Designing and interpreting HIV noninferiority trials in naive and experienced patients

Same-day versus rapid ART initiation in HIV-positive individuals presenting with symptoms of tuberculosis: Protocol for an open-label randomized non-inferiority trial in Lesotho and Malawi

BACKGROUND

In absence of contraindications, same-day initiation (SDI) of antiretroviral therapy (ART) is recommended for people testing HIV-positive who are ready to start treatment. Until 2021, World Health Organization (WHO) guidelines considered the presence of TB symptoms (presumptive TB) a contraindication to SDI due to the risk of TB-immune reconstitution inflammatory syndrome (TB-IRIS). To reduce TB-IRIS risk, ART initiation was recommended to be postponed until results of TB investigations were available, and TB treatment initiated if active TB was confirmed. In 2021, the WHO guidelines changed to recommending SDI even in the presence of TB symptoms without awaiting results of TB investigations based on the assumption that TB investigations often unnecessarily delay ART initiation, increasing the risk for pre-ART attrition from care, and noting that the clinical relevance of TB-IRIS outside the central nervous system remains unclear. However, this guideline change was not based on conclusive evidence, and it remains unclear whether SDI of ART or TB test results should be prioritized in people with HIV (PWH) and presumptive TB.

DESIGN AND METHODS

SaDAPT is an open-label, pragmatic, parallel, 1:1 individually randomized, non-inferiority trial comparing two strategies for the timing of ART initiation in PWH with presumptive TB ("ART first" versus "TB results first"). PWH in Lesotho and Malawi, aged 12 years and older (re)initiating ART who have at least one TB symptom (cough, fever, night sweats or weight loss) and no signs of intracranial infection are eligible. After a baseline assessment, participants in the "ART first" arm will be offered SDI of ART, while those in the "TB results first" arm will be offered ART only after active TB has been confirmed or refuted. We hypothesize that the "ART first" approach is safe and non-inferior to the "TB results first" approach with regard to HIV viral suppression (<400 copies/ml) six months after enrolment. Secondary outcomes include retention in care and adverse events consistent with TB-IRIS.

EXPECTED OUTCOMES

SaDAPT will provide evidence on the safety and effects of SDI of ART in PWH with presumptive TB in a pragmatic clinical trial setting.

TRIAL REGISTRATION

The trial has been registered on clinicaltrials.gov (NCT05452616; July 11 2022).

Time to rethink endpoints for new clinical trials of antiretrovirals? Long-term re-suppression of HIV RNA with integrase inhibitors

: In the ADVANCE study of first-line treatment, there were 48 participants with HIV RNA at least 50 copies/ml in the week 48 window who had subsequent follow-up data available with no change in randomized treatment. More participants achieved virological re-suppression in the TAF/FTC+DTG and TDF/FTC+DTG arms (26/34, 76%) than on TDF/FTC/EFV (6/14 = 43%; P = 0.0421). It is unclear whether participants with HIV RNA at least 50 copies/ml at week 48 should be termed 'virological failures' on integrase inhibitor-based treatment.

Dolutegravir-Based or Low-Dose Efavirenz-Based Regimen for the Treatment of HIV-1

BACKGROUND

An efavirenz-based regimen (with a 600-mg dose of efavirenz, known as EFV600) was the World Health Organization preferred first-line treatment for human immunodeficiency virus type 1 (HIV-1) infection until June 2018. Given concerns about side effects, dolutegravir-based and low-dose efavirenz-based combinations have been considered as first-line treatments for HIV-1 in resource-limited settings.

METHODS

We conducted an open-label, multicenter, randomized, phase 3 noninferiority trial in Cameroon. Adults with HIV-1 infection who had not received antiretroviral therapy and had an HIV-1 RNA level (viral load) of at least 1000 copies per milliliter were randomly assigned to receive either dolutegravir or the reference treatment of low-dose efavirenz (a 400-mg dose, known as EFV400), combined with tenofovir and lamivudine. The primary end point was the proportion of participants with a viral load of less than 50 copies per milliliter at week 48, on the basis of the Food and Drug Administration snapshot algorithm. The difference between treatment groups was calculated, and noninferiority was tested with a margin of 10 percentage points.

