2′-Fluoro-2′,3′-Dideoxyarabinosyladenine (F-ddA): Activity against Drug-Resistant Human Immunodeficiency Virus Strains and Clades A-E

2′-Fluoro-2′,3′-dideoxyarabinosyladenine (F-ddA), an anti-human immunodeficiency virus (HIV) drug currently in clinical trial, was compared with zidovudine (AZT), ddl and ddC for anti-HIV activity and potency in HIV-1 strains both sensitive and resistant to zidovudine, ddl and non-nucleoside reverse transcriptase inhibitors. A variety of host cell systems [MT-2, MT-4, phytohaemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC)] was used. F-ddA was effective against each of the drug-resistant isolates, including the strain resistant to ddl, the other purine dideoxynucleoside evaluated in this study. The anti-HIV-1 activities of F-ddA and zidovudine were also determined against clades A-E in PHA-PBMCs. Although activities were similar, zidovudine was significantly more potent than F-ddA in the PHA-PBMC system.