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Manuscript Number: 207-698R1
Title: HIV-1 Drug Resistance in HIV-1-Infected Children in the United Kingdom from 1998 to 2004.
Short Title: Resistance in Paediatric HIV infection
Article Type: Original Studies
Keywords: Human Immunodeficiency Virus; Children; Genotyping; Antiretroviral Therapy; Resistant
Mutations.
Corresponding Author: Dr. Rana Chakraborty, MD DPhil (Oxon)
Corresponding Author's Institution: St George's Hospital
First Author: Rana Chakraborty, MD DPhil (Oxon)
Order of Authors: Rana Chakraborty, MD DPhil (Oxon); Colette J Smith; David Dunn; Hannah Green; Trinh
Duong; Katja Doerholt; Andrew Riordon; Hermione Lyall; Pat Tookey; Karina Butler; Caroline A Sabin; Di
Gibb; Deenan Pillay
Manuscript Region of Origin: UNITED KINGDOM
Abstract: Background
Estimates of the prevalence of HIV-1 drug resistance in children are important for assessing requirements
for available drug classes and modeling the spread of resistance. There is a paucity of relevant studies and
recommendations in this challenging group.
Methods
We therefore reviewed HIV-1 genotypes from 200/979 (20%) HIV-infected children in the UK CHIPS cohort
(343 resistance tests).
Results
3/44 samples had major primary resistance mutations before ART. The proportion of children with a
resistance test and HIV-1 VL > 1,000 c/ml increased over time (6% in 1998 - 23% in 2004). 3-class
resistance was noted in 42 samples (14.1%). 35 tests were performed in children with previous exposure to
HAART, but who had stopped treatment 13 (0.1-135) weeks previously. Mutations decreased significantly
with time off treatment (r=-0.4; p=0.02).
Conclusions
Our study highlights underutilization of resistance testing and the need for prompt genotyping after drug
discontinuation. This may lead to an underestimation of the burden of HIV-1 resistance. Care for HIV-1infected infants and children may be improved with larger surveillance data and child-specific guidelines for
resistance testing.
Suggested Reviewers:
Manuscript (Submitted as Word file including body, acknowledgments, references, and legend if applicable)
HIV-1 Drug Resistance in HIV-1-Infected
Children in the United Kingdom from 1998 to
2004.
Short Title: Resistance in Paediatric HIV infection
Rana Chakraborty1*, Colette J Smith2, David Dunn3, Hannah Green3, Trinh
Duong3, Katja Doerholt3, Andrew Riordon4, Hermione Lyall5, Pat Tookey6, Karina
Butler7, Caroline A Sabin2, Di Gibb3, Deenan Pillay8 on behalf of Collaborative
HIV Paediatric Study (CHIPS) and UK Collaborative Group on HIV Drug
Resistance
*Corresponding author
1 Paediatric Infectious Diseases Unit, St George’s Hospital, London
2 Department of Primary Care and Population Sciences, Royal Free and University College Medical School,
London
3. MRC (UK) Clinical Trials Unit, London
4. Royal Liverpool Children’s Hospital
5. St Mary's Hospital, London
6. Institute of Child Health, London
7. Our Lady's Children’s Hospital Crumlin, Dublin
8. Centre for Virology, Royal Free and University College Medical School, University College, London, and Centre for
Infections, Health Protection Agency, London
Potential conflicts of interest: none reported.
Funding sources: None
Key Words: Human Immunodeficiency Virus, Children, Genotyping, Antiretroviral
Therapy, Resistant Mutations.
1
Abstract
Background
Estimates of the prevalence of HIV-1 drug resistance in children are important for
assessing requirements for available drug classes and modeling the spread of
resistance. There is a paucity of relevant studies and recommendations in this
challenging group.
Methods
We therefore reviewed HIV-1 genotypes from 200/979 (20%) HIV-infected
children in the UK CHIPS cohort (343 resistance tests).
Results
3/44 samples had major primary resistance mutations before ART. The
proportion of children with a resistance test and HIV-1 VL > 1,000 c/ml increased
over time (6% in 1998 – 23% in 2004). 3-class resistance was noted in 42
samples (14.1%). 35 tests were performed in children with previous exposure to
HAART, but who had stopped treatment 13 (0.1-135) weeks previously.
