Bicyclic hydroxy-1H-pyrrolopyridine-trione containing HIV-1 integrase inhibitors

HIV-1 integrase (IN) is a validated therapeutic target for the treatment of AIDS. However, the emergence of resistance to raltegravir, the sole marketed FDA-approved IN inhibitor, emphasizes the need to develop second-generation inhibitors that retain efficacy against clinically relevant IN mutants. We report herein bicyclic hydroxy-1H-pyrrolopyridine-triones as a new family of HIV-1 integrase inhibitors that were efficiently prepared using a key 'Pummerer cyclization deprotonation cycloaddition' cascade of imidosulfoxides. In in vitro HIV-1 integrase assays, the analogs showed low micromolar inhibitory potencies with selectivity for strand transfer reactions as compared with 3'-processing inhibition. A representative inhibitor (5e) retained most of its inhibitory potency against the three major raltegravir-resistant IN mutant enzymes, G140S/Q148H, Y143R, and N155H. In antiviral assays employing viral vectors coding these IN mutants, compound 5e was approximately 200- and 20-fold less affected than raltegravir against the G140S/Q148H and Y143R mutations, respectively. Against the N155H mutation, 5e was approximately 10-fold less affected than raltegravir. Thus, our new compounds represent a novel structural class that may be further developed to overcome resistance to raltegravir, particularly in the case of the G140S/Q148H mutations.     

Resistance associated mutations to dolutegravir (S/GSK1349572) in HIV-infected patients--impact of HIV subtypes and prior raltegravir experience

Dolutegravir (S/GSK1349572) is a second-generation HIV-1 integrase inhibitor (INI) in advanced clinical development. It has shown good antiviral activity in most patients with prior raltegravir failure, although changes at the integrase codon 148, particularly when combined with other mutations, confer reduced susceptibility and may impair dolutegravir activity. Mutations believed to be associated with dolutegravir resistance at positions 92, 101, 124, 148, 153, and 193 were assessed in patients either INI-na?ve or experiencing failure to raltegravir-based regimens. The integrase coding region was sequenced using an in-house nested-PCR protocol. HIV-1 subtyping was carried out using the Stanford algorithm. A total of 638 plasma samples were analyzed from 535 INI-na?ve and 103 raltegravir-experienced patients. Non-B subtypes were recognized in 20.8% patients. Mutations L101I and T124A were significantly more prevalent in patients with non-B subtypes (66.9% vs. 45.7% for L101I; 61.7% vs. 25.9% for T124A; and 39.1% vs. 12.7% for L101I+T124A; p<0.001 in all cases). E92Q and Q148H/R were only seen in raltegravir-experienced patients and exclusively infected with subtype B (1.9% vs. 0%, p=0.026, for E92Q and 12.6% vs. 0%, p<0.001, for Q148H/R). On the contrary, T124A was more frequent in INI-na?ve than raltegravir-experienced patients (35.1% vs. 24.3%, p=0.040). S153Y/F was absent in this dataset. Polymorphic changes L101I and T124A were more frequent in HIV-1 non-B than B subtypes. T124A was more frequent in INI-na?ve patients but E92Q and Q148H/R were only seen in raltegravir-experienced individuals. Thus, both HIV-1 subtype and raltegravir exposure may influence the antiviral activity of dolutegravir.     

In-vivo selection of the mutation F121Y in a patient failing raltegravir containing salvage regimen

