Introduction of effective antiretroviral therapy (ART) has significantly reduced mortality and morbidity in adults and children [1,2]. However, virological response to ART has typically been poorer in children [3,4] compared to adults . As most HIV-infected children are vertically infected, start therapy at relatively young ages and will need to take ART lifelong, poorer virological response and the potential for subsequent emergence of resistance is a cause for concern.
A large number of randomized trials provide a robust evidence base for the treatment of adults with combination ART: although the majority are of short duration (48 weeks), the number reporting long-term follow-up (3 years and beyond) is increasing [5–8]. In contrast, randomized trials comparing different ART combinations in previously untreated children are few [9–11]. Differences in available formulations, variable pharmacokinetics and robustness of dosing recommendations, as well as reliance on caregivers to give medications may all lead to differing relative efficacy in adults and children both short and long term. The PENTA 5 trial has previously reported that at both 24 and 48 weeks after initiation of ART, regimens including abacavir as one of the nucleoside analogue reverse transcriptase inhibitors (NRTIs) were more effective than zidovudine/lamivudine in reducing in log10 HIV-1 RNA and suppressing HIV-1 RNA < 400 copies/ml . All regimens were generally well tolerated and the incidence of suspected hypersensitivity to abacavir (3%) was similar to that observed in adults. Here we consider long-term efficacy over 5 years of regimens including combinations of abacavir, lamivudine and/or zidovudine in previously untreated children in the PENTA 5 trial.
PENTA 5 trial design
PENTA 5 was a 48-week randomized controlled trial comparing three dual NRTI combinations, with or without nelfinavir, as first-line ART . One-hundred and twenty-eight ART-naive children were randomized between January 1998 and April 1999 from 34 centres in nine countries, to zidovudine/lamivudine (n = 36) or zidovudine/abacavir (n = 45) or lamivudine/abacavir (n = 47). Asymptomatic children (n = 55) were also randomized to receive nelfinavir or nelfinavir placebo in a factorial design (Part A); children with more advanced disease (n = 73) received open-label nelfinavir (Part B). Therefore 103 of the 128 children initiated ART with three drugs; the remaining 25 started dual NRTI therapy only. Children in Part A were unblinded to nefinavir/placebo allocation when the last child enrolled reached 24 weeks of follow-up.
One child was lost to follow-up after 3 days, and one died from sepsis in the first month after starting lamivudine/abacavir/nefinavir. All other children were followed beyond 48 weeks (Fig. 1). Ethics committees for each centre approved long-term follow-up and primary caregivers and children, where appropriate, gave written consent. All CD4 cell counts and percentages, HIV-1 RNA measurements, local resistance test results, ART received, AIDS events and growth measurements were collected annually; additional toxicity data was not collected. Results from centralized resistance testing up to 48 weeks have been reported elsewhere ; a trial sample was also requested for centralized viral load and resistance testing at 3 years.
All analyses are intention-to-treat (ignoring changes to randomized treatment) based on the 126 children followed after 48 weeks. Baseline values were those before and nearest to randomization (within 4 weeks). Changes from baseline were calculated from the closest value to nominal assessment years, within a quarter-year window either side. We calculated changes in HIV-1 RNA using normal interval regression , replacing values below the lower limit of quantification with the interval in which the true value could lie (e.g. for values < 50 copies/ml, the interval [0,50] copies/ml was used). Proportions were compared using exact tests. Because of minor imbalances in baseline characteristics and receipt of nelfinavir in the NRTI groups, all analyses were adjusted for age, HIV-1 RNA and CD4% at baseline; plus allocation to nelfinavir in Part A or Part B, or placebo in Part A . Adjusted analyses of proportions used logistic regression with Wald tests. Generalized Estimating Equations were used for global tests of differences between randomized groups over the entire study period (1–5 years), also adjusted for minor baseline imbalances . Significance tests compared all three randomized groups, i.e., testing the hypothesis that the effect of at least one treatment group on outcome is different from the other groups. Analyses were also repeated restricted to children allocated to nelfinavir at trial entry (i.e., initiating ART with three drugs), and similar results were obtained. CD4 cell counts, height and weight were expressed as Z scores with reference to healthy uninfected children [15,16].
One-hundred and twenty-six children were followed after 48 weeks (n = 36/zidovudine/lamivudine, n = 44/zidovudine/abacavir, n = 46/lamivudine/abacavir) (Fig. 1). At randomization, their median age was 5.4 years (range, 0.3–16.7 years), median CD4% was 22% [interquartile range (IQR), 13–29%], mean HIV-1 RNA was 5.1 log10 copies/ml (SD 0.8); 11 children (9%) had had an AIDS-defining event.
