Decrease In HIV-1 RNA Research Articles

Overcoming Resistance: Virologic Response to a Salvage Regimen with the Combination of Ritonavir plus Indinavir

Purpose: To explore the possibility of overcoming resistance to protease inhibitors (PIs) and to determine the resistance cutoff values that continue to predict treatment failure with a dual PI regimen. Method: We performed a prospective study of 53 patients who had failed in several PIs and who were included in a ritonavir (RTV) plus indinavir (IDV) salvage regimen. Median HIV RNA level decrease was evaluated according to resistance assays and indinavir trough levels. Results: Eighty-seven percent of patients had previously failed on an IDV-containing regimen. Overall, median HIV RNA decrease was –1.25 log10 copies/mL after 3 months on therapy. A significant blunted virologic response was observed only in isolates with more than 12 substitutions including the V82A (–0.75 vs. –1.3 log10 copies/mL; p = .04), or in isolates with more than 30 fold-increase in the IC50 (–0.43 vs. –1.2 log10 copies/mL). Higher drug levels were observed in patients with resistant isolates who achieved an HIV RNA decrease greater than 1 log (1742 vs. 1100 ng/mL). Conclusion: Our preliminary data suggest the possibility of overcoming resistance with the combination of RTV plus IDV. They also suggest the need for establishing new resistance cutoff values when using PIs in combination.

Overcoming Resistance: Virologic Response to a Salvage Regimen with the Combination of Ritonavir plus Indinavir

Purpose: To explore the possibility of overcoming resistance to protease inhibitors (PIs) and to determine the resistance cutoff values that continue to predict treatment failure with a dual PI regimen. Method: We performed a prospective study of 53 patients who had failed in several PIs and who were included in a ritonavir (RTV) plus indinavir (IDV) salvage regimen. Median HIV RNA level decrease was evaluated according to resistance assays and indinavir trough levels. Results: Eighty-seven percent of patients had previously failed on an IDV-containing regimen. Overall, median HIV RNA decrease was –1.25 log10 copies/mL after 3 months on therapy. A significant blunted virologic response was observed only in isolates with more than 12 substitutions including the V82A (–0.75 vs. –1.3 log10 copies/mL; p = .04), or in isolates with more than 30 fold-increase in the IC50 (–0.43 vs. –1.2 log10 copies/mL). Higher drug levels were observed in patients with resistant isolates who achieved an HIV RNA decrease greater than 1 log (1742 vs. 1100 ng/mL). Conclusion: Our preliminary data suggest the possibility of overcoming resistance with the combination of RTV plus IDV. They also suggest the need for establishing new resistance cutoff values when using PIs in combination.

Individualizing salvage regimens

Individualizing salvage regimens

Cross-resistance among nonnucleoside reverse transcriptase inhibitors limits recycling efavirenz after nevirapine failure.

Heterogeneity in genotype mutations associated with resistance of HIV to nonnucleoside reverse transcriptase inhibitors (NNRTIs) should allow identification of patients failing nevirapine (NVP) who might benefit from efavirenz (EFV)-containing salvage regimens. To establish the feasibility of recycling EFV after failure of NVP-containing regimens genotypic data on 103 NVP-failed patients were analyzed to evaluate the prevalence of EFV resistance-conferring mutations. A clinically significant resistance to EFV was found in 50 of 103 (58%) of NVP-failed subjects. Furthermore, the 3-month virological response to salvage regimens containing EFV was assessed in patients previously treated with NVP and carrying single mutations conferring resistance to this drug. A proportion of HIV RNA less than 500 copies/ml at 3 months was obtained only in 2 of 12 (17%) of EFV-treated subjects compared with 35 of 67 (52%) of those without NNRTI mutations (OR, 0.18; 95% CI, 0.03-0.79). The median HIV-1 RNA decrease after 3 months was -0.63 log(10) among patients carrying single NNRTI-associated mutations compared with -1.32 log(10) among those without any NNRTI mutations. No virological response was observed in six patients harboring a single Y181C/I mutation. On the basis of the present data, sequential use of NNRTIs should be avoided in the management of treatment failure.

Therapeutic drug monitoring as a tool in treating HIV infection.