RESULTS

A total of 613 participants received at least one dose of the assigned regimen. At week 48, a viral load of less than 50 copies per milliliter was observed in 231 of 310 participants (74.5%) in the dolutegravir group and in 209 of 303 participants (69.0%) in the EFV400 group, with a difference of 5.5 percentage points (95% confidence interval [CI], -1.6 to 12.7; P<0.001 for noninferiority). Among those with a baseline viral load of at least 100,000 copies per milliliter, a viral load of less than 50 copies per milliliter was observed in 137 of 207 participants (66.2%) in the dolutegravir group and in 123 of 200 participants (61.5%) in the EFV400 group, with a difference of 4.7 percentage points (95% CI, -4.6 to 14.0). Virologic failure (a viral load of >1000 copies per milliliter) was observed in 3 participants in the dolutegravir group (with none acquiring drug-resistance mutations) and in 16 participants in the EFV400 group. More weight gain was observed in the dolutegravir group than in the EFV400 group (median weight gain, 5.0 kg vs. 3.0 kg; incidence of obesity, 12.3% vs. 5.4%).

CONCLUSIONS

In HIV-1-infected adults in Cameroon, a dolutegravir-based regimen was noninferior to an EFV400-based reference regimen with regard to viral suppression at week 48. Among participants who had a viral load of at least 100,000 copies per milliliter when antiretroviral therapy was initiated, fewer participants than expected had viral suppression. (Funded by Unitaid and the French National Agency for AIDS Research; NAMSAL ANRS 12313 ClinicalTrials.gov number, NCT02777229.).

Dolutegravir plus Two Different Prodrugs of Tenofovir to Treat HIV

BACKGROUND

Two drugs under consideration for inclusion in antiretroviral therapy (ART) regimens for human immunodeficiency virus (HIV) infection are dolutegravir (DTG) and tenofovir alafenamide fumarate (TAF). There are limited data on their use in low- and middle-income countries.

METHODS

We conducted a 96-week, phase 3, investigator-led, open-label, randomized trial in South Africa, in which we compared a triple-therapy combination of emtricitabine (FTC) and DTG plus either of two tenofovir prodrugs - TAF (TAF-based group) or tenofovir disoproxil fumarate (TDF) (TDF-based group) - against the local standard-of-care regimen of TDF-FTC-efavirenz (standard-care group). Inclusion criteria included an age of 12 years or older, no receipt of ART in the previous 6 months, a creatinine clearance of more than 60 ml per minute (>80 ml per minute in patients younger than 19 years of age), and an HIV type 1 (HIV-1) RNA level of 500 copies or more per milliliter. The primary end point was the percentage of patients with a 48-week HIV-1 RNA level of less than 50 copies per milliliter (as determined with the Snapshot algorithm from the Food and Drug Administration; noninferiority margin, -10 percentage points). We report the primary (48-week) efficacy and safety data.

RESULTS

A total of 1053 patients underwent randomization from February 2017 through May 2018. More than 99% of the patients were black, and 59% were female. The mean age was 32 years, and the mean CD4 count was 337 cells per cubic millimeter. At week 48, the percentage of patients with an HIV-1 RNA level of less than 50 copies per milliliter was 84% in the TAF-based group, 85% in the TDF-based group, and 79% in the standard-care group, findings that indicate that the DTG-containing regimens were noninferior to the standard-care regimen. The number of patients who discontinued the trial regimen was higher in the standard-care group than in the other two groups. In the per-protocol population, the standard-care regimen had equivalent potency to the other two regimens. The TAF-based regimen had less effect on bone density and renal function than the other regimens. Weight increase (both lean and fat mass) was greatest in the TAF-based group and among female patients (mean increase, 6.4 kg in the TAF-based group, 3.2 kg in the TDF-based group, and 1.7 kg in the standard-care group). No resistance to integrase inhibitors was identified in patients receiving the DTG-containing regimens.

CONCLUSIONS

Treatment with DTG combined with either of two tenofovir prodrugs (TAF and TDF) showed noninferior efficacy to treatment with the standard-care regimen. There was significantly more weight gain with the DTG-containing regimens, especially in combination with TAF, than with the standard-care regimen. (ADVANCE ClinicalTrials.gov number, NCT03122262.).

Low-dose ritonavir-boosted darunavir once daily versus ritonavir-boosted lopinavir for participants with less than 50 HIV RNA copies per mL (WRHI 052): a randomised, open-label, phase 3, non-inferiority trial

BACKGROUND

Pilot studies suggest that ritonavir-boosted darunavir could show high efficacy at doses below those currently approved. We investigated whether switch to 400 mg of darunavir boosted with 100 mg ritonavir once daily could show equivalent efficacy to continuation of ritonavir-boosted lopinavir (a protease inhibitor commonly used in low-income and middle-income countries) for individuals with HIV RNA suppression.

