Cytotoxic interactions of tumor necrosis factor, melphalan and 41.8 °C hyperthermia

Experience with limb perfusion-hyperthermia, TNF, and l-PAM suggests dramatic clinical responses in sarcoma and malignant melanoma. To extrapolate these results to clinical 41.8 °C whole-body hyperthermia (WBH) and systemic therapy, we studied the cytotoxic interactions of TNF, l-PAM and hyperthermia in L929 cells. The optimal sequence was TNF preceding 41.8 °C hyperthermia by 48 h, and l-PAM given simultaneously with heat. Trimodality synergism between TNF, hyperthermia and l-PAM was demonstrated. Non-cytotoxic doses of TNF had a superadditive interaction with l-PAM/heat. Conversely, non-cytotoxic doses of l-PAM had super-additive interactions with TNF followed by hyperthermia. Relative to therapeutic index, we studied WBH, l-PAM and TNF in non-tumor bearing mice. The optimal trimodality sequence did not result in increased normal tissue toxicity compared to l-PAM alone. The concentrations and sequencing of TNF and l-PAM studied are consistent with clinical application to WBH.