The first-generation nonnucleoside reverse transcriptase inhibitors (NNRTIs), efavirenz and nevirapine, have a low genetic barrier to the development of resistance. Extensive cross-resistance between these agents effectively limits NNRTI use to one failed regimen [1,2]. Efavirenz and nevirapine are associated with neuropsychiatric and hepatic events, respectively, which limit their utility among patient populations with existing comorbidities [3–8].
Etravirine (TMC125) is a next-generation NNRTI active against wild-type and NNRTI-resistant virus , which broadens the possible use of NNRTIs in treatment-experienced patients. The DUET-1 and DUET-2 trials were designed to investigate the efficacy and safety of etravirine in combination with other antiretroviral agents in clinically advanced, three antiretroviral class-experienced, human immunodeficiency virus type 1 (HIV-1)-infected adult patients who had evidence of viral replication and HIV-1 strains resistant to an NNRTI and other antiretroviral agents. Both trials were of identical design, allowing a robust, prespecified, pooled analysis. Results from 24-week analyses of the individual DUET (TMC125 to Demonstrate Undetectable viral load in patients Experienced with ARV Therapy) trials demonstrated better efficacy and comparable tolerability (except for rash) with etravirine versus the placebo group [10,11].
The primary aim of this pooled 48-week analysis was to evaluate whether etravirine, as part of combination therapy, could maintain the efficacy and safety findings over the longer term in treatment-experienced, HIV-1-infected patients.
The trials were conducted in 185 centers in 19 countries: Argentina, Brazil, Chile, France, Mexico, Panama, Puerto Rico, Thailand and the United States for DUET-1, and Australia, Belgium, Canada, France, Germany, Italy, The Netherlands, Poland, Portugal, Spain, UK and the United States for DUET-2. Patients were recruited between November 2005 and July 2006. Eligible patients were adult male or female treatment-experienced, HIV-1-infected patients on a stable but virologically failing regimen for at least 8 weeks, with plasma viral load more than 5000 copies/ml. Patients had at least one documented NNRTI mutation at screening or from prior genotypic analysis and at least three of the following primary protease inhibitor mutations  at screening: D30N, V32I, L33F, M46I/L, I47A/V, G48V, I50L/V, V82A/F/L/S/T, I84V, N88S or L90M. NNRTI mutations used in the entry criteria were A98G, L100I, K101E/P/Q, K103H/N/S/T, V106A/M, V108I, E138G/K/Q, V179I/F/G, Y181C/I/V, Y188C/H/L, G190A/E/S, P225H, F227C, M230I/L, P236L, K238N/T and Y318F. Major exclusion criteria included any currently active AIDS-defining illness or clinically significant disease, chronic hepatitis B or C or both with transaminases more than five times upper limit of normal or liver impairment and pregnant or breastfeeding female patients.
Written informed consent was obtained from all participants prior to conducting any trial-related procedures. The trial protocol was reviewed and approved by Independent Ethics Committees or Institutional Review Boards. The trials were conducted according to the principles of Good Clinical Practice, the Declaration of Helsinki and the European Union Clinical Trials Directive.
Study design and treatments
Details of the study design and methodology have been reported previously [10,11]. Briefly, the DUET trials are 48-week, randomized, double-blind, placebo-controlled, multicenter phase III trials, with an optional additional 48-week treatment period. Patients were randomized 1: 1 to receive etravirine 200 mg or placebo, both administered twice daily following a meal. All patients also received a background regimen of darunavir/ritonavir 600/100 mg bid and at least two other investigator-selected nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) and optional enfuvirtide.
Randomization was stratified by the intended use of enfuvirtide in the background regimen [reuse, no use or first time use (de novo)], previous use of darunavir/ritonavir and screening plasma viral load (<30 000 or ≥30 000 copies/ml). Patients who reused or did not use enfuvirtide were grouped together (i.e. not de novo) as their primary outcome responses were expected to be similar. De-novo enfuvirtide use was limited to a maximum of 40% of patients. Treatment adherence was assessed with selected questions from the AIDS Clinical Trials Group compliance questionnaire.
Classification of virologic failure leading to trial withdrawal has been described in detail previously [10,11]. Patients with a grade 3 or 4 skin event or allergic reaction, grade 4 confirmed laboratory abnormality, who developed clinical hepatitis, became pregnant or had a disallowed change in background regimen, were withdrawn. Patients who experienced less than 1 log10 reduction in plasma viral load from baseline or viral rebound at week 24 or later could enroll in an open-label, rollover trial (TMC125-C217) and receive etravirine and darunavir/ritonavir with a background regimen (ClinicalTrials.gov reference NCT00359021).