METHODS

In the WRHI 052 study, a randomised, parallel-group, open-label, non-inferiority phase 3 trial, adults who were HIV-1 positive were enrolled in Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa. Eligible participants were 18 years or older, who tolerated ritonavir-boosted lopinavir in combination with two nucleoside analogues (standard of care) for 6 months or more, and had plasma HIV-1 RNA of less than 50 copies per mL within 60 days of enrolment. We randomly assigned participants (1:1), using a computer-generated randomisation plan, to switch to darunavir (400 mg) boosted with ritonavir (100 mg) once daily or remain on ritonavir-boosted lopinavir (800 mg [plus 200 mg ritonavir]), with nucleoside analogues left unchanged. The primary endpoint was the proportion of patients with less than 50 HIV-1 RNA copies per mL at week 48 (US Food and Drug Administration snapshot algorithm; non-inferiority margin -4%). Primary and safety analyses included participants receiving at least one dose of darunavir boosted with ritonavir. This trial is registered with ClinicalTrials.gov, number NCT02671383.

FINDINGS

Between June 30, 2016, and June 15, 2017, 148 participants were assigned to ritonavir-boosted darunavir 400 mg and 152 continued on their lopinavir-containing regimen. Four (3%) patients in the darunavir group and three (2%) in the lopinavir group discontinued before week 48. At week 48, darunavir was non-inferior to lopinavir for the primary outcome (142 [96%] of 148 participants on darunavir had <50 HIV-1 RNA copies per mL vs 143 [94%] of 152 participants on lopinavir; difference 1·9% [95% CI -3·4 to 7·3]), with a predefined margin of -4%. More participants taking darunavir (30 [20%] participants) had drug-related adverse events than those on lopinavir (eight [5%]), but the adverse events were generally asymptomatic and resolved when switching back to lopinavir. Elevated liver transaminase in three (1%; one symptomatic) darunavir participants led to study withdrawal; all transaminase elevations resolved on restarting lopinavir.

INTERPRETATION

Low-dose ritonavir-boosted darunavir might be a safe and efficacious switch option to maintain HIV suppression for patients on lopinavir. However, an adequately powered and designed study in viraemic participants is needed.

FUNDING

South African Medical Research Council, United States Agency for International Development, and US National Institute of Allergy and Infectious Diseases.

Superiority and non-inferiority: two sides of the same coin?

Background

The classification of phase 3 trials as superiority or non-inferiority has become routine, and it is widely accepted that there are important differences between the two types of trial in their design, analysis and interpretation.

Main text

There is a clear rationale for the superiority/non-inferiority framework in the context of regulatory trials. The focus of our article is non-regulatory trials with a public health objective. First, using two examples from infectious disease research, we show that the classification of superiority or non-inferiority trials is not always straightforward. Second, we show that several arguments for different approaches to the design, analysis and interpretation of superiority and non-inferiority trials are unconvincing when examined in detail. We consider, in particular, the calculation of sample size (and the choice of delta or the non-inferiority margin), intention-to-treat versus per-protocol analyses, and one-sided versus two-sided confidence intervals. We argue that the superiority/non-inferiority framework is not just unnecessary but can have a detrimental effect, being a barrier to clear scientific thought and communication. In particular, it places undue emphasis on tests for significance or non-inferiority at the expense of estimation. We emphasise that these concerns apply to phase 3 non-regulatory trials in general, not just to those where the classification of the trial as superiority or non-inferiority is ambiguous.

Conclusions

Guidelines and statistical practice should abandon the sharp division between superiority and non-inferiority phase 3 non-regulatory trials and be more closely aligned to the clinical and public health questions that motivate the trial.

Choice of antiretroviral drugs for continued treatment scale-up in a public health approach: what more do we need to know?

INTRODUCTION

There have been several important developments in antiretroviral treatment in the past two years. Randomized clinical trials have been conducted to evaluate a lower dose of efavirenz (400 mg once daily). Integrase inhibitors such as dolutegravir have been approved for first-line treatment. A new formulation of tenofovir (alafenamide) has been developed and has shown equivalent efficacy to tenofovir in randomized trials. Two-drug combination treatments have been evaluated in treatment-naïve and -experienced patients. The novel pharmacokinetic booster cobicistat has been compared to ritonavir in terms of pharmacokinetics, efficacy and safety. The objective of this commentary is to assess recent developments in antiretroviral drug treatment to determine whether new treatments should be included in new international guidelines.

DISCUSSION

The use of first-line treatment with tenofovir and efavirenz at the standard 600 mg once-daily dose should remain the first-choice standard of care treatment. Evidence supporting a switch to efavirenz 400 mg once daily or integrase inhibitors is sufficient to consider these drugs as alternative first-line options, but more data are needed on their use in pregnant women and people with TB co-infection. The use of new formulations of tenofovir is currently too preliminary to justify immediate adoption and scale-up across HIV programmes in low- and middle-income countries. The evidence supporting use of two-drug combinations is not considered strong enough to justify changed recommendations from use of standard triple drug combinations. Cobicistat does not offer significant safety advantages over ritonavir as a pharmacokinetic booster.