Follow-up and clinical events
Median follow-up to 15 November 2005 was 5.8 years (range, 3.1–7.8 years). Two of the 126 children followed beyond 1 year were lost to follow-up at 3.1 and 3.9 years after randomization respectively, and a further 16 children were last seen alive between 4 and 5 years. Six children had new AIDS events within 5 years of randomization (four before and two after 48 weeks); there were no recurrent AIDS events. One child died at 3.1 years following Hodgkin's lymphoma, leaving 94%, 93%, 96% alive without a new or recurrent AIDS event at 5 years in the zidovudine/lamivudine, zidovudine/abacavir and lamivudine/abacavir groups respectively (Kaplan–Meier proportions, P = 0.87, log-rank test).
Antiretroviral treatment to 5 years
Up to 5 years, children in the zidovudine/lamivudine and zidovudine/abacavir groups had been exposed to a median (range) of four (three to nine) and four (two to six) drugs compared to only three (two to seven) in the lamivudine/abacavir group (P = 0.13, Kruskal–Wallis test). At 5 years, 37 (29%) children had switched to second-line therapy (three or more new drugs compared to the original regimen, n = 29) or were off ART (n = 8) [14 (39%), 14 (32%) and 9 (20%) respectively; P =0.15, exact test].
As expected, the proportion of child-time spent taking the randomized antiretroviral drugs decreased over time. Between 0 to 2.5 years after randomization, approximately 85% of child-time was spent taking the two NRTI drugs exactly as randomized in all groups. However, between 2.5 to 5 years, the proportion still taking randomized NRTIs was lower in the zidovudine groups (61%, 54%) than the lamivudine/abacavir group (69%). Other non-randomized NRTIs were also taken more in the zidovudine groups during this time: didanosine and stavudine in the zidovudine/lamivudine and the lamivudine/abacavir groups (26%, 27% and 14%, 13% respectively), and lamivudine, didanosine and stavudine in the zidovudine/abacavir group (Fig. 2). The proportion of child-time spent taking nelfinavir decreased over time in all groups; between 2.5 and 5 years, the proportion of child-time spent taking lopinavir, efavirenz and nevirapine was 11%, 14% and 12% in the zidovudine/lamivudine group respectively, 2%, 13% and 6% in the zidovudine/abacavir group and 0%, 16% and 4% in the lamivudine/abacavir group.
By 5 years, 17 (47%), 28 (64%) and 18 (39%) children were taking NRTIs other than randomized in the zidovudine/lamivudine, zidovudine/abacavir and lamivudine/abacavir groups respectively (P = 0.06, exact test) (Fig. 1), but 18% (3/17), 50% (14/28) and 50% (9/18) of these changes were either early single drug substitutions for toxicity (< 24 weeks after randomization) or switches in children with viral suppression (plasma HIV-1 RNA viral load < 400 copies/ml) for simplification, toxicity or child/carer request. Ten of the 12 switches for simplification were to triple NRTI (zidovudine/lamivudine/abacavir). Overall, excluding early single drug switches for toxicity, 17 (47%) children randomized to zidovudine/lamivudine, 16 (36%) to zidovudine/abacavir and 10 (22%) to lamivudine/abacavir had substituted or added one or more drugs (i.e., including changes to non-NRTIs) with HIV-1 RNA > 400 copies/ml by 5 years (P = 0.04, log-rank test).
HIV-1 RNA, CD4% and growth at and to 5 years
The mean (SE) reduction in HIV-1 RNA from baseline to 5 years was 2.3 (0.36) and 2.5 (0.35) log10 copies/ml in the zidovudine/lamivudine and zidovudine/abacavir groups compared to 3.4 (0.37) in the lamivudine/abacavir group (P = 0.001 at 5 years, global P < 0.001) (Fig. 2). There was no evidence that this difference between randomized groups increased or decreased over time (heterogeneity P = 0.5). Of the 105 (83%) children with HIV-1 RNA measured at 5 years, suppression was greatest in the lamivudine/abacavir arm: 55%, 50% and 79% had HIV-1 RNA < 400 copies/ml in the three NRTI groups respectively (P = 0.03 at 5 years, global P = 0.003), with 32%, 25% and 63% <50 copies/ml (P = 0.003 at 5 years, global P = 0.006) (Table 1). Similar results were seen restricting the analysis to children allocated to nelfinavir at trial entry (i.e., initiating ART with three drugs) (Table 1). There was no evidence that the difference in HIV-1 RNA supression between the randomized groups varied over time (heterogeneity P = 0.4 < 400 copies/ml, P = 0.1 < 50 copies/ml). Similar results were obtained when the analysis was restricted to the selected subgroup of children remaining on randomized NRTIs (on treatment analysis, at 5 years, 53%, 60% and 76% had HIV-1 RNA < 400 copies/ml, and 27%, 27% and 67% had HIV-1 RNA < 50 copies/ml in the three NRTI groups respectively).
