Rt. Davey et al., PLASMA VIREMIA AS A SENSITIVE INDICATOR OF THE ANTIRETROVIRAL ACTIVITY OF L-697,661, Proceedings of the National Academy of Sciences of the United Statesof America, 90(12), 1993, pp. 5608-5612
L-697,661 is a non-nucleoside analogue with potent, selective inhibito
ry activity against the reverse transcriptase of human immunodeficienc
y virus type 1 (HIV-1). The present study evaluated the potential role
of this compound in the treatment of HIV-1-infected patients in a dou
ble-blinded, placebo- and zidovudine-controlled trial using plasma vir
emia as a marker of antiviral activity and real-time phenotypic evalua
tion of viral isolates for the emergence of resistance. Participants r
eceived 12 weeks of either placebo, 25 mg twice a day, 100 mg three ti
mes a day, or 500 mg twice a day of L-697,661, or zidovudine, 100 mg r
ive times a day. Mean logarithmic reciprocal titers of plasma virus in
patients taking either L-697,661 or zidovudine decreased by week 4 of
therapy; for L-697,661 recipients these changes were dose-dependent a
nd, at the highest dose tested, were comparable in magnitude to those
seen with zidovudine. Viral suppression induced by L-697,661 persisted
through 8 weeks of treatment but decreased by week 12. This rebound p
aralleled emergence of viral isolates showing resistance to L-697,661.
We conclude that although L-697,661 has potent antiretroviral activit
y in vivo, its utility may be compromised by rapid emergence of L-697,
661-resistant virus. Plasma viremia is a highly sensitive technique af
fording considerable utility in the early testing of such agents.