CONCLUSIONS

For continued scale-up of antiretroviral treatment in low- and middle-income countries, use of first-line triple combinations including efavirenz 600 mg once daily is supported by the largest evidence base. Additional studies are underway to evaluate new treatments in key populations, and these results may justify changes to these recommendations.

Some current issues in the design of HIV noninferiority trials

Since the introduction of protease inhibitors and their combination with two nucleoside reverse transcriptase inhibitors in tri-therapy, there has been a continuous improvement in the efficacy of antiretroviral treatments. Such combinations have been rendered even more effective by the introduction of non-nucleoside reverse transcriptase inhibitors and, more recently, integrase inhibitors. This progress has led to a move away from superiority designs towards noninferiority designs for randomized clinical trials for HIV. Noninferiority trials aim to demonstrate that a new regimen is no worse than the current standard. The methodological issues associated with such designs have been discussed, but recent HIV trials provide us with an opportunity to consider the choice of hypotheses. Recent HIV trials have been overpowered, due to the assumption of lower success rates than observed and the enrollment of a large number of patients. The use of stratified statistical methods for primary endpoint analysis, with sample size calculated by classical methods (without stratification), also increases the statistical power. Some HIV trials have a statistical power close to 99%. Surprisingly, the results of some previous studies or phase II trials are not taken into account when designing the corresponding phase III trials. We discuss alternative hypotheses and designs.

Once-daily dolutegravir versus darunavir plus ritonavir in antiretroviral-naive adults with HIV-1 infection (FLAMINGO): 48 week results from the randomised open-label phase 3b study

BACKGROUND

Dolutegravir has been shown to be non-inferior to an integrase inhibitor and superior to a non-nucleoside reverse transcriptase inhibitor (NNRTI). In FLAMINGO, we compared dolutegravir with darunavir plus ritonavir in individuals naive for antiretroviral therapy.

METHODS

In this multicentre, open-label, phase 3b, non-inferiority study, HIV-1-infected antiretroviral therapy-naive adults with HIV-1 RNA concentration of 1000 copies per mL or more and no resistance at screening were randomly assigned (1:1) to receive either dolutegravir 50 mg once daily or darunavir 800 mg plus ritonavir 100 mg once daily, with investigator-selected tenofovir-emtricitabine or abacavir-lamivudine. Randomisation was stratified by screening HIV-1 RNA (≤100,000 or >100,000 copies per mL) and nucleoside reverse transcriptase inhibitor (NRTI) selection. The primary endpoint was the proportion of patients with HIV-1 RNA concentration lower than 50 copies per mL (Food and Drug Administration [FDA] snapshot algorithm) at week 48 with a 12% non-inferiority margin. This trial is registered with ClinicalTrials.gov, NCT01449929.

FINDINGS

Recruitment began on Oct 31, 2011, and was completed on May 24, 2012, in 64 research centres in nine countries worldwide. Of 595 patients screened, 484 patients were included in the analysis (242 in each group). At week 48, 217 (90%) patients receiving dolutegravir and 200 (83%) patients receiving darunavir plus ritonavir had HIV-1 RNA of less than 50 copies per mL (adjusted difference 7·1%, 95% CI 0·9-13·2), non-inferiority and on pre-specified secondary analysis dolutegravir was superior (p=0·025). Confirmed virological failure occurred in two (<1%) patients in each group; we recorded no treatment-emergent resistance in either group. Discontinuation due to adverse events or stopping criteria was less frequent for dolutegravir (four [2%] patients) than for darunavir plus ritonavir (ten [4%] patients) and contributed to the difference in response rates. The most commonly reported (≥10%) adverse events were diarrhoea (dolutegravir 41 [17%] patients vs darunavir plus ritonavir 70 [29%] patients), nausea (39 [16%] vs 43 [18%]), and headache (37 [15%] vs 24 [10%]). Patients receiving dolutegravir had significantly fewer low-density lipoprotein values of grade 2 or higher (11 [2%] vs 36 [7%]; p=0·0001).

INTERPRETATION

Once-daily dolutegravir was superior to once-daily darunavir plus ritonavir. Once-daily dolutegravir in combination with fixed-dose NRTIs represents an effective new treatment option for HIV-1-infected, treatment-naive patients.

FUNDING

ViiV Healthcare and Shionogi & Co.

When can HIV clinical trials detect treatment effects on drug resistance?

