Hyperthermic potentiation of doxorubicin and 4'-epi-doxorubicin in a transplantable neurogenic rat tumor (BT4A) in BD IX rats

The combined effect of hyperthermia and doxorubicin on the neurogenic rat cell line BT4C was found to be synergistic in vitro. The present investigation was initiated to study if this synergistic effect also could be obtained in vivo. An enhanced effect occurred when doxorubicin and 4'-epi-doxorubicin 7 mg/kg body weight were given 30 minutes prior to local water bath hyperthermia (one hour at 44.0 degrees C). The local side effects of the combined treatment did not increase above that of hyperthermia alone. Therefore, local hyperthermia may become a useful modality for enhancement of the effect of anthracyclines on tumors with marginal drug sensitivity or bulky tumors with poor drug penetration.