Increases in height-for-age and weight-for-age were significantly greater in the lamivudine/abacavir group (global P = 0.001 and P = 0.04 respectively) (Fig. 2). Further there was a trend towards an increasing benefit from lamivudine/abacavir in weight-for-age compared to the other randomized groups over time (heterogeneity P = 0.09), but no variation in effects on height-for-age (heterogeneity P = 0.6). Of the 102 (81%) children with CD4 cell count measured at 5 years, mean (SE) increase in CD4% was 12% (2%) in the zidovudine/lamivudine group, 9% (2%) in the zidovudine/abacavir group and 12% (2%) in the lamivudine/abacavir group (P = 0.2), which were similar to increases from baseline to 1 year (8%, 7% and 7% respectively, P = 0.5) and to 3 years (9%, 7% and 9% respectively, P = 0.5). However, whilst CD4% varies less with age than CD4 absolute cell count, younger children still tend to have higher percentages and children in the lamivudine/abacavir group were younger. Adjusting more fully for age imbalances using age-adjusted CD4 z-score , there was a trend towards greater increases in the lamivudine/abacavir group at 5 years [mean (SE) increase 1.0 (1.4), 1.4 (1.3) and 2.4 (1.4) in the three NRTI groups respectively], but this was not statistically significant (P = 0.5).
Children randomized to dual NRTI
Twenty-four children (7 zidovudine/lamivudine, 11 zidovudine/abacavir, 6 lamivudine/abacavir) were randomized to nelfinavir placebo in Part A and thus initiated ART with only two drugs. At 5 years, 7 (29%) children were still taking randomized dual NRTI therapy; none were taking zidovudine/lamivudine, 3/11 (27%) were taking zidovudine/abacavir, and 4/6 (83%) were taking lamivudine/abacavir. Four of the 7 children remaining on dual therapy had HIV-1 RNA < 400 copies/ml through to 5 years (1/3 zidovudine/abacavir, 3/4 lamivudine/abacavir), and the remaining three had HIV-1 RNA < 4000 copies/ml. Of the 17 children who moved from dual NRTI treatment, 12 started triple therapy, one child switched from zidovudine/lamivudine to lamivudine/stavudine at 1 year (last seen at 5 years) and four children stopped ART (one child subsequently started triple therapy 2 years after stopping; three children were still off treatment 3, 4 and 6.5 years after stopping).
Sixteen children had one or more resistance tests after 1 year whilst still on their randomized NRTI, having either never achieved HIV-1 RNA < 400 copies/ml (n = 3) or rebounded after initial suppression (n = 13, HIV-1 RNA < 400 copies/ml and then > 2000 copies/ml, confirmed). All four children who had received zidovudine/lamivudine (two also received nelfinavir) developed M184V alone by 1 year and all subsequently developed thymidine analogue mutations (TAM) [M41L (n = 4), T215Y (n = 2), D67N (n = 1), K70R (n = 1), L210W (n = 1)] whilst maintaining M184V. In contrast four of the six children who received zidovudine/abacavir (all six also received nelfinavir) maintained wild-type virus despite ongoing viral replication and without documented ART interruption (last resistance test at 3–4.5 years, with latest HIV-1 RNA 2343–13210 copies/ml); the other two children had wild-type virus at year 1 but developed TAM at 3–3.5 years (D67N, K70R and K219Q; M41L, D67N, L210W, T215F/Y). Two of the six children who had received lamivudine/abacavir had only the M184V mutation by 3 and 5 years respectively (both received nelfinavir). The remaining four children had ‘non-TAM’ mutations by year 1 [L74V (n = 4), M184V (n = 4), K65R (n = 3), Y115F (n = 1), one also received nelfinavir], which were maintained in two children, lost in one child without other mutations (HIV-1 RNA 70,841 copies/ml, no documented interruptions in ART, also received nelfinavir) and replaced by TAM at 4.5 years in one child (D67N, K70R, K219Q, HIV-1 RNA 2106 copies/ml, no documented change in ART). Overall, the majority of children who received nelfinavir developed nelfinavir mutations by the first test and kept them or developed more over time.