Methods of sampling patients for resistance testing, and statistical analyses of HIV drug resistance, have not been standardised in HIV clinical trials. We analysed methods of genotyping and rates of treatment-emergent drug resistance from 27 clinical trials identified from a MEDLINE search. Sample size calculations were conducted using NQUERY software, assuming 5% significance level, 80% power and 1:1 randomisation. The percentage of patients with treatment-emergent IAS-USA mutations after 96 weeks ranged from 1.8% to 9.1% for first-line 2NRTI/NNRTI treatments, 0.6% to 6.3% for first-line 2NRTI/PI/r treatments and 0.0% to 2.0% in switch trials of boosted PIs. The prevalence of drug resistance was higher in trials with no screening for drug resistance at baseline, where the HIV RNA cut-off for genotyping was >50 copies/mL, where patients were tested for drug resistance after discontinuation of treatment, and where follow-up times were 96 weeks or longer. HIV clinical trials could be designed to detect differences in the risk of HIV drug resistance between treatments, as an analysis supporting HIV RNA suppression as the primary endpoint. However, this would require a standardised approach, with intent-to-treat analyses, testing of all samples with HIV RNA>50 copies/mL and genotyping after drug discontinuation.

Etravirine as a Switching Option for Patients with HIV RNA Suppression: A Review of Recent Trials

Unlike other nonnucleoside reverse transcriptase inhibitors, etravirine is only approved for use in treatment-experienced patients. In the DUET 1 and 2 trials, 1203 highly treatment-experienced patients were randomized to etravirine or placebo, in combination with darunavir/ritonavir and optimized background treatment. In these trials, etravirine showed significantly higher rates of HIV RNA suppression when compared with placebo (61% versus 40% at Week 48). There was no significant rise of lipids or neuropsychiatric adverse events, but there was an increase in the risk of rash with etravirine treatment. In the SENSE trial, which evaluated etravirine and efavirenz in 157 treatment-naïve patients in combination with 2 nucleoside analogues, there was a lower risk of lipid elevations and neuropsychiatric adverse events with etravirine when compared to efavirenz. Etravirine has been evaluated in three randomized switching studies. In the SSAT029 switch trial, 38 patients who had neuropsychiatric adverse events possibly related to efavirenz showed an improvement in these after switching to etravirine. The Swiss Switch-EE recruited 58 individuals without neuropsychiatric adverse events who were receiving efavirenz, and no benefit was shown when switching to etravirine. In the Spanish ETRA-SWITCH trial (n = 46), there were improvements in lipids when individuals switched from a protease inhibitor to etravirine. These switching trials were conducted in patients with full HIV RNA suppression: <50 copies/mL and with no history of virological failure or resistance to therapy. The results from these three randomized switching studies suggest a possible new role for etravirine, in combination with two nucleoside analogues, as a switching option for those with HIV RNA suppression but who are reporting adverse events possibly related to antiretroviral therapy. However a large well-powered trial would need to be conducted to strengthen the evidence from the pilot studies conducted so far.

Dolutegravir plus abacavir-lamivudine for the treatment of HIV-1 infection

BACKGROUND

Dolutegravir (S/GSK1349572), a once-daily, unboosted integrase inhibitor, was recently approved in the United States for the treatment of human immunodeficiency virus type 1 (HIV-1) infection in combination with other antiretroviral agents. Dolutegravir, in combination with abacavir-lamivudine, may provide a simplified regimen.

METHODS

We conducted a randomized, double-blind, phase 3 study involving adult participants who had not received previous therapy for HIV-1 infection and who had an HIV-1 RNA level of 1000 copies per milliliter or more. Participants were randomly assigned to dolutegravir at a dose of 50 mg plus abacavir-lamivudine once daily (DTG-ABC-3TC group) or combination therapy with efavirenz-tenofovir disoproxil fumarate (DF)-emtricitabine once daily (EFV-TDF-FTC group). The primary end point was the proportion of participants with an HIV-1 RNA level of less than 50 copies per milliliter at week 48. Secondary end points included the time to viral suppression, the change from baseline in CD4+ T-cell count, safety, and viral resistance.

RESULTS

A total of 833 participants received at least one dose of study drug. At week 48, the proportion of participants with an HIV-1 RNA level of less than 50 copies per milliliter was significantly higher in the DTG-ABC-3TC group than in the EFV-TDF-FTC group (88% vs. 81%, P=0.003), thus meeting the criterion for superiority. The DTG-ABC-3TC group had a shorter median time to viral suppression than did the EFV-TDF-FTC group (28 vs. 84 days, P<0.001), as well as greater increases in CD4+ T-cell count (267 vs. 208 per cubic millimeter, P<0.001). The proportion of participants who discontinued therapy owing to adverse events was lower in the DTG-ABC-3TC group than in the EFV-TDF-FTC group (2% vs. 10%); rash and neuropsychiatric events (including abnormal dreams, anxiety, dizziness, and somnolence) were significantly more common in the EFV-TDF-FTC group, whereas insomnia was reported more frequently in the DTG-ABC-3TC group. No participants in the DTG-ABC-3TC group had detectable antiviral resistance; one tenofovir DF-associated mutation and four efavirenz-associated mutations were detected in participants with virologic failure in the EFV-TDF-FTC group.