Mutations decreased significantly with time off treatment (r=-0.4; p=0.02).
Conclusions
Our study highlights underutilization of resistance testing and the need for prompt
genotyping after drug discontinuation. This may lead to an underestimation of the
2
burden of HIV-1 resistance. Care for HIV-1-infected infants and children may be
improved with larger surveillance data and child-specific guidelines for resistance
testing.
3
Introduction
The treatment of human immunodeficiency virus type 1 (HIV-1) infection with
highly active antiretroviral therapy (HAART) significantly reduces the levels of
viral RNA in plasma and lymphoid tissue [1-3]. This reduction is associated with a
marked decline in HIV-1-related morbidity and mortality [4]. Failure to respond to
HAART with virological rebound may be associated with the emergence of drugresistant virus [5]. Viral gene sequence–based resistance testing or genotyping
may be used to guide subsequent treatment choices. More than 50 drug
resistance–associated mutations have been identified that, either alone or in
combination, confer variable resistance to one or more drugs within a specific
class [6]. Thus, HIV genotyping may serve as an important diagnostic tool for
optimizing therapy in individuals with drug-resistant infection [7].
Significant variations can influence the emergence of drug resistance–associated
mutations under selective pressure from HAART. These differences may reflect
high peak viral loads following primary infection, delayed attainment of virologic
set point during clinical latency in the first years following vertical transmission
[8], and transmission of HIV-1 with primary resistance to HAART [9]. It is
important to undertake population-based estimations of drug resistance in HIV-1infected infants and children.
4
The aims of this study were therefore to summarize the total number of
resistance tests performed on a large group of HIV-1-infected children and young
people in the UK within the Collaborative HIV in Paediatric Study (CHIPS) cohort,
and to document how the number of resistance tests undertaken for routine
clinical purposes changed over time. We investigated the proportion of samples
suggesting at least one major protease inhibitor (PI), non-nucleoside reverse
transcriptase inhibitor (NNRTI) or nucleoside reverse transcriptase inhibitor
(NRTI) mutation, or with documented resistance to all three main drug classes.
Finally, we calculated the prevalence of documented resistance as a proportion
of the number of children under follow-up who were receiving HAART and as a
proportion of the number under follow-up failing therapy.
5
Methods
Children and young people included in this study were participants in the UK and
Ireland Collaborative Paediatric HIV Study (CHIPS) cohort
[www.chipscohort.ac.uk]. This is a multi-centre cohort of HIV-1-infected children
including clinical, laboratory and treatment data on children from 43 centres,
representing around 85% of all HIV-1-infected children reported to the National
Study of HIV in Pregnancy and Childhood (NSHPC)
[http://www.bhiva.org/chiva/protocols/study.html]. Study methods have been
described elsewhere [10]. Age varied from under one to 20 years.
Children in CHIPS under follow-up in the UK between 1st January 1998 and
31st December 2004 were included to correspond with the dates at any time
point for which resistance tests were available. Children were defined as failing
HAART in a particular calendar year if they had at least one viral load
measurement during the year >1,000 copies/ml after receiving therapy for >16
weeks.
The proportion of samples and of HIV-1-infected children demonstrating
resistance to at least one of the three main drug (PI, NNRTI & NRTI) classes on
at least one occasion was estimated by year and stratified by whether the child
had ever received antiretroviral therapy at the time of the resistance test.
6
We considered at which time point during a child’s care the resistance test was
performed, concentrating on treatment status (naïve, currently receiving HAART,
not currently receiving therapy but with previous exposure to HAART) and the
association with individual drug mutations. This analysis was repeated, but to
only include those children who had been failing HAART during the year of
interest.
Information on resistance testing was obtained from the UK HIV Drug
Resistance Database, which consists of routinely performed HIV-1 drug
resistance tests in adults and children within the UK [11]. Resistance data were
matched to CHIPS subjects using patient identifiers, including clinic number and
date of birth. Resistance was defined as the detection of one or more major
mutations in the 2005 International AIDS Society-USA guidelines [12], plus
selected additional mutations (in reverse transcriptase, any mutation at G190 or
T215; in protease, V32I and I47V/A in combination, or seven or more minor
lopinavir mutations).