There are very few randomized trials of combination ART in chronically HIV-infected, previously untreated children. Indeed, apart from the ongoing PENPACT 1 trial addressing questions about initial ART and switching strategies , PENTA 5 is the only such post monotherapy randomized trial to report from well-resourced countries. PENTA 5 was also the first trial in adults or children to report on the use of lamivudine/abacavir as part of a triple therapy regimen. Here we have demonstrated long-term sustained virological superiority of lamivudine/abacavir compared with either zidovudine/lamivudine or zidovudine/abacavir beyond 5 years. Further, the benefits from this regimen in terms of growth identified over the short-term appear to persist and even increase over time. Although nelfinavir is no longer a preferred first-line option in children, we do not consider there to be strong a priori reasons for qualitatively different results with the main choices available to paediatricians today (efavirenz, nevirapine, kaletra).
Only one child died and two developed AIDS over a median of nearly 5 years additional follow-up after week 48, all these events occurring within the first 3 years. The single death (from lymphoma) may not have been preventable with ART in any case. In accordance with the week 48 results , significant differences between the NRTI groups in terms of increases in CD4 percent were not apparent at 5 years; although adjustment for natural variation in absolute CD4 counts with age  suggested greater CD4 cell gains may have occurred in the lamivudine/abacavir group in line with changes in HIV-1 RNA and growth. Thus overall, in spite of differences in virological and growth outcomes, children appear to do well clinically and immunologically on all regimens.
Suppression of HIV-1 viral load was sustained at similar levels between 1 and 5 years and overall less than one-third of children switched to second-line therapy (three or more new drugs compared to the original regimen), lowest in the lamivudine/abacavir group. Further, in the lamivudine/abacavir group, only 22% had ever substituted or added one or more drugs at a time of incomplete viral suppression (HIV-1 RNA > 400 copies/ml) when resistance potentially could have arisen. There were also clear trends to longer use of this combination as dual NRTI and less use of other non-trial PIs and NNRTIs in this group. This is encouraging; also considering that nelfinavir is a relatively low potency PI with a high pill burden and relatively low acceptability by self-report from carers and children in PENTA 5 . Few data on rates of drug substitutions and switch to second-line therapy have been reported in paediatric cohort studies, although anecdotally rates appear to be lower than in adults, most likely due to a combination of more limited drug choices for children, innate conservatism among parents and paediatricians and the fact that children frequently maintain clinical and immunological benefit in the face of virological failure. In this study, more substitutions occurred for non-failure and non-toxicity reasons, reflecting clinical practice and particularly efforts to simplify therapy, which are often not captured in short-term trials.
The extended period of randomized treatment despite continuing viral replication in some children allowed a detailed exploration of resistance evolution according to NRTIs received in 16 children. These data suggest that the order and pattern of resistance may be dependent on the combinations of NRTI utilized, which in turn can potentially determine cross resistance patterns to other reverse transcriptase inhibitors. The most striking differences were observed between children on zidovudine/lamivudine and lamivudine/abacavir. In the former, the initial emergence of M184V was followed by thymidine analogue mutations, generally of the TAM-1 pathway. This is now a well-recognized pattern within clinical practice . By contrast resistance in the lamivudine/abacavir group was characterized by the initial appearance of M184V plus K65R and/or L74V. It has previously been observed that the poor fitness of viruses containing both 65 and 74 mutations explains the absence of such mutational patterns in clinical databases [19,20], and that these mutations are not found on the same genome . However, we observed the co-existence of these mutations in three children receiving this combination, as also described by Lanier et al. , although by consensus sequencing of plasma virus. It is interesting to speculate whether the co-existence of M184V in all three cases facilitated ongoing replication, although previous studies demonstrate the initial emergence of M184V and K65R on different genome . Nevertheless, the relative fitness disadvantage of such viruses may explain the modest viral load rebound observed for these children.
It is important to speculate on the relative risks and benefits of a lamivudine/labacavir combination; to what degree should the potential for emergence of such resistance patterns be counterbalanced by the clear virological advantages and improved growth with this combination for children, as demonstrated in this study? Phenotypic assessment of viruses containing K65R does indeed demonstrate extensive cross resistance to all nucleoside/nucleotide analogues other than zidovudine . However, more data regarding in vivo activity of non-zidovudine nucleoside analogues in the face of this mutation are required before developing evidence-based drug sequencing strategies. At the present time, the relative advantages of being infected with a virus containing extensive TAMs with M184V against one containing K65R, L74V and M184V remain unclear, and we consider that treatment regimens be guided by virological and clinical efficacy data.
