Evolution of resistance mutations pattern in HIV-1-infected patients during intensification therapy with a boosted protease inhibitor
Blanco, José La; Biglia, M Alejandraa; Arnedo, Mireiab; Martínez, Estebana; Mallolas, Josepa; Milinkovic, Anaa; Laguno, Montserrata; Larrousse, Mariaa; Leon, Agathea; Lonca, Montserrata; García, Felipea; Miró, José Ma; Pumarola, Tomásb; Gatell, José Ma
aInfectious Diseases Service
bMicrobiology Service, IDIBAPS, Hospital Clínic, Faculty of Medicine, University of Barcelona, Barcelona, Spain.
Received 14 December, 2004
Accepted 11 January, 2005
Intensification therapy adding a boosted protease inhibitor (PI) to a failing regimen has the potential to worsen the resistance profile. Sixty-six patients included in four different boosted PI intensification studies were assessed and resistance mutations in the reverse transcriptase and protease genes were evaluated at baseline and 4 weeks after the initiation of the intensification strategy. Only one of the 66 patients developed changes in their pattern of mutations able to generate or increase resistance to new drugs.
Intensification therapy adding a boosted protease inhibitor (PI) to a failing regimen has the potential to worsen the resistance profile. Sixty-six patients included in four different boosted PI intensification studies were assessed, and the resistance mutations in the reverse transcriptase (RT) and protease genes were evaluated at baseline and 4 weeks after the initiation of the intensification strategy. Only one of the 66 patients (1.5%) developed changes in their pattern of mutations able to generate or increase resistance to new drugs.
Intensification therapy is a strategy that can be used to improve the virological response in patients with an intermediate level of resistance  or a low degree of virological failure [2–6]. There are two ways of intensifying therapy: by incorporating one or more new drugs in a failing regimen  or by boosting with a low dose of ritonavir a regimen containing a PI-unboosted PI .
The selection of resistance mutations is one of the major causes of treatment failure . The development of new HIV RT or protease resistance mutations has been demonstrated within the short period of time between the blood drawn for resistance testing and the availability of the results , or shortly after the initiation of an intensification strategy . Because there are almost no data about the evolution of resistance-associated mutations early after the initiation of a strategy of intensifying therapy, we examined this issue by pooling together data from several pilot studies of boosted PI intensification. We selected patients with the following criteria: (i) patients failing an unboosted PI or a non-nucleoside reverse transcriptase inhibitor-containing regimen in which the non-nucleoside reverse transcriptase inhibitor or the PI was replaced by the same or another PI (saquinavir , indinavir , amprenavir ) but boosted with a low dose of ritonavir or lopinavir/ritonavir  until the results of the resistance test became available; and (ii) patients with a plasma viral load (PVL) remaining above 1000 copies/ml after 4 weeks of treatment.
Seventy-six patients were eligible. Eighteen remained with a PVL above 1000 copies/ml at week 4. Of these, HIV RNA could be amplified in 10, who were included in this study. The eight patients that could not be amplified had a PVL ranging between 1000 and 3000 copies/ml. Adherence in all of these patients was above 95%, measured by pill count and by a self-administered questionnaire.
Genotypic resistance analysis was performed using the TruGene HIV-1 assay (Visible Genetics Inc., Toronto, Canada) and the interpretation of resistance sequences was done by the Sequence Stanford Database. RT and protease sequences were interpreted using a publicly available algorithm, HIV RT and Protease Sequence Database (http://hivdb.stanford.edu), updated in August 2002. Plasma drug levels of saquinavir, indinavir, amprenavir, lopinavir and ritonavir were determined at week 4 using a rapid, simple and sensitive high-performance liquid chromatography assay, developed and validated for the simultaneous quantification of the HIV PI indinavir, ritonavir, amprenavir, saquinavir, nelfinavir and lopinavir in human plasma, at the Pharmacology Department of the Hospital Clinic (Barcelona, Spain) .
Changes in genotypic mutation patterns from baseline to week 4 after introducing the intensification therapy could be assessed in 10 patients. The median baseline values of viral load and CD4 cell count were 26 450 copies/ml (range 11 100–1 000 000) and 316 cells/μl (range 31–594), respectively. The median decrease in viral load and increase in CD4 cell count at week 4 were 0.605 log10/ml (from 0.11 to 1.98) and over 25 cells/mm3, respectively.
The evolution of HIV resistance-associated mutations is shown in Table 1. Five of these 10 patients (50%; representing 6% of the total number of 76) either lost or gained a RT or a protease resistance-associated mutation. All mutations detected at baseline were also present at week 4, with the exception of an L210W mutation in one patient. Five patients accumulated new mutations by week 4 (two out of 10 patients accumulated primary mutations, one out of 10 secondary mutations, and four out of 10 polymorphic site mutations). However, in only one patient did the new mutation have potential clinical significance according to Stanford Database interpretation. This patient, who had a previous history of zalcitabine drug exposure, and was receiving lamivudine plus stavudine plus indinavir and was intensified with ritonavir-boosted indinavir, gained a T69N mutation that meant a change of susceptibility to stavudine and zalcitabine from susceptible and intermediate resistant to intermediate resistant and resistant, respectively. Four out of 10 patients developed nucleoside reverse transcriptase inhibitor mutations (K70R, T69N, K219Q and a polymorphism G333E). The acquisition of mutations K70R and K219Q in patient number 3, who was failing a zidovudine-containing regimen, was associated with the loss of the L210W mutation, with no change in the pattern of drug susceptibility according to the Stanford Database algorithm interpretation. Two out of 10 patients (20%) developed new PI mutations (L63P and I93L), which do not cause any appreciable change in the susceptibility to any PI. In a logistic regression model, statistically significant differences were found between the five patients who showed changes in genotypic mutation patterns during intensification therapy in the magnitude of viral load drop (Δ PVL at week 4 > 0.5 log10) at week 4 (P < 0.05) compared with the five who did not develop changes. Conversely, no statistical differences were found in terms of the number of previous treatments, baseline PVL, CD4 cell count, or virtual inhibitory quotient for the boosted PI used in intensification therapy.
