Sequence dependence of administration of human recombinant tumor necrosis factor and interleukin-2 in murine tumor therapy.

Simultaneous administration of recombinant human tumor necrosis factor (rhTNF) and interleukin-2 (rhIL-2) has been shown to block tumor take in murine models. We investigated the effects of sequence and schedule of administration as a function of tumor burden with two tumor models (B16 and Meth A). rhTNF followed by rhIL-2 had extraordinary antitumor efficacy, but rhIL-2 followed by rhTNF was much less effective. Sequential rhTNF/rhIL-2 therapy resulted in complete tumor regression, whereas simultaneous therapy resulted in complete tumor regression, whereas simultaneous therapy resulted in only reduced growth rate. Experiments with genetically immunodeficient mice suggested that T cell factors may be required for synergistic antitumor activity.