Lack of effects of recombinant human interleukin-4 on in vitro colony formation of freshly explanted human tumor cells.

Interleukin-4 is a highly pleiotropic T-cell derived lymphokine that has been reported to stimulate a host cell-mediated antitumor response. Recombinant human interleukin-4 (rhuIL-4) is currently undergoing clinical phase I trials. We have studied the growth modulating effects of rhuIL-4 on a variety of freshly explanted human tumor specimens using an in vitro soft agar cloning system. Final concentrations of 0.1 to 10 ng/ml were used in continuous incubation experiments. Of 147 specimens, 73 (50%) were evaluable for the determination of tumor growth modulating activity. The most common tumor types recruited included breast, non-small cell lung, ovarian cancer and melanoma. Stimulation of tumor colony forming units (colony formation > or = 1.5 x controls) was observed in 0/73 tumors. Similarly, only 1/73 (1.3%) specimens (a non-small cell lung cancer) had a significant decrease in tumor colony forming units (colony formation < or = 0.5 x controls) at 1 ng/ml. We conclude that rhuIL-4 is not a direct modulator of tumor colony formation in vitro. However, antitumor effects could perhaps be achieved in vivo via the immune-modulating effects of Interleukin-4.