CONCLUSIONS

Dolutegravir plus abacavir-lamivudine had a better safety profile and was more effective through 48 weeks than the regimen with efavirenz-tenofovir DF-emtricitabine. (Funded by ViiV Healthcare; SINGLE ClinicalTrials.gov number, NCT01263015 .).

Deficient reporting and interpretation of non-inferiority randomized clinical trials in HIV patients: a systematic review

OBJECTIVES

Non-inferiority (NI) randomized clinical trials (RCTs) commonly evaluate efficacy of new antiretroviral (ARV) drugs in human immunodeficiency virus (HIV) patients. Their reporting and interpretation have not been systematically evaluated. We evaluated the reporting of NI RCTs in HIV patients according to the CONSORT statement and assessed the degree of misinterpretation of RCTs when NI was inconclusive or not established.

DESIGN

Systematic review.

METHODS

PubMed, Web of Science, and Scopus were reviewed until December 2011. Selection and extraction was performed independently by three reviewers.

RESULTS

Of the 42 RCTs (n = 21,919; range 41-3,316) selected, 23 were in ARV-naïve and 19 in ARV-experienced patients. Twenty-seven (64%) RCTs provided information about prior RCTs of the active comparator, and 37 (88%) used 2-sided CIs. Two thirds of trials used a NI margin between 10 and 12%, although only 12 explained the method to determine it. Blinding was used in 9 studies only. The main conclusion was based on both intention-to-treat (ITT) and per protocol (PP) analyses in 5 trials, on PP analysis only in 4 studies, and on ITT only in 31 studies. Eleven of 16 studies with NI inconclusive or not established highlighted NI or equivalence, and distracted readers with positive secondary results.

CONCLUSIONS

There is poor reporting and interpretation of NI RCTs performed in HIV patients. Maximizing the reporting of the method of NI margin determination, use of blinding and both ITT and PP analyses, and interpreting negative NI according to actual primary findings will improve the understanding of results and their translation into clinical practice.

Once-daily dolutegravir versus raltegravir in antiretroviral-naive adults with HIV-1 infection: 48 week results from the randomised, double-blind, non-inferiority SPRING-2 study

BACKGROUND

Dolutegravir (S/GSK1349572) is a once-daily HIV integrase inhibitor with potent antiviral activity and a favourable safety profile. We compared dolutegravir with HIV integrase inhibitor raltegravir, as initial treatment for adults with HIV-1.

METHODS

SPRING-2 is a 96 week, phase 3, randomised, double-blind, active-controlled, non-inferiority study that began on Oct 19, 2010, at 100 sites in Canada, USA, Australia, and Europe. Treatment-naive adults (aged ≥ 18 years) with HIV-1 infection and HIV-1 RNA concentrations of 1000 copies per mL or greater were randomly assigned (1:1) via a computer-generated randomisation sequence to receive either dolutegravir (50 mg once daily) or raltegravir (400 mg twice daily). Study drugs were given with coformulated tenofovir/emtricitabine or abacavir/lamivudine. Randomisation was stratified by screening HIV-1 RNA (≤ 100,000 copies per mL or >100,000 copies per mL) and nucleoside reverse transcriptase inhibitor backbone. Investigators were not masked to HIV-1 RNA results before randomisation. The primary endpoint was the proportion of participants with HIV-1 RNA less than 50 copies per mL at 48 weeks, with a 10% non-inferiority margin. Main secondary endpoints were changes from baseline in CD4 cell counts, incidence and severity of adverse events, changes in laboratory parameters, and genotypic or phenotypic evidence of resistance. Our primary analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01227824.

FINDINGS

411 patients were randomly allocated to receive dolutegravir and 411 to receive raltegravir and received at least one dose of study drug. At 48 weeks, 361 (88%) patients in the dolutegravir group achieved an HIV-1 RNA value of less than 50 copies per mL compared with 351 (85%) in the raltegravir group (adjusted difference 2·5%; 95% CI -2·2 to 7·1). Adverse events were similar between treatment groups. The most common events were nausea (59 [14%] patients in the dolutegravir group vs 53 [13%] in the raltegravir group), headache (51 [12%] vs 48 [12%]), nasopharyngitis (46 [11%] vs 48 [12%]), and diarrhoea (47 [11%] in each group). Few patients had drug-related serious adverse events (three [<1%] vs five [1%]), and few had adverse events leading to discontinuation (ten [2%] vs seven [2%] in each group). CD4 cell counts increased from baseline to week 48 in both treatment groups by a median of 230 cells per μL. Rates of graded laboratory toxic effects were similar. We noted no evidence of treatment-emergent resistance in patients with virological failure on dolutegravir, whereas of the patients with virologic failure who received raltegravir, one (6%) had integrase treatment-emergent resistance and four (21%) had nucleoside reverse transcriptase inhibitors treatment-emergent resistance.

