16th International HIV Drug Resistance Workshop 12-16 June 2007, Barbados

IN VITRO SELECTION AND CHARACTERIZATION OF VIRUSES RESISTANT TO R1206, A NOVEL NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITOR

Antivir Ther. 2007; 12:S35 (abstract no. 33)

G Su ¹, Y Li¹, A Paul², J Hang¹, S Harris¹, H Hogg¹, J Dunn¹, N Cammack¹, K Klumpp¹ and G Heilek^1
1Roche Palo Alto LLC, Palo Alto, CA, USA; ²Gilead Sciences, Inc., Foster City, CA, USA

BACKGROUND: R1206 is a prodrug of RO-0335 and represents a new class of potent diphenylether nonnucleoside reverse transcriptase inhibitors. RO-0335 is broadly active against NNRTI resistant HIV-1 variants. A sequential passaging experiment was performed to identify mutations selected by RO-0335 in vitro.

METHODS: Passaging was carried out with HIV-1 HXB2 at low MOI in MT-4 cells with increasing concentrations of RO-0335. Breakthrough viruses were characterized by pool genotypic and phenotypic analysis. Clonal sequencing was performed on the virus obtained at the highest drug concentration. The contribution of individual mutations were determined by the characterization of site directed mutant viruses and recombinant HIV-RT enzymes using RO-0335 and reference compounds efavirenz and TMC-125.

RESULTS: RO-0335 inhibited HIV-1 HXB2 replication in MT-4 cells with an IC₅₀ value of 1.3 nM. In a sequential passaging experiment, the concentration of RO-0335 was increased from 1 nM to 10 µM within 13 passaging steps. Pool sequencing of breakthrough viruses identified the selection of F227C at passage 4 and V106A, F227C and M230L at passage 12. Clonal analysis of viruses selected under 10 µM of drug pressure of RO-0335 identified the triple mutation of V106A/F227C/M230L. The combination of these site directed mutations was associated with resistance to RO-0335 when determined with isolated recombinant HIV-RT enzymes or engineered viruses. Importantly, the pathway to resistance selection with RO- 0335 was different as compared to that of TMC-125 and efavirenz, consistent with differences in binding interactions to HIV-RT.

CONCLUSIONS: RO-0335 represents a series of novel NNRTIs with high antiviral potency against wild-type and NNRTI-resistant HIV-1. Passaging of wild-type HIV-1 in MT-4 cells under increasing drug pressure of RO-0335 identified the triple mutation V106A/F227C/M230L conferring resistance to RO-0335, whereas the individual mutations were not sufficient to confer significant levels of resistance.

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2007-06-12
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