Historically zidovudine has been preferred as a first-line NRTI. However abacavir has been added to the list of NRTI recommended for first-line therapy in the revised (2006) WHO guidelines  and is commonly used in Europe . Of all antiretrovirals, abacavir is one of the NRTIs with least effect on mitochondrial DNA [26,27], and, unlike zidovudine, has little haematologic toxicity which may be important in settings where malaria is common. In addition, toxicity rates to abacavir are likely to be lower in African compared with Caucasian children because of polymorphisms leading to less abacavir hypersensitivity in Africans, although clinical vigilance for the presence of hypersensitivity remains paramount. The rates of adverse reactions to abacavir were considerably lower than to nevirapine in African adults in a recently reported double-blind substudy of DART, the Nevirapine Or Abacavir (NORA) trial . Of additional value for adherence, abacavir and lamivudine can be given once daily; the PENTA 13 trial showed equivalent pharmacokinetics and continued viral load suppression in children over 3 years of age after switching from twice to once daily lamivudine and/or abacavir . Further lamivudine and abacavir are low volume, reasonably pleasant tasting liquids, whereas zidovudine liquid has higher volume and requires storage in brown glass containers because of light sensitivity. Simplifying ART for children and carers is an important objective in HIV management, and may be of particular value for children approaching teenage years. If fixed dose combination ‘baby tablets’ of abacavir/lamivudine could be made, this could add an important potent simple once-daily alternative to the inconvenient single liquid formulation NRTI drugs currently available for children in resource-limited settings. Five-year data suggest that lamivudine/abacavir is more effective in terms of virological response and increase in height and weight than zidovudine/lamivudine or zidovudine/abacavir and should be preferred as first-line NRTI backbone in triple therapy regimens.
We thank all the children, families and staff from all the centres participating in the PENTA 5 Trial.
H. Green, D.M. Gibb, A.S. Walker, D. Pillay, K. Butler, F. Candeias, G. Castelli-Gattinara, A. Compagnucci, M. Della Negra, A. de Rossi, C. Feiterna-Sperling, C. Giaquinto, L. Harper, J. Levy, Y. Saidi, U. Wintergerst.
Medical Research Council Clinical Trials Unit, UK
A. Babiker, L. Buck, J. Darbyshire, L. Farrelly, D.M. Gibb, H. Green, L. Harper, D. Johnson, P. Kelleher, A. Newberry, A. Poland, G. Wait, A.S. Walker.
INSERM SC10, France
J.P. Aboulker, A. Compagnucci, M. Debré, V. Eliette, S. Girard, S. Leonardo, Y. Saidi
Executive Committee for PENTA 5
J.P. Aboulker, A. Babiker, A. Compagnucci, J. Darbyshire, M. Debré, M. Gersten (Agouron), C. Giaquinto (chairperson), D.M. Gibb, W. Snowdon (GlaxoSmithKline)
PENTA Steering Committee
J.P. Aboulker, A. Babiker, S. Blanche, A.-B. Bohlin, K. Butler, G. Castelli-Gattinara, P. Clayden, J. Darbyshire, M. Debré, R. de Groot, M. Della Negra, D. Duicelescu, A. Faye, C. Giaquinto (chairperson), D.M. Gibb, C. Griscelli, I. Grosch-Wörner, C. Kind, M. Lallemant, J. Levy, H. Lyall, M. Marczynska, M.J. Mellado Peña, D. Nadal, C. Peckham, J.T. Ramos Amador, L. Rosado, C. Rudin, H. Scherpbier, M. Sharland, M. Stevanovic, P.A. Tovo, G. Tudor-Williams, N. Valerius, A.S. Walker, U. Wintergerst, V. Wahn.
PENTA 5 DSMC
C. Hill (chairperson), P. Lepage, A. Pozniak, S. Vella. Secretary R. Withnall
Belgium: Hôpital Saint Pierre, Brussels: J. Levy, M. Hainaut, A. Peltier, S. Carlier*, G. Zissis**.
Brazil: Instituto de Infectologia ‘Emilio Ribas’, São Paolo: M. Della Negra, W. Queiroz; Fleury Laboratories, São Paolo: L.P. Feitosa**, D. Oliveira**.
France: Centre Hospitalier Universitaire, Nantes: F. Mechinaud, V. Reliquet, F. Ballerau*, A. Lepelletier*, S. Billaudel**, V. Ferre**.
Germany: Virchow-Klinikum, Humboldt-Universität zu Berlin: I. Grosch-Wörner, R. Weigel, K. Seel, C. Feiterna-Sperling, D. Ohlendorf*, G. Riße*, C Müller**; Universitäts-Kinderklinik Düsseldorf: V. Wahn, T. Niehues, J. Ndagijimana, G. Horneff, S. Gudowius, N. Vente**; Universitäts-Kinderklinik Eppendorf, Hamburg: R. Ganschow, G. Englert. Universitat zu Köln: T. Simon, R. Vossen*, H. Pfister**; Universitäts-kinderkliniken, Munich: U. Wintergerst, G. Notheis, G. Strotmann, S. Schlieben.