7
Results
Nine hundred and seventy nine children in the CHIPS cohort from the UK
received care between 1st January 1998 and 31st December 2004. Of these,
200 (20.4%) had at least one resistance test. 75% and 47% of children were of
black African ethnicity and born outside the UK, respectively. A diagnosis of
HIV infection had been established after birth in 85% of the cohort and had
occurred as a result of vertical transmission in nearly all infants and children.
A total of 343 resistance test results on the 200 children were available, with 129
(64.5%) having one resistance test result, 38 (19.0%) having 2 test results, 13
(6.5%) three tests and 20 (10.0%) between 4 to 8 tests. Of the 343 test results,
44 (12.8%) were from antiretroviral naïve- and 299 (87.2%) from antiretroviral
experienced children, respectively.
An increasing number of resistance tests were performed each year with the
greatest number in 2004 (n = 89). The number of tests performed in samples
from antiretroviral naïve subjects in 1998 was much higher than in any other year
(n = 26) reflecting recruitment into a clinical (PENTA) trial, with 5 tests performed
in 1999, 1-2 tests performed annually between 2000 to 2003, and 8 in 2004.
Underutilisation of drug resistance testing at the time of virological rebound
8
We next considered resistance tests at the time of virological failure, considering
the number of children who had a genotype performed when failing therapy
according to calendar year. In 1998, 9 (5.7%) of 159 children failing ART had a
resistance test performed [Figure 1]. This proportion gradually increased but by
2004 genotypes were still requested in only 23.3% (47 of 202) of HIV-1-infected
children failing therapy.
Drug resistance in ‘naïve’ children
Of the total of 44 tests performed in naïve children prior to the commencement of
HAART, the median (range) viral load and CD4 percentage at the time of the test
was 5.4 (4.0, 7.0) log copies/ml and 17% (0%, 39%) respectively. The median
(range) age of children at the time of the test was 4.9 (0.0, 17.0) years. Three
samples (6.8%) contained major primary resistance mutations to NRTI’s and also
to NNRTI’s in one child. None of the biological mothers of the three children had
documented evidence of antenatal prophylaxis with ART to reduce vertical
transmission.
Resistance in treated children
When considering the resistance tests performed in antiretroviral experienced
children, the percentage of samples containing at least one major NRTI mutation
peaked in 1999 and maintained a sustained decline thereafter perhaps reflecting
better virologic control with HAART [Figure 2]. The percentage of samples with at
least one major PI mutation peaked in 2000 but decreased in subsequent years
9
until 2004 perhaps reflecting the introduction of protease inhibitors with ritonavir
boosting [Figure 2]. The percentage of samples with at least one major NNRTI
mutation steadily increased between 1998 -2003. This trend may reflect the
increased use of these drugs as first-line therapy and the rapid emergence of
class resistance to these drugs during transient or sustained suboptimal
adherence [Figure 2]. Two hundred and sixty four resistance tests were
performed in children with on-going HAART exposure; 35 tests were performed
in children not currently receiving therapy but with previous exposure to HAART.
Forty samples had virus that demonstrated resistance to NRTIs only (13.4%), 6
to PIs only (2.0%), and 41 to NNRTIs only (13.7%). Forty-seven samples
demonstrated resistance to PIs and NRTIs (15.7%), 3 to PIs and NNRTIs (1.0%),
and 83 to NNRTIs and NRTIs (27.8%). Three-class resistance was found in 42
samples (14.1%) [Figure 3]. Thirty seven samples had no documented major
mutations identified (12.4%).
Of the 299 samples taken in ART-experienced patients, 76 (25.4%) were
performed in teenagers (aged 13 years or older). There were differences in the
observed resistance mutations in teenagers compared to adults, perhaps related
to a longer potential ART-exposure time amongst older children. 30 (13.5%), 51
(22.9%), 110 (49.3%) and 32 (14.4%) of those aged <13 years had evidence of
resistance to 0, 1, 2 and 3 drug classes, respectively. For the teenagers, these
figures were 7 (9.2%), 36 (47.4%), 23 (30.3%) and 10 (13.2%) respectively.