INTERPRETATION

The non-inferior efficacy and similar safety profile of dolutegravir compared with raltegravir means that if approved, combination treatment with once-daily dolutegravir and fixed-dose nucleoside reverse transcriptase inhibitors would be an effective new option for treatment of HIV-1 in treatment-naive patients.

FUNDING

ViiV Healthcare.

Design of HIV noninferiority trials: where are we going?

Since the introduction of zidovudine, a nucleoside analogue reverse transcriptase inhibitor, there has been continuous improvement in the efficacy of antiretroviral treatments. Briefly, antiretroviral therapy moved from the era of zidovudine monotherapy to a combination of two analogues of the reverse transcriptase and then to triple-drug therapy with the introduction of protease inhibitors in 1996. The efficacy of triple-drug combinations was further consolidated with the introduction of the non-nucleoside analogue reverse transcriptase inhibitor. Beyond 1996, the impressive improvement in efficacy has implied that death and clinical endpoints could not be reasonably used as primary efficacy endpoints. Recent studies used plasma viral load as surrogate endpoints to evaluate efficacy of antiretroviral combinations. Progress in antiretroviral efficacy has also led to a move from superiority to noninferiority design. Methodological issues in noninferiority design have been already criticized, but recent trials provide a good opportunity for discussing some key features of that design. Recent studies are used to illustrate some inconsistencies in the choice of response rates, power and noninferiority margin. It appears that HIV noninferiority trials are overpowered by assuming lower success rates than those observed, enrolling a large number of patients and choosing a large margin. Consequently, failure to demonstrate noninferiority is uncommon. Novel designs or endpoints should be introduced emphasizing the expected benefits in terms of toxicity, adherence, resistance or costs.

Impact of baseline HIV-1 RNA levels on initial highly active antiretroviral therapy outcome: a meta-analysis of 12,370 patients in 21 clinical trials*

BACKGROUND

Individual randomized trials of first-line antiretroviral treatment do not consistently show an association between higher baseline HIV-1 RNA and lower efficacy.

METHODS

A MEDLINE search identified 21 HIV clinical trials with published analyses of antiretroviral efficacy by baseline HIV-1 RNA, using a standardized efficacy endpoint of HIV-1 RNA suppression <50 copies/mL at week 48.

RESULTS

Among 21 clinical trials identified, eight evaluated only nonnucleoside reverse transcriptase inhibitor (NNRTI)-based combinations, eight evaluated only protease inhibitor-based regimens and five compared different treatment classes. Ten of the trials included tenofovir (TDF)/emtricitabine (FTC) as only nucleoside reverse transcriptase inhibitor (NRTI) backbone, in addition but not restricted to abacavir (ABC)/lamivudine (3TC) (n = 7), zidovudine (ZDV)/3TC (n = 4) and stavudine (d4T)/3TC (n = 1). Across trials, the mean percentage of patients achieving HIV-1 RNA < 50 copies/mL at week 48 was 81.5% (5322 of 6814) for patients with baseline HIV-1 RNA < 100 000, vs. 72.6% (3949 of 5556) for patients with HIV-1 RNA > 100 000 copies/mL. In the meta-analysis, the absolute difference in efficacy between low and high HIV-1 RNA subgroups was 7.4% [95% confidence interval (CI) 5.9-8.9%; P < 0.001]. This difference was consistent in trials of NNRTI-based treatments (difference = 6.9%; 95% CI 4.3-9.6%), protease inhibitor-based treatments (difference = 8.4%; 95% CI 6.0-10.8%) and integrase or chemokine (C-C motif) receptor 5 (CCR5)-based treatments (difference = 6.0%; 95% CI 2.1-9.9%) and for trials using TDF/FTC (difference = 8.4%; 95% CI 6.0-10.8%); there was no evidence for heterogeneity of this difference between trials (Cochran's Q test; not significant).

CONCLUSIONS

In this meta-analysis of 21 first-line clinical trials, rates of HIV-1 RNA suppression at week 48 were significantly lower for patients w ith baseline HIV-1 RNA > 100 000 copies/mL (P < 0.001). This difference in efficacy was consistent across trials of different treatment classes and NRTI backbones.

