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Biomedical subjects

Koen Andries

Publications and source records attributed to Koen Andries.

At least 19 recordsLinked to original sources
PubMed2006

A dual chamber model of female cervical mucosa for the study of HIV transmission and for the evaluation of candidate HIV microbicides.

A dual chamber system was established to model heterosexual HIV transmission. Cell-associated, but not cell-free HIV, added to a confluent layer of cervical epithelial cells in the apical chamber, reproducibly infected monocyte-derived dendritic cells (MO-DC) and CD4(+) T cells in the basal compartment. Only minimal epithelial transmigration of HIV-infected mononuclear cells (HIV-PBMCs) was observed. Most evidence points to transepithelial migration of virus, released from HIV-PBMCs after their activation by epithelial cells. We used this model for evaluation of the therapeutic index of various potentially preventive antiviral compounds, including non-nucleoside reverse transcriptase inhibitors (NNRTIs, including UC781 and various diaryltriazines and diarylpyrimidines), poly-anionic entry inhibitors (including PRO2000, cellulose sulphate, dextrane sulphate 5000 and polystyrene sulphonate) and the fusion inhibitor T-20. The epithelium was pre-treated with compound and incubated with HIV-PBMCs for 24 h. Afterwards the apical chamber was removed and MO-DC/CD4(+) T cell co-cultures were further cultured without compound. NNRTIs, including a TMC120 gel, blocked infection of the sub-epithelial targets at sub-micromolar concentrations. Polyanionic entry inhibitors (up to 100 microg/ml) and T-20 (up to 449 microg/ml) failed to inhibit transmission. Moreover, whereas the NNRTIs used interfered with epithelial integrity with cervical epithelium only at very high concentrations, the evaluated entry inhibitors showed toxicity at concentrations that did not prevent infection.

Anti-HIV Agents↗
PubMed2006

Structure-activity relationship in the 3-iodo-4-phenoxypyridinone (IOPY) series: The nature of the C-3 substituent on anti-HIV activity.

As part of a systematic SAR study on the 3-iodo-4-phenoxypyridinone 3 (IOPY) type non-nucleoside reverse transcriptase inhibitors, the analogues 4a-4z bearing different C-3 substituents were synthesized and evaluated for their anti-HIV activity against wild-type HIV-1 and four of the principal HIV mutant strains (K103N, Y181C, Y188L, and I100L). The results show that the 3-vinyl analogue 4j is the only compound which displays anti-HIV activity comparable to IOPY 3, and in this respect represents a possible back-up to this lead molecule.

Anti-HIV Agents↗
PubMed2006

Combinations of R207910 with drugs used to treat multidrug-resistant tuberculosis have the potential to shorten treatment duration.

The objective of the present study was to identify the optimal R207910-containing regimen to administer to patients who cannot receive rifampin (RIF) and isoniazid (INH) because of multidrug-resistant tuberculosis (MDR-TB), concomitant use of antiretroviral drugs, or toxicity. Mice were infected intravenously with 5 x 10(6) CFU of the H37Rv strain and treated five times per week with R207910 alone or various combinations of R207910 with the second-line drugs amikacin (AMK), pyrazinamide (PZA), moxifloxacin (MXF), and ethionamide (ETH). All R207910-containing regimens were significantly more active than the non-R207910-containing regimens after 1 month of therapy. When given for 2 months, R207910 alone was more active than the WHO standard first-line regimen RIF-INH-PZA. When R207910 was combined with second-line drugs, the combinations were more active than the currently recommended regimen of MDR-TB AMK-ETH-MXF-PZA, and culture negativity of both the lungs and spleen was reached after 2 months of treatment in almost every case.

Animals↗
PubMed2006

Alignment of capsid protein VP1 sequences of all human rhinovirus prototype strains: conserved motifs and functional domains.

An alignment was made of the deduced amino acid sequences of the entire capsid protein VP1 of all human rhinovirus (HRV) prototype strains to examine conserved motifs in the primary structure. A set of previously proposed crucially important amino acids in the footprints of the two known receptor molecules was not conserved in a receptor group-specific way. In contrast, VP1 and VP3 amino acids in the minor receptor-group strains corresponding to most of the predicted ICAM-1 footprint definitely differed from those of the ICAM-1-using major receptor-group strains. Previous antiviral-sensitivity classification showed an almost-complete agreement with the species classification and a fair correlation with amino acids aligning in the antiviral pocket. It was concluded that systematic alignment of sequences of related virus strains can be used to test hypotheses derived from molecular studies of individual model viruses and to generate ideas for future studies on virus structure and replication.

