The danish protease inhibitor study: a randomized study comparing the virological efficacy of 3 protease inhibitor-containing regimens for the treatment of human immunodeficiency virus type 1 infection

Genetic evolution of HIV in patients remaining on a stable HAART regimen despite insufficient viral suppression

Our objective was to investigate whether steadily increasing resistance levels are inevitable in the course of a failing but unchanged Highly Active Antiretroviral Therapy (HAART) regimen. Patients having an unchanged HAART regimen and a good CD4 response (100 cells/microl above nadir) despite consistent HIV-RNA levels above 200 copies/ml were included in the study. The study period spanned at least 12 months and included 47 plasma samples from 17 patients that were sequenced and analysed with respect to evolutionary changes. At inclusion, the median CD4 count was 300 cells/ml (inter-quartile range (IQR): 231-380) and the median HIV-RNA was 2000 copies/ml (IQR: 1301-6090). Reverse transcription inhibitor (RTI) mutations increased 0.5 mutations per y (STD = 0.8 mutations per y), while major protease inhibitor (PI) resistance mutations increased at a rate of 0.2 mutations per y (STD = 0.8 mutations per y) and minor PI resistance mutations increased at a rate of 0.3 mutations per y (STD = 0.7 mutations per y). The rate at which RTI mutations accumulated decreased during the study period (p = 0.035). Interestingly, the rate of mutation accumulation was not associated with HIV-RNA level. The majority of patients kept accumulating new resistance mutations. However, 3 out of 17 patients with viral failure were caught in an apparent mutational deadlock, thus the development of additional resistance during a failing HAART is not inevitable. We hypothesize that certain patterns of mutations can cause a mutational deadlock where the evolutionary benefit of further resistance mutation is limited if the patient is kept on a stable HAART regimen.

Unmeasured confounding caused slightly better response to HAART within than outside a randomized controlled trial

OBJECTIVE

To compare the outcome of highly active antiretroviral therapy (HAART) in HIV-infected patients initiating equivalent regimens within and outside a randomized controlled trial (RCT).

STUDY DESIGN AND SETTING

The Danish Protease Inhibitor Study (DAPIS) was a national multicenter RCT comparing initial treatment with indinavir, ritonavir, or saquinavir/ritonavir during 96 weeks. From the Danish HIV Cohort Study we identified all patients initiating one of these protease-inhibitor-based HAART regimens: 425 patients within DAPIS and 677 outside the trial. We compared viral load, CD4 count response, and mortality.

RESULTS

At weeks 96 and 240, trial participants were more likely than nonparticipants to have undetectable viral load (adjusted odds ratio [adOR] 1.28 [95% CI=0.94-1.74] and 1.70 [95% CI=1.16-2.50]) and a CD4 increase > or =100 cells/microl (adOR 1.37 [95% CI=1.03-1.82] and 1.53 [95% CI=1.04-2.25]). For antiretroviral-experienced, but not for antiretroviral-naïve patients, trial participants had a lower risk of death (mortality rate ratio [MRR]=0.46 [95% CI=0.27-0.77]) than nonparticipants. This effect was moderated in adjusted analyses (MRR=0.60 [0.33-1.07]).

CONCLUSIONS

Compared to nontrial patients, trial participants had better response to HAART. The differences were small defying the notion that results obtained in RCTs are unachievable in routine clinical practice.

Bioavailability and Pharmacokinetic Model for Ritonavir in the Rat

The aim of this study is to investigate in vivo the oral bioavailability of ritonavir and to evaluate the pharmacokinetic model that best describes the plasma concentration behavior after oral and intravenous administration. Male Wistar rats were intravenously administered at 3 mg dose of pure ritonavir and oral administered at 4.6 +/- 2.5 mg of diluted Norvir. Blood samples were taken by means of the jugular vein for a 24 h period of time. An analytical high-performance liquid chromatography (HPLC) technique was developed in order to quantify ritonavir plasma concentrations. A nonlinear modeling approach was used to estimate the pharmacokinetic parameters of interest. Results showed that a two-compartmental model with zero-order kinetic in the incorporation process of ritonavir into the body better fitted intravenous and oral data. The estimated oral bioavailability by means of noncompartmental and compartmental approaches resulted in 74% and 76.4%, respectively. These values confirm the ones obtained by other authors in the rat. In conclusion, a zero-order kinetic in the incorporation process at the administered doses suggests the saturation of the possible specialized transport mechanisms involved in the incorporation of ritonavir into the body. These results could justify the use of low doses of ritonavir when improving the bioavailability of other protease inhibitors (PIs) is required.

