Inge Dierynck

Once-daily darunavir/ritonavir vs. lopinavir/ritonavir in treatment-naive, HIV-1-infected patients: 96-week analysis.

Objective:Present 96-week data from ongoing ARTEMIS (AntiRetroviral Therapy with TMC114 ExaMined In Naive Subjects) trial. Methods:Randomized, open-label, phase III trial of antiretroviral-naive patients with HIV-1 RNA at least 5000 copies/ml (stratified by HIV-1 RNA and CD4 cell count) receiving darunavir/ritonavir (DRV/r) 800/100 mg once daily or lopinavir/ritonavir (LPV/r) 800/200 mg total daily dose (twice daily or once daily) and fixed-dose tenofovir/emtricitabine. Primary outcome measure was noninferiority of DRV/r vs. LPV/r in virologic response (<50 copies/ml, time-to-loss of virologic response) at 96 weeks (secondary outcome: superiority). Results:Six hundred eighty-nine patients were enrolled. At week 96, significantly more DRV/r (79%) than LPV/r patients (71%) had viral load less than 50 copies/ml, confirming statistical noninferiority (estimated difference: 8.4%; 95% confidence interval 1.9–14.8; P < 0.001; per-protocol) and superiority (P = 0.012; intent-to-treat) in virologic response. Median CD4 cell count increases from baseline were 171 and 188 cells/μl for DRV/r and LPV/r, respectively (P = 0.57; noncompleter=failure). Overall, 4% of DRV/r patients and 9% of LPV/r patients discontinued treatment due to adverse events. Lower rates of grade 2–4 treatment-related diarrhea were seen with DRV/r (4%) vs. LPV/r (11%; P < 0.001), whereas grade 2–4 treatment-related rash occurred infrequently in both arms (3 vs. 1%, respectively; P = 0.273). DRV/r patients had smaller median increases in triglycerides (0.1 and 0.6 mmol/l, respectively, P < 0.0001) and total cholesterol (0.6 and 0.9 mmol/l, respectively; P < 0.0001) than LPV/r patients; levels remained below National Cholesterol Education Program cut-offs for DRV/r. Conclusion:At week 96, once-daily DRV/r was both statistically noninferior and superior in virologic response to LPV/r, with a more favorable gastrointestinal and lipid profile, confirming DRV/r as an effective, well tolerated, and durable option for antiretroviral-naive patients.

Binding Kinetics of Darunavir to Human Immunodeficiency Virus Type 1 Protease Explain the Potent Antiviral Activity and High Genetic Barrier

ABSTRACT The high incidence of cross-resistance between human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs) limits their sequential use. This necessitates the development of PIs with a high genetic barrier and a broad spectrum of activity against PI-resistant HIV, such as tipranavir and darunavir (TMC114). We performed a surface plasmon resonance-based kinetic study to investigate the impact of PI resistance-associated mutations on the protease binding of five PIs used clinically: amprenavir, atazanavir, darunavir, lopinavir, and tipranavir. With wild-type protease, the binding affinity of darunavir was more than 100-fold higher than with the other PIs, due to a very slow dissociation rate. Consequently, the dissociative half-life of darunavir was much higher (>240 h) than that of the other PIs, including darunavirs structural analogue amprenavir. The influence of protease mutations on the binding kinetics was tested with five multidrug-resistant (MDR) proteases derived from clinical isolates harboring 10 to 14 PI resistance-associated mutations with a decreased susceptibility to various PIs. In general, all PIs bound to the MDR proteases with lower binding affinities, caused mainly by a faster dissociation rate. For amprenavir, atazanavir, lopinavir, and tipranavir, the decrease in affinity with MDR proteases resulted in reduced antiviral activity. For darunavir, however, a nearly 1,000-fold decrease in binding affinity did not translate into a weaker antiviral activity; a further decrease in affinity was required for the reduced antiviral effect. These observations provide a mechanistic explanation for darunavirs potent antiviral activity and high genetic barrier to the development of resistance.