Ireland: Our Lady's Hospital for Sick Children, Dublin: K. Butler, E. Hayes, M. O'Mara, J. Fanning*, F. Goggins*, S. Moriarty*, M. Byrne.
Italy: Ospedale Regionale di Bolzano: L. Battisti; Spedali Civili, Brescia: M. Duse, S. Timpano, E. Uberti, P. Crispino, P. Carrara, F. Fomia, R. Schumacher, A. Manca**; Ospedale Meyer, Florence: L. Galli, M. de Martino; Istituto G Gaslini, Genova: F. Fioredda, E. Pontali, R. Rosso; Ospedale Civile, Modena: M. Cellini, C. Baraldi, M. Portolani**, M. Meacci**, P. Pietrosemoli**; Università di Napoli ‘Federico II’: A. Guarino, M.I. Spagnuola, R. Berni Canani, V. Giacomet, P. Laccetti**, M. Gobbo**; Università di Padova: C. Giaquinto, V. Giacomet, R. D'Elia, O. Rampon, V. Balasso, A. de Rossi**, M. Zanchetta**; IRCCS Policlinico San Matteo, Pavia: D. Caselli, A. Maccabruni, E. Cattaneo**, V. Landini**; Ospedale Bambino Gesù, Rome: G. Castelli-Gattinara, S. Bernardi, A. Krzysztofiak, C. Tancredi, P. Rossi**, L Pansani**; Università degli Studi di Torino: E. Palomba, C. Gabiano; Ospedale S. Chiara, Trento: A. Mazza, G. Rossetti**; Ospedale S. Bortolo, Vicenza: R. Nicolin, A. Timillero.
Portugal: Hospital de Dona Estefania, Lisbon: L. Rosado, F. Candeias, G. Santos, M.L. Ramos Ribeiro, M.C. Almeida, M.H. Lourenço**, R. Antunes**
Spain: Instituto de Salud Carlos III, Madrid: M.J. Mellado Peña**, P.M. Fontenlos, ML Carillo de Albornoz*, P. Martinez Santos; Hospital Son Dureta, Palma de Mallorca: L. Ciria Calavia, J. Dueñas Morales, J. Serra Devecchi*, O. Delgado, N. Matamoros**.
UK: Bristol Royal Hospital for Sick Children, Bristol: A. Foot, H. Kershaw, C. Kelly*; PHL Regional Virus Laboratory, Bristol: O. Caul**; Ninewells Hospital and Medical School, Dundee: W. Tarnow-Mordi, J. Petrie, A. McDowell*, P. McIntyre**, K. Appleyard**; Ealing Hospital, Middlesex: K. Sloper, V. Shah, K. Cheema*, A. Aali**; Royal Edinburgh Hospital for Sick Children, J. Mok, R. Russell, A. Brewster*, N. Richardson*; City Hospital, Edinburgh: S. Burns**; Great Ormond St Hospital for Children NHS Trust, London: D. Gibb, V. Novelli. N. Klein, L. McGee, S. Ewen, J. Flynn, V. Yeung*; King's College Hospital, London: C. Ball, K. Himid, D. Nayagam, D. Graham, S. Hawkins, A. Barrie*, K. Stringer*, S. Jones*, N. Weerasooriya*, M. Zuckerman**, P. Bracken**; Newham General Hospital, London: D. Gibb, E. Cooper, T. Fisher, R. Barrie, S. Liebeschuetz, S. Wong, U. Patel* (deceased); Royal Free Hospital, London: V. Van Someren, K. Moshal, S. McKenna, L. Perry*, T. Gundlach**; St Bartholemew's Hospital, London: J. Norman**; St George's Hospital, London: M. Sharland, M Richardson, S. Donaghy, S. Storey, Z. Mitchla*, C. Wells*, J. Booth** (deceased), A. Shipp** D. Butcher**; St Mary's Hospital, London: G. Tudor-Williams, H. Lyall, J. White, S. Head, C. Walsh, C. Hanley, S. Campbell, S. Lambers*, K. O'Hara*; C. Stainsby**; St Thomas' Hospital, London: G. Du Mont, R Cross, T. Solanki*, S. Swanton*, S. O'Shea**, A. Tilsey**; University College London Medical School: S. Kaye**; Children's Hospital, Sheffield: A. Finn, S. Choo, R. Lakshman, J. Hobbs, L. Barr*; Sheffield Public Health Laboratory, Sheffield G Bell**, A. Siddens**.
