Bridging the Gap: Conference Record [Abstract book, International Conference on AIDS (12th: 1998: Geneva, Switzerland)]

12th World AIDS Conference

Abstracts 32302-32306 581

Method: Genotypic HIV drug resistance assay was performed using plasma
HIV RNA. Protease and reverse transcriptase (RT) genes were ampified by PCR
in order to be sequenced. These pts were included in a randomized pilot study
(VIRADAPT) in order to adapt the antiretroviral treatment according to genotypic
mutations.
Results are presented in the table.
Conclusions: Only 10% of pts had no major mutation on the RT gene. On the
contrary, 46% of pts had no genotypic evidence of protease resistance. Nevertheless significant polymorphism was observed in protease gene sequences with
predominant substitutions occurring at amino acid residues 10, 12, 13, 15, 35, 36,
37, 54, 63, 64, 71, 77, 93,... The usefulness of genotypic resistance determination
in treatment adaptation is currently evaluated.
S32302 1 Resistance related mutations in HIV-1 pol gene of
patients treated with a combination of ritonavir and
saquinavir (ANRS 069 pilot study)
Annick Ruffault1, C. Arvieux2, I. Renard1, E. Belli Ssant3, J.F. Delfra Issy4,
O. Guist 'Hau1, C. Michelet2. 1Laboratoire Virologie Chru Pontchaillou, 35033
Rennes Cedex 9; 2Clinique des Maladies Infectieuses, Rennes; 3Laboratoire de
Pharmacologie Rennes; 4 Hopital du Kremlin-Bicetre, Paris, France
Objective: To define the genotypic resistance pattern following prolonged therapy with the association of ritonavir and saquinavir in patients pre-treated and
continuing AZT and 3TC.
Patients and Method: Sixteen patients naive of protease inhibitor (PI), pretreated with various nucleoside analogs and at least 3 months of AZT-3TC, were
treated with a combination of saquinavir and ritonavir and followed until week
(W) 48. HIV RNA PCR Roche Amplicor (<50 copies/ml), Murex line probe HIV-1
reverse transcriptase (RT) assay on plasma samples and sequencing of the protease domain on plasma and PBMC were performed at baseline and at W24/28,
36 and 48.
Results: Baseline values were: mean CD4 103 ~ 60/mm3 and mean viral
load (VL) 4.86 loglo copies/ml. Median HW RNA decrease was 2.95 logo1 (range
0-3.68). Eight patients had VL < 50 copies/ml at W48 (8 out of 12 compliant patients). At baseline, different mutations associated to RT-inhibitors were observed
in 15 out of 16 patients (codon 41, 69/70, 74, 184 and 215). Return to wild type
was seen in 5 out of 12 patients for whom amplification of plasma was possible
at W24-36 and W48, at codon 41 (2 patients), 69/70 (2), 184 (1) and 215 (1).
At baseline, a high degree of polyporphism was observed in the protease gene
for all 16 patients in comparison to consensus sequence (HXB2). Under treatment
with PI, some of these mutations in plasma returned to the consensus sequence.
Only 3 substitutions corresponding to known PI resistance profile appeared in 3
patients, at W28 (184V) or W48 (1541/V, V82A/V): two patients were non compliant with VL > 5.5 loglo copies/ml at W24 and one other had a therapeutic
discontinuation for several weeks.
Conclusion: This study (i) confirms a high level of genetic diversity of HIVprotease gene derived from PI naive patients (ii) shows a long term and strong
efficacy of the ritonavir-saquinavir combination in patients with genotypic resistance to AZT and 3TC (iii) lack of emergence of protease mutations in patients
with complete suppression of viremia.
S32303 Viral resistance in a randomised trial comparing cyclical
and concurrent therapy for HIV infection
Richard S. Tedder. On Behalf of the QUATTRO Trial Steering Committee; Dept.
of Virology, Windeyer Building, University College Med. School, 46 Cleveland
St., London, UK
Background: Changes in viral load and sensitivity were measured in a randomised open trial comparing zidovudine (AZT) plus lamivudine (3TC) plus
loviride (LVR) plus zalcitabine (ddC) given concurrently (QT4) or cyclically (QC4:
each drug for 8 weeks in the above order) with AZT plus 3TC (QT2) for a total of
64 weeks. Population and methods: 100 (34 QT4, 34 QC4, 32 QT2) participants
were recruited and HIV RNA and CD4 measured at baseline, every 4 weeks
up to 32 weeks and then every 8 weeks (plus 2 weeks after the start of each
cycle). Viral resistance populations (RVPs) were measured using a point mutation
assay (PMA) for codons 69/74 (ddC), 181 (LVR), 184 (3TC), 41/70/215 (AZT) and
expressed as % of viral populations mutated at each codon. Phenotypic assays
were undertaken in a subset. Analyses were based on intent to treat.
Results: QT4 had the best and most sustained effect on viral load and CD4
count. QC4 had the worst initial response but by 64 weeks was not significantly
different from the QT2. Codons 69 and 181: at 32 and 64 weeks a few carried
minor RVPs (4-50%). Codon 215: dominant RVPs (>50%) were seen in 10%
QT4, 10% QC4, 29% QT2 at 32 weeks and 31% QT4, 17% QC4, 25% QT2 at
64 weeks. Codon 184: dominant RVPs were commonly seen, but least common
in QC4; at 32 weeks in 88% QT4, 44% QC4, 88% QT2 and at 64 weeks in 96%
QT4, 76% QC4, 88% QT2. Mutations at 184 appeared rapidly after initiation of
3TC, declined in QC4 when 3TC was stopped, increasing rapidly when it was
given again. Studies to explore the emergence of mutations associated with AZT

in QC4, the relationship between genotypic and phenotypic assays and the 64
week RT sequence are ongoing and will be reported including analyses restricted
to time on treatment.
Conclusion: The study provides unique comparative data on the kinetics of
viral response to short periods of monotherapy with RT inhibitors which have
implications for the selection of therapies in patients who have already received
them.