10
Major drug class mutations in 264 tests among children receiving HAART
Of the 264 tests performed in children receiving HAART, the median (range) viral
load and CD4 percentage at the time of the test was 4.3 (1.7, 6.0; 20 with a
missing viral load) log copies/ml and 20% (0%, 56%; 25 missing) respectively.
Children had been exposed to a median (range) of 5 (1, 15) drugs; 187 (70.8%)
had received at least one PI and 188 (71.2%) at least one NNRTI. The median
(range) length of exposure to ART at the time of the test was 3.8 (0.1, 12.7)
years. The median (range) age at the time of the test was 9.6 (0.5, 20.1) years.
The most common NRTIs that children had ever been exposed to were
lamivudine (219; 83.0%), zidovudine (204; 77.3%), stavudine (178; 67.4%),
didanosine (173; 65.5%), abacavir (113; 42.8%) and tenofovir (34; 12.9%). One
hundred and thirty seven children had previously received nevirapine (51.9%)
and 77 (29.2%) efavirenz. The most commonly prescribed PIs included nelfinavir
(168; 63.6%), ritonavir (76; 28.8%), lopinavir (57; 21.6%) and saquinavir (19;
7.2%).
The most common specific mutations detected on the RT gene included M41L
(75 samples; 28.4%), D67N (81; 30.7%), K70R (57; 21.6%), M184I/V (97;
36.7%), L210W (51; 19.3%), K219Q (34; 12.9%), K103N (68; 25.8%) and
Y181C/I (83; 31.4%). For the 215 position, 69 samples had the Y mutation, 29
the F mutation, 5 the I mutation, 2 the N mutation, and one sample each for H, X
and C. For the 190 position, 50 samples had the A mutation, 5 the S mutation, 3
11
the E mutation and 1 sample had the N mutation. The most commonly detected
specific mutations on the protease gene included D30N (29; 11.0%), M46I/L (43;
16.3%) and L90M (39; 14.8%).
Major drug class mutations in 35 tests among children with previous but not
current exposure to HAART
Of the 35 tests performed in HIV-1-infected children not currently receiving
therapy but with previous exposure to HAART, the median (range) viral load,
CD4 percentage and age at the time of the test was 4.6 (2.7, 6.4) log copies/ml,
19% (1%, 38%) and 10.5 (0.3, 20.2) years respectively. Children had been
exposed to a median (range) of 5 (1, 11) drugs; 17 had received at least one PI
(48.6%) and 20 at least one NNRTI (57.1%). The median (range) length of
exposure to ART at the time of resistance testing was 4.2 (0.1, 9.7) years.
The most commonly observed specific mutations on the RT gene included
M41L (25.7%), D67N (17.1%), M184I/V (22.9%), L210W (17.1%) and Y181C/I
(22.9%). Mutations observed on the protease gene were M46I/L (5.7%),
V82A/F/T/S/L (2.9%) and L90M (2.9%).
The median (range) time from stopping all HAART to the time of the resistance
test was 13.6 (0.1, 135.1) weeks. As the time from stopping therapy to the time of
the resistance test increased, the number of drug-related mutations detected
decreased with a correlation coefficient of -0.40 (p=0.02; [Figure 4]), highlighting
12
the need to perform resistance tests immediately after drug discontinuation to
ensure clinical utility.
13
Discussion
There are over 20 available antiretroviral drugs from 4 classes to treat HIV-1infected infants and children using triple or quadruple-combination HAART.
