TMC114, a novel human immunodeficiency virus type 1 protease inhibitor active against protease inhibitor-resistant viruses, including a broad range of clinical isolates

Abstract

The purpose of this study was to characterize the antiviral activity, cytotoxicity, and mechanism of action of TMC114, a novel human immunodeficiency virus type 1 (HIV-1) protease inhibitor (PI). TMC114 exhibited potent anti-HIV activity with a 50% effective concentration (EC50) of 1 to 5 nM and a 90% effective concentration of 2.7 to 13 nM. TMC114 exhibited no cytotoxicity at concentrations up to 100 muM (selectivity index, >20,000). All viruses in a panel of 19 recombinant clinical isolates carrying multiple protease mutations and demonstrating resistance to an average of five other PIs, were susceptible to TMC114, defined as a fold change in EC50 of <4. TMC114 was also effective against the majority of 1,501 PI-resistant recombinant viruses derived from recent clinical samples, with EC50s of <10 nM for 75% of the samples. In sequential passage experiments using HIV-1 LAI, two mutations (R41T and K70E) were selected. One selected virus showed a 10-fold reduction in susceptibility to TMC114, but <10-fold reductions in susceptibility to the current PIs (atazanavir was not assessed), except saquinavir. However, when the selected mutations were introduced into a laboratory strain by site-directed mutagenesis, they had no effect on susceptibility to TMC114 or other PIs. There was no evidence of antagonism between TMC114 and any currently available PIs or reverse transcriptase inhibitors. Combinations with ritonavir, nelfinavir, and amprenavir showed some evidence of synergy. These results suggest that TMC114 is a potential candidate for the treatment of both naive and PI-experienced patients with HIV.

FIG. 1.

Structure of TMC114.

FIG. 2.

Activity of TMC114 and currently approved protease inhibitors against PI-resistant viruses. Differences from the subtype B consensus at amino acid positions implicated in PI resistance according to the International AIDS Society-USA drug resistance mutation figures are presented (14). IDV, indinavir; RTV, ritonavir; NFV, nelfinavir; SQV, saquinavir; APV, amprenavir; LPV, lopinavir. Median values of at least three determinations are presented, except for RTV and strains r13022, r13023, r13026, r13032, and r13036; for SQV and strain r13032; and for LPV and strains r130230 to r13024, r13026 to r13033, and r13035 to r13037, where only two determinations were available.

FIG. 3.

Antiviral activity of different protease inhibitors tested against a panel of 1,501 recent recombinant clinical isolates resistant to at least one protease inhibitor. (A) EC₅₀; black shading, EC₅₀ > 100 nM; grey shading, EC₅₀ < 100 nM > 10 nM; white, EC₅₀ < 10 nM. (B) Fold change in EC₅₀ compared to the wild type; black shading, fold change > 10; grey shading, fold change < 10 > 4; white, fold change < 4.

FIG. 4.

In vitro selection of resistant HIV in the presence of nelfinavir, amprenavir, lopinavir, or TMC114. Selection curves have been normalized, and starting selection concentrations were 10, 20, 100, and 100 nM for TMC114, lopinavir, amprenavir, and nelfinavir, respectively. Each passage corresponds to 3 to 4 days. Passage 75 corresponds to 260 days. Genotypes of virus strains selected at defined time points (indicated by enlarged symbols) list all changes from the starting strain, HIV-1 LAI.