An updated systematic overview of triple combination therapy in antiretroviral-naive HIV-infected adults

OBJECTIVE

To compare the effectiveness of three drug combination antiretroviral therapy (ART) in treatment-naive HIV-infected persons, and identify the predictors of responses.

DESIGN AND METHODS

Overview of trials identified by searching public domain publications and conference presentations. The three-drug combination therapy was defined as two nucleoside reverse transcriptase inhibitors (NRTI) or nucleotide and NRTI, and either: (1) a protease inhibitor (PI); (2) a non-nucleoside RTI (NNRTI); (3) a third NRTI; or (4) a ritonavir-boosted PI (BPI). Week 24 and 48 results for the proportions of patients with plasma HIV RNA levels < 400 and < 50 copies/ml, and change in CD4(+) cell counts were recorded.

RESULTS

Fifty-three trials met the entry criteria, and enrolled 14 264 patients into 90 treatment arms. Overall 55% of patients had plasma HIV RNA levels < 50 copies/ml at week 48 and this percentage increased with later publication dates. In unadjusted pairwise comparisons at week 48, significantly greater percentages of patients receiving NNRTI (64%) and BPI (64%) had RNA < 50 copies/ml than NRTI (54%) or PI (43%), and CD4(+) cell count increases were significantly greater in the BPI group (+200 cells/microl) than the PI (+179), NNRTI (+173), or NRTI (+161) groups. Pill count and percentage of patients with week 48 plasma HIV RNA levels < 50 copies/ml were correlated in the univariate analysis (P = 0.0053; r = -0.323), but pill count was not a significant predictor in the multivariate analyses. Drug class and baseline CD4(+) cell counts were significant predictors, but explained only a modest amount of the treatment effect, (R(2) = 0.355).

CONCLUSIONS

NNRTI and BPI-containing regimens offer superior virologic suppression over 48 weeks, supporting existing guidelines for the choice of initial ART. Pill count was not a consistent predictor of virologic suppression.

Clinical trial methodology and clinical cohorts: the importance of complete follow-up in trials evaluating the virological efficacy of anti-HIV medicines

PURPOSE OF REVIEW

It has been common practice in randomized trials of HIV medicines to classify switches away from the original therapy as failures in analyses of virological effect, in line with an HIV-RNA measurement above a given level of quantification. This approach precludes the ability to identify the possible effects of a given therapy on those of a subsequent therapy. This review explores whether there have been changes in the reporting of randomized trials since the importance of continuous follow-up throughout the study period was initially raised 2 years ago.

RECENT FINDINGS

Follow-up is still likely to be discontinued at a premature switch from study medication in a large number of the randomized trials published in 2002-2003. However, some studies, all initiated by investigators, did follow patients throughout the study period. In three of the studies, the proportions of patients with virological failure assessed with and without data after the premature discontinuation of randomized therapy could be elicited. Substantial differences were seen in the comparisons of two highly active antiretroviral therapy regimens according to the choice of analytical approach. In all three studies significant differences were observed between the regimens according to one approach, but not to the other.

SUMMARY

The notation of treatment switch equals failure leads to an imprecise measurement of virological effect, and complete follow-up throughout the study period should be strongly encouraged, thus enabling several supplementary analyses of the virological effect of the treatment strategies being compared.

[A randomized clinical trial to compare the effectiveness of indinavir, ritonavir and saquinavir]

BACKGROUND AND OBJECTIVE

HIV protease inhibitors (PI) were licensed without a direct evidence of their relative efficacy.

PATIENTS AND METHOD

137 patients attending our clinics between November 1997 and March 1998, to whom treatment with a PI was recommended, were randomized to receive indinavir (IDV), saquinavir (SQV) or ritonavir (RTV). Main outcome variables were one-year mean changes in HIV-RNA plasma concentrations and CD4 cells counts and proportion of patients with HIV viral load below level of detection.