Despite its success antiretroviral therapy (ART) is still associated with a significant risk of toxicity and subsequent virological failure. Pending the introduction of drugs with greater potency and durability one of the most pressing priorities in HIV treatment is to identify ways in which to maximize the efficacy of existing therapeutic options while minimizing its toxicity. Resistance testing has been shown to be one such strategy. Therapeutic drug monitoring (TDM) for HIV drugs has been widely proposed as another tool by which treatment may be optimized. There are some parallels with resistance testing not least the potential difficulties or pitfalls in interpreting test results and the understandable pressure for provision of this service in the face of increasingly limited treatment options notwithstanding the current lack of data from controlled clinical studies. In this reviews we shall discuss the value of TDM in the context of a ‘monitoring service (in other words drug concentrations are provided in conjunction with interpretation and advice) rather than a facility for ‘measuring drug concentrations. This distinction is important since the interpretation of drug concentrations is fraught with complexity. (excerpt)

The relationship between virus load response to highly active antiretroviral therapy and change in CD4 cell counts: A report from the Women's interagency HIV study.

The relationship between the pattern of virus load response to highly active antiretroviral therapy (HAART) and CD4 lymphocyte response was assessed in a cohort of 249 human immunodeficiency virus (HIV) type 1-infected women at 3 times: 1 before and 2 after initiation of therapy, with follow-up of 6-12 months. Patients with a durable response to HAART (i.e., >1 log decrease in HIV-1 RNA sustained for the study periods) had a continuous and significant increase in CD4 cell counts over time, whereas those with no response (<0.5 log decrease in HIV-1 RNA) had a slight decline. Patients with a mixed response (initial decrease >1 log, followed by a subsequent decrease <0.5 log) had an increase in CD4 cell count, followed by a plateau. The trend in CD4 cell count differed significantly by response to HAART, with those patients who experienced a durable response having significantly higher CD4 cell counts than others.

Human immunodeficiency virus type 1 RNA level and CD4 count as prognostic markers and surrogate end points: a meta-analysis. HIV Surrogate Marker Collaborative Group.

To evaluate treatment-mediated changes in HIV-1 RNA and CD4 count as prognostic markers and surrogate end points for disease progression (AIDS/death). Data from 13,045 subjects in all 16 randomized trials comparing nucleoside analogue reverse transcriptase inhibitors and having HIV-1 RNA measurements at 24 weeks were obtained. A total of 3146 subjects had HIV-1 RNA and CD4 count determinations at 24 weeks after starting treatment. At Week 24, the percentage of subjects experiencing an HIV-1 RNA decrease of >1 log10 copies/ml or a CD4 count increase of >33% was similar (22% vs. 25%). Changes in both markers at Week 24 were significant independent predictors of AIDS/death: across trials, the average reduction in hazard was 51% per 1 log10 HIV-1 RNA copies/ml decrease (95% confidence interval: 41%, 59%) and 20% per 33% CD4 count increase (17%, 24%). In univariate analyses, the hazard ratio for AIDS/death in randomized treatment comparisons was significantly associated with differences between treatments in mean area under the curve of HIV-1 RNA changes to Weeks 8 and 24 (AUCMB) and mean CD4 change at Week 24, but, in multivariate analysis, only mean CD4 change was significant. Change in HIV-1 RNA, particularly using AUCMB, and in CD4 count should be measured to aid patient management and evaluation of treatment activity in clinical trials. However, short-term changes in these markers are imperfect as surrogate end points for long-term clinical outcome because two randomized treatment comparisons may show similar differences between treatments in marker changes but not similar differences in progression to AIDS/death.

Can HCV affect the efficacy of anti-HIV treatment?

To evaluate the impact of new antiretroviral combinations (HAART: Highly Active Anti Retroviral Therapy) on HCV replication and liver enzyme levels, we analysed the changes in HCV viremia and aminotransferase levels in HIV and HCV co-infected patients. Moreover, to evaluate the influence of HCV infection on the efficacy of HAART, we compared the virological, immunological and biochemical response to antiretroviral combinations in anti-HIV positive subjects with or without HCV infection. We enrolled eight consecutive outpatients with HIV-HCV coinfection and with indications for HAART (Group A). For each patient in group A, we selected an anti-HIV negative patient with indications for HAART, pair-matched for age, sex, risk factor for HIV infection, presumed duration of infection, number of CD4 cells, HIV viremia and treatment schedule (Group B). A statistically significant increase in CD4 in both groups was found at 1st, 3rd and 6th month of antiretroviral therapy. A decrease in HIV-RNA in both groups was observed at 1st and 6th month of treatment. The percentage of patients with undetectable HIV-RNA at the 1st month was higher in Group B than in Group A (8/8 vs. 3/8, p = 0.025). Basal HCV-RNA viremia was very high in each case and no variations during treatment were observed. During therapy the aminotransferase levels slightly decreased in Group A and consistently increased in Group B. In Group A the differences were not significant to the statistical analysis; in Group B the aminotransferase levels at 3rd and 6th month were significantly higher than those observed at the baseline.