Pharmacokinetics, safety and efficacy of darunavir/ ritonavir in treatment-experienced children and adolescents

Objective:To assess pharmacokinetics, safety and efficacy of darunavir/ritonavir (DRV/r) and optimized background regimen in treatment-experienced patients (6–17 years). Design:Forty-eight-week, open-label, two-part, phase II study. Methods:In part I, 44 patients were randomized (1: 1 ratio) to receive a body weight-adjusted, adult-equivalent dose (group A) or a 20–33% higher DRV/r twice daily (b.i.d.) dose (group B). Pharmacokinetics, safety and efficacy were assessed following 2-week dosing (part I), which determined dosing for part II (evaluated 48-week safety and efficacy). Results:In part I, both groups met the protocol-specified criteria for pharmacokinetics and showed favorable tolerability and efficacy. The following body-weight doses were selected: DRV/r 375/50 mg b.i.d. (20–<30 kg), 450/60 mg b.i.d. (30–<40 kg) and 600/100 mg b.i.d. (≥40 kg); these gave an AUC24h, C0h and Cmax of 102, 114 and 112%, respectively, versus the corresponding mean adult pharmacokinetic parameter. In part II, 80 patients received DRV/r (median age: 14 years, mean baseline HIV-1 RNA: 4.64 log10copies/ml). One patient (1%) discontinued (treatment-unrelated grade 3 anxiety). An abnormal mean baseline triglyceride level was normalized at 48 weeks (P < 0.01). At week 48, 65% had at least 1.0 log10HIV-1 RNA reduction; 59 and 48% achieved HIV-1 RNA less than 400 and less than 50 copies/ml, respectively (time-to-loss-of-virologic response). Mean age-adjusted weight z-score increased by 0.2 (P = 0.003). Conclusion:In treatment-experienced children and adolescents, DRV/r showed comparable exposure to adults with appropriate dose selection, favorable safety and tolerability, improved body weight and significant virologic response. DRV/r is a valuable therapeutic option for this population.

Characterization of virologic failure patients on darunavir/ritonavir in treatment-experienced patients.

Objective:Characterization of resistance development in virologic failure patients on the protease inhibitor darunavir administered with low-dose ritonavir (DRV/r) in the 48-week analysis of TMC114/r In Treatment-experienced pAtients Naive to lopinavir (TITAN). Design:TITAN is a randomized, controlled, open-label, phase III, noninferiority trial comparing the efficacy and safety of DRV/r with that of lopinavir/ritonavir (LPV/r) in HIV-1-infected, treatment-experienced, LPV-naive patients. The primary endpoint was the proportion of patients with HIV-1 RNA less than 400 copies/ml at week 48. Methods:Patients received DRV/r 600/100 mg twice daily (n = 298) or LPV/r 400/100 mg twice daily (n = 297), and an optimized background regimen. Patients who lost or never achieved HIV-1 RNA less than 400 copies/ml after week 16 were considered virologic failure patients. Genotyping and phenotyping were performed. Results:The virologic failure rate in the DRV/r arm (10%, n = 31) was lower than in the LPV/r arm (22%, n = 65). Furthermore, fewer virologic failure patients in the DRV/r arm than in the LPV/r arm developed primary protease inhibitor mutations (6 vs. 20) or nucleoside reverse transcriptase inhibitor resistance-associated mutations (4 vs. 15). In addition, fewer virologic failure patients on DRV/r than on LPV/r lost susceptibility to the protease inhibitor (3 vs. 13) or nucleoside reverse transcriptase inhibitor(s) (3 vs. 14) used in the treatment regimen or to other protease inhibitors. Most DRV/r-treated virologic failure patients retained susceptibility to all protease inhibitors. Conclusion:In treatment-experienced, LPV-naive patients, the overall virologic failure rate in the DRV/r arm was low and was associated with limited resistance development. These findings showed that the use of DRV/r in earlier lines of treatment was less likely to lead to cross-resistance to other protease inhibitors compared with LPV/r.

Crystal Structure of Lysine Sulfonamide Inhibitor Reveals the Displacement of the Conserved Flap Water Molecule in Human Immunodeficiency Virus Type 1 Protease

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) protease has been continuously evolving and developing resistance to all of the protease inhibitors. This requires the development of new inhibitors that bind to the protease in a novel fashion. Most of the inhibitors that are on the market are peptidomimetics, where a conserved water molecule mediates hydrogen bonding interactions between the inhibitors and the flaps of the protease. Recently a new class of inhibitors, lysine sulfonamides, was developed to combat the resistant variants of HIV protease. Here we report the crystal structure of a lysine sulfonamide. This inhibitor binds to the active site of HIV-1 protease in a novel manner, displacing the conserved water and making extensive hydrogen bonds with every region of the active site.