RESULTS

Mean HIV viral load reductions were 0.95 for SQV, 0.72 for IDV and 0.65 for RTV (p = 0.44), equaling losses and changes to failures. In a standard intent-to-treat analysis, mean changes in viral load were 1.16, 1.01 and 1.50 (p = 0.21), respectively. The proportion of patients with undetectable viral load was 50%, with no differences between treatment arms.

CONCLUSIONS

No differences were observed in the effectiveness of SQV, IDV and RTV.

Low efficacy and high frequency of adverse events in a randomized trial of the triple nucleoside regimen abacavir, stavudine and didanosine

BACKGROUND

Highly active antiretroviral therapy containing three nucleoside reverse transcriptase inhibitors has been somewhat successful, but the clinical efficacy is unclear.

METHODS

Randomized, controlled, open-label trial of 180 antiretroviral drug-naive HIV-infected patients allocated to a regimen of abacavir, stavudine and didanosine (A/S/D, n = 60), ritonavir and saquinavir (R/S 400/400 mg twice daily; n = 60) or nelfinavir and nevirapine (N/N 1250/200 mg twice daily; n = 60); the latter two in combination with lamivudine and zidovudine. The primary endpoint was HIV plasma RNA < or = 20 copies/ml after 48 weeks.

RESULTS

At baseline, the median CD4 cell count was 161 x 106 cells/l (range, 0-920) and the HIV RNA was 5.0 log10 copies/ml (range, 2.7-6.7). At 48 weeks, 43% in the A/S/D arm had a HIV RNA < or = 20 copies/ml, compared with 69% in the N/N arm (P < 0.01) and 62% in the R/S arm (P < 0.05). In a multivariate analysis, the A/S/D arm had an odds ratio of obtaining a viral load of < or = 20 copies/ml at week 48 of 0.25 [95% confidence interval (CI) 0.10-0.59] versus N/N and 0.53 (95% CI, 0.33-0.83) versus R/S. The A/S/D arm had a particularly poor outcome in patients with higher viral load and AIDS at baseline: 63% had to discontinue A/S/D (any drug). Side effects were more frequent in the A/S/D arm and included neuropathy 27%, suspicion of hypersensitivity 12%, and increase in lactate accompanied by systemic symptoms 8%.

CONCLUSION

The A/S/D regimen had a low efficacy and a high frequency of adverse events and cannot be recommended.

Antiretroviral Therapy: When and What to Start-- An American Perspective

The major US treatment guidelines recently recommended starting antiretroviral therapy (ART) later in the course of HIV infection due to an increasing awareness of the difficulties associated with these regimens. Most of the data to support this change come from observational cohort studies. When deciding to start ART, a number of patient-specific factors and other issues should be considered. Given the many choices for initial ART, one should individualize the choice, taking into account antiretroviral regimen potency, durability, side effects, toxicities, and convenience to ensure a sustained clinical benefit for the patient.

A Randomized Trial Comparing Initial Haart Regimens of Nelfinavir/Nevirapine and Ritonavir/Saquinavir in Combination with Two Nucleoside Reverse Transcriptase Inhibitors

Background

A triple-class HAART regimen may be associated with a better virological effect than conventional regimens, but may also lead to toxicity and more profound resistance.

Methods

Randomized, controlled, open-label trial of 233 protease inhibitor- and non-nucleoside reverse transcriptase inhibitor-naive HIV-infected patients allocated to a regimen of nelfinavir and nevirapine (1250/200 mg twice daily; n=118) or ritonavir and saquinavir (400/400 mg twice daily; n=115), both in combination with two nucleoside reverse transcriptase inhibitors. The primary end-point was HIV RNA ≤20 copies/ml after 48 weeks (missing value=failure). Patients remained under follow-up also in case of switch from the randomized therapy.

Results

At baseline, the median CD4 cell counts were 126 (range: 0–942) (nelfinavir/nevirapine) and 150 (0–642) (ritonavir/saquinavir) cells/mm3, and HIV RNA measurements 5.0 copies/ml (1.3–6.4) in both groups. A total of 102 (86%) and 101 (88%) were antiretroviral-naive. Within 48 weeks, 35 and 44% discontinued randomized therapy; P=0.13. Of these, 80 and 73% switched therapy due to adverse events; P=0.99. At week 48, 69 and 56%, respectively, had a HIV RNA ≤20 copies/ml; P=0.037.