Sponsorship: PENTA is a Concerted Action of the European Commission, supported by BIOMED 2 contact BMH4-CT96-0836 and Fifth Framework Program contract QLK2-2000-00150. The Medical Research Council provides support to the MRC HIV Clinical Trials Unit and the Agence Nationale de Recherche sur le Sida (ANRS) provides support for INSERM SC10. These two trials centres jointly coordinate the PENTA studies. Italian collaborating centres were supported by a grant from the Istituto Superiore di Sanità - Progetto Terapia Antivirale 2004, 2005; and those in Spain by a grant from Comunidad Autonoma de Madrid, Spain. PENTA activities are also supported by the PENTA Foundation. Glaxo-Wellcome provided lamivudine and abacavir, and Agouron provided nelfinvair and matching placebo. Both pharmaceutical companies also contributed funding for the co-ordination of the PENTA 5 trial.
1. Palella FJ, Delaney KM, Moorman AC, Loveless MO, Fuhrer J, Satten GA, et al
. Declining morbidity and mortality among patients with advanced human immunodeficiency virus infection. HIV Outpatient Study Investigators. N Engl J Med 1998; 338:853–860.
2. Gibb DM, Duong T, Tookey PA, Sharland M, Tudor-Williams G, Novelli et al
. Decline in mortality, AIDS, and hospital admissions in perinatally HIV-1 infected children in the United Kingdom and Ireland
3. Van Rossum AM, Fraaij PL, de Groot R. Efficacy of highly active antiretroviral therapy in HIV-1 infected children. Lancet Infect Dis 2002; 2:93–102.
4. Walker AS, Doerholt K, Sharland M, Gibb DM, Collaborative HIV Paediatric Study (CHIPS) Steering Committee. Response to highly active antiretroviral therapy varies with age: the UK and Ireland Collaborative HIV Paediatric Study. AIDS 2004; 18:1915–1924.
5. Bartlett J, Fath M, DeMasi R, Quinn J, Hermes A, Rousseau F. An updated meta-analysis of triple combination therapy in antiretroviral-naïve HIV-infected adults. Twelfth Conference on Retroviruses and Opportunistic Infections.
Boston, MA, February 2005 [abstract?].
6. Robbins GK, De Gruttola V, Shafer RW, Smeaton LM, Snyder SW, Pettinelli C, et al
, AIDS Clinical Trials Group 384 Team. Comparison of sequential three-drug regimens as initial therapy for HIV-1 infection. N Engl J Med 2003; 349:2293–2303.
7. van Leth F, Phanuphak P, Ruxrungtham K, Baraldi E, Miller S, Gazzard B, et al
. Comparison of first-line antiretroviral therapy with regimens including nevirapine, efavirenz, or both drugs, plus stavudine and lamivudine: a randomised open-label trial, the 2NN Study. Lancet 2004; 363:1253–1263.
8. Gallant JE, DeJesus E, Arribas JR, Pozniak AL, Gazzard B, Campo RE, Study 934 Group. Tenofovir DF, emtricitabine, and efavrienz vs. zidovudine, lamivudine, and efavirenz for HIV. N Engl J Med 2006; 354:251–260.
9. McKinney RE Jr, Johnson GM, Stanley K, Yong FH, Keller A, O'Donnell KJ, et al
. A randomised study of combined zidovudine-lamivudine versus didanosine monotherapy in children with symptomatic therapy-naïve HIV-1 infection. The Pediatric AIDS Clinical Trials Group Protocol 300 Study Team. J Pediatr 1998; 133:500–508.
10. Paediatric European Network for Treatment of AIDS (PENTA). A randomised trial to compare dual nucleoside-analogue reverse transcriptase inhibitor regimens (ZDV+3TC or ZDV+ABC or 3TC+ABC) with and without a protease inhibitor (nelfinavir) in previously untreated HIV-infected children: The PENTA 5 Trial
11. Gibb DM, Melvin A, Compagnucci A, McKinney R, Tudor-Williams G, Walker AS, et al.
on behalf of the PENPACT 1 Trial. Choice of first-line ART regimen in PENPACT 1: a randomized trial of combination antiretroviral regimens and treatment switching strategies in antiretroviral naive children >30 days and <18 years of age
. XV International Conference on AIDS.
Bangkok, July 2004 [abstract TuPeB4442].
12. Gibb DM, Walker AS, Kaye S, De Rossi A, Ait-Khaled M, Pillay D, et al
. Evolution of antiretroviral phenotypic and genotypic drug resistance in antiretroviral naïve HIV-1 infected children treated with abacavir/lamivudine, zidovudine/lamivudine or abacavir/zidovudine, with or without nelfinavir (the PENTA 5 trial). Antiviral Therapy 2002; 7:293–303.