The primary endpoint was the proportion of patients who achieved a confirmed viral load less than 50 copies/ml [intent-to-treat (ITT) analysis, time-to-loss of virologic response imputation algorithm (TLOVR)] at week 24. Secondary endpoints were antiviral efficacy at all time points (including the proportion of patients with viral load less than 50 copies/ml or less than 400 copies/ml and change in viral load from baseline), changes in CD4 cell count, the proportion of patients experiencing a clinical event (composite of new AIDS-defining illness or death or both), change in HIV-1 genotype and drug susceptibility and safety and tolerability.
Plasma viral load was determined by the Roche Amplicor HIV-1 monitor ultra sensitive test (version 1.5; Roche Diagnostics, Basel, Switzerland). Immunologic change was determined by CD4 cell count. A confirmed virologic response or loss of response required two consecutive values beyond the relevant threshold. Viral phenotype and genotype were performed using the Antivirogram and vircoTYPE HIV-1 assays (Virco BVBA, Mechelen, Belgium), respectively.
All adverse events from the Centers for Disease Control and Prevention list of Category C events and clinical entities that may indicate a Category C event were systematically reviewed and validated by an independent adjudication panel, which was blind to treatment allocation (see Acknowledgments section). Case definitions applicable to the identification and adjudication of the clinical events were prepared based on previously described methods . The analysis of clinical endpoints was adjusted for the stratification factors, but baseline characteristics were not used in the definition of the clinical events.
The sample size was calculated for the 24-week primary endpoint based on interim data from the POWER (Performance Of TMC114/r When Evaluated in treatment-experienced patients with PI Resistance) trials as previously described [10,11]. The 48-week pooled DUET analysis was prespecified, and the sample size was powered based on the expected response rates at week 24.
At the time of this analysis, all patients had received at least 48 weeks of treatment or discontinued earlier. All statistical tests were interpreted at the two-sided 5% significance level (95% confidence) and performed using SGS Life Science Services with SAS Version 9.1. Except for resistance analyses, statistical tests and imputation methods are identical to those used for each trial at week 24 [10,11] and were performed on the ITT population (i.e. all randomized patients who took at least one dose of trial medication irrespective of protocol compliance or ineligibility). To reduce bias in the resistance analyses, patients who discontinued the trial for reasons other than virologic failure and/or used de-novo enfuvirtide were excluded.
The statistical interaction between treatment effect and enfuvirtide use was investigated by Breslow–Day test. According to the trial protocols, if the Breslow–Day test P value for this interaction was less than 0.20, the primary Cochran–Mantel–Haenszel test for the between-group comparison of the data on the TLOVR-imputed virologic response (viral load less than 50 copies/ml) must be conducted separately for the two enfuvirtide categories, de novo and not de novo (reused or did not use enfuvirtide). In this case, the Cochran–Mantel–Haenszel test controlled for previous use of darunavir (yes or no) and baseline viral load (less than 30 000 or at least 30 000 copies/ml). Because the interaction between treatment effect and enfuvirtide use was significant at week 48 (Breslow–Day test P = 0.1862; prespecified significance level was 0.20), the primary analysis was conducted separately for enfuvirtide use as well as for the overall population.
In the analysis of virologic response by number of active background antiretrovirals according to phenotypic sensitivity score (PSS), darunavir was classed as fully active if the fold-change in 50% effective concentration (fold-change) was 10 or less. Enfuvirtide was considered active if used de novo. NRTIs were considered active if fold-change was less than the cutoffs used in the Antivirogram assay. Etravirine resistance data were excluded from the PSS calculations [10,11].
An additional analysis of the pooled 24-week DUET data identified 17 etravirine resistance-associated mutations (RAMs) associated with a reduction in response to etravirine: V90I, A98G, L100I, K101E/H/P, V106I, E138A, V179D/F/T, Y181C/I/V, G190A/S and M230L . A weighted scoring system was developed whereby etravirine RAMs were allocated relative weight factors according to their impact on response and fold-change. The relative weight factors were determined using matched genotypic and phenotypic data from DUET (n = 406) and from a panel of NNRTI-resistant, recombinant HIV-1 clinical isolates (n = 4248). The relative weight of each etravirine RAM present at baseline was then added to give each patient's weighted genotypic score . Virologic response was found to be a function of the baseline-weighted genotypic score. Three response categories were defined, corresponding to weighted genotypic scores of 0–2 (highest virologic response rate with etravirine: 74%), 2.5–3.5 (intermediate response: 52%) and at least 4 (reduced response: 38%).