Conclusion

A regimen of nelfinavir/nevirapine had a favourable virological effect and tolerability over a 48-week period compared with ritonavir/saquinavir, when administered in combination with two nucleoside reverse transcriptase inhibitors. However, more extensive follow-up is required to determine the long-term consequences of triple class HAART regimens, including the development of broad drug resistance.

Virological and immunological profiles among patients with undetectable viral load followed prospectively for 24 months

OBJECTIVE

To quantify HIV-RNA in plasma, in lymphoid tissue and proviral DNA in peripheral blood mononuclear cells and to relate these to immunological markers among patients with plasma viral load counts of </= 200 HIV-RNA copies/mL.

METHODS

A prospective study of one hundred and three patients was undertaken with an inclusion criteria of plasma viral load of </= 200 copies/mL. The patients had advanced HIV infection; 25% had developed AIDS. Patients were seen every 6 months for a period of 2 years.

RESULTS

The median plasma viral load was < 20 copies/mL with no increase during follow-up. Thirty-one per cent had plasma viral load of </= 20 copies/mL at all visits, 44% had >/= 1 measurement with 21-200 and 25% had >/= 1 sample with plasma HIV-RNA > 200 copies/mL. Lymphoid tissue viral load was low at enrolment and declined further during follow-up. Baseline HIV-DNA and immunoglobulin (IgA) differed significantly between the plasma viral load rebound groups (P < 0.05).

CONCLUSION

In this cohort, selected solely on the basis of having a plasma viral load of </= 200 copies/mL, we found stable or declining viral loads in the measured compartments during 2 years of follow-up. Baseline HIV-DNA and IgA levels were higher among patients with less complete virological suppression relative to patients with persistently undetectable plasma HIV-RNA. Hence, a high cellular level of HIV-DNA and high plasma IgA may predict subsequent development of low-grade viraemia.

Ritonavir/Saquinavir plus One Nucleoside Reverse Transcriptase Inhibitor (NRTI) versus Indinavir plus Two Nrtis in Protease Inhibitor-Naive HIV-1-Infected Adults (Iris Study)

Objectives

To compare the efficacy, tolerability and safety of a ritonavir 400 mg/saquinavir hard gel fomulation 400 mg twice daily versus an indinavir 800 mg once every 8 h containing first-line protease inhibitor (PI) treatment regimen.

Methods

Open, randomized, multicentre clinical trial. PI-naive patients received either ritonavir/saquinavir and one nucleoside reverse transcriptase inhibitor (NRTI) or indinavir and two NRTIs. Intention-to-treat (ITT) and on-treatment (OT) analyses were performed.

Results

The baseline characteristics of the study participants were similar in both arms, 67 patients (37%) were naive to antiretroviral treatment. The proportion of patients who achieved a plasma viral load below the level of detection of 400 copies/ml at week 48 was 43% (39/90) in the ritonavir/saquinavir arm and 63% (57/90) in the indinavir arm ( P=0.005, ITT analysis). Using an OT analysis, these percentages were 84% and 88%, respectively ( P=0.6). There were more drop-outs in the ritonavir/saquinavir arm than in the indinavir arm (35.6% (32/90) versus 15.6% (14/90), P=0.002), mainly due to gastro-intestinal side-effects. Abnormal liver tests and increased lipids levels were more frequently reported in the ritonavir/saquinavir arm than in the indinavir arm.

Conclusion

In PI-naive patients, indinavir in combination with two NRTIs was more effective and better tolerated than ritonavir/saquinavir plus one NRTI. Both treatments were very effective for patients who were able to tolerate them.

Combination of Protease Inhibitors for the Treatment of HIV-1-Infected Patients: A Review of Pharmacokinetics and Clinical Experience

The use of highly active antiretroviral therapy, the combination of at least three different antiretroviral drugs for the treatment of HIV-1 infection, has greatly improved the prognosis for HIV-1-infected patients. The efficacy of a combination of a protease inhibitor (PI) plus two nucleoside analogue reverse transcriptase inhibitors has been well established over a period of up to 3 years. However, virological treatment failure has been reported in 40–60% of unselected patients within 1 year after initiation of a PI-containing regimen. This observation may, at least in part, be attributed to the poor pharmacokinetic characteristics of the PIs. Given as a single agent the PIs have several pharmacokinetic limitations; relatively short plasma-elimination half-lives and a modest and variable oral bioavailability, which is, for some of the PIs, influenced by food. To overcome these suboptimal pharmacokinetics, high doses (requiring large numbers of pills) must be ingested, often with food restrictions, which complicates patient adherence to the prescribed regimen.