Raltegravir is an integrase inhibitor (INI) licensed for clinical use and other INI are in advanced stage of development. Different resistance mutations in HIV integrase from patients using these antiretroviral drugs have been described and G148H/R/K, N155H and less frequently Y143C/H/R are considered major resistant mutations to raltegravir. Both Stanford Database and Geno2Pheno list F121Y as conferring intermediate resistance "in vitro" both to raltegravir and elvitegravir. We report for the first time the "in vivo" selection F121Y and evolution to Y143R in a 31years old male clade B HIV-1 infected patient failing a raltegravir-containing salvage regimen. Plasma samples nine months prior to raltegravir (RAL-Na?ve) and at weeks 32, 40 and 88 after RAL-containing regimen were analyzed. Antiretroviral susceptibility was evaluated at Stanford and Geno2Pheno from sequences obtained with RT-PCR. After a Viral load at week 12 below 50 copies/mL, viremia raised at week 20 to 4.5log10. The emergence of F121Y was observed at week 32 and 40, alongside with L74I, T97A, Q137H and V151I. At week 88 F121Y was no longer detected, L74I and T97A were maintained and Y143R emerged. F121Y might be an alternative pathway to Y143R. Changing of RAL-containing regimen upon the identification of F121Y might avoid the evolution of raltegravir resistance.     

HIV-1 integrase inhibitors: an emerging clinical reality

From the discovery of HIV-1 integrase (IN) inhibitors using enzyme-based assays in 1992, it has taken 15 years to achieve success in human clinical trials. Currently available antiretroviral drugs set high clinical standards in efficacy and long-term safety for upcoming novel HIV/AIDS therapeutic agents. The results from advanced stages of human clinical trials with IN inhibitors indicate a promising future for these compounds as a novel class of antiretroviral drugs. Success and failure of previously discovered antiretroviral drugs have taught us that there are no magic bullets in eradicating HIV. However, approval of drugs selectively targeting IN has long been awaited. There is once again a surge of interest in the field focusing on clinical development of IN inhibitors. Here, we summarise the current status of IN inhibitors under clinical development. These agents include S-1360, GSK-364735, L-870,810, L-870,812, MK-0518, GS-9137, L-900564, GS-9224, and BMS-707035. Promising antiviral activity has already been achieved with MK-0518 and GS-9137 in late-stage clinical studies.     

Dynamic escape of pre-existing raltegravir-resistant HIV-1 from raltegravir selection pressure

Using quantitative deep HIV-1 sequencing in a subject who developed virological failure to deep salvage therapy with raltegravir, we found that most Q148R and N155H mutants detected at the time of virological failure originated from pre-existing minority Q148R and N155H variants through independent evolutionary clusters. Double 148R+N155H mutants were also detected in 1.7% of viruses at virological failure in association with E138K and/or G163R. Our findings illustrate the ability of HIV-1 to escape from suboptimal antiretroviral drug pressure through selection of pre-existing drug-resistant mutants, underscoring the importance of using fully active antiretroviral regimens to treat all HIV-1-infected subjects.     

HIV-1-infected patients with advanced disease failing a raltegravir-containing salvage regimen in São Paulo,Brazil

Raltegravir (RAL) is the first licensed antiretroviral integrase inhibitor that may be used both for treatment-naïve human immunodeficiency virus type 1 (HIV-1) patients and for salvage therapy. The Brazilian public free access programme limits its use for salvage therapy, with scarce information regarding RAL resistance from patients failing a RAL-containing salvage regimen. This study evaluated RAL resistance mutations detected by population sequencing in 69 HIV-infected patients with advanced disease failing a RAL-containing regimen in a real-world setting. RAL resistance mutations were identified in 47/69 patients (68%). The most common salvage regimen, used by 56/69 patients (81%), included lamivudine, tenofovir, darunavir/ritonavir and RAL. At failure, major RAL resistance mutations included Q148H/R/K (21/47; 45%), N155H (14/47; 30%), Y143R/H/C (3/47; 6%) and E92Q (1/47; 2%). Most samples with Q148H/R/K also showed G140S/A/C (21/47; 45%). RAL resistance was significantly associated with less than two active drugs in the optimised background therapy regimen at failure [39/39 (100%) vs. 9/17 (53%); P < 0.001] and with a longer cumulative duration with detectable viraemia (viral load >50 copies/mL) (86 weeks vs. 32 weeks; P = 0.001). A high frequency of RAL mutations was observed in this study. In addition, these results reinforce the importance of close monitoring of RAL-containing regimens to reduce the time of failure and consequent resistance accumulation.     