Correspondingly, a lower clinical cutoff of 3 (highest response) for etravirine and an intermediate clinical cutoff of 13 (intermediate response) were identified . However, an upper clinical cutoff above which patients received little or no benefit from etravirine could not be determined.
Patient disposition and baseline characteristics
The disposition of patients during screening and treatment is shown in Fig. 1. Baseline characteristics and demographic data were well balanced between treatment groups (Table 1). During the screening period, 11.6% of patients were taking an NNRTI. Eight percent of patients in each treatment group had no documented previous NNRTI use. However, in line with the inclusion criteria for each trial, these patients had at least one NNRTI RAM documented at screening or from genotyping prior to trial entry. Median (range) exposure to study drugs for patients in the etravirine and placebo groups was 52.3 (1.6–85) and 51.0 (3.4–80) weeks, respectively.
The investigator-selected background regimen was similar between groups. Overall, 554 (46%) patients used enfuvirtide in the background regimen, with 312 (26%) using enfuvirtide de novo. Of note, a higher proportion of patients in the placebo group than in the etravirine group had darunavir fold-change less than 2 at baseline. A higher proportion of patients in the etravirine group than in the placebo group had darunavir fold-change more than 40. In total, 318 (53%) patients in the etravirine group and 328 (55%) in the placebo group were receiving less than two active drugs in the background regimen.
Virologic and immunologic responses
The primary and secondary virologic and immunologic endpoints, for both the overall population and according to enfuvirtide use (primary prespecified analysis), are shown in Table 2. Significantly more patients receiving etravirine than placebo achieved viral load less than 50 copies/ml (61 vs. 40%, respectively; P < 0.0001) (Fig. 2a), regardless of the total number of active antiretrovirals (determined by phenotype) in the background regimen (Fig. 2b). Virologic response rates increased in both groups with an increasing number of active background agents.
In patients who achieved viral load less than 50 copies/ml at week 24, suppression was sustained to week 48 in 92% (334/363) and 89% (218/246) of patients in the etravirine and placebo groups, respectively. Approximately one-third of those patients with a viral load between 50 and 400 copies/ml at week 24 [35% (29/83) in the etravirine group; 31% (21/67) in the placebo group] went on to achieve a viral load less than 50 copies/ml at week 48. Patients taking etravirine achieved a virologic response significantly more quickly than with placebo (median 15.7 weeks and 32.7 weeks for etravirine and placebo, respectively; P < 0.0001).
Factors predicting virologic response
Factors found to predict virologic response (proportion of patients with viral load less than 50 copies/ml) at 48 weeks in both treatment groups were baseline viral load (76, 61 and 49% responders for less than 30 000, 30 000–100 000 and more than 100 000 copies/ml, respectively, for the etravirine group, P < 0.0001), baseline CD4 cell count (45, 65, 74 and 72% responders for less than 50, 50–200, 200–300 and at least 350 cells/μl, respectively for the etravirine group, P = 0.0059), adherence (16, 59 and 63 responders for less than 95, at least 95–less than or equal to 97.5 and more than 97.5% adherence, respectively for the etravirine group, P < 0.0001), number of active agents in the background regimen (Fig. 2b; P < 0.0001), number of previously used NNRTIs (43, 66 and 58% responders for 0, 1 and at least 2 NNRTIs for the etravirine group, P = 0.0052) and enfuvirtide use (59, 52 and 71% responders for enfuvirtide not used, reused and used de novo for the etravirine group, P = 0.0018). At week 48, a consistently higher proportion of patients in the etravirine group achieved viral load less than 50 copies/ml than those in the placebo group, even after accounting for these factors in a multivariate analysis (data not shown). Race, sex, HIV-1 clade, use of an NNRTI during screening and previous experience with efavirenz or nevirapine were not predictive of response.
