Duration and predictors of CD4 T-cell gains in patients who continue combination therapy despite detectable plasma viremia.

BACKGROUND: Sustained elevations in CD4 cell counts commonly occur despite incomplete viral suppression with protease inhibitor-based antiretroviral therapy. OBJECTIVES: To determine the incidence and risk factors associated with return of CD4 cell count to pre-therapy levels in patients experiencing virologic failure of protease inhibitor therapy. DESIGN: This is a clinic-based cohort study of HIV-infected adults who failed to maintain durable viral suppression on a protease inhibitor-based regimen. MAIN OUTCOME MEASURES: Virologic failure was defined as persistent plasma HIV RNA level > 500 copies/ml. Immunologic failure was defined as return of CD4 cell count to pre-therapy levels. RESULTS: A total of 291 patients experienced virologic failure on a protease inhibitor-based regimen and had a treatment-mediated CD4 cell increase above pre-therapy levels at the time of virologic failure. If patient data were censored at the time a successful salvage regimen was initiated, then the median time to immunologic failure after the onset of virologic failure was 3 years. If patient data were also censored at the time therapy was discontinued, then 36.8% of the cohort experienced immunologic failure after 3 years of continuous virologic failure. The change in viral load from a pre-treatment baseline, and not the absolute level of viremia achieved, was a strong and independent predictor of immunologic failure. Discontinuing therapy was associated with immunologic failure independent of viral load changes. CONCLUSION: Reduction in T CD4+ cell numbers may eventually occur during prolonged virologic failure of a protease inhibitor-based regimen and is predicted by the degree of virologic suppression below a pre-therapy 'set-point'.     

Factors associated with clinical and virological failure in patients receiving a triple therapy including a protease inhibitor

OBJECTIVE: To determine the predictors of virological and clinical failure in patients receiving a protease inhibitor as part of triple therapy. METHODS: From the French Hospital Database on HIV, 1402 protease inhibitor-naive patients starting a highly active antiretroviral therapy regimen with ritonavir, saquinavir-hard gel capsule (hgc) or indinavir between July 1996 and March 1997, and with measured HIV RNA at baseline and at 12 months, were studied for progression to a new AIDS-defining event (ADE) or death. Virological failure was defined as plasma HIV RNA > 1000 copies/ml at 12 months. Multivariate analyses were performed using Cox models for clinical outcomes and logistic regression for virological outcomes. RESULTS: During a median follow-up of 14.1 months, 94 (6.7%) patients experienced an ADE or died. At 12 months, 700 patients (49.9%) had virological failure. In the multivariate analysis, baseline CD4 cell count and viral load were found to be independent predictors of both virological and clinical failure. Neither the type of the first protease inhibitor taken nor previous antiretroviral therapy experience was associated with risk of clinical progression. For virological failure, the use of saquinavir-hgc was associated with a significant 1.96-fold increase in risk compared with indinavir; pre-treated patients were at higher risk than antiretroviral therapy-naive patients. CONCLUSION: In this study with large samples of patients, the use of saquinavir-hgc was associated with higher risk of virological failure at 12 months than were ritonavir and indinavir; no differences between protease inhibitors were found for clinical progression. As biases cannot be excluded, a longer duration of follow-up will be necessary to answer the question of whether the results are really discrepant or simply reflect the delay between virological failure and clinical manifestations.     

Sustained CD4+ T cell response after virologic failure of protease inhibitor-based regimens in patients with human immunodeficiency virus infection

The relationship between plasma human immunodeficiency virus (HIV) RNA levels and peripheral CD4+ T cell counts was examined in 380 HIV-infected adults receiving long-term protease inhibitor therapy. Patients experiencing virologic failure (persistent HIV RNA >500 copies RNA/mL) generally had CD4+ T cell counts that remained greater than pretherapy baseline levels, at least through 96 weeks of follow-up. The CD4+ T cell response was directly and independently related to degree of viral suppression below the pretreatment baseline. For any given HIV RNA level measured 12 weeks after virologic failure, subsequent CD4+ T cell decline was slower in patients receiving a protease inhibitor-based regimen than in a historical control group of untreated patients. These observations suggest that transient or partial declines in plasma HIV RNA levels can have sustained effects on CD4+ T cell levels.     

