Synergistic effects of hyperthermia and intratumorous injection of anti-cancer drugs.

In an attempt to improve the combined effects of hyperthermia and anti-cancer drugs, an intratumorous (i.t.) injection of the drugs was performed and its effect compared with that obtained by intraperitoneal (i.p.) injection. Using Lewis lung carcinoma growing in the legs of BDF1 mice, weakly toxic drug derivatives, Aclarubicin (ACR), a new platinum complex (DWA2114R), or Peplomycin (PEP) were injected either into the center of the tumors, or intraperitoneally, before or after usual hyperthemia in a 43.5-43.7 degrees C water bath for 45 min. The effects on tumor growth delay and the number of lung metastases were assessed, and the enhancement ratios (ERs) due to the combination were calculated. Tumor growth inhibition by i.t. injection was enhanced additively with ACR (ER; 1.2) and synergistically with DWA2114R (ER; 3.49) and PEP (ER; 2.4) plus hyperthermia. Hyperthermia after i.t. injections of DWA2114R (ER; 3.4) was more effective than either i.t. or i.p. injections after hyperthermia (ER; 2.4). Lung metastases were also inhibited significantly by the combination of hyperthermia and drugs, except when emulsified PEP was injected three times. It was concluded that the i.t. injection of DWA2114R was of value when used in combination with hyperthermia.