Positive drug–drug interactions increase the exposure to the PIs, allowing administration of lower doses at reduced dosing frequencies with less dietary restrictions. In addition to increasing the potency of an antiretroviral regimen, combinations of PIs may enhance patient adherence, both of which will contribute to a more durable suppression of viral replication. The favourable pharmacokinetics of PIs in combination are a result of interactions through cytochrome P450 3A4 (CYP3A4) isoenzymes and, possibly, the multi-drug transporting P-glycoprotein (P-gp). Antiretroviral synergy between PIs and non-overlapping primary resistance patterns in the HIV-1 protease genome may further enhance the anti-retroviral potency and durability of combinations of PIs. Many combinations contain ritonavir because this PI has the most pronounced inhibiting effects on CYP3A4. The combination of saquinavir and ritonavir, both in a dose of 400 mg twice-a-day, is the most studied double PI combination, with clinical experience extending over 3 years. Combination of a PI with a low dose of ritonavir (≤400 mg/day), only to boost its pharmacokinetic properties, seems an attractive option for patients who cannot tolerate higher doses of ritonavir. A recently introduced PI, lopinavir, has been co-formulated with low-dose ritonavir, which allows for a convenient three-capsules, twice-a-day dosing regimen. In an attempt to prolong suppression of viral replication combinations of PIs are becoming increasingly popular. However, further clinical studies are needed to identify the optimal combinations for treatment of antiretroviral naive and experienced HIV-1-infected patients. This review covers combinations of saquinavir, indinavir, nelfinavir, amprenavir and lopinavir with different doses of ritonavir, as well as the combinations of saquinavir and indinavir with nelfinavir.

Analysis of Virological Efficacy in Trials of Antiretroviral Regimens: Drawbacks of Not Including Viral Load Measurements after Premature Discontinuation of Therapy

Objectives

To compare two analytic approaches to assess the virological effect of HAART according to the intention-to-treat (ITT) principle.

Material

Data from 2318 patients enrolled in 10 randomised clinical trials (RCTs) and from 3091 patients followed in an observation cohort (EuroSIDA) starting their first HAART regimen.

Methods

Two classifications of defining virological response 48 weeks after starting the therapy to be evaluated were compared: 1) only patients remaining on the therapy and having a plasma viral load (pVL) below a given cut-off level at week 48 were classified as responders (ITT/s=f); and 2) patients with a pVL below a given cut-off at week 48 whether they remained on initial assigned therapy or switched therapy were responders (ITT/s incl). In both analyses, patients with missing data at week 48 were classified as failures (i.e., non-responders).

Results

According to ITT/s=f, 22–70% of the patients starting a HAART regimen in a RCT experienced a virological response at week 48. Only two RCTs had complete follow-up data ( n=424): between 29 and 62% achieved a virological response at week 48 in the six treatment arms evaluated in the studies according to ITT/s=f, and 41–72% according to ITT/s incl. Among those who discontinued the therapy to be evaluated in these two trials, 13–45% (cohort: 39–74%) subsequently experienced a virological response at week 48. The subsequent response rates were associated with the reason for discontinuation (toxicity versus confirmed virological failure: 63 vs 33%), varied largely across regimens and were not associated with the discontinuation rate.

Conclusions

Discontinuation of follow-up at switch from the therapy to be evaluated remains common in anti-retroviral treatment trials, but leads to an imprecise and incomplete assessment of the intrinsic effect of a given regimen. Complete follow-up of all patients should be encouraged strongly as this will allow for several complementary analytic approaches and a focus on optimal treatment strategies rather than specific regimens.

Concentration-controlled compared with conventional antiretroviral therapy for HIV infection

OBJECTIVES

To demonstrate the feasibility of a concentration-controlled approach to combination antiretroviral therapy, and to compare the virological responses and safety of this strategy versus conventional fixed-dose therapy.

DESIGN

A prospective, randomized, 52 week, open-label trial of concentration-controlled compared with conventional dose zidovudine, lamivudine, and indinavir therapy conduced in a university-based general clinical research center in the United States.