Baseline etravirine fold-change was also a significant predictor of virologic response at 48 weeks in the etravirine-treated patient arm (P < 0.0001). The greatest virologic response rate with etravirine was observed in patients with minimal resistance to etravirine (baseline etravirine fold-change 3 or less and weighted genotypic score of 0–2) (Table 3). The majority of patients in DUET had an etravirine baseline fold-change of 3 or less (65%; 779/1190) and weighted genotypic score of 0–2 (56%; 227/406). Responses were higher with etravirine than in the overall placebo group in patients with weighted genotypic scores less than 4 (72 vs. 44%, respectively; P < 0.0001). A reduced response to etravirine was seen in patients with baseline fold-change more than 13 (overall population: 48%; 35/73) or weighted genotypic score of at least 4 (46%; 46/100). Results showing greater virologic response between etravirine genotypic and phenotypic subgroups and overall placebo were generally similar in the not de-novo subgroup and overall group.
Among the 17 etravirine RAMs, the presence at baseline of V179D, V179F, V179T, Y181V or G190S were associated with the largest impact on virologic response to etravirine. In the DUET studies, these mutations were each present in less than 5% of patients at baseline. The most prevalent NNRTI substitution at baseline, K103N, was not associated with a reduced response to etravirine and thus not classified as an etravirine RAM.
At week 48, a significantly lower proportion of patients in the etravirine group experienced at least one confirmed or probable AIDS-defining illness or death (independently adjudicated) than in the placebo group (Table 2). Mean time to AIDS-defining illness or death was longer in the etravirine group than in the placebo group (59 vs. 45 weeks; P = 0.0108). The most commonly reported confirmed or probable AIDS-defining illnesses (in 6 or more patients) in the etravirine and placebo groups, respectively, were Candida esophagitis (one vs. nine patients), Pneumocystis jiroveci pneumonia (three vs. six patients), herpes simplex (four vs. four patients), Mycobacterium avium complex infection (two vs. five patients), cytomegalovirus retinitis (one vs. five patients) and Kaposi's sarcoma (two vs. four patients). During the treatment period, deaths occurred in 20 placebo-treated and 12 etravirine-treated patients. Of these, death was the first clinical event to occur in seven out of 20 patients receiving placebo and eight out of 12 patients receiving etravirine (1.2 vs. 1.3% overall, respectively).
Safety and tolerability
The safety assessment was based on all data from 1203 patients. No new safety concerns were identified in the 48-week analysis compared with week 24 (Table 4). The majority of adverse events were grade 1 or 2 in severity. The incidence of grade 3 or 4 adverse events was comparable between treatment groups. Any deaths that occurred in the etravirine group were considered not or doubtfully related to trial medication and were mostly associated with HIV-1 disease progression.
Rash was the only adverse event to occur significantly more frequently with etravirine than with placebo (19.2 vs. 10.9%, P = 0.0001 prespecified Fisher's exact test). Within the etravirine group, rash was mild-to-moderate in severity (17.9% grade 1 or 2, 1.3% grade 3 and no grade 4 rashes reported), occurred primarily in the second week of therapy (median time-to-onset was 14 days; range 1–473 days) and was infrequent after week 4. Rash generally resolved within 1–2 weeks on continued therapy (median duration of 15 days; range 1–402 days). A total of 2.2% of HIV-1-infected patients receiving etravirine discontinued due to rash; there were no grade 3 rashes or discontinuations due to rash in the placebo group. One placebo patient developed Stevens–Johnson Syndrome after approximately 3 months of treatment, most likely related to a nonantiretroviral medication. The incidence of rash was higher in women (30.0%) than in men (18.0%; P = 0.0365) in the etravirine group. Patients with a history of NNRTI-related rash did not appear to be at increased risk for the development of etravirine-related rash compared with patients with no history of NNRTI-related rash (22 vs. 19%, respectively). There was no association between baseline CD4 cell count and development of rash for etravirine, regardless of sex. No relationship was apparent between the incidence and severity of rash and exposure to etravirine.
The overall incidence of nervous system and psychiatric-related disorders (including but not limited to headache, dizziness, insomnia, depression and abnormal dreams/nightmares) was low. Events were mostly grade 1 or 2 in severity and comparable between the etravirine and placebo groups (Table 4). The incidence of hepatic adverse events and profile of laboratory abnormalities, including hepatic and lipid parameters, was generally comparable between groups and mostly grade 1 or 2 in severity. There were no consistent or clinically relevant changes in laboratory, vital signs or electrocardiogram data, including QTc interval.