Drug resistance commonly occurs secondary to a number of factors that are
distinct from HIV-1-infected adults receiving HAART, and tend to be most
prominent in the youngest children. These include a lack of age-appropriate
formulations; a paucity of pharmacokinetic, safety and efficacy data resulting in
sub-therapeutic concentrations of active drug within plasma; high peak viral loads
and prolonged time to attain a virologic set point during clinical latency in the first
few years following vertical transmission [8], and transmission of HIV-1 with
primary resistance as a result of maternal treatment/prophylaxis [9]. These
concerns were highlighted by Menson and co-workers who documented
considerable under-dosing of antiretrovirals in the UK and Ireland based on
current best evidence in HIV-infected infants and children [13]. Poor adherence is
often further compromised during adolescence [14]. Resistance to a drug may
result in cross-resistance to other drugs within the same class, thereby limiting
the long-term efficacy of treatment and future therapeutic options [15]. These
difficulties highlight the importance of population-based surveys of drug
resistance during childhood and adolescence. The CHIPS database represents a
resource for audit and clinical research reflecting the largest published study of
HIV-1 drug resistance in paediatrics using single test results per calendar unit, in
a treatment-experienced population.
14
Our study may underestimate the burden of HIV-1 resistance in the treated
population. Only 21% of those with a detectable viral load measurement whilst
receiving HAART had a resistance test undertaken. Resistance testing is rarely
requested in infants and children with detectable viral load who eventually do not
switch therapy. Not all resistance tests may have been included in the final
analysis because of a failure to match records due to inaccurate identifiers.
Furthermore resistance may emerge at viral loads below the levels required for
successful testing [16]. In addition, among those who stopped therapy prior to
their resistance test, the median time from stopping all HAART to the time of the
resistance test was 13.6 weeks. As this period increased, the number of drugrelated mutations detected decreased, contributing further to an underestimation
of resistance prevalence in this population. This observation highlights the need
for clinicians caring for HIV-1-infected children to request resistance tests
immediately after drug discontinuation before potential reversion to wild type
virus as the major species.
Genotypic resistance evaluation has become standard of care according to most
current guidelines on ART management when changing therapy in HIV-infected
adults failing HAART [5, 17]. The British HIV Association (BHIVA) recommends
resistance testing at the time of switching therapy in treatment-experienced
patients, and also recommends testing at the time of HIV diagnosis and at the
time of commencing HAART [http://www.bhiva.org/].This is despite variable
evidence from randomized trials comparing the subsequent virological response
15
following ART change guided by HIV resistance testing compared with regimens
selected by antiretroviral exposure history [18, 19]. Guidelines on resistance
testing in HIV-1-infected infants and children are limited by a paucity of studies
reflecting smaller cohort sizes, and no trials apart from PERA - which
demonstrated no virological benefit from regimens selected after resistance
testing [20]. This cohort review cannot assess the potential benefit of genotyping
in antiretroviral-experienced infants and children compared to regimens selected
by antiretroviral exposure history. However given the overall increase in
prevalence of HIV-1 resistance mutations an extrapolation of BHIVA guidelines
on HIV resistance to HIV-1-infected infants and children could be considered.
This is reflected in the increased prevalence of primary HIV-1 resistance
mutations among HIV-1- infected adults [11] and the detection of primary
mutations in vertically-infected infants born to mothers with antiretroviral
exposure [9]. Detection of primary HIV-1 resistance mutations in 3 infants from
this study lends support for resistance testing in all newly diagnosed infants. This
last observation contrasts with findings from our group which reported in 2002
that no primary HIV-1 resistance mutations were detected at baseline in protease
or RT among 113 children [21].
Extensive 3-class resistance was noted in a significant proportion of resistance
tests (12%), which is higher than the level observed in adults in the UK
(approximately 5%) [22], and may limit future therapeutic options for adolescents
being transferred to adult clinics. Resistance to NRTIs may reflect exposure to
16
these drugs as mono- or dual therapy prior to 1997 before combination HAART
became the standard of care. Resistance to NNRTIs reflect the relatively rapid
emergence of class resistance to these drugs compared to boosted PIs during
transient suboptimal adherence. Common mutations detected included Y188C/I,
K103N and G190any, which can all induce pan-class resistance, and can be
transmitted as primary mutations if break-through vertical transmission occurs
following maternal or infant exposure to nevirapine. Common PI-associated
mutations in treatment-experienced children included D30N and L33F, which are
associated with resistance to nelfinavir and ritonavir and may reflect increased
usage of unboosted PIs just after combination HAART became the standard of
care [23]. M46I/F, V82/A/F/T/S/L and L90M are associated with resistance to
lopinavir, amprenavir and atazanavir; these drugs were more commonly
prescribed from 2002.