HCVRNA increase during antiretroviral treatment (ART) induced HIVRNA rapid phase decline: An evidence of virus-virus interaction?

Background: Liver damage has been described in HIV+ patients with HCV coinfeetion undergoing combination ART. Aims and Methods. In order to assess the relationship between CD4, CD8,HIVRNA, HCVRNA (both measured by bDNA) and liver enzymes during combination antiretroviral treatment (ART), we measured these parameters in 12 HIVHCV coinfected patients on the day before, 3, 7, 14, 28, 56 and 84 days after starting: d4T and 3TC in all, Indinavir in 6 and Nevirapine in 6. Results: HIVRNA declined rapidly and significantly. CD4 raised slowly. CD8 cells and liver enzymes were stable. HCVRNA show a significant increase (7.55 +/at day 14 7.61 +/-at day 21 vs. 7.35 +/at baseline M+/SE log copies/mi p<0.05) independent from Indinavir use. Increase of HCVRNA levels was observed in 10/12 patients all showing a 2 log decrease of HIVRNA and was not related to liver damage. An ALT increase greater than 100% was observed in 4/12 patients all showing HCVRNA increase. Conclusions: The relationship between HCVRNA increase and decline of HIVRNA suggests interference between the two viruses. HCVRNA increase may elicit liver damage only in a minority of patients. Viral hepatitis: basic aspects

RNase L Inhibitor Is Induced during Human Immunodeficiency Virus Type 1 Infection and Down Regulates the 2-5A/RNase L Pathway in Human T Cells

The interferon-regulated 2-5A/RNase L pathway plays a major role in the antiviral and antiproliferative activities of these cytokines. Several viruses, however, have evolved strategies to escape the antiviral activity of the 2-5A/RNase L pathway. In this context, we have cloned a cDNA coding for the RNase L inhibitor (RLI), a protein that specifically inhibits RNase L and whose regulated expression in picornavirus-infected cells down regulates the activity of the 2-5A/RNase L pathway. We show here that RLI increases during the course of human immunodeficiency virus type 1 (HIV-1) infection, which may be related to the downregulation of RNase L activity that has been described to occur in HIV-infected cells. In order to establish a possible causal relationship between these observations, we have stably transfected H9 cells with RLI sense or antisense cDNA-expressing vectors. The overexpression of RLI causes a decrease in RNase L activity and a twofold enhancement of HIV production. This increase in HIV replication correlates with an increase in HIV RNA and proteins. In contrast, reduction of RLI levels in RLI antisense cDNA-expressing clones reverses the inhibition of RNase L activity associated with HIV multiplication and leads to a threefold decrease in the viral load. This anti-HIV activity correlated with a decrease in HIV RNA and proteins. These findings demonstrate that the level of RLI, via its modulation of RNase L activity, can severely impair HIV replication and suggest the involvement of RLI in the inhibition of the 2-5A/RNase L system observed during HIV infection.

Quantification of HIV-1 viral load in lymphoid and blood cells: assessment during four-drug combination therapy.