In summary, intensifying with a boosted PI in virologically failing patients does not seem to increase the number of clinically significant mutations or worsen the resistance profile at one month.
Sponsorship: This study was partly supported by Red de Grupos de Investigacion en SIDA (RIS) del FISS.
1. Department of Health and Human Services (DHHS). Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents
. Available at: http://aidsinfo.nih.gov
. Accessed 23 March 2004.
2. Mallolas J, Blanco JL, Sarasa M, Arnedo M, López-Pua Y, Martinez E, et al. Intensification with saquinavir soft gel plus ritonavir once-daily in patients failing on saquinavir hard gel plus two nucleoside analogs reverse transcriptase inhibitors
. In: 1st IAS Conference on HIV Pathogenesis and Treatment
. Buenos Aires, Argentina, July 2001 [Abstract 675].
3. Blanco JL, Mallolas J, Sarasa M, Arnedo M, Milinkovik A, López-Pua Y, et al. Preliminary results of intensification therapy with amprenavir (APV)/ritonavir (RTV) in two differents doses: 1200 (APV)/200 (RTV) QD vs 600 (APV)/100 (RTV) BID (RTV) in a heavily pretreated patients failing HAART
. In: XIVth International AIDS Conference
. Barcelona, Spain, July 2002 [Abstract TuBeB4580].
4. Blanco JL, Mallolas J, Sarasa M, Arnedo M, Milinkovik A, López-Pua Y, et al. Intensification therapy with lopinavir/ritonavir (Kaletra) in heavily pretreated patients failing HAART
. In: XIVth International AIDS Conference
. Barcelona, Spain, July 2002 [Abstract TuBeB4581].
5. Mallolas J, Blanco JL, Sarasa M, Giner V, Martinez E, Garcia-Viejo MA, et al
. Dose-finding study of once-daily indinavir/ritonavir plus zidovudine and lamivudine in HIV-infected patients. J Acquir Immune Defic Syndr 2000; 25:229–235.
6. Molina J, Marcelin AG, Pavie J, Merle C, Troccaz M, Leleu G, et al. Didanosine (ddI) in treatment-experienced HIV-infected patients: results from a randomized double-blind study (AI454-176 Jaguar)
. Presented at 43rd International Conference on Antimicrobial Agents and Chemotherapy
. Chicago, IL, 13-16 September 2003 [Abstract H-447].
7. Clavel F, Hance AJ. HIV drug resistance. N Engl J Med 2004; 350:1023–1035.
8. Birch C, Middleton T, Hales G, Cooper D, Law M, Crowes S, et al
. Limited evolution of HIV antiretroviral drug resistance-associated mutations during the performance of drug resistance testing [Brief Report]. J Acquir Immune Defic Syndr 2003; 32:57–61.
9. Squires K, Pozniak AL, Pierone G, Steinhart CR, Berger D, Bellos NC, et al
. Tenofovir disoproxil fumarate in nucleoside-resistant HIV-1 infection. Ann Intern Med 2003; 139:313–320.
10. Sarasa M, Lopez-Pua Y, Mallolas J, Blanco JL, Gatell JM, Carne X. Simultaneous determination of the HIV-protease inhibitors indinavir, amprenavir, ritonavir, saquinavir and nelfinavir in human plasma by reversed-phase high performance liquid chromatography. J Chromatogr 2001; 757:325–332.
This article has been cited 4 time(s).
Journal of Drug TargetingIntracellular signal-responsive artificial gene regulationJournal of Drug Targeting
Enfermedades Infecciosas Y Microbiologia ClinicaGenotypic resistance in HIV-1 infected patients with persistent low-level viremiaEnfermedades Infecciosas Y Microbiologia Clinica
Antiretroviral activity of didanosine in patients with different clusters of reverse transcriptase mutations
HIV-1 Genotypic Drug Resistance Interpretation Rules-2009 Spanish Guidelines
AIDS Reviews, 11(1):
© 2005 Lippincott Williams & Wilkins, Inc.
What does "Remember me" mean?
By checking this box, you'll stay logged in until you logout. You'll get easier access to your articles, collections,
media, and all your other content, even if you close your browser or shut down your
To protect your most sensitive data and activities (like changing your password),
we'll ask you to re-enter your password when you access these services.
What if I'm on a computer that I share with others?
If you're using a public computer or you share this computer with others, we recommend
that you uncheck the "Remember me" box.
Data is temporarily unavailable. Please try again soon.