ABSTRACT
We generated a novel nonpeptidic protease inhibitor (PI), GRL-02031, by incorporating a stereochemically defined fused cyclopentanyltetrahydrofuran (Cp-THF) which exerted potent activity against a wide spectrum of human immunodeficiency virus type 1 (HIV-1) isolates, including multidrug-resistant HIV-1 variants. GRL-02031 was highly potent against laboratory HIV-1 strains and primary clinical isolates, including subtypes A, B, C, and E (50% effective concentration [EC50] range, 0.015 to 0.038 μM), with minimal cytotoxicity (50% cytotoxic concentration, >100 μM in CD4+ MT-2 cells), although it was less active against two HIV-2 strains (HIV-2EHO and HIV-2ROD) (EC50, ∼0.60 μM) than against HIV-1 strains. GRL-02031 at relatively low concentrations blocked the infection and replication of each of the HIV-1NL4-3 variants exposed to and selected by up to 5 μM of saquinavir, amprenavir, indinavir, nelfinavir, or ritonavir and 1 μM of lopinavir or atazanavir (EC50 range, 0.036 to 0.14 μM). GRL-02031 was also potent against multi-PI-resistant clinical HIV-1 variants isolated from patients who had no response to the conventional antiretroviral regimens that then existed, with EC50s ranging from 0.014 to 0.042 μM (changes in the EC50s were less than twofold the EC50 for wild-type HIV-1). Upon selection of HIV-1NL4-3 in the presence of GRL-02031, mutants carrying L10F, L33F, M46I, I47V, Q58E, V82I, I84V, and I85V in the protease-encoding region and G62R (within p17), L363M (p24-p2 cleavage site), R409K (within p7), and I437T (p7-p1 cleavage site) in the gag-encoding region emerged. GRL-02031 was potent against a variety of HIV-1NL4-3-based molecular infectious clones containing a single primary mutation reported previously or a combination of such mutations, although it was slightly less active against HIV-1 variants containing consecutive amino acid substitutions: M46I and I47V or I84V and I85V. Structural modeling analysis demonstrated a distinct bimodal binding of GRL-02031 to protease, which may provide advantages to GRL-02031 in blocking the replication of a wide spectrum of HIV-1 variants resistant to PIs and in delaying the development of resistance of HIV-1 to GRL-02031. The present data warrant the further development of GRL-02031 as a potential therapeutic agent for the treatment of infections with primary and multidrug-resistant HIV-1 variants.
Activity against Human Immunodeficiency Virus Type 1, Intracellular Metabolism, and Effects on Human DNA Polymerases of 4′-Ethynyl-2-Fluoro-2′-Deoxyadenosine