S32304 Genotypic resistance patterns in HIV-infected naive
patients receiving a four-drug combination therapy
Alain M. Lafeuillade1, C. Poggi2, L. Chollet2, G. Hittinger3, M.P. Pradie2,
N. Profizi2. 1 Unite Infectiologie, Hopital Chalucet, Toulon; 2Hopital Toulon-La
Seyne, La Seyne Sur Mer; 3Hopital Chalucet, Toulon, France
Objectives: to assess the evolution of genotypic resistance patterns present in
plasma, PBMC and lymph node cells (LNMC) of 18 naive patients receiving a
four-drug regimen.
Design: open pilot study for 6 months with extended phases to 12 and 18
months.
Methods: patients were treated with ZDV + ddl + 3TC + Saquinavir at standard
doses. The RT gene from plasma RNA was analysed using the LiPA before
therapy. RT and Protease (PR) genes from PBMC and LNMC proviral DNA were
sequenced before and 6-18 months after therapy. 54 PBMC samples and 26
LNMC samples have already been analysed.
Results: CD4+ T cell count was 277 ~ 42/p L and plasma RNA was 5.1 ~ 0.15
log copies/ml at baseline. Plasma RNA dropped <200 copies/mi within 6 months
in each case (<20 copies/ml in 75% cases). Only 1 patient showed a mutation
(M41L) associated with RTI resistance at baseline in PBMC and plasma. In 13/18
cases M41L (13) and/or T215Y (10) mutations were detected in PBMC and/or
LNMC within 6-12 months after initiating therapy. In the 3 patients analysed so
far at baseline in LNMC by LiPA and DNA sequencing, minor viral populations
with mutations conferring resistance to RTI have been detected. Subsequent
analyses after 12-18 months of quadruple therapy showed that these mutations
were no longer found in PBMC of patients with prolonged response. No evolution
of mutations found in the PR gene was observed during the trial; most patients
already having L101, M361 and L63P mutations at baseline.
Conclusion: Analysing proviral DNA in patients with long-term control of HIV
replication can show the selection of viral mutants already present in LNMC before
therapy and their detection in PBMC. Continuing the same regimen demonstrates
that they do not predict subsequent drug failure but reflect progressive effect on
different proviral pools. Plasma RNA sequencing is in progress in 2 cases who
stopped all drugs after 20 months.
S32305 1The clinical utility of viral genotyping in HIV+ patients
failing protease inhibitor-based highly active
antiretroviral therapy
Ross Hewitt1, L.D. Esch2, A.E. Esch2, M.J. Shelton2, G.D. Morse2. 1462 Grider
St. Buffalo, NY; 2Suny at Buffalo, NY, USA
Objective: To determine the clinical utility of viral genotyping in patients (pts)
failing protease inhibitor-based highly active antiretroviral therapy (HAART)
Design: Retrospective chart review
Methods: We examined 68 genotype results from 64 patients from 5/97 to
11/97 and observed whether the pts' antiretroviral regimens were changed subsequent to receiving genotype results and whether pts experienced a virologic
response. Response was defined as a decrease in HIV-RNA of at least 1 log on
the new regimen. Pts were categorized as either responders or non-responders.
The number and type of specific protease gene mutations was correlated with
response.
Results: 11 samples were unable to be amplified. The HAART regimen was
changed after reviewing the results of 37/57 remaining genotypes. 9/37 pts have
no virologic follow-up, leaving 28 evaluable: 13 (42%) responded >4 weeks. 5/13
(42%) responders had at least a 2 log decrease in HIV-RNA. Mean baseline
HIV-RNA for responders (127,000, range 19,000-509,000) was not different (p =
NS) for non-responders (254,000, range: 27,000-630,000). 8 responders and 7
non-responders had none or 1 protease inhibitor (PI) gene mutation. 5 responders
and 8 non-responders had >2 PI mutations. 3 responders and 9 non-responders
had a codon 90 mutation (p < 0.05). 11 (85%) responders and 7 (47%) nonresponders had their PI switched (p = 0.037). The number of previous PIs used
was not different between groups (p = NS).
Conclusions: In patients failing HAART, use of viral genotype to assist in the
selection of a new HAART regimen resulted in a response rate of only 42%. A
codon 90 mutation was associated with lack of response. Patients who lacked PI
gene mutations and whose PI was not switched had poorer outcomes. Knowledge of viral genotype, PI trough serum concentration and medication adherence
enhancement intervention may result in improved virologic response to HAART.
32306 Mutations conferring resistance to zidovudine diminish
the virologic response to stavudine plus didanosine
therapy
Jacques Izopet, A. Bicari-See, C. Pasquier, E. Bonnet, B. Marchou, J. Puel,
P. Massip. Laboratoire De Virologie - Hospital Purpan - Place Du Docteur
Baylac, 31059 Toulouse cedex, Service Des Maladies Infectieuses - Hospital,
Purpan, Toulouse, France
Objective: To evaluate the influence of genotypic zidovudine resistance on the

antiviral effect of the combination of D4T and ddl in patients previously treated
with AZT + ddC.
Methods: 20 patients who had been treated with AZT + ddC for a median
duration of 11 months (range, 7-42) were switched to D4T (40 mg BID) + ddl
(200 mg BID) in an open pilot study lasting 6-months. The CDC classes were A
(n = 10) and B (n = 10). The median baseline CD4 count was 285/mm3 (range,
170-424) and the median baseline plasma viral RNA (Monitor" assay) was 4.6