Capsid↗
PubMed2006

Genetic basis for natural and acquired resistance to the diarylquinoline R207910 in mycobacteria.

The atpE gene encoding the subunit c of the ATP synthase of Mycobacterium tuberculosis, the target of the new diarylquinoline drug R207910, has been sequenced from in vitro mutants resistant to the drug. The previously reported mutation A63P and a new mutation, I66M, were found. The genetic diversity of atpE in 13 mycobacterial species was also investigated, revealing that the region involved in resistance to R207910 is conserved, except in Mycobacterium xenopi in which the highly conserved residue Ala63 is replaced by Met, a modification that may be associated with the natural resistance of M. xenopi to R207910.

Amino Acid Sequence↗
PubMed2005

Crystal structures for HIV-1 reverse transcriptase in complexes with three pyridinone derivatives: a new class of non-nucleoside inhibitors effective against a broad range of drug-resistant strains.

In the treatment of AIDS, the efficacy of all drugs, including non-nucleoside inhibitors (NNRTIs) of HIV-1 reverse transcriptase (RT), has been limited by the rapid appearance of drug-resistant viruses. Lys103Asn, Tyr181Cys, and Tyr188Leu are some of the most common RT mutations that cause resistance to NNRTIs in the clinic. We report X-ray crystal structures for RT complexed with three different pyridinone derivatives, R157208, R165481, and R221239, at 2.95, 2.9, and 2.43 A resolution, respectively. All three ligands exhibit nanomolar or subnanomolar inhibitory activity against wild-type RT, but varying activities against drug-resistant mutants. R165481 and R221239 differ from most NNRTIs in that binding does not involve significant contacts with Tyr181. These compounds strongly inhibit wild-type HIV-1 RT and drug-resistant variants, including Tyr181Cys and Lys103Asn RT. These properties result in part from an iodine atom on the pyridinone ring of both inhibitors that interacts with the main-chain carbonyl oxygen of Tyr188. An acrylonitrile substituent on R165481 substantially improves the activity of the compound against wild-type RT (and several mutants) and provides a way to generate novel inhibitors that could interact with conserved elements of HIV-1 RT at the polymerase catalytic site. In R221239, there is a flexible linker to a furan ring that permits interactions with Val106, Phe227, and Pro236. These contacts appear to enhance the inhibitory activity of R221239 against the HIV-1 strains that carry the Val106Ala, Tyr188Leu, and Phe227Cys mutations.

Crystallography, X-Ray↗
PubMed2005

Synthesis of novel diarylpyrimidine analogues and their antiviral activity against human immunodeficiency virus type 1.

This paper reports the synthesis and the antiviral properties of new diarylpyrimidine (DAPY) compounds as nonnucleoside reverse transcriptase inhibitors (NNRTIs). The synthesis program around this new DAPY series was further optimized to produce compounds displaying improved activity against a panel of eight clinically relevant single and double mutant strains of human immunodeficiency virus type 1 (HIV-1).

Anti-HIV Agents↗
PubMed2005

In search of a novel anti-HIV drug: multidisciplinary coordination in the discovery of 4-[[4-[[4-[(1E)-2-cyanoethenyl]-2,6-dimethylphenyl]amino]-2- pyrimidinyl]amino]benzonitrile (R278474, rilpivirine).

Ideally, an anti-HIV drug should (1) be highly active against wild-type and mutant HIV without allowing breakthrough; (2) have high oral bioavailability and long elimination half-life, allowing once-daily oral treatment at low doses; (3) have minimal adverse effects; and (4) be easy to synthesize and formulate. R278474, a new diarylpyrimidine (DAPY) non-nucleoside reverse transcriptase inhibitor (NNRTI), appears to meet these criteria and to be suitable for high compliance oral treatment of HIV-1 infection. The discovery of R278474 was the result of a coordinated multidisciplinary effort involving medicinal chemists, virologists, crystallographers, molecular modelers, toxicologists, analytical chemists, pharmacists, and many others.

