Open-label phase I study of combination therapy with zidovudine and interferon-beta in patients with AIDS-related...

The aim of this study was to identify a safe and tolerable dose of recombinant interferon-beta (IFN-beta) used in conjunction with a fixed dose of zidovudine in patients with early-stage, good-prognosis AIDS-related Kaposi's sarcoma. We conducted a phase I, dose-escalation controlled trial of 22.5, 45 of 90 million units of IFN-beta given by daily subcutaneous injection with 500 mg per day of oral zidovudine. At the time of this study, this was standard of care for HIV infection. Patients were sequentially enrolled at three medical centers. Tumor response, drug tolerance, antiviral studies and CD4 changes were assessed. Four patients were enrolled at each dose level, and escalation proceeded when at least four patients had tolerated two weeks of therapy without dose-limiting toxicity. ACTG Kaposi's sarcoma tumor response criteria were used to assess response. Fifteen patients were enrolled. The combination of IFN-beta and zidovudine was well tolerated, and the dose-limiting toxicities were local skin necrosis and systemic symptoms. Despite generally good prognostic characteristics, only two patients achieved a clinical complete response and three addition patients had stable disease for a prolonged period of time (range 24-44 weeks). There was no correlation between baseline CD4 cell counts and tumor response, nor between the antiviral effect of IFN-beta as measured by decreases in immune-complex dissociated p24 antigen and tumor response. Higher doses of IFN-beta did not result in more tumor responses or in greater antiviral activity. The maximum tolerated dose of IFN-beta in combination with 500 mg per day of zidovudine was 45 million units by subcutaneous injection per day. IFN-beta is well tolerated in patients with AIDS-related Kaposi's sarcoma when used in conjunction with zidovudine. However, the antitumor response rate in good-prognosis patients is low. Further studies of this agent should be in the context of four-drug antiretroviral regimens where viral suppression is greatest and any antitumor activity of IFN-beta may be observed.