The pooled 48-week results from the DUET trials demonstrate that the superior virologic efficacy observed with etravirine versus placebo (both with a background regimen) is sustained to 48 weeks. At 48 weeks, 61% of patients receiving etravirine compared with 40% in the placebo plus background regimen group responded with a confirmed undetectable viral load of less than 50 copies/ml, which is the revised treatment goal for all treatment-experienced HIV-infected patients [3,17–20]. As all patients from both groups received darunavir, the relatively high efficacy rate in the placebo group is in accordance with the efficacy rate observed in the POWER trials (45%) . The difference between the two groups reflects the added efficacy with the addition of etravirine.
This article is the first to describe the independently adjudicated data on clinical events in the DUET trials. A significant benefit in favor of the etravirine group versus the placebo group was seen in terms of the proportion of patients experiencing clinical events (6 vs. 10%; P = 0.0408) and the mean time to clinical events (59 vs. 45 weeks; P = 0.0108). As recently highlighted by Hirschel and Perneger , morbidity and mortality, not just surrogate laboratory endpoints, are of substantial interest in the management of patients with highly resistant virus.
A statistically significantly greater response in the etravirine group than in the placebo group was also observed regardless of the number of active background agents. However, in line with current treatment guidelines [3,17–19], the use of an increasing number of other active antiretrovirals with etravirine was associated with an increased likelihood of treatment response.
Data from the current analysis illustrate the activity of etravirine against NNRTI-resistant virus. This is in line with in-vitro data that demonstrated a low propensity for the development of resistance to etravirine, as well as potent activity of this agent against HIV-1 virus with NNRTI RAMs [9,23]. The lowest virologic response rate with etravirine was observed in the subgroup of patients with an etravirine-weighted genotypic score of at least 4 at baseline. However, responses were higher with etravirine than with placebo in patients with weighted genotypic scores less than 4, and the majority of patients had a baseline etravirine-weighted genotypic score less than 4 (81%). Moreover, K103N, the most prevalent NNRTI mutation in the DUET studies at baseline in accordance with the overall resistance profile in NNRTI-experienced patients in the clinics, did not affect response to etravirine.
When data were analyzed by enfuvirtide use, it was found that the virologic response (less than 50 copies/ml) was significantly greater in the etravirine group versus the placebo group, regardless of enfuvirtide use. This is despite the imbalance between groups in baseline darunavir fold-change in patients who used enfuvirtide de novo and is in contrast with the pooled 24-week findings. At 24 weeks, there was no significant difference in response between the etravirine and placebo groups in patients who used de-novo enfuvirtide (67 vs. 61%, P = 0.276) . The greater between-group difference at week 48 (13%) than week 24 (6%) might be explained by the longer time-to-reach undetectable viral load among those with viral load of at least 100 000 copies/ml at baseline  (over a third of patients); the requirement for viral load to be confirmed as undetectable on two consecutive visits and a loss of response among some patients in the placebo group.
This 48-week pooled analysis of the DUET trials confirms the safety and tolerability profile of etravirine observed in the 24-week analysis [10,11]. Aside from rash, which generally occurred early and infrequently led to etravirine discontinuation, tolerability in the etravirine group was generally comparable with that in the placebo group, particularly in terms of hepatic, gastrointestinal and neuropsychiatric events. No new safety concerns were identified.
Among the limitations of the current study is that no information was generated on the use of etravirine with protease inhibitors other than darunavir. On the basis of inclusion criteria of at least three primary protease inhibitor mutations at screening, the boosted protease inhibitors that would be most likely to retain activity were tipranavir and darunavir. Tipranavir/ritonavir was found to substantially decrease etravirine exposure in healthy volunteers , so for the purposes of this study, coadministration was not allowed. Similarly, recently licensed agents that were experimental at the time of DUET enrolment, such as raltegravir and maraviroc, were not allowed because information on drug–drug interactions was lacking at trial onset. However, available findings from recent drug interaction studies demonstrate that the combination of etravirine with these agents is feasible [27,28], albeit dose adjustment of maraviroc may be necessary. Of late, the TRIO National agency for AIDS Research; Agence nationale de recherches sur la sida trial has shown excellent antiviral activity and good tolerability in a new three-drug combination of etravirine, darunavir and raltegravir .
