Background: Effective HIV protease inhibitors must combine potency towards wild-type and mutant variants of HIV with oral bioavailability such that drug levels in relevant tissues continuously exceed that required for inhibition of virus replication. Computer-aided design led to the discovery of cyclic urea inhibitors of the HIV protease. We set out to improve the physical properties and oral bioavailability of these compounds. Results: We have synthesized DMP 450 (his-methanesulfonic acid salt), a water-soluble cyclic urea compound and a potent inhibitor of HIV replication in cell culture that also inhibits variants of HIV with single amino acid substitutions in the protease. DMP 450 is highly selective for HIV protease, consistent with displacement of the retrovirus-specific structural water molecule. Single doses of IO mg kg-t DMP 450 result in plasma levels in man in excess of that required to inhibit wild-type and several mutant HIVs. A plasmid-based, in viva assay model suggests that maintenance of plasma levels of DMP 450 near the antiviral IC,, suppresses HIV protease activity in the animal. We did identify mutants that are resistant to DMP 450, however; multiple mutations within the protease gene caused a significant reduction in the antiviral response. Conclusions: DMP 450 is a significant advance within the cyclic urea class of HIV protease inhibitors due to its exceptional oral bioavailability. The data presented here suggest that an optimal cyclic urea will provide clinical benefit in treating AIDS if it combines favorable pharmacokinetics with potent activity against not only single mutants of HIV, but also multiply-mutant variants.

Protease inhibitors are another class of compounds for treatment of human immunodeficiency virus (E1IV)-caused diease. The emergence of resitance to the current antl-HIV drugs makes the determination of potential resistance to protease inhibitors imperative. Here we describe the isolation of an HIV type 1 (HIV-1) resistant to an IHV-protease inhibitor.Serial passage of HIV-1 (strain RF) in the presence of the inhibitor, [2-pyridylacetylisoleucylphenylalanyl-4(CHOH)J2 (P9941), failed to yield a stock of virus with a r t phenotype. However, variants of the virus with 6-to 8-fold reduced sensitivity to P9941 were selcted by using a combination ofplaque assay and endpoint titration. Genetic analysis and computer modeing of the variant proteases revealed a single change in the codon for amino acid 82 (Val -) Ala), which resulted in a protease with lower affinity and reduced sensitivity to this inhibitor and certain, but not all, related inhibitors.

No abstract