To assess the antiretroviral effect of a combination of zidovudine, didanosine, lamivudine and saquinavir in plasma, peripheral blood mononuclear cells (PBMC) and lymph-node mononuclear cells (LNMC) after 8 weeks. Ten HIV-1 antiretroviral therapy-naive patients were given a combination of oral zidovudine (200 mg three times daily), oral didanosine (200 twice a day), oral lamivudine (150 mg twice a day) and oral saquinavir (600 mg three times daily). HIV-1 plasma RNA was measured by quantitative reverse transcriptase (RT)-polymerase chain reaction (PCR). Infectious HIV-1 in PBMC and LNMC was measured by a coculture technique. HIV-1 RNA in PBMC and LNMC was quantified by RT-PCR. Proviral DNA titres in PBMC and LNMC were measured by endpoint dilution PCR. CD4 T-cells were analysed by flow cytometry. CD4 cell counts rose in all patients (mean increase of 125 +/- 71 CD4 cells x 10(6)/l) and the benefit was greater for patients with fewer than 350 CD4 cells x 10(6)/l (mean increase of 159 +/- 74 CD4 cells x 10(6)/l). Plasma HIV-1 RNA decreased exponentially in all patients (mean decrease of 3.1 log10 after 8 weeks with a mean half-life of 2.2 +/- 0.6 days). HIV-1 RNA showed a decrease of 3.07 log10 in PBMC and of 2.1 log10 in LNMC. The decrease in plasma HIV-1 RNA was consistently associated with the decrease in LNMC. These data were supported by a concomitant drop of HIV-1 infectious titres in PBMC (mean decrease of 1.41 log10) and in LNMC (mean decrease of 2.54 log). These data show a significant antiretroviral effect of this four-drug combination in blood and lymphoid tissues. However, a greater decrease in HIV-1 RNA was observed in PBMC and in plasma than in lymph node cells.

The effect on human immunodeficiency virus type 1 RNA levels in cerebrospinal fluid after initiation of zidovudine or didanosine.

Human immunodeficiency virus type 1 (HIV-1) RNA, neopterin, and beta2-microglobulin levels were analyzed in cerebrospinal fluid (CSF) and serum before and 3-13 months after initiation of antiretroviral monotherapy in 16 HIV-1-infected persons. Twenty-one treatment periods, 13 after initiation of zidovudine and 8 after initiation of didanosine, were studied. During zidovudine treatment, CSF HIV RNA levels decreased by a mean of 1.05 log10 (-91%, P < .01), and CSF neopterin and beta2-microglobulin levels by 57% and 33%, respectively (P < .01). No reduction was seen during didanosine treatment in CSF HIV RNA (+0.13 log10, not significant), CSF neopterin, or beta2-microglobulin levels. Changes in CSF HIV RNA levels correlated with changes in CSF neopterin and beta2-microglobulin (r(s) = .81 and .83, respectively, P < .001). The decrease in HIV RNA was significantly larger in CSF than in serum following zidovudine treatment (P < .01). These data demonstrate that zidovudine is a potent reducer of central nervous system virus load, which may be important for long-term neuroprotection.

Antiretroviral effect of zidovudine-didanosine combination on blood and lymph nodes.

To evaluate the antiretroviral effect of a combination of zidovudine (ZDV) and didanosine (ddl) on plasma, peripheral blood mononuclear cells (PBMC) and lymph nodes after 24 weeks. Eight patients naive of antiretroviral therapy were followed by monthly blood samples and two surgical lymph-node biopsies taken at baseline and after 24 weeks. CD4+ T cells were counted monthly by flow cytometry. Plasma HIV-1 RNA was measured monthly by polymerase chain reaction (PCR). Infectious cellular viraemia was measured monthly by a culture technique. Proviral DNA titres in PBMC were measured by endpoint dilution PCR at baseline and 24 weeks. Infectious HIV-1 and proviral DNA titres were measured in the lymph-node mononuclear cells (LNMC). The total HIV-1 RNA content of lymph nodes was measured by PCR. In some cases, phenotypic resistance to ZDV was measured, and codon 215 and 74 mutations in PBMC and LNMC were analysed. A mean increase in CD4 cell count of 122 x 10(6)/l, a mean decrease in HIV-1 RNA of 1.47 log10 in plasma and a mean decrease in HIV-1 DNA titre of 0.63 log10 were found after 24 weeks of therapy. Nevertheless, there were no statistically significant changes in the mean infectious HIV-1 titre in PBMC and LNMC, in the HIV-1 DNA titre in LNMC or in the total lymph-node HIV-1 RNA burden at week 24. Phenotypic or genotypic markers of drug resistance were rarely found in PBMC at week 24, although they were detected in LNMC from some patients. A discrepancy in the therapeutic effect can be observed between lymphoid organs and blood after 24 weeks of therapy with ZDV and ddl. This difference could be explained by the insufficient antiretroviral potency of this combination facing the significant viral burden present in lymph nodes. Development of drug resistance in this compartment prior to blood can be demonstrated in some cases, although other mechanisms remain to be investigated in future studies to explain this difference.