Administration, Oral↗
PubMed2005

4-Benzyl and 4-benzoyl-3-dimethylaminopyridin-2(1H)-ones: in vitro evaluation of new C-3-amino-substituted and C-5,6-alkyl-substituted analogues against clinically important HIV mutant strains.

In a program to optimize the anti-HIV activity of the 4-benzyl and 4-benzoyl-3-dimethylaminopyridinones 9 and 10, lead compounds in a new class of highly potent non-nucleoside type inhibitors of HIV-1 reverse transcriptase, modification of the alkyl substitutents at the C-5 and C-6 positions on the pyridinone ring and of the substitutents on the C-3 amino group has been studied. Of the 17 new 5/6-modified analogues prepared, compounds 31b and 32b substituted at C-5 by an extended nonpolar chain containing an ether function and a C-6 methyl group and compound 35 bearing a C-5 ethyl/C-6 hydroxymethyl substituent pattern were selected on the basis of their in vitro activity against wild-type HIV and the three principle mutant strains, K103N, Y181C, and Y188L. When tested further, it was shown that these molecules, and in particular compound 35, are globally more active than 9, 10, and efavirenz against an additional eight single [L100I, K101E, V106A, E138K, V179E, G190A/S, and F227C] and four double HIV mutant strains [L100I + K103N, K101E + K103N, K103N + Y181C, and F227L + V106A], which are clinically relevant. Concerning modulation of the N-3 substituent, 36 new analogues were prepared. Of these, the N-methyl-N-(2-methoxyethyl)-substituted compounds 40, 42, and 62, as well as the doubly modified compounds 77a and 77b, were selected from the initial screen and were subsequently shown to be active at sub-micromolar concentrations (IC(50)'s) against all the other mutant strains except K103N + Y181C and F227L + V106A. Two possible, but distinct, modes of binding of these analogues in RT were suggested from molecular modeling studies. The preferred mode of binding for compound 62, corresponding to the predicted "orientation 1", was revealed in the X-ray crystal structure of the compound 62-RT complex.

Anti-HIV Agents↗
PubMed2005

TMC125 displays a high genetic barrier to the development of resistance: evidence from in vitro selection experiments.

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.

Amino Acid Sequence↗
PubMed2004

A diarylquinoline drug active on the ATP synthase of Mycobacterium tuberculosis.

The incidence of tuberculosis has been increasing substantially on a worldwide basis over the past decade, but no tuberculosis-specific drugs have been discovered in 40 years. We identified a diarylquinoline, R207910, that potently inhibits both drug-sensitive and drug-resistant Mycobacterium tuberculosis in vitro (minimum inhibitory concentration 0.06 mug/ml). In mice, R207910 exceeded the bactericidal activities of isoniazid and rifampin by at least 1 log unit. Substitution of drugs included in the World Health Organization's first-line tuberculosis treatment regimen (rifampin, isoniazid, and pyrazinamide) with R207910 accelerated bactericidal activity, leading to complete culture conversion after 2 months of treatment in some combinations. A single dose of R207910 inhibited mycobacterial growth for 1 week. Plasma levels associated with efficacy in mice were well tolerated in healthy human volunteers. Mutants selected in vitro suggest that the drug targets the proton pump of adenosine triphosphate (ATP) synthase.

Amino Acid Sequence↗
PubMed2004

4-benzyl- and 4-benzoyl-3-dimethylaminopyridin-2(1H)-ones, a new family of potent anti-HIV agents: optimization and in vitro evaluation against clinically important HIV mutant strains.

