A Novel Bis-Tetrahydrofuranylurethane-Containing Nonpeptidic Protease Inhibitor (PI), GRL-98065, Is Potent against Multiple-PI-Resistant Human Immunodeficiency Virus In Vitro

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Abstract
We designed, synthesized, and identified GRL-98065, a novel nonpeptidic human immunodeficiency virus type 1 (HIV-1) protease inhibitor (PI) containing the structure-based designed privileged cyclic ether-derived nonpeptide P2 ligand, 3(R),3a(S),6a(R)-bis-tetrahydrofuranylurethane (bis-THF), and a sulfonamide isostere, which is highly potent against laboratory HIV-1 strains and primary clinical isolates (50% effective concentration [EC50], 0.0002 to 0.0005 μM) with minimal cytotoxicity (50% cytotoxicity, 35.7 μM in CD4+ MT-2 cells). GRL-98065 blocked the infectivity and replication of each of the HIV-1NL4-3 variants exposed to and selected by up to a 5 μM concentration of saquinavir, indinavir, nelfinavir, or ritonavir and a 1 μM concentration of lopinavir or atazanavir (EC50, 0.0015 to 0.0075 μM), although it was less active against HIV-1NL4-3 selected by amprenavir (EC50, 0.032 μM). GRL-98065 was also potent against multiple-PI-resistant clinical HIV-1 variants isolated from patients who had no response to existing antiviral regimens after having received a variety of antiviral agents, HIV-1 isolates of various subtypes, and HIV-2 isolates examined. Structural analyses revealed that the close contact of GRL-98065 with the main chain of the protease active-site amino acids (Asp29 and Asp30) is important for its potency and wide-spectrum activity against multiple-PI-resistant HIV-1 variants. The present data demonstrate that the privileged nonpeptide P2 ligand, bis-THF, is critical for the binding of GRL-98065 to the HIV protease substrate binding site and that this scaffold can confer highly potent antiviral activity against a wide spectrum of HIV isolates.