S/GSK1349572, a new integrase inhibitor for the treatment of HIV: promises and challenges

INTRODUCTION: The recent introduction of integrase inhibitors (INIs) into the HIV treatment armentarium has had a significant impact on HIV treatment. However, at present, raltegravir twice daily is the only licensed INI featuring a lower genetic barrier compared with boosted protease inhibitors. S/GSK1349572 represents a new INI in current development. It is a once-daily, unboosted INI with low pharmacokinetic variability and predictable exposure-response relationship. Phase IIb studies in antiretroviral-na?ve patients have demonstrated non-inferiority to efavirenz-based HIV therapy. Phase II studies in INI-experienced patients show partially retained activity in vivo. Overall, the safety profile of S/GSK1349572 in all studies completed has been very favorable. AREAS COVERED: A Pubmed and Medline search was carried out on all articles on S/GSK1349572 from 2005 to 2010, including recent abstract presentations from major HIV conferences (CROI 2010, WAC2010, EACS2009, HIV10 and ICAAC2010). The reader will become acquainted with the unique properties of this new INI and will understand the current promises and challenges of the data available from S/GSK1349572. EXPERT OPINION: S/GSK1349572 represents a new, unboosted, once-daily INI in development with distinct pharmacokinetics and resistance profile, which has showed promising potency and tolerability in the first clinical studies.     

Resistance to HIV-1 integrase inhibitors: A structural perspective

Strand-transfer inhibitors, of which raltegravir, elvitegravir and S/GSK1349572, is a new class of antiretrovirals that inhibit HIV integrase-catalyzed insertion of the HIV-1 genome into cell chromosomes. The results of clinical trials were very encouraging regarding their viral efficiency and tolerance. However resistance mutations were identified in patients failing to respond to treatment with these inhibitors, involving primary mutations as well as numerous secondary mutations. This review focuses on recent advanced computational studies that have highlighted the contribution of those residues subject to primary mutations and the role of conformational flexibility of the enzyme in binding to strand-transfer inhibitors.     

S/GSK1349572, a new integrase inhibitor for the treatment of HIV: promises and challenges

Introduction: The recent introduction of integrase inhibitors (INIs) into the HIV treatment armentarium has had a significant impact on HIV treatment. However, at present, raltegravir twice daily is the only licensed INI featuring a lower genetic barrier compared with boosted protease inhibitors. S/GSK1349572 represents a new INI in current development. It is a once-daily, unboosted INI with low pharmacokinetic variability and predictable exposure-response relationship. Phase IIb studies in antiretroviral-naïve patients have demonstrated non-inferiority to efavirenz-based HIV therapy. Phase II studies in INI-experienced patients show partially retained activity in vivo. Overall, the safety profile of S/GSK1349572 in all studies completed has been very favorable.

Areas covered: A Pubmed and Medline search was carried out on all articles on S/GSK1349572 from 2005 to 2010, including recent abstract presentations from major HIV conferences (CROI 2010, WAC2010, EACS2009, HIV10 and ICAAC2010). The reader will become acquainted with the unique properties of this new INI and will understand the current promises and challenges of the data available from S/GSK1349572.

Expert opinion: S/GSK1349572 represents a new, unboosted, once-daily INI in development with distinct pharmacokinetics and resistance profile, which has showed promising potency and tolerability in the first clinical studies.     

