammatory drugs, regarding bladder weight and survival were detectable.

CONCLUSIONS

The efficacy of BCG therapy in murine orthotopic bladder cancer is dependent on BCG viability and is not compromised by ASA or POF. Clinical trials to evaluate the efficacy of routine ASA or POF to reduce BCG side effects in patients, using self-assessment criteria, should be initiated.