In DUET, most patients were not on a failing NNRTI-containing regimen during the screening period. NNRTI RAMS were present in 88% of patients at baseline, confirming the persistence of some NNRTI mutations in the absence of drug pressure [30,31]. However, not all possible RAMS may have been detected in circulating viral strains at baseline, potentially resulting in an underestimation of the true impact of baseline resistance to etravirine on virologic outcome.
After 48 weeks, etravirine plus background regimen demonstrated durable virologic and immunologic responses, which were superior to the placebo group in treatment-experienced, HIV-1-infected adult patients. The incidence of clinical events was lower with etravirine plus background regimen than with placebo plus background regimen. No new safety concerns were identified at 48 weeks. With the exception of rash, the incidence of adverse events and laboratory abnormalities in the etravirine group was generally comparable to that in the placebo group. The DUET studies demonstrate the clinical utility of etravirine in treatment-experienced patients with resistance to NNRTI and other antiretroviral agents and highlight the clinical benefit that is now achievable from an NNRTI with activity in the face of multidrug resistance.
Disclaimers and sources of support: This clinical trial was sponsored by Tibotec Pharmaceuticals Ltd. The authors received medical writing support from Gardiner-Caldwell Communications Ltd, Macclesfield, UK, which was funded by Tibotec Pharmaceuticals Ltd.
Recruitment for DUET-1 and DUET-2 started from November 2005 and finished in July 2006 and June 2006, respectively. Both trials were conducted by the trial sponsor and developer of etravirine and darunavir, Tibotec Pharmaceuticals Ltd. Data were collected and analyzed by the trial sponsor, and all authors had full access to the data.
Data and analyses were checked by two different groups: SGS International (the clinical research organization) cleaned the data, did the analyses and performed an internal check. Tibotec independently checked the data and analyses with alternative methods. The corresponding author had full access to all of the data, takes responsibility for the integrity of the data and the accuracy of the data analysis and had the final responsibility to submit the manuscript for publication.
Authors' declaration of potential conflicts of interest and financial disclosures: All study investigators received research funding from Tibotec to support their patients' participation in this trial. C.K. and J.L. declare that they have no further conflict of interest. R.H. has received honorarium or consultant fees from Abbott, Boehringer Ingelheim, Bristol-Myers Squibb, Gilead Sciences, Merck, Schering and Roche and has received research support from Abbott, GlaxoSmithKline, Pfizer and Tibotec. A.L. has acted as a consultant, participated in advisory boards or speaker bureaus or in the conduct of clinical trials for Abbott, Bristol Myers Squibb, Gilead, Tibotec, Merck, Pfizer, Roche, GlaxoSmithKline and Boehringer Ingelheim. J.V.M. has received honoraria for participation in Advisory Boards for GlaxoSmithKline, Pfizer and Roche. He has given lectures for Abbott, Bristol Myers Squibb, Gilead, GlaxoSmithKline, Merck, Pfizer, Roche and Tibotec and conducted clinical trials for Abbott, Boehringer Ingelheim, Bristol Myers Squibb, Gilead, GlaxoSmithKline, Merck, Pfizer, Roche and Tibotec. J.-M.M. has received honoraria for participation in Advisory Boards and/or lectures for Abbott, Bristol Myers Squibb, Gilead, Pfizer, GlaxoSmithKline and Tibotec. M.S. has received honoraria for participation in Advisory Boards and/or lectures for Abbott, Bristol Myers Squibb, Gilead, Merck, Pfizer, Roche and Monogram. M.P., G.P., J.V., B.W. and G.D.S. are employees of the trial sponsor, Tibotec Pharmaceuticals Ltd.
Role of authors: C.K., R.H., J.L., A.L., J.V.M., J.-M.M. and M.S. participated in the recruitment of patients and reporting of data for those patients. M.P., G.P., J.V., B.W. and G.D.S. contributed to the design, conduct and analysis of the trial. All authors participated in the development of the manuscript, interpretation of the data and approved the final version of the manuscript.
In addition to the authors, the following investigators and contributors were involved in the trial design, conduct and analysis of the trials.