Outcome and predictors of failure of highly active antiretroviral therapy: one-year follow-up of a cohort of human immunodeficiency virus type 1-infected persons

The outcome and predictors of virologic treatment failure of highly active antiretroviral therapy (HAART) were determined for 271 human immunodeficiency virus (HIV)-infected protease inhibitor-naive persons. During a follow-up of 48 weeks after the initiation of HAART, 6.3% of patients experienced at least one new AIDS-defining event, and 3.0% died. Virologic treatment failure occurred in 40% (indinavir, 27%; ritonavir, 30%; saquinavir, 59%; ritonavir plus saquinavir, 32%; chi2, P=.001). Risk factors for treatment failure were baseline plasma HIV-1 RNA (odds ratio [OR], 1.70 per log10 copies increase in plasma HIV-1 RNA), baseline CD4 cell count (OR, 1. 35 per 100 CD4 cells/mm3 decrease), and use of saquinavir versus other protease inhibitors (OR, 3.21). During the first year of treatment, 53% of all patients changed (part of) their original HAART regimen at least once. This was significantly more frequent for regimens containing saquinavir (62%; 27% for virologic failure) or ritonavir (64%; 55% for intolerance) as single protease inhibitor.     

Factors associated with virological response in HIV-infected patients failing antiretroviral therapy: a prospective cohort study

OBJECTIVES: To assess the antiviral response to optimized therapy following genotypic resistance testing and to identify factors associated with virological response in HIV-1-infected patients failing antiretroviral therapy. METHODS: A prospective cohort study was conducted in 344 HIV-1-infected patients who underwent genotypic resistance testing because of virological failure. Virological response was defined as a plasma HIV RNA level below 200 HIV-1 RNA copies/mL or a drop of plasma viral load from baseline of more than 1 log10. A multivariate logistic regression analysis was performed to identify factors associated with virological response. RESULTS: The median age of the patients was 40 years, with a male to female ratio of 4:1. Fifty-one per cent of patients had received the three major classes of antiretrovirals and the median duration of previous antiretroviral therapy was 4.6 years. At baseline, the median plasma HIV RNA level was 4.4 log10 copies/mL and the median CD4 cell count was 274 cells/microL. At 3 months, 55% of patients (188 of 344) had a virological response, which was sustained at 6 months (53%). Predictors of virological response were exposure to two or fewer protease inhibitors [odds ratio (OR) 1.8; P=0.046], and use in optimized therapy of a new class of antiretrovirals (OR 2.9; P=0.006), of more than two new drugs (OR 3.0; P<0.0001), of abacavir (OR 1.9; P=0.03), or of lopinavir/ritonavir (OR 3.7; P=0.0002). CONCLUSIONS: A high proportion of patients achieved a short-term virological response in this cohort study. Patients with the least experience of protease inhibitor treatment and in whom a new class of antiretroviral, more than two new drugs, abacavir or lopinavir/ritonavir was used in optimized therapy had the best virological outcome.     

Virological response to protease inhibitor therapy in an HIV clinic cohort

OBJECTIVE: New antiretroviral strategies aim to reduce plasma HIV RNA (viral load) to below the limits of detectability of assays with the objective of reducing viral replication in order to stop or reverse the pathogenic process and prevent development of drug resistance. First use of a protease inhibitor might offer the most realistic chance of achieving this aim. Our objective was to study the virological response to protease inhibitors in patients taking them for the first time. METHODS: A total of 901 patients from a large outpatient clinic were followed a mean of 15 months from the time of starting a protease inhibitor until 1 May 1998. Viral load and CD4 cell count measurements were made on average every 34 days. RESULTS: Overall there was a 79% [95% confidence interval (CI), 76-82] probability of the patients achieving a viral load < 500 copies/ml by 24 weeks after starting the protease inhibitor. In a multiple Cox regression model, those with lower initial viral load [relative hazard (RH), 0.72; P < 0.0001], higher CD4 cell count (RH, 1.07; P = 0.002), those starting other new drugs at same time as the protease inhibitor (RH, 1.46 for two versus none; P = 0.003), those who were antiretroviral-naive, and those using indinavir or nelfinavir were more likely to achieve such levels. In those 651 patients achieving viral load < 500 copies/ml within 24 weeks, there was an estimated 53% (95% CI, 51-55) probability of rebound of viral load to > 500 copies/ml by 52 weeks from the first undetectable value. Again, those who had started other new drugs at the same time as the protease inhibitor (RH, 0.57; P = 0.003 for starting two versus none) tended to experience a lower probability of viral load rebound, as did those with higher initial CD4 cell count (RH, 0.87 per 100 x 10(6)/l higher; P = 0.0007). Those who took saquinavir achieved less durable virological responses than those who took other protease inhibitors. CONCLUSIONS: Starting protease inhibitor therapy with two other new antiretroviral drugs simultaneously with protease inhibitor therapy offers a better best chance of achieving sustained viral load < 500 copies/ml than starting fewer new drugs.     

