Effect of isonicotinic acid hydrazide on the intratumor injection of BCG.

Rats with established subcutaneous tumors were treated by repeated intratumor injections of BCG over a 5-week period. Isonicotinic acid hydrazide (INH) was given to some rats to determine if this drug decreased the effect of BCG on local tumor growth. INH alone had no effect on either survival or tumor volume. Rats treated with either BCG or BCG and INH had prolonged survivals and smaller tumor volumes than did controls rats. In these experiments, INH did not decrease the effect of BCG on local tumor growth. However, the intratumor injection of BCG in rats receiving INH systematically was associated with better survival and smaller tumor volumes compared to the intratumor injection of BCG alone.