For DUET-1 trial: From Argentina: H.A. Ariza, J. Benetucci, P. Cahn, L.M. Calanni, I. Cassetti, J. Corral, D.O. David, A. Krolewiecki, M.H. Losso, P. Patterson, R.A. Teijeiro; Brazil: B. Grinsztejn, C.A. da Cunha, E.G. Kallas, E.M. Netto, J.H. Pilotto, J. Suleiman, A. Timerman; Chile: J. Ballesteros, R. Northland; Costa Rica: A.A. Alvilés Montoya, G. Herrera Martinez, A. Solano Chinchilla; France: M. Dupon, J.M. Livrozet, P. Morlat, G. Pialoux, C. Piketty, I. Poizot-Martin; Mexico: J. Andrade-Villanueva, G. Reyes-Terán, J. Sierra-Madero; Panama: A. Canton, A. Rodriguez, N. Sosa; Puerto Rico: J.O. Morales Ramirez, J.L. Santana Bagur, R. Soto-Malave; Thailand: T. Anekthananon, P. Mootsikapun, K. Ruxrungtham; USA: M. Albrecht, N. Bellos, R. Bolan, P. Brachman, C. Brinson, F. Cruickshank, R. Elion, W.J. Fessel, T. Hawkins, S. Hodder, P. Hutcherson, T. Jefferson, H. Katner, C. Kinder, M. Kozal, J. Leider, T. Mills, D. McDonough, K. Mounzer, J. Nadler, D. Norris, W. O'Brien, G. Pierone, K. Raben, B. Rashbaum, M. Rawlings, B. Rodwick, P. Ruane, J. Sampson, S. Schrader, A. Scribner, M. Sension, D. Sweet, B. Wade, D. Wheeler, A. Wilkin, T. Wills, M. Wohlfeiler and K. Workowski.
For DUET-2 trial: From Australia: J. Chuah, D. Cooper, B. Eu, J. Hoy, C. Workman; Belgium: N. Clumeck, R. Colebunders, M. Moutschen; Canada: J. Gill, K. Gough, P. Junod, D. Kilby, J. Montaner, A. Rachlis, B. Trottier, C.M. Tsoukas, S.L. Walmsley; France: C. Arvieux, L. Cotte, J.F. Delfraissy, P.M. Girard, B. Marchou, D. Vittecoq, Y. Yazdanpanah, P. Yeni; Germany: K. Arastéh, S. Esser, G. Fätkenheuer, H. Gellermann, K. Göbels, F.D. Goebel, H. Jäger, A. Moll, J.K. Rockstroh, D. Schuster, S. Staszewski, A. Stoehr; Italy: A. Antinori, G. Carosi, G. Di Perri, R. Esposito, F. Mazzotta, G. Pagano, E. Raise, S. Rusconi, L. Sighinolfi, F. Suter; The Netherlands: P.H.J. Frissen, J.M. Prins, B.J.A. Rijnders; Poland: A. Horban; Portugal: F. Antunes, M. Miranda, J. Vera; Spain: B. Clotet, P. Domingo, G. Garcia, J.M. Gatell, J. González-Lahoz, J. López-Aldeguer, D. Podzamczer; UK: P. Easterbrook, M. Fisher, M. Johnson, C. Orkin, E. Wilkins; USA: B. Barnett, J. Baxter, G. Beatty, D. Berger, C. Borkert, T. Campell, C. Cohen, M. Conant, J. Ernst, C. Farthing, T. File, M. Frank, J.E. Gallant, R.N. Greenberg, C. Hicks, D.T. Jayaweera, S. Kerkar, N. Markowitz, C. Martorell, C. McDonald, D. McMahon, M. Mogyoros, R.A. Myers Jr, G. Richmond, K. Sathasivam, S Schneider, H. Schrager, P. Shalit, F.P. Siegal, L. Sloan, K. Smith, S. Smith, P. Tebas, L.S. Tkatch and W. Towner.
The authors thank the patients and their families, investigators, the Data and Safety Monitoring Board, members of the cardiac events/death adjudication panel [Jens Lundgren (chair), Christian Funck-Brentano, Annette Sjøl], members of the clinical events/death adjudication panel (Joe Eron, Peter Reiss, Melanie Thompson and Rainer Weber) and Tibotec study personnel for their participation and support during the DUET trials. Special thanks go to Steven Nijs, MSc, and the TMC125-C206 and TMC125-C216 trial teams for their contributions.
The authors also acknowledge the medical writers Ryan Woodrow, BSc (Hons), Ian Woolveridge, PhD, and Kerry Padilla-Dumlao, MD, of Gardiner-Caldwell Communications for their assistance in drafting the manuscript and coordinating author contributions.
Trial registration: The DUET-1 and DUET-2 trials (TMC125-C206 and TMC125-C216) are registered with ClinicalTrials.gov (NCT00254046 and NCT00255099).
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