ADDITION OF INTERLEUKIN-12 TO LOW-DOSE INTERLEUKIN-2 TREATMENT IMPROVES ANTITUMOR EFFICACY IN-VIVO

Interleukin 12 (IL-12) enhances lysis mediated by NK- and lymphokine activated killer (LAK) cells. It also causes proliferation of IL-2 stimulated T and NK cells in vitro. For these IL-2 complementing properties murine pulmonary metastases of a coloncarcinoma line were treated with IL-12 and IL-2 or with the individual agents. Results were compared to sham treated controls. IL-2 alone mediated significant tumor reduction but provoked pulmonary edema and concomittand toxicity, graded in three steps. IL-12 combined with an IL-2 dose reduced by 81% still resulted in significant antitumoral activity. Toxicity, however, was not discernable from sham treated controls. IL-12 thus appears as an attractive cytokine for combination with IL-2 in antitumor therapy. Particularly treatment of tumors, like gastrointestinal tract cancers, so far mainly resistant to cell mediated antitumor therapy, might profit from this approach.