Treatment of Kaposi's sarcoma with interferon alfa-2b (Intron A).

The activity of the alpha interferons against AIDS-related Kaposi's sarcoma (KS) has been demonstrated in numerous clinical trials. Unfortunately, most reports have involved small patient cohorts and a variety of dosages and schedules of administration. We report here a series of Phase II trials with interferon alfa-2b (Intron A, Schering Corp., Kenilworth, NJ) involving 114 patients using three dose regimens. Patients received 50 X 10(6) IU/m2 intravenously (high dose), 30 X 10(6) IU/m2 subcutaneously (intermediate dose), or 1 X 10(6) IU/m2 subcutaneously (low dose). Clinical responses were seen in all regimens and, overall, 35% of the patients obtained complete or partial remissions. The response rates in the low-, intermediate-, and high-dose groups were 33%, 28%, and 45%, respectively. In addition, high-dose therapy was associated with more rapid time to response. Patients with low-stage (I or II) disease and those who lack B symptoms were more likely to respond to therapy; i.e., response rates for patients without B symptoms were 38%, 44%, and 60% in the low-, intermediate-, and high-dose groups, respectively. Seventy (61%) patients had died at the time of data collection, with a median survival of 15 months. Disease stage and the presence of B symptoms significantly affected mortality. Responders enjoyed significantly longer survival (P less than 0.10) than did nonresponders both overall and when adjusted for disease stage. Interferon alfa-2b was generally well tolerated, although almost all patients experienced flu-like symptoms. No life-threatening toxicities occurred and only six (6%) patients discontinued treatment due to adverse reactions. No significant improvement in immunologic parameters was detected during this study. These studies suggest that, in this disease setting, interferon alfa-2b may be acting through direct antiproliferative effects rather than as an immunomodulator, and higher doses appear to be more effective than very low doses.