2′,3′-Didehydro-3′-deoxythymidine (d4T) in Patients with AIDS or AIDS-Related Complex: A Phase I Trial

2′,3′-didehydro-3′-deoxythymidine (d4T) is a pyrimidine analogue and inhibitor of reverse transcriptase with potent in vitro activity against human immunodeficiency virus (HIV). A phase I trial of d4T was conducted in 41 HIV-infected patients, 12 with AIDS and 29 with AIDS-related complex (ARC). Thirty-six patients were evaluatable. The maximum tolerated dose was 2 mg/kg/day. The dose-limiting toxicity was sensory peripheral neuropathy, which occurred in 20 patients (55%). Four patients (11%) developed hepatotoxicity. Five (14%) developed anemia requiring a transfusion but not discontinuation of drug. The mean ± SE plasma elimination half-life at all dose levelswas 1.2 ± 0.09 h. Increased or stable absolute CD4 counts were seen in most patients. The majority of patients with detectable serum p24 antigen levelshad a persistent decrease by 6 months. d4T is a promising drug for patients with AIDS or ARC. This clinical trial is continuing to determine the minimal effective dose.