The 4-benzyl and 4-benzoyl-3-dimethylaminopyridinones 13 and 14 are representatives of a new class of highly potent non nucleoside type inhibitors of HIV-1 reverse transcriptase. To conduct SAR studies on these two lead compounds, 102 new analogues were prepared. Thirty-three compounds displayed nanomolar range activity in vitro against wild-type HIV-1, and among these, 18 were active against the 103N, Y181C, and Y188L mutant strains with IC50 values inferior to 1 microM. Evaluation of this group of analogues against an additional eight single [100I, 101E, 106A, 138K, 179E, 190A, 190S, 227C] and four double HIV mutant strains [100I + 103N, 101E + 103N, 103N + 181C, and 227L + 106A], which are often present in HIV infected patients, permitted the selection of eight compounds, 17x, 18b, 18c, 18f, 18g, 27, 30, and 42, which are globally more active than the lead molecules 13/14, emivirine and the currently used NNRTI, nevirapine. Further comparison of the 3'-CN-substituted benzoylpyridinone compound 18c, and the corresponding 3'-acrylonitrile-substituted analogue 30, to efavirenz, the reference molecule in anti-HIV therapy today, revealed that the pyridinone analogues displayed a superior inhibition profile in the in vitro cellular assay system. These results form a solid basis for continued optimization of the pyridinone series.

Alkynes↗
PubMed2004

Roles of conformational and positional adaptability in structure-based design of TMC125-R165335 (etravirine) and related non-nucleoside reverse transcriptase inhibitors that are highly potent and effective against wild-type and drug-resistant HIV-1 variants.

Anti-AIDS drug candidate and non-nucleoside reverse transcriptase inhibitor (NNRTI) TMC125-R165335 (etravirine) caused an initial drop in viral load similar to that observed with a five-drug combination in naïve patients and retains potency in patients infected with NNRTI-resistant HIV-1 variants. TMC125-R165335 and related anti-AIDS drug candidates can bind the enzyme RT in multiple conformations and thereby escape the effects of drug-resistance mutations. Structural studies showed that this inhibitor and other diarylpyrimidine (DAPY) analogues can adapt to changes in the NNRTI-binding pocket in several ways: (1). DAPY analogues can bind in at least two conformationally distinct modes; (2). within a given binding mode, torsional flexibility ("wiggling") of DAPY analogues permits access to numerous conformational variants; and (3). the compact design of the DAPY analogues permits significant repositioning and reorientation (translation and rotation) within the pocket ("jiggling"). Such adaptations appear to be critical for potency against wild-type and a wide range of drug-resistant mutant HIV-1 RTs. Exploitation of favorable components of inhibitor conformational flexibility (such as torsional flexibility about strategically located chemical bonds) can be a powerful drug design concept, especially for designing drugs that will be effective against rapidly mutating targets.

Anti-HIV Agents↗
PubMed2004

A series of diaryltriazines and diarylpyrimidines are highly potent nonnucleoside reverse transcriptase inhibitors with possible applications as microbicides.

An in vitro model of monocyte-derived dendritic cells (MO-DC) and CD4(+) T cells, representing the primary targets of sexual human immunodeficiency virus (HIV) transmission, was used to evaluate the antiviral and immune suppressive activity of new classes of nonnucleoside reverse transcriptase inhibitors, diaryltriazines (DATAs) and diarylpyrimidines (DAPYs), compared to the reference compounds UC-781 and PMPA. Antiviral activity (as reflected by the 50% effective concentration [EC(50)]) was determined by treating HIV-infected MO-DC/CD4(+)-T-cell cocultures with a dose range of a compound during 14 days, followed by analysis of supernatants in HIV p24 antigen enzyme-linked immunosorbent assay. A limited, 24-h treatment evaluated the compounds as microbicides. Viral rescue was evaluated in a PCR by monitoring proviral DNA in secondary cultures with phytohemagglutinin-interleukin-2 blasts. We determined 50% immunosuppressive concentrations in mixed leukocyte cultures of MO-DC and allogeneic T cells, with compound either continuously present or present only during the first 24 h. The EC(50) values of DATA and DAPY compounds ranged from 0.05 to 3 nM compared to 50 nM for UC-781 and 89 nM for PMPA. When evaluated in the "microbicide" setting, the most potent compounds completely blocked HIV infection at 10 to 100 nM. The immunosuppressive concentrations were well above the EC(50), resulting in favorable therapeutic indices for all compounds tested. The DATA and DAPY compounds described here are more potent than earlier reverse transcriptase inhibitors and show favorable pharmacological profiles in vitro. They could strengthen the antiretroviral armamentarium and might be useful as microbicides.

Anti-Infective Agents↗
PubMed2004

TMC125, a novel next-generation nonnucleoside reverse transcriptase inhibitor active against nonnucleoside reverse transcriptase inhibitor-resistant human immunodeficiency virus type 1.

