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New PI GRL-02031, Potent Against Resistant HIV in vitro
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"Determination of Resistance Profile of GRL-02031, a Novel Nonpeptidic Protease Inhibitor Containing a Cyclopentanyltetrahydrofuran Moiety"
Reported by Jules Levin
13th CROI, Feb 5-8, 2006, Denver
Yasuhiro Koh*1, H Nakata1, H Ogata-Aoki1, M Nakayama1, S Leschenko2, A Ghosh2, and H Mitsuya1,3
1Kumamoto Univ Sch of Med, Japan; 2Purdue Univ, West Lafayette, IN, US; and 3NCI, NIH, DHHS, Bethesda, MD, US
This research group has recently generated a novel nonpeptidic protease inhibitor (PI), GRL-02031, by incorporating a stereochemically defined fused cyclopentanyltetrahydrofuran (Cp-THF), which exerts potent activity against a wide spectrum of HIV-1 isolates including multi-drug-resistant HIV-1 variants (HIVMDR). The resaerchers attempted to select GRL-02031-resistant variants by propagating a laboratory X4 HIV-1 strain (HIV-1NL4-3) in MT-4 cells in the presence of increasing concentrations of GRL-02031 and determined the activity profile of GRL-02031 against a variety of HIV-1NL4-3-based molecular infectious HIV-1 clones.
PI-resistant variants were selected in vitro by propagating HIV-1NL4-3 in the presence of increasing concentrations of various PI using MT-4 cells. Anti-HIV-1 activity of various PI against a variety of molecular HIV-1 clones was determined by exploiting the p24 assay using MT-4 cells.
RESULTS
Upon the selection of GRL-02031-resistant HIV-1 in the presence of as much as 5 _M of GRL-02031, mutations including L10F, L33F, M46I, I47V, Q58E, V82I, I84V, and I85V in the protease-encoding region and G62R (p17), L363M (p24/p2 cleavage site), R409K (p7), and I437T (p7/p1 cleavage site) in the gag-encoding region emerged.
No significant changes in IC50 values of GRL-02031 were observed in infectious HIV-1 clones containing one of such amino acid substitutions. A moderate but significant reduction in drug susceptibility (~3-fold difference in IC50 values) was seen when the virus acquired 2 mutations (M46I/I47V or I84V/I85V).
Further increase in IC50 values was seen when 4 (L10F/I47V/V82I/I85V) or 5 (L10F/M46I/I47V/V82I/I85V) substitutions were introduced. We also generated molecular clones containing a primary mutation such as D30N, G48V, I50V, and L90M, and determined IC50 values of GRL-02031.
GRL-02031 was potent against all such molecular clones with IC50 value differences by 0.7- to 1.7-fold in comparison with the IC50 value against HIV-1NL4-3, although HIV-1D30N and HIV-1G48V showed substantial resistance to nelfinavir (5.6-fold) and saquinavir (5.1-fold), respectively.
The authors concluded that the present data suggest that HIV-1 develops substantial resistance to GRL-02031 only when it acquires >4 mutations in its protease, a unique property considering the propensity of PI to permit HIV-1 to develop high degrees of drug resistance with 1 or a few amino acid substitutions.
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