Weekly oral etoposide in patients with Kaposi's sarcoma associated with human immunodeficiency virus infection: a phase I multicenter trial of the AIDS Clinical Trials Group.

We conducted a Phase I trial to evaluate the safety, maximally tolerated dose (MTD), antitumor activity, and pharmacology of once-weekly oral etoposide in patients with Kaposi's sarcoma (KS) and AIDS. From September 1990 to October 1991, 27 eligible patients with biopsy-confirmed KS were treated at six etoposide dose levels, ranging from 150 to 400 mg weekly. Patients were treated until their tumor progressed or until unacceptable toxicity developed. On the first day of therapy, etoposide plasma concentrations were measured by high-performance liquid chromatography. The MTD was defined as the etoposide dose that induced reversible grade 3 toxicity in three of six patients during the first 4 weeks. Although dose-limiting toxicity was uncommon during the first 4 weeks of treatment (three of 27 patients), and the MTD was not reached, with longer treatment > 50% of patients developed dose-limiting toxicities, most commonly neutropenia. Responses were observed at all dosage levels (except 350 mg weekly), with partial tumor regression documented in nine (36%) of 25 evaluable patients. There was marked variability in etoposide area under the plasma concentration versus time curve, elimination half-time (t1/2), and urinary excretion. These pharmacokinetic features were not, however, associated with the presence of gastrointestinal symptoms, the severity of side effects, or tumor response. We conclude that weekly oral etoposide can be safely administered to patients with AIDS and KS. The observed antitumor effects over a wide range of doses support further studies with very low and minimally toxic etoposide doses, alone or in combination with other agents.