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are potent inhibitors of human immunodeficiency virus type 1 (HIV-1); however, currently marketed NNRTIs rapidly select resistant virus, and cross-resistance within the class is extensive. A parallel screening strategy was applied to test candidates from a series of diarylpyrimidines against wild-type and resistant HIV strains carrying clinically relevant mutations. Serum protein binding and metabolic stability were addressed early in the selection process. The emerging clinical candidate, TMC125, was highly active against wild-type HIV-1 (50% effective concentration [EC50] = 1.4 to 4.8 nM) and showed some activity against HIV-2 (EC50 = 3.5 microM). TMC125 also inhibited a series of HIV-1 group M subtypes and circulating recombinant forms and a group O virus. Incubation of TMC125 with human liver microsomal fractions suggested good metabolic stability (15% decrease in drug concentration and 7% decrease in antiviral activity after 120 min). Although TMC125 is highly protein bound, its antiviral effect was not reduced by the presence of 45 mg of human serum albumin/ml, 1 mg of alpha1-acid glycoprotein/ml, or 50% human serum. In an initial screen for activity against a panel of 25 viruses carrying single and double reverse transcriptase amino acid substitutions associated with NNRTI resistance, the EC50 of TMC125 was <5 nM for 19 viruses, including the double mutants K101E+K103N and K103N+Y181C. TMC125 also retained activity (EC50 < 100 nM) against 97% of 1,081 recent clinically derived recombinant viruses resistant to at least one of the currently marketed NNRTIs. TMC125 is a potent next generation NNRTI, with the potential for use in individuals infected with NNRTI-resistant virus.

Cell Line↗
PubMed2004

Correlations between factors determining the pharmacokinetics and antiviral activity of HIV-1 non-nucleoside reverse transcriptase inhibitors of the diaryltriazine and diarylpyrimidine classes of compounds.

OBJECTIVE: To investigate the important factors that determine the bioavailability and the antiviral activity of the diaryltriazine (DATA) and diarylpyrimidine (DAPY) non-nucleoside reverse transcriptase inhibitors (NNRTIs) of HIV-1 in animal species and humans using cell-based assays, physicochemical and computed parameters. METHODS: This naturalistic study included 15 parameters ranging from molecular mechanics calculations to phase I clinical trials. The calculated parameters were solvent-accessible surface area (SASA), polar surface area and Gibbs free energy of solvation. Physicochemical parameters comprised lipophilicity (octanol/water partition coefficient [cLogP]), ionisation constant (pKa), solubility and aggregate radius. Cell-based assays included human colonic adenocarcinoma cell (Caco-2) permeability (transepithelial transport), drug metabolism and antiviral activity (negative logarithm of the molar effective concentration inhibiting viral replication by 50% [pEC50]). Exposure was tested in rats, dogs and human volunteers. RESULTS: Of the 15 parameters, eight correlated consistently among one another. Exposure (area under the plasma concentration-time curve [AUC]) in humans correlated positively with that in rats (r = 1.00), with transepithelial transport (r = 0.83), lipophilicity (r = 0.60), ionisability (r = 0.89), hydrodynamic radius of aggregates (r = 0.66) and with antiviral activity (r = 0.61). Exposure in humans was also seen to correlate negatively with SASA (r = -0.89). No consistent correlation was found between exposure in dogs and the eight parameters. Of the 14 DATA/DAPY molecules, 11 form aggregates with radii between 34 and 100 nm. CONCLUSIONS: We observed correlations between exposure in humans with exposure in rats, transepithelial transport (Caco-2 cells), ionisability, lipophilicity, aggregate radius and SASA in the class of DATA/DAPY NNRTI compounds. The lipophilic DATA/DAPY compounds form aggregates. It can be assumed that absorption in the intestinal tract and endocytosis in infected cells of these lipophilic compounds are governed by the common phenomenon of aggregate formation. As the lymphatic system offers a pathway for intestinal uptake of aggregates, this may offer a therapeutic advantage in the treatment of HIV-1 infection. Although it was not the objective of the study, we found that the rat was a better in vivo model than the dog for the prediction of systemic exposure in this particular set of compounds.

Animals↗