Six-year follow-up of HIV-1-infected adults in a clinical trial of antiretroviral therapy with indinavir, zidovudine, and lamivudine

OBJECTIVE: To assess virological and immunological responses and toxicity in subjects receiving combination antiretroviral therapy. DESIGN: Six-year follow-up of a single arm of a randomized study of combination antiretroviral therapy. METHODS: HIV-infected, zidovudine-experienced patients originally randomized to receive indinavir, zidovudine, and lamivudine had HIV RNA levels and CD4 cell counts assessed over 6 years. Information was collected by questionnaire from subjects who discontinued the study regimen before 6 years. Both on-study and post-study responses were assessed. RESULTS: Of 33 subjects, 16 (48%) discontinued before 6 years of follow-up. After 6 years, 16 (53%) and 14 (47%) of 30 contributing subjects had HIV RNA levels < 500 and < 50 copies/ml, respectively, and the median increase in CD4 cell count from baseline for 28 contributing subjects was 268 x 10(6) cells/l. Treatment-limiting nephrolithiasis occurred in four subjects. Of the 16 subjects who discontinued the study, 12 had post-study questionnaire data available and seven had HIV RNA < 500 copies/ml on a post-study regimen. In an exploratory analysis combining both on-study and post-study data at approximately 6 years, 26 (79%) and 19 (58%) of 33 had HIV RNA levels < 500 and < 50 copies/ml, respectively, and the median increase in CD4 cell count from baseline was 344 x 106 cells/l. CONCLUSIONS: Antiretroviral therapy with indinavir, zidovudine, and lamivudine suppressed HIV viremia and produced continued CD4 cell increases in a majority of subjects for 6 years. Most subjects who discontinued study medications had HIV RNA levels suppressed on post-study therapy. Though based on a small group, this study demonstrates the durable effects of antiretroviral therapy.     

Long-term trends in CD4 cell counts and impact of viral failure in individuals starting antiretroviral therapy: UK Collaborative HIV Cohort (CHIC) study

Objective

The aim of the study was to describe trends in CD4 cell counts in HIV‐infected patients after initiation of combination antiretroviral therapy (cART), according to CD4 cell count at initiation (baseline), and to quantify the implications of virological failure for these trends.

Methods

Eligible participants from the UK Collaborative HIV Cohort (CHIC) were antiretroviral‐naïve and started cART after 1997. Random effects were used to model CD4 cell count trends, accounting for multiple measurements within participants. We assessed whether CD4 cell count trends varied according to baseline CD4 cell count and separately in participants with and without post‐cART virological failure. Effects of post‐cART virological failure (>1000 HIV‐1 RNA copies/mL) on subsequent CD4 cell counts were evaluated.

Findings

A total of 7069 participants were included in the analysis (median follow‐up in all baseline CD4 cell count groups was ≥35 months). Among participants without virological failure ≥6 months after the start of cART, CD4 cell counts continued to increase up to 8 years, with little evidence that differences between baseline CD4 cell count groups diminished over time. Virological failure ≥6 months after the start of cART was associated with lower subsequent CD4 cell counts, with greater CD4 cell count reduction for more recent virological failure and higher viral load.

Conclusions

Post‐cART CD4 cell counts are strongly related to pre‐cART CD4 cell counts. CD4 cell count recovery is greatest in individuals who can avoid viral loads >1000 copies/mL while on cART.