In vitro resistance selections using elvitegravir, raltegravir, and two metabolites of elvitegravir M1 and M4

Elvitegravir is a strand transfer inhibitor of HIV-1 integrase that is currently undergoing phase 3 clinical testing. The two predominant metabolites of elvitegravir, M1 and M4 (elvitegravir hydroxide and elvitegravir glucuronide), have been shown to inhibit HIV-1 integrase in vitro. While they are markedly less potent than elvitegravir and present only at low levels in plasma clinically, we investigated their potential to select for elvitegravir resistance in vitro. Resistance selection experiments using metabolites M1 and M4 led to the development of the previously reported elvitegravir integrase resistance mutations H51Y, T66A, E92G, and S147G, as well as a novel S153F substitution. Additional resistance selection experiments using elvitegravir led to the development of previously reported integrase inhibitor resistance mutations (T66I, F121Y, and S153Y) as well as a novel R263K integrase mutation. Phenotypic analyses of site-directed mutants with these mutations demonstrated broad cross-resistance between elvitegravir and its M1 and M4 metabolites with more limited cross-resistance to the integrase inhibitor raltegravir. Overall, our in vitro studies demonstrate that the resistance profile of the M1 and M4 metabolites of elvitegravir overlaps with that of the parent molecule elvitegravir; as such, their presence at low levels is not considered clinically relevant.     

Characterization of resistance mutations against HCV ketoamide protease inhibitors

An issue of clinical importance in the development of new antivirals for HCV is emergence of resistance. Several resistance loci to ketoamide inhibitors of the NS3/4A protease have been identified (residues V36, T54, R155, A156, and V170) by replicon and clinical studies. Using SCH 567312, a more potent protease inhibitor derived from SCH 503034 (boceprevir) series, we identified two new positions (Q41 and F43) that confer resistance to the ketoamide class. The catalytic efficiency of protease enzymes was not affected by most resistance mutations, whereas replicon fitness varied with specific mutations. SCH 503034 and another ketoamide inhibitor, VX-950 (telaprevir), showed moderate losses of activity against most resistance mutations (< or =10-fold); the highest resistance level was conferred by mutations at A156 locus. Although SCH 503034 and VX-950 bind similarly to the active site, differences in resistance level were observed with specific mutations. Changes at V36 and R155 had more severe impact on VX-950, whereas mutations at Q41, F43 and V170 conferred higher resistance to SCH 503034. Structural analysis of resistance mutations on inhibitor binding is discussed.     

艾滋病病毒耐药研究的新进展(摘要)

由于未采用最佳治疗方案或者病人未能坚持高效抗逆转录病毒疗法(HAART),导致人体免疫缺损病毒-Ⅰ(HIV-1)耐药的出现。然而,即使患者能够很好地坚持HAART治疗,也很难长期维持检测水平以下的病毒载量。通常来说,单个HIV-Ⅰ靶基因的变异,即可特异性导致病毒对相应抗逆转录病毒药物的耐药。但是,应用3种药物联合治疗时,病毒至少需要有针对3种抗逆转录病毒药物的变异才会引起耐药和治疗失败。这些耐药突变的出现常为暂时性的,并与药物的半衰期(t1/2)和耐药株的病毒活力有关。特异性的耐药突变在主要的药物种类中,即核苷类似物逆转录酶抑制剂(NRTI,如nevi-rapine)、非核苷类似物逆转录酶抑制剂(NNRTI,如AZT)、蛋白酶抑制剂(PI,如nelfinavir)和整合酶抑制剂(INI,如raltegra-vir),已广为人知。然而,由于HIV-1的基因背景及二次变异的差异,病毒的耐药水平可能高低不一。另外,特异性的抗逆转录病毒药物CCR5拮抗剂(如maraviroc)可通过多种未知机制及途径选择耐药突变。基于在乌干达、中国、阿根廷和其他一些国家的研究,本研究所研发了1种检测耐药的新技术。该技术不仅可检测B亚型(主要流行于欧洲和北美),还可检测其他不同亚型HIV中新出现的耐药。为更好了解表型耐药情况,还研发了1种新的应用PCR技术从患者体内快速扩增HIV靶基因,利用酵母重组技术克隆其进入HIV基因组中。然后用产生的嵌合病毒做药物敏感试验。较之细菌克隆技术、酵母重组技术允许克隆更大的HIV基因,且不需要特别的克隆位点。由于表型分析法更为常用且费用较高,也研发了1种基因型耐药分析法。该方法是在绝大多数耐药突变位点上应用特异性寡核苷酸连接法分辨出该突变位点的存在与否。耐药突变的频率由多功能流式荧光检测仪测定。     