PATIENTS

Forty antiretroviral-naive individuals with plasma HIV-RNA levels > 5000 copies/ml.

INTERVENTIONS

Zidovudine, lamivudine, and indinavir plasma concentrations were measured in all participants. Doses were adjusted in those assigned to concentration-controlled therapy to achieve levels equal to or greater than target values.

MAIN OUTCOME MEASURES

The proportion of patients who achieved the desired drug concentrations, the proportion of patients with HIV-RNA levels < 50 copies/ml at week 52, and safety and tolerance in the concentration-controlled versus conventional therapy arms.

RESULTS

Significantly more concentration-controlled recipients achieved the desired concentration targets for all three drugs: 15 of 16 concentration-controlled recipients compared with nine of 17 conventional recipients (P = 0.017) had HIV-RNA levels < 50 copies/ml at week 52. No difference was observed in the occurrence of drug-related clinical events or laboratory abnormalities between the two treatment arms.

CONCLUSION

Concentration-controlled therapy implemented simultaneously for three antiretroviral agents was feasible, as well tolerated as conventional therapy, and resulted in a greater proportion of recipients with HIV-RNA levels < 50 copies/ml after 52 weeks. These findings provide a scientific basis to challenge the accepted practice of administering the same dose of antiretroviral agents to all adults, ignoring the concentrations actually achieved.

Long-term efficacy and safety of ritonavir/indinavir at 400/400 mg twice a day in combination with two nucleoside reverse transcriptase inhibitors as first line antiretroviral therapy

OBJECTIVE

To determine the long-term antiretroviral efficacy and tolerability of dual protease inhibitor (PI) therapy with indinavir (IDV)/ritonavir (RTV) at 400/400 mg twice a day (BID) in combination with two nucleoside reverse trancriptase inhibitors (NRTIs).

DESIGN AND METHODS

In an open-label, uncontrolled multicentre clinical trial, antiretroviral therapy naive patients (n = 93) with a high median baseline HIV-1 RNA level of 210 000 copies/mL (range 17 000-2 943 000) and a median CD4 cell count of 195 copies/microL (range 4-656 copies/microL) were started on a regimen of either zidovudine (ZDV)/lamivudine (3TC) (49%), stavudine (d4T)/3TC (38%) or d4T/didanosine (ddI) (14%) plus RTV and IDV, each at 400 mg BID. CD4 cell counts and HIV RNA were determined at 4-week intervals for a duration of 72 weeks. Statistical analysis was performed on treatment as well as by intent to treat, where missing values were counted as failures.

RESULTS

HIV RNA levels below the limit of detection were achieved in 59.5% (< 80 copies/mL) and 63% (< 500 copies/mL) of patients according to the intent to treat analysis at week 72. In the on treatment analysis, the proportion of patients reaching an undetectable viral load was 94.5% (< 80 copies/mL) and 100% (< 500 copies/mL), respectively. Apart from diarrhoea and nausea, serum lipid abnormalities were identified as the most prominent adverse reaction. No cases of nephrotoxicity occurred during the entire observation period of 72 weeks.

CONCLUSIONS

Our results demonstrate that quadruple therapy with RTV/IDV and two NRTIs induces potent, durable and safe HIV suppression and might be particularly beneficial as a first line therapy for patients with a high baseline viral load.

Comparison of the effectiveness of non-nucleoside reverse transcriptase inhibitor-containing and protease inhibitor-containing regimens using observational databases

OBJECTIVES

To compare the effectiveness of first protease inhibitor (PI)-containing and non-nucleoside reverse transcriptase inhibitor (NNRTI)-containing regimens.

METHODS

Data were analysed from three large HIV patient databases: Apache HIV Insight (APACHE), Target Management Services (TMS) and Clinical Partners (CP). The effectiveness of therapy was the time taken for HIV-1 RNA to fall below detectable levels on first highly active antiretroviral therapy regimen (PI- or NNRTI-containing) and the subsequent time to failure (two consecutive detectable measurements). Comparisons were made using proportional hazards models, adjusting for differences in age, sex, previous reverse transcriptase inhibitor use, calendar year and baseline viral load and CD4 T-cell count.