Management of HIV-1-infected children will become increasingly complex as
more children develop extensive multi-class resistant viruses. These concerns
may be addressed with larger paediatric surveillance studies and the
development of guidelines on resistance testing. We recommend that resistance
testing is obtained in all newly diagnosed children regardless of age at diagnosis
and whether or not their mother received ART during pregnancy. In addition, as
for HIV-infected adults, testing should be considered during virological failure.
17
18
19
20
Figure 4 – Number of major IAS mutations observed in each resistance test
sample taken after the child had stopped antiretroviral therapy, according to the
time since ART was stopped
Number of resistance mutations
9
8
7
6
5
4
3
2
1
0
0
12
24
36
48
60
72
84
96
108 120 132 144
Time from stopping ART to resistance test
21
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24
ACKNOWLEDGEMENTS
We would like to thank AS Walker, Ali Judd and CS Peckham for their comments on the paper.
Committees and participants (in alphabetical order):
CHIPS Steering Committee: K Butler, K Doerholt, S Donaghy, DT Dunn, T Duong, DM Gibb,
A Judd, EGH Lyall, J Masters, E Menson, V Novelli, CS Peckham, A Riordan, M Sharland, D
Shingadia, PA Tookey, G Tudor-Williams, G Wait
MRC Clinical Trials Unit: DT Dunn, T Duong, L Farrelly, DM Gibb, D Johnson, A Judd, G
Wait, AS Walker
National Study of HIV in Pregnancy & Childhood, Institute of Child Health: J Masters,
CS Peckham, PA Tookey
We thank the staff, families & children from the following hospitals who participate in
CHIPS (in alphabetical order):
Republic of Ireland: Our Lady's Children’s Hospital Crumlin, Dublin: K Butler, A Walsh.
UK: Birmingham Heartlands Hospital, Birmingham: Y Heath, J Sills; Blackpool Victoria
Hospital, Blackpool: N Laycock; Bristol Royal Hospital for Children, Bristol: A Finn, A Foot,
L Hutchison; Central Middlesex Hospital, London: M Le Provost, A Williams; Chase Farm
Hospital, Middlesex: I Pollock; Chelsea and Westminster Hospital, London: D Hamadache,
EGH Lyall, P Seery; Ealing Hospital, Middlesex: V Shah, K Sloper; Glasgow Royal
Hospital for Sick Children, Glasgow: C Doherty, R Hague; Great Ormond St Hospital for
Children, London: M Clapson, S Fasolo, J Flynn, DM Gibb, N Klein, K Moshal, V Novelli, D
Shingadia; Hillingdon Hospital, London: A Kakoo; Homerton University Hospital, London:
D Gurtin; John Radcliffe Hospital, Oxford: A Pollard, S Segal; King's College Hospital,
London: C Ball, S Hawkins, D Nayagam; Leeds General Infirmary, Leeds: P Chetcuti;
Leicester Royal Infirmary, Leicester: M Green, J Houghton; Luton and Dunstable
Hospital, Luton: M Connan, M Eisenhut; Mayday University Hospital, Croydon: J
Baverstock, J Handsforth; Milton Keynes General Hospital, Milton Keynes: PK Roy;
Newcastle General Hospital, Newcastle: J Clarke, K Doerholt, C Waruiru; Newham General
28
Hospital, London: C Donoghue, E Cooper, S Liebeschuetz, S Wong; Ninewells Hospital
and Medical School, Dundee: T Lornie; North Manchester General Hospital, Manchester:
C Murphy, T Tan; North Middlesex Hospital, London: J Daniels, EGH Lyall, B SampsonDavis; Northampton General Hospital, Northampton: F Thompson; Northwick Park
Hospital, Middlesex; M Le Provost, A Williams; Nottingham City Hospital, Nottingham: D
Curnock, A Smyth, M Yanney; Queen Elizabeth Hospital, Woolwich: W Faulknall, S Mitchell;
Royal Belfast Hospital for Sick Children, Belfast: S Christie; Royal Edinburgh Hospital
for Sick Children, Edinburgh: J Mok; Royal Free Hospital, London: S McKenna, V Van
Someren; Royal Liverpool Children’s Hospital, Liverpool: C Benson, A Riordan; Royal
London Hospital, London: B Ramaboea, A Riddell; Royal Preston Hospital, Preston: AN
Campbell; Sheffield Children's Hospital, Sheffield: J Hobbs, F Shackley; St George's
25
Hospital, London: R Chakraborty, S Donaghy, R Fluke, M Sharland, S Storey, C Wells; St
Mary's Hospital, London: D Hamadache, C Hanley, EGH Lyall, G Tudor-Williams, C Walsh,
S Walters; St Thomas' Hospital, London: R Cross, G Du Mont, E Menson; University
Hospital Lewisham, London: D Scott, J Stroobant; University Hospital of North
Staffordshire, Stoke On Trent: P McMaster; University Hospital of Wales, Cardiff: B O'
Hare; Wexham Park, Slough: R Jones; Whipps Cross Hospital, London: K Gardiner;
Whittington Hospital, London: H McKinnon.
