The selective anticancer agent pb-100 inhibits interleukin-6 induced enhancement of glioblastoma cell-proliferation in-vitro.

The multifunctional cytokine interleukin-6 behaves as a growth factor for various malignancies. It is produced in significant amounts by glioblastoma cells. When exogenous IL-6 is added (pg/ml) to culture medium of human glioblastoma cells and normal (non malignant) astrocytes used as controls, it exerts a dose dependent and differential effect on these two cell lines. Enhancement of cell proliferation is twice as high for glioblastoma cells as for astrocytes. In vitro, the novel anticancer agent PB-100 (mu g/ml) dose dependently inhibits this stimulatory activity. In addition, increasing PB-100 concentrations finally induce death of the malignant cells, yet do not impede multiplication of normal astrocytes. PB-100 does not abolish IL-6 production by cells, but keeps its level down to physiological values. PB-100 should therefore find its place in therapies requiring control of IL-6 production.