Sequence changes in the human adenovirus type 5 DNA polymerase associated with resistance to the broad spectrum antiviral cidofovir

Although there is currently no FDA approved antiviral treatment for adenovirus (Ad) infections, the broad spectrum antiviral cidofovir (CDV) has demonstrated potent inhibitory activity against many Ad serotypes in vitro and in an in vivo ocular replication model. The clinical potential of CDV prompted the assessment for the emergence of CDV resistance in Ad5. Serial passage of Ad5 in increasing concentrations of CDV resulted in derivation of four different Ad5 variants with increased resistance to CDV. CDV resistance was demonstrated by ability to replicate viral DNA in infected cells at CDV concentrations that inhibit the parental virus, by ability to form plaques in CDV concentrations of >20 microg/ml and by increased progeny release following infection and growth in media containing CDV. Using marker rescue, the loci for CDV resistance in variant R1 was shown to be mediated by one residue change L741S, one of two mutations within the R1 encoded DNA polymerase. The CDV-resistant variants R4, R5 and R6 also contained mutations in their respective DNA polymerase sequences, but these were different from R1; variant R4 contained two changes (F740I and V180I), whereas both R5 and R6 variants contained the non-conserved mutation A359E. R6 contained additional alterations L554F and V817L. The location of the R1 change is close to a region of the DNA polymerase which is conserved with other polymerases that is predicted to involve nucleotide binding.     

Functional Analysis of SNPs Variants of BCRP/ABCG2

PURPOSE: The aim of the current study was to identify the effect of single nucleotide polymorphisms (SNPs) in breast cancer resistance protein (BCRP/ABCG2) on its localization, expression level, and transport activity. METHODS: The cellular localization was identified using the wild type and seven different SNP variants of BCRP (V12M, Q141K, A149P, R163K, Q166E, P269S, and S441N BCRP) after transfection of their cDNAs in plasmid vector to LLC-PK1 cells. Their expression levels and transport activities were determined using the membrane vesicles from HEK293 cells infected with the recombinant adenoviruses containing these kinds of BCRP cDNAs. RESULTS: Wild type and six different SNP variants of BCRP other than S441N BCRP were expressed on the apical membrane, whereas S441N BCRP showed intracellular localization. The expression levels of Q141K and S441N BCRP proteins were significantly lower compared with the wild type and the other five variants. Furthermore, the transport activity of E1S, DHEAS, MTX, and PAH normalized by the expression level of BCRP protein was almost the same for the wild type, V12M, Q141K, A149P, R163K, Q166E, and P269S BCRP. CONCLUSIONS: These results suggest that Q141K SNPs may associate with a lower expression level, and S441N SNPs may affect both the expression level and cellular localization. It is possible that subjects with these polymorphisms may have lower expression level of BCRP protein and, consequently, a reduced ability to export these substrates.     

Resistance to raltegravir highlights integrase mutations at codon 148 in conferring cross-resistance to a second-generation HIV-1 integrase inhibitor