UK Collaborative Group on HIV Drug Resistance Steering Committee
Sheila Burns, Royal Infirmary of Edinburgh; Sheila Cameron, Gartnavel General Hospital,
Glasgow; Patricia Cane, Health Protection Agency, Porton Down; Ian Chrystie, Guy’s and St.
Thomas’ NHS Foundation Trust, London; Duncan Churchill, Brighton and Sussex University
Hospitals NHS Trust; Valerie Delpech, Deenan Pillay, Health Protection Agency-Centre for
Infections London; David Dunn, Esther Fearnhill, Hannah Green, Kholoud Porter, MRC
Clinical Trials Unit,* London; Philippa Easterbrook, Mark Zuckerman, King’s College Hospital,
London; Anna Maria Geretti, Royal Free NHS Trust, London; Paul Kellam, Deenan Pillay,
Andrew Phillips, Caroline Sabin, Royal Free and University College Medical School, London;
David Goldberg, Health Protection Scotland, Glasgow; Mark Gompels, Southmead Hospital,
Bristol; Antony Hale, Leeds Teaching Hospitals NHS Trust; Steve Kaye, St. Marys Hospital,
London; Andrew Leigh-Brown, University of Edinburgh; Chloe Orkin, St. Bartholemews
Hospital, London; Anton Pozniak, Chelsea & Westminster Hospital, London; Gerry Robb,
Department of Health, London; Erasmus Smit, Health Protection Agency, Birmingham
Heartlands Hospital; Peter Tilston, Manchester Royal Infirmary; Ian Williams, Mortimer Market
Centre, London.,
* Coordinating Centre
26
Responses to Reviewers
Paediatric Infectious Diseases
5th Floor, Lanesborough Wing
Rana Chakraborty
Consultant Paediatrician
St George’s Hospital
Blackshaw Road
London
SW17 0QT
Phone: 020 8725 3262
Fax: 020 8725 1208
Email: [email protected]
Tuesday, November 20, 2007
Dear Dr McCracken and Dr Nelson
Re: PIDJ - MS Submission 207-698
Thank you for accepting the above manuscript for publication in PIDJ. Naturally we are delighted that
the reviewers and editors find this a topical and important subject to inform the readership. We
have submitted changes to the manuscript to reflect the very helpful suggestions of the reviewers.
In addition a ‘point by point’ response is supplied in this correspondence.
Yours sincerely,
Rana Chakraborty MD, MSc, FAAP, FRCPCH, D.Phil (Oxon)
St George’s Healthcare NHS Trust Incorporating: St George’s Hospital, Bolingbroke Hospital, Wolfson Rehabilitation Centre
Chairman: Naaz Coker Chief Executive: David Astley
Reviewer # 1:
1. Within the age range of children found to have mutations on therapy is there any skewing
eg are adolescents - where adherence is more of an issue - more likely to have mutations?