RESULTS

The type of regimen was not associated with time to undetectable viral load in any of the three databases, all of which had high power to detect a difference. PI-containing regimens were significantly less likely to fail after reaching undetectable viral loads for APACHE and CP patients (relative hazard, 1.7; 95% confidence interval, 1.3--2.1 and relative hazard, 1.6; 95% confidence interval, 1.0--2.5 respectively). These results remained significant after allowing for an unmeasured confounder with moderate effect on risk. No significant association between time to failure and regimen was found for TMS patients, possibly due to low power (67% to detect a relative hazard of 1.5). No difference was found between regimens in the time taken for an increase of > 100 x 10(9)cells/l in CD4 T-cell count. In the APACHE database, those on NNRTI-containing regimens were more likely to have a failing CD4 T-cell response.

CONCLUSIONS

PI-containing regimens have a lower risk of treatment failure than NNRTI-containing regimens.

Clinical outcome among HIV-infected patients starting saquinavir hard gel compared to ritonavir or indinavir

OBJECTIVE

To compare the clinical response among patients who initiate protease inhibitor therapies with different virological potency.

DESIGN

We analysed patients who started indinavir, ritonavir or saquinavir hard gel capsule (hgc) as part of at least triple therapy during prospective follow-up within the EuroSIDA study.

METHODS

Changes in plasma viral load (pVL) and CD4 cell count from baseline were compared between treatment groups. Time to new AIDS-defining events and death were compared in Kaplan--Meier models, and Cox models were established to further assess differences in clinical progression (new AIDS/death). Adjustment was made for differences in baseline parameters, in particular pVL, CD4 cell count, and region of Europe.

RESULTS

A total of 2708 patients (median follow-up: 30 months) were included, of which 556 started ritonavir (21%), 1342 indinavir (50%), and 810 saquinavir hgc (30%). The three groups were fairly evenly balanced at baseline regarding CD4 count, previous diagnosis of AIDS and pVL, After 12 months, the median changes in CD4 cell count were 90, 96 and 74 x 10(6) cells/l, respectively;P < 0.001, the proportions of patients with pVL < 500 copies/ml were 47, 54 and 41%; P < 0.001, and the proportions with clinical progression were 11.9, 9.2 and 11.9%, respectively; P = 0.20 (log-rank test). In multivariate models the relative risk of clinical progression for indinavir compared with saquinavir hgc was: 0.77 (0.60--0.99); P = 0.043, and for ritonavir 0.83 (0.62--1.11); P = 0.20.

CONCLUSIONS

Saquinavir hgc was associated with an inferior long-term clinical response relative to indinavir, which was consistent with the observed differences in virological and immunological responses.

Low body weight and type of protease inhibitor predict discontinuation and treatment-limiting adverse drug reactions among HIV-infected patients starting a protease inhibitor regimen: consistent results from a randomized trial and an observational cohort

OBJECTIVES

To assess predictors for discontinuation and treatment-limiting adverse drug reactions (TLADR) among patients starting their first protease inhibitor (PI).

METHODS

Data on patients starting a PI regimen (indinavir, ritonavir, ritonavir/saquinavir and saquinavir hard gel) in a randomized trial (RAS, n = 318) and an observational cohort (OBC, n = 505) were used to document reasons for discontinuation and TLADR. Risk factors for discontinuation of the initial PI/developing TLADR were assessed in Cox models.

RESULTS

A total of 43 (RAS) and 48% (OBC) discontinued the initial PI therapy within less than 2 years. In both populations TLADR were the most common reason for discontinuation. The incidence of TLADR in RAS was: 8.5 (indinavir), 66.0 (ritonavir), 15.6 (saquinavir hard gel) per 100 person-years of follow-up (P < 0.001). Body weight and type of PI initiated were independent risk factors for treatment discontinuation and TLADR in both groups. In OBC, the risk of developing TLADR increased by 12% per 5 kg lower body weight when starting the PI regimen [the relative hazard (RH) was 1.12 (95% confidence interval: 1.05-1.19) per 5 kg lighter], and starting ritonavir was associated with a three- to sixfold higher risk of TLADR relative to other PI regimens. Very similar results were documented in RAS [RH for body weight was 1.18 (1.07-1.29)].

CONCLUSIONS

Nearly half of the patients stopped treatment with the initial PI, most commonly as a result of adverse drug reactions. Low body weight and initiation of ritonavir relative to other PIs were associated with an increased risk of TLADRs. Very consistent results were found in a randomized trial and an observational cohort.