TMC125 Displays a High Genetic Barrier to the Development of Resistance: Evidence from In Vitro Selection Experiments

Tibotec, Mechelen, Belgium.
Journal of Virology (Impact Factor: 4.44). 11/2005; 79(20):12773-82. DOI: 10.1128/JVI.79.20.12773-12782.2005
Source: PubMed


TMC125 is a potent new investigational nonnucleoside reverse transcriptase inhibitor (NNRTI) that is active against human immunodeficiency virus type 1 (HIV-1) with resistance to currently licensed NNRTIs. Sequential passage experiments with both wild-type virus and NNRTI-resistant virus were performed to identify mutations selected by TMC125 in vitro. In addition to "classic" selection experiments at a low multiplicity of infection (MOI) with increasing concentrations of inhibitors, experiments at a high MOI with fixed concentrations of inhibitors were performed to ensure a standardized comparison between TMC125 and current NNRTIs. Both low- and high-MOI experiments demonstrated that the development of resistance to TMC125 required multiple mutations which frequently conferred cross-resistance to efavirenz and nevirapine. In high-MOI experiments, 1 muM TMC125 completely inhibited the breakthrough of resistant virus from wild-type and NNRTI-resistant HIV-1, in contrast to efavirenz and nevirapine. Furthermore, breakthrough of virus from site-directed mutant (SDM) SDM-K103N/Y181C occurred at the same time or later with TMC125 as breakthrough from wild-type HIV-1 with efavirenz or nevirapine. The selection experiments identified mutations selected by TMC125 that included known NNRTI-associated mutations L100I, Y181C, G190E, M230L, and Y318F and the novel mutations V179I and V179F. Testing the antiviral activity of TMC125 against a panel of SDMs indicated that the impact of these individual mutations on resistance was highly dependent upon the presence and identity of coexisting mutations. These results demonstrate that TMC125 has a unique profile of activity against NNRTI-resistant virus and possesses a high genetic barrier to the development of resistance in vitro.

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    • "Consequently, many children infected with HIV in the late 1990s, who are adolescents today, may have been maintained on single, dual, or other nonsuppressive regimens for years at a time, only to accumulate enormous numbers of resistance mutations to the commonly used classes of ARVs.19 NVP and EFV have been the mainstay of cART in children when prescribed with a two-drug nucleoside reverse transcriptase inhibitor (NRTI) backbone, especially in developing countries. However, the first-generation NNRTIs have a low genetic barrier to resistance, such that upon VF, two signature point mutations, Y181C (NVP) and K103N (EFV), often develop, which have traditionally rendered the entire class of drugs useless.20 ETR has a much higher threshold for the development of resistance than NVP or EFV, requiring three or more of a certain group of ETR resistance-associated mutations (RAMs) to lose efficacy.21 In addition, the signature EFV point mutation, the K103N, seems to have little, if any, effect on the success of ETR in adults with this mutation.7,22 "
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    ABSTRACT: Pediatric patients infected with human immunodeficiency virus (HIV) are now living longer, healthier lives due to the advent of combined antiretroviral (ARV) therapy, including regimens that often contain non-nucleoside reverse transcriptase inhibitors (NNRTIs). However, first-generation NNRTIs such as nevirapine (NVP) and efavirenz (EFV) have a low genetic barrier to resistance, and both drugs can become ineffective with a single viral point mutation. New agents with activity against resistant viral strains must be available to salvage children and adolescents with virologic failure after NNRTI use. One such drug, etravirine, an oral second-generation NNRTI approved for use in the US in heavily treatment-experienced HIV-1-infected adults in 2008, is accumulating data in this younger population. Etravirine became approved by the US Food and Drug Administration in early 2012 to be used in combination with other ARV medications in HIV-1-infected children aged 6 years to <18 years who are failing their regimens with HIV-1 strains resistant to NNRTIs and other ARVs. This approval was largely based on data from a prospective, open-label, phase II clinical trial in this age group prescribed etravirine at 5.2 mg/kg twice daily (up to the adult dose of 200 mg twice daily) in combination with an investigator-selected optimized background regimen. Currently available 48-week follow-up data show complete viral suppression (<50 copies/mL) in 56% of the patients, with relatively few serious adverse events attributed to the drug. Additional studies and case reports from the field suggest its utility in clinical practice. This review is designed to increase the background understanding of this drug in pediatric HIV providers, to lay out the current pediatric data to support its use, and to define its practical role in the treatment of HIV-infected children now and in the future.
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    • "However, based on the weighted mutation score algorithm for the prediction of ETR susceptibility [Vingerhoets et al., 2010b], some of the HIV-1 isolated strains (23.6%) had mutations or combinations of mutations associated with intermediate resistance to ETR. Furthermore, L100I was the most prevalent ETR RAM found (16.4%) and in combination with K103N, a first-generation NNRTIs RAM widely present in EFV resistant viruses [Tambuyzer et al., 2009], was described to be associated in vitro with intermediate resistance to ETR [Vingerhoets et al., 2005]. Therefore, careful genotypic analysis is necessary when the use of ETR is considered. "
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    ABSTRACT: Etravirine (ETR) is a non-nucleoside analogue reverse transcriptase inhibitor (NNRTI) with a high genetic barrier to the development of resistance and with potential activity against Human immunodeficiency virus type 1 (HIV-1) strains resistant to first-generation NNRTIs. The objective of this study was to investigate the prevalence of ETR resistance associated mutations (RAMs) in HIV-1 strains isolated from infected individuals failing efavirenz (EFV), as well as to evaluate possible differences in the distribution of ETR RAMs between subtype B and non-B genetic variants. Nucleotide sequences of the protease and partial reverse transcriptase (RT) coding regions of the pol gene of 55 HIV-1 strains isolated from infected individuals failing EFV on regular follow-up at a reference center in Portugal, were retrospectively analyzed. The most prevalent ETR RAMs observed were L100I, V90I, and K101E, with a prevalence of 16.4% (n = 9), 9.1% (n = 5), and 5.5% (n = 3), respectively. Overall, 47.3% (n = 26) of the nucleotide sequences had at least one ETR RAM: 38.2% (n = 21) had one ETR RAM, 7.3% (n = 4) had two ETR RAMs and 1.8% (n = 1) had three ETR RAMs. No statistically significant differences were found in the distribution of ETR RAMs between subtype B and non-B genetic variants. The results demonstrate that ETR rescue therapy is a viable option in treatment-experienced individuals failing EFV and suggests that ETR may be equally useful in HIV-1 infections caused by different genetic variants.
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    • "4-[6-Amino-5-bromo-2-[(4-cyanophenyl)amino] pyrimidin-4-yl]oxy-3,5- dimethylbenzonitrile (etravirine; ETR) is a second-generation NNRTI that, like other NNRTIs, functions by binding noncompetitively to HIV reverse transcriptase, thereby preventing synthesis of DNA from the RNA genome of the virus. As a diarylpyrimidine, ETR has a high capacity for isomerization, which allows it to effectively bind to and inhibit common mutated forms of the viral enzyme (Andries et al., 2004; Vingerhoets et al., 2005; Gupta et al., This work was supported by the PhRMA Foundation (Research Starter Grant in Pharmacology/Toxicology; to N.N.B.). The AB SCIEX QTRAP 5500 mass spectrometer was purchased using a grant from the National Institutes of Health National Center for Research Resources [Grant 1S10-RR27733]; the Waters Acquity ultraperformance liquid chromatograph interfaced with the AB SCIEX QTRAP 5500 mass spectrometer was purchased with funds provided by the Pendleton Foundation Trust. "
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