On P.10 and 11 we have added the following paragraph: ‘Of the 299 samples taken in ART-experienced
patients, 76 (25.4%) were performed in teenagers (aged 13 years or older). There were differences in the
observed resistance mutations in teenagers compared to adults, perhaps related to a longer potential ARTexposure time amongst older children. 30 (13.5%), 51 (22.9%), 110 (49.3%) and 32 (14.4%) of those aged <13
years had evidence of resistance to 0, 1, 2 and 3 drug classes, respectively. For the teenagers, these figures
were 7 (9.2%), 36 (47.4%), 23 (30.3%) and 10 (13.2%) respectively’.
2. The legend to figure 4 is rather misleading and should be corrected.
The legend now reads: ‘Number of major IAS mutations observed in each resistance test sample taken after the
child had stopped antiretroviral therapy, according to the time since ART was stopped’
St George’s Healthcare NHS Trust Incorporating: St George’s Hospital, Bolingbroke Hospital, Wolfson Rehabilitation Centre
Chairman: Naaz Coker Chief Executive: David Astley
Reviewer # 2:
1. p. 9 - They give us too much detail on the resistance patterns in those 3 children (p.9),
given the inherent randomness in a sample size of 3.
rd
We have removed the following sentences from the 3 paragraph on this page ‘Two samples from antiretroviral
naïve children in 2002 both demonstrated resistance to NRTIs; one sample from 2004 demonstrated resistance
to both NNRTIs and NRTIs. Mutations included the M184I/V mutation in reverse transcriptase and the Y188L
mutation in a 19- week old infant previously naïve to HAART. The M184I/V, the T215C and the K219E
mutations were detected in a second 2 year-old toddler. The T215I mutation was also detected in a third infant
aged 8 weeks’.
2. p. 12 - There's too much detail on resisatnce patterns in children previously treated with
HAART.
The relevant paragraph on P.9 has been shortened considerably into one paragraph and now reads: ‘Of the
total of 44 tests performed in naïve children prior to the commencement of HAART, the median (range) viral
load and CD4 percentage at the time of the test was 5.4 (4.0, 7.0) log copies/ml and 17% (0%, 39%)
respectively. The median (range) age of children at the time of the test was 4.9 (0.0, 17.0) years. Three samples
(6.8%) contained major primary resistance mutations to NRTI’s and also to NNRTI’s in one child. None of the
biological mothers of the three children had documented evidence of antenatal prophylaxis with ART to reduce
vertical transmission’.
3. p. 13 - The discussion runs a bit long
The following sentences/paragraphs have been removed:
‘…adversely impacting on survival’…
‘….are accentuated in an HIV-1-infected infant facing a lifetime of treatment and’…
….’However, this is a relatively small sample size compared to equivalent reports from HIV-1-infected adults.
Studies with a larger number of participants may be required to assess significant differences in the frequency of
mutations between HIV-1-infected children and their adult counterparts, particularly if analyzed according to
age-group within childhood. The impact of viral subtype and secondary minor mutations on RT and protease
genotype was not assessed in this study’….
….’It is important to recognize that’….
..’reflecting an underutilization of this resource’….
..’the only randomized study performed in children’…
….’also had the longest follow-up’…
…’but the choice of regimens available at the time and the way paediatricians may have used the test results
may have contributed to this negative outcome’…
…..’This may account for the underutilization of resistance testing by clinicians caring for children’…
…..’The M184V mutation may confer clinical benefit and suppress replication in children during salvage therapy
by inducing less-fit virus [23]’…..
…..’Common mutations detected included the thymidine analogue mutations (M41L, D67N, K70R, L74V,
L210W and K219Q/E) and M184V’….
….’secondary to the increased presence of primary resistant mutations and overall estimated prevalence of
antiretroviral resistance’….
Reference 23 was therefore removed - Frenkel LM, Burchett SK, Aldrovandi GM et al. HIV-1 reverse
transcriptase (RT) M184V/I improves the rate of suppression of viral replication by salvage therapy. Abstract
463, 8th Conference on Retroviruses and Opportunistic Infections, Chicago, February 4 – 8.
Thank you.
St George’s Healthcare NHS Trust Incorporating: St George’s Hospital, Bolingbroke Hospital, Wolfson Rehabilitation Centre
Chairman: Naaz Coker Chief Executive: David Astley