Treatment of AIDS has been directed toward the underlying retroviral infection as well as toward specific opportunistic infections and malignancies that are associated with the syndrome. The most extensively studied drugs are reverse transcriptase inhibitors such as AZT and other nucleoside analogs, including didanosine (ddI) and dideoxycytidine (ddC). The most extensive clinical experience has been achieved with AZT. These clinical trials indicated a decreased incidence of opportunistic infection and increased survival in patients with AIDS. However, AZT treatment is associated with dose-limiting toxicities. Additionally, identification of resistance to AZT has increased the need to test the effectiveness of AZT in combination with other drugs. CD4-IgG is capable of binding to HIV envelope protein (gp120) and inhibiting HIV infectivity in test tube studies. Potential therapeutic benefit in patients with HIV infection may be derived from CD4-IgG.

AMENDED: Previously, rCD4-IgG had been administered on a mcg/kg basis. Subjects now receive rCD4-IgG as a fixed dose. Changes to the maintenance schedule were made to accommodate the new dosages. Original design: This study is divided into two parts: A pharmacokinetic evaluation, and a safety evaluation. The pharmacokinetic evaluation is done in selected patients. For the safety evaluation patients will receive rCD4-IgG at a fixed dose level twice weekly by intravenous bolus injection (over 1 minute) for 12 weeks. Zidovudine (AZT) is administered orally 3 times daily at one of two dose levels. Eight subjects, at least 4 of whom with p24 levels greater than 75 pg/m, are entered at each dose level of CD4-IgG beginning with dose level 1. If 3 or more patients at a dose level experience grade 3 or 4 toxicity then no further patients will be added to that or higher dose levels. Pharmacokinetics of CD4-IgG alone and in combination with AZT is evaluated in patients at dose level 2 only. Patients receive one IV bolus of CD4-IgG on day 1 and samples are drawn beginning 15-30 minutes prior to the CD4-IgG injection. There is an 8 day washout period. Beginning on day 9 and continuing through day 24, patients receive AZT daily. CD4-IgG is administered by IV bolus on day 16. Samples are drawn beginning 15-30 minutes prior to the injection of CD4-IgG. The pharmacokinetic evaluation terminates 8 days after the second CD4-IgG injection (day 24). Extended treatment will be made available to patients at the discretion of the Principal Investigator.