Raltegravir is the first integrase strand-transfer inhibitor (INSTI) approved for use in highly active antiretroviral therapy (HAART) for the management of HIV infection. Resistance to antiretrovirals can compromise the efficacy of HAART regimens. Therefore it is important to understand the emergence of resistance to RAL and cross-resistance to other INSTIs including potential second-generation INSTIs such as MK-2048.We have now studied the question of whether in vitro resistance selection (IVRS) with RAL initiated with viruses derived from clinical isolates would result in selection of resistance mutations consistent with those arising during treatment regimens with HAART containing RAL. Some correlation was observed between the primary mutations selected in vitro and during therapy, initiated with viruses with identical IN sequences. Additionally, phenotypic cross-resistance conferred by specific mutations to RAL and MK-2048 was quantified. N155H, a RAL-associated primary resistance mutation, was selected after IVRS with MK-2048, suggesting similar mechanisms of resistance to RAL and MK-2048. This was confirmed by phenotypic analysis of 766 clonal viruses harboring IN sequences isolated at the point of virological failure from 106 patients on HAART (including RAL), where mutation Q148H/K/R together with additional secondary mutations conferred reduced susceptibility to both RAL and MK-2048. A homology model of full length HIV-1 integrase complexed with viral DNA and RAL or MK-2048, based on an X-ray structure of the prototype foamy virus integrase-DNA complex, was used to explain resistance to RAL and cross-resistance to MK-2048. These findings will be important for the further discovery and profiling of next-generation INSTIs.     

ABL激酶区突变的检测与伊马替尼耐药

目的研究慢性粒细胞白血病(chronic myeloid leukemia,CML)患者ABL酪氨酸激酶区突变及伊马替尼耐药。方法用巢式RT-PCR对35例CML患者骨髓液BCR-ABL mRNA内ABL激酶区序列进行逆转录、扩增,测序和同源性比较分析ABL激酶区突变,并分析其伊马替尼耐药。结果 35例患者检出突变16例,阳性率45.71%。CML慢性期、加速期、急变期患者突变率分别为47.83%(11/23)、50%(1/2)和40%(4/10),其差异无显著性(P=0.858);16例突变患者中,共检出26种点突变,包括Y253H、T315I、F317L、M351T、L387F、A380D、H396R、G398R、D455G、E459K和1例185 bp碱基缺失突变等。其中A269V、D274G、S286G、V299M、C305Y、R307W、G312R、I314V、L324Q、K356E、D381G、K403E、K419E、L471P、A474T和S485P突变暂未见文献报道,可能为新的突变。在这些新发现的突变中,D274G、S286G、C305Y和K356E等突变可能与伊马替尼(imatinib,IM)治疗抗性有关。结论约半数患者存在ABL激酶区突变,突变位点广泛,性质多样,既存在单一位点突变,也可多位点同时存在,突变的发生与年龄、性别无关,部分突变与伊马替尼耐药有关。ABL基因激酶区突变检测有助于酪氨酸激酶抑制剂疗效的评估、治疗方案的调整。     

HIV integrase inhibitors: a new era in the treatment of HIV

Introduction: Integrase inhibitors (INIs) are the latest class of antiretroviral drugs approved for the treatment of HIV infection and are becoming ‘standard’ drugs in the treatment of both naïve as well as heavily pretreated individuals with HIV.

Areas covered: Data on efficacy, safety, tolerability, pharmacokinetics, drug-drug interactions and resistance are reviewed from the pivotal Phase III clinical trials published in PubMed high-impact medical journals or presented at international meetings.

Expert opinion: Due to their outstanding data of efficacy, tolerability, safety – shared by all three drugs (raltegravir, elvitegravir, dolutegravir) currently belonging to this new family of antiretrovirals – INIs have become part of the recommended initial antiretroviral therapy options. Some differences in dosing, drug-drug interactions and robustness/genetic barrier among the three drugs will provide the physician the characteristics to make the best choice.     

'In vitro' development of metronidazole, erythromycin, amoxicillin and gentamicin resistance in Helicobacter pylori

Serial passage of 37 Helicobacter pylori clinical isolates on increasing concentrations of metronidazole rapidly produced five strains with MICs up to 512 fold higher than those for the original strains. For these five metronidazole-resistant strains the MICs of erythromycin, gentamicin and amoxicillin were unchanged. When they were submitted to the same technique for these last antimicrobial agents, only one strain developed high level resistance to erythromycin and gentamicin having MIC values respectively up to 32 and 64-fold increased. Finally, no amoxicillin-resistant Helicobacter pylori could be obtained.