Virological characterization of patients failing darunavir/ritonavir or lopinavir/ritonavir treatment in the ARTEMIS study: 96-week analysis

BACKGROUND In the Phase III ARTEMIS Trial, treatment-naive patients received once-daily darunavir/ritonavir (DRV/r) 800/100 mg (n = 343) or lopinavir/ritonavir (LPV/r) 800/200 mg (total daily dose; n = 346) plus fixed-dose tenofovir disoproxil fumarate/emtricitabine. The primary outcome measure was non-inferiority of DRV/r versus LPV/r (HIV type-1 [HIV-1] RNA<50 copies/ml). Here, a detailed 96-week resistance analysis is presented. METHODS Virological failures (VFs) were defined as patients who had lost (rebounders) or who had never achieved (never suppressed) HIV-1 RNA < 50 copies/ml after week 12. Genotypic and phenotypic determinations were performed on plasma samples with HIV-1 RNA ≥ 50 copies/ml. The end point was defined as the last on-treatment visit with available genotype and/or phenotype. RESULTS The VF rate was significantly lower in DRV/r (12%, n = 40) versus LPV/r patients (17%, n = 59; P = 0.0437). Among DRV/r patients, 24 rebounded and 16 were never suppressed, whereas among LPV/r patients, 33 rebounded and 26 were never suppressed. Transient HIV-1 RNA increases (≥ 50 copies/ml) occurred in 50% (n = 12) DRV/r and 48% (n = 16) LPV/r rebounders; these viral levels returned to undetectable by end point without any changes to the study regimen. No major (primary) protease inhibitor (PI) resistance-associated mutations (RAMs) developed in VFs with an available genotype at baseline and end point, and almost all developing minor PI RAMs were polymorphic. At end point, all VFs with available phenotypes at baseline and end point remained susceptible to all PIs, including study PIs. CONCLUSIONS The VF rate was lower with DRV/r than LPV/r. The findings of this resistance analysis confirmed the lack of development of major PI RAMs and the preservation of phenotypic susceptibility to all PIs in patients with VF.

In vitro susceptibility and virological outcome to darunavir and lopinavir are independent of HIV type-1 subtype in treatment-naive patients.

BACKGROUND The effect of HIV type-1 (HIV-1) subtype on in vitro susceptibility and virological response to darunavir (DRV) and lopinavir (LPV) was studied using a broad panel of primary isolates, and in recombinant clinical isolates from treatment-naive, HIV-1-infected patients in the Phase III trial, AntiRetroviral Therapy with TMC114 ExaMined In naive Subjects (ARTEMIS). METHODS Patients received DRV/ritonavir (DRV/r) 800/100 mg once daily (n=343) or LPV/ritonavir (LPV/r) 800/200 mg total daily dose (n=346), plus a fixed daily dose of emtricitabine and tenofovir disoproxil fumarate. RESULTS DRV demonstrated high antiviral activity against a broad panel of HIV-1 major group (M) and outlier group (O) primary isolates in peripheral blood mononuclear cells, with a median 50% effective concentration (EC(50)) of 0.52 nM. Most (61%) patients in ARTEMIS harboured HIV-1 subtype B; other prevalent subtypes were C (13%) and CRF01_AE (17%); 9% harboured other subtypes. Median EC(50) values (interquartile range) for DRV were 1.79 nM (1.3-2.6) for subtype B, 1.12 nM (0.8-1.4) for C and 1.27 nM (1.0-1.7) for CRF01_AE. Virological response to DRV/r (HIV-1 RNA<50 copies/ml [intent-to-treat, time-to-loss of virological response algorithm]) was 81%, 87% and 85% for patients with subtype B, C and CRF01_AE infections, respectively. Similar results were observed in the LPV/r treatment group. CONCLUSIONS In vitro susceptibility to DRV was comparable across HIV-1 subtypes in a broad panel of primary isolates and in recombinant clinical isolates. Once daily DRV/r 800/100 mg and LPV/r 800/200 mg were highly effective in ARTEMIS irrespective of the HIV-1 subtype studied, confirming their broad anti-HIV-1 activity.

TMC310911, a Novel Human Immunodeficiency Virus Type 1 Protease Inhibitor, Shows In Vitro an Improved Resistance Profile and Higher Genetic Barrier to Resistance Compared with Current Protease Inhibitors

