Synergism of tumor necrosis factor-alpha and melphalan in systemic and regional administration: animal study

Tumor necrosis factor (TNF) is a highly cytotoxic cytokine. However, due to its severe side effects, the only clinical situation allowing its administration in humans is isolated limb perfusion (ILP). Early studies have shown that TNF alone is of limited efficacy even at high doses via ILP, and that a chemotherapeutic agent needs to be added. The most commonly used drug in this setting is melphalan which is considered to be synergistic with TNF. However, since melphalan has not been commonly used in sarcoma, we believed that confirmation of its synergistic effect with TNF in an experimental sarcoma model could prove valuable for future drug choice. B16F10 melanoma and CT26 colon carcinoma cells were injected subcutaneously (s.c.) into mice, while GF fibrosarcoma cells were injected s.c. into the hindleg of Wistar rats. The animals were then divided into four treatment groups: TNF alone, melphalan alone, TNF and melphalan, and 0.9% NaCl controls. Mice were treated with intraperitoneal injections and rats by ILP. TNF dosage was 20 microgram for mice and 200 microgram for rats. Melphalan was given at 5-10 mg/kg for both mice and rats. Results showed synergism of TNF and melphalan in both modes of therapy. In the systemic administration groups (mice carrying B16F10 and CT26 tumors), tumors increased in size in all but the combined TNF-melphalan group. In the regional delivery groups (rats carrying GF sarcoma cells treated via ILP), there was a 16% decrease in tumor volume in rats treated with TNF alone, a 29% decrease in rats treated with melphalan, and a 75% decrease in the combined TNF-melphalan group. In conclusion, TNF and melphalan proved to be highly synergistic in both systemic and regional delivery. This fact makes melphalan an adequate choice for TNF perfusion in advanced limb malignancies.