13. Marschner IC, Betensky RA, DeGruttola V, Hammer SM, Kuritzkes DR. Clinical trials using HIV-1 RNA-based primary endpoints: Statistical analysis and potential biases. J Acquir Immune Defic Syndr 1999; 20:220–227.
14. Liang K-Y, Zeger SL. Longitudinal data analysis using generalized linear models. Biometrika 1986; 73:13–22.
15. Wade AM, Ades AE. Age related reference ranges: significance test for models and confidence intervals for centiles. Stat Med 1994; 13:2359–2367.
16. Freeman JV, Cole TJ, Chinn S, Jones PRM, White EM, Preece MA. Cross-sectional stature and weight references curves for the UK 1990. Arch Dis Child 1995; 73:17–24.
17. Gibb DM, Goodall RL, Giacomet V, McGee L, Compagnucci A, Lyall H, Paediatric European Network for Treatment of AIDS Steering Committee. Adherence to prescribed antiretroviral therapy in human immunodeficiency virus-infected children in the PENTA 5 trial. Pediatr Infect Dis J 2003; 22:56–62.
18. Cozzi-Lepri A, Ruiz L, Loveday C, Phillips AN, Clotet B, Reiss P, et al
, EuroSIDA Study Group. Thymidine analogue mutation profiles: factors associated with acquiring specific profiles and their impact on the virological response to therapy. Antiviral Therapy 2005; 10:791–802.
19. Deval J, Navarro JM, Selmi B, Courcambeck J, Boretto J, Halfon P, et al
. A loss of viral replicative capacity correlates with altered DNA polymerization kinetics by the human immunodeficiency virus reverse transcriptase bearing the K65R and L74V dideoxynucleoside resistance substitutions. J Biol Chem 2004; 279:25489–25496.
20. Sharma PL, Nurpeisov V, Lee K, Skaggs S, Di San Filippo CA, Schinazi RF. Replication-dependent 65R→K reversion in human immunodeficiency virus type 1 reverse transcriptase double mutant K65R + L74V. Virology 2004; 321:222–234.
21. Wirden M, Malet I, Derache A, Marcelin AG, Roquebert B, Simon A, et al
. Clonal analyses of HIV quasispecies in patients harbouring plasma genotype with K65R mutation associated with thymidine analogue mutations or L74V substitution. AIDS 2005; 19:630–632.
22. Lanier ER, Givens N, Stone C, Griffin P, Gibb D, Walker S, et al
. Effect of concurrent zidovudine use on the resistance pathway selected by abacavir-containing regimens. HIV Medicine 2004; 5:394–399.
23. Delaunay C, Brun-Vezinet F, Landman R, Collin G, Peytavin G, Trylesinski A, et al
. Comparative selection of the K65R and M184V/I mutations in human immunodeficiency virus type 1-infected patients enrolled in a trial of first-line triple-nucleoside analog therapy (Tonus IMEA 021). J Virol 2005; 79:9572–9578.
24. White KL, Margot NA, Ly JK, Chen JM, Ray AS, Pavelko M, et al
. A combination of decreased NRTI incorporation and decreased excision determines the resistance profile of HIV-1 K65R RT. AIDS 2005; 19:1751–1760.
25. World Health Organization. Antiretroviral therapy of HIV infection in infants and children in resource-limited settings, towards universal access: recommendations for a public health approach (2006 revision)
. Geneva: WHO; 2006.
26. Birkus G, Hitchcock JMH, Cihlar T. Assessment of mitochondrial toxicity in human cells treated with tenofovir: comparison with other nucleoside reverse transcriptase inhibitors. Antimicrob Agents Chemother 2002; 46:716–723.
27. Moyle G. Mechanisms of HIV and nucleoside reverse transcriptase inhibitor injury to mitochondria. Antivir Ther 2005; 10(Suppl 2):M47–M52.
28. Munderi P on behalf of the DART trial team. Safety of nevirapine compared to abacavir on a background of zidovudine/lamivudine as first-line antiretroviral therapy: a randomised double-blind trial
. Thirteenth Conference on Retroviruses and Opportunistic Infections.
Denver, CO, February 2006 [abstract 109LB].
29. Bergshoeff A, Burger D, Verweij C, Farrelly L, Flynn J, Le Provost M, et al
. Plasma pharmacokinetics of once- versus twice- daily lamivudine and abacavir: simplification of combination treatment in HIV-1 infected children (PENTA-13). Antiviral Ther 2005; 10:239–246.