ABSTRACT TMC310911 is a novel human immunodeficiency virus type 1 (HIV-1) protease inhibitor (PI) structurally closely related to darunavir (DRV) but with improved virological characteristics. TMC310911 has potent activity against wild-type (WT) HIV-1 (median 50% effective concentration [EC50], 14 nM) and a wide spectrum of recombinant HIV-1 clinical isolates, including multiple-PI-resistant strains with decreased susceptibility to currently approved PIs (fold change [FC] in EC50, >10). For a panel of 2,011 recombinant clinical isolates with decreased susceptibility to at least one of the currently approved PIs, the FC in TMC310911 EC50 was ≤4 for 82% of isolates and ≤10 for 96% of isolates. The FC in TMC310911 EC50 was ≤4 and ≤10 for 72% and 94% of isolates with decreased susceptibility to DRV, respectively. In vitro resistance selection (IVRS) experiments with WT virus and TMC310911 selected for mutations R41G or R41E, but selection of resistant virus required a longer time than IVRS performed with WT virus and DRV. IVRS performed with r13025, a multiple-PI-resistant recombinant clinical isolate, and TMC310911 selected for mutations L10F, I47V, and L90M (FC in TMC310911 EC50 = 16). IVRS performed with r13025 in the presence of DRV required less time and resulted in more PI resistance-associated mutations (V32I, I50V, G73S, L76V, and V82I; FC in DRV EC50 = 258). The activity against a comprehensive panel of PI-resistant mutants and the limited in vitro selection of resistant viruses under drug pressure suggest that TMC310911 represents a potential drug candidate for the management of HIV-1 infection for a broad range of patients, including those with multiple PI resistance.

An OPTIMIZE Study Retrospective Analysis for Management of Telaprevir-Treated Hepatitis C Virus (HCV)-Infected Patients by Use of the Abbott RealTime HCV RNA Assay

ABSTRACT Protease inhibitor (PI)-based response-guided triple therapies for hepatitis C virus (HCV) infection are still widely used. Noncirrhotic treatment-naive and prior relapser patients receiving telaprevir-based treatment are eligible for shorter, 24-week total therapy if HCV RNA is undetectable at both weeks 4 and 12. In this study, the concordance in HCV RNA assessments between the Roche High Pure System/Cobas TaqMan and Abbott RealTime HCV RNA assays and the impacts of different HCV RNA cutoffs on treatment outcome were evaluated. A total of 2,629 samples from 663 HCV genotype 1 patients receiving telaprevir/pegylated interferon/ribavirin in OPTIMIZE were analyzed using the High Pure System and reanalyzed using Abbott RealTime (limits of detection, 15.1 IU/ml versus 8.3 IU/ml; limits of quantification, 25 IU/ml versus 12 IU/ml, respectively). Overall, good concordance was observed between the assays. Using undetectable HCV RNA at week 4, 34% of the patients would be eligible for shorter treatment duration with Abbott RealTime versus 72% with the High Pure System. However, using <12 IU/ml for Abbott RealTime, a similar proportion (74%) would be eligible. Of the patients receiving 24-week total therapy, 87% achieved a sustained virologic response with undetectable HCV RNA by the High Pure System or <12 IU/ml by Abbott RealTime; however, 92% of the patients with undetectable HCV RNA by Abbott RealTime achieved a sustained virologic response. Using undetectable HCV RNA as the cutoff, the more sensitive Abbott RealTime assay would identify fewer patients eligible for shorter treatment than the High Pure System. Our data confirm the <12-IU/ml cutoff, as previously established in other studies of the Abbott RealTime assay, to determine eligibility for shortened PI-based HCV treatment. (The study was registered with ClinicalTrials.gov under registration no. NCT01241760.)

Short communication: activity of etravirine on different HIV type 1 subtypes: in vitro susceptibility in treatment-naive patients and week 48 pooled DUET study data.

Etravirine (ETR) has previously shown potent in vitro activity against different primary HIV-1 isolates and demonstrated durable efficacy in treatment-experienced, HIV-1-infected patients in the Phase III DUET studies. The antiviral activity and efficacy of ETR against HIV-1 subtypes B and non-B were further investigated. The effect of HIV-1 subtype on ETR fold change in EC(50) value (FC) was analyzed in HIV-1 recombinant clinical isolates from 673 treatment-naive patients enrolled in other Tibotec studies. Subgroup analyses from the DUET studies of the effect of HIV-1 subtype on the proportion of patients with viral load (VL) <50 HIV-1 RNA copies/ml were also conducted using pooled week 48 data. Genotype/subtype and phenotype determinations were performed using the vircoTYPE HIV-1 and Antivirogram assays, respectively. In vitro results from treatment-naive patients indicated comparable median ETR FC in virus isolates from patients infected with subtype B or non-B (1.1 vs. 1.2, respectively). HIV-1 subtype data were available for 594 and 595 patients in the ETR and placebo groups of the DUET studies, respectively; 94% of patients harbored subtype B. Baseline characteristics were similar across the different subtypes, with the exception of a higher number of sensitive NRTIs used in patients with subtype non-B. At week 48, virological responses in the ETR group were higher in patients with subtype non-B versus B (73% vs. 60%, respectively). ETR was equally effective in suppressing viral replication in patients infected with HIV-1 subtype B or various HIV-1 non-B subtypes.