Exacerbation of epidemic Kaposi's sarcoma with a combination of interleukin-2 and beta-interferon: results of a phase 2 study.

Epidemic Kaposi's sarcoma (EKS) is the most common neoplastic manifestation of acquired immune deficiency syndrome (AIDS). The underlying immune deficiency can be partially reversed in vitro with interleukin-2 (IL-2). The type 1 interferons (IFN), alpha and beta, inhibit the growth of the etiologic agent of AIDS, the human immunodeficiency virus, have antitumor activity against Kaposi's sarcoma, and are synergistic with IL-2 in stimulating natural killer cell activity. Four patients with EKS were treated three times weekly with simultaneous intravenous injections of recombinant IL-2 (5 X 10(6) Cetus units/m2) and recombinant IFN-beta (6 X 10(6) units/m2). All patients had generalized disease, were without systemic symptoms, had no prior opportunistic infection, and had stable disease at the initiation of therapy. No patient had an objective response. Three patients exhibited rapid disease progression within 2-4 weeks of starting treatment, necessitating discontinuation of therapy and early closure of the study. This adverse result may have resulted from the significant levels of gamma-interferon (IFN-gamma) that can be generated with this dose and schedule of IL-2. Investigators using IL-2 should monitor IFN-gamma levels and avoid intermediate to high-dose bolus IL-2 therapy in patients with EKS.