Optimizing HIV treatment

PURPOSE OF REVIEW

There are at least seven million people eligible for antiretroviral treatment but not receiving it. An additional 19 million people will need to start treatment in the future, as their HIV disease progresses. Funding for Universal Access to HIV treatment has been restricted by the Global Financial Crisis.

RECENT FINDINGS

There are three large randomized trials ongoing, designed to establish the efficacy of lower than approved doses of antiretrovirals. If successful, the results of these trials could lower costs of antiretrovirals and improve the safety profiles. Clinical trials evaluating efavirenz, atazanavir, ritonavir and stavudine are discussed. The costs of these and other antiretrovirals are presented.

SUMMARY

The results of these trials could significantly lower the costs of Universal Access. Assuming 15 million people on antiretroviral treatment, the reduction in unit costs of tenofovir (TDF)/3TC/efavirenz from dose optimization of efavirenz to 400 mg once daily would save US$16 per person, leading to an overall saving of US$192 million per year. The switch from zidovudine (ZDV)/3TC/atazanavir (ATV)/r 300/100 once daily to dolutegravir along with ATV/r 200/50 once daily would save US$267 per person, leading to an overall saving of US$801 million. The combined saving in costs from first- and second-line treatment would therefore be US$993 million per year.

Fidaxomicin versus vancomycin for Clostridium difficile infection: meta-analysis of pivotal randomized controlled trials

Two recently completed phase 3 trials (003 and 004) showed fidaxomicin to be noninferior to vancomycin for curing Clostridium difficile infection (CDI) and superior for reducing CDI recurrences. In both studies, adults with active CDI were randomized to receive blinded fidaxomicin 200 mg twice daily or vancomycin 125 mg 4 times a day for 10 days. Post hoc exploratory intent-to-treat (ITT) time-to-event analyses were undertaken on the combined study 003 and 004 data, using fixed-effects meta-analysis and Cox regression models. ITT analysis of the combined 003/004 data for 1164 patients showed that fidaxomicin reduced persistent diarrhea, recurrence, or death by 40% (95% confidence interval [CI], 26%–51%; P < .0001) compared with vancomycin through day 40. A 37% (95% CI, 2%–60%; P = .037) reduction in persistent diarrhea or death was evident through day 12 (heterogeneity P = .50 vs 13–40 days), driven by 7 (1.2%) fidaxomicin versus 17 (2.9%) vancomycin deaths at <12 days. Low albumin level, low eosinophil count, and CDI treatment preenrollment were risk factors for persistent diarrhea or death at 12 days, and CDI in the previous 3 months was a risk factor for recurrence (all P < .01). Fidaxomicin has the potential to substantially improve outcomes from CDI.

Adjusting for covariates in non-inferiority studies with margins defined as risk differences

Adjusting for covariates makes efficient use of data and can improve the precision of study results or even reduce sample sizes. There is no easy way to adjust for covariates in a non-inferiority study for which the margin is defined as a risk difference. Adjustment is straightforward on the logit scale, but reviews of clinical studies suggest that the analysis is more often conducted on the more interpretable risk-difference scale. We examined four methods that allow for adjustment on the risk-difference scale: stratified analysis with Cochran-Mantel-Haenszel (CMH) weights, binomial regression with an identity link, the use of a Taylor approximation to convert results from the logit to the risk-difference scale and converting the risk-difference margin to the odds-ratio scale. These methods were compared using simulated data based on trials in HIV. We found that the CMH had the best trade-off between increased efficiency in the presence of predictive covariates and problems in analysis at extreme response rates. These results were shared with regulatory agencies in Europe and the USA, and the advice received is described.

The MONET trial: week 144 analysis of the efficacy of darunavir/ritonavir (DRV/r) monotherapy versus DRV/r plus two nucleoside reverse transcriptase inhibitors, for patients with viral load < 50 HIV-1 RNA copies/mL at baseline

BACKGROUND

In the MONotherapy in Europe with Tmc114 (MONET) trial, darunavir/ritonavir (DRV/r) monotherapy showed noninferior efficacy vs. two nucleoside reverse transcriptase inhibitors (NRTIs) plus DRV/r at the primary 48-week analysis. The trial was continued to week 144 to assess the durability of the results.

METHODS

A total of 256 patients with viral load < 50 HIV-1 RNA copies/mL on current highly active antiretroviral therapy (HAART) for at least 6 months switched to DRV/r 800/100 mg once daily, either as monotherapy (n=127) or with two NRTIs (n=129). Treatment failure was defined as two consecutive HIV RNA levels above 50 copies/mL [time to loss of virological response (TLOVR)] by week 144, or discontinuation of study drugs.

RESULTS

Eighty-one per cent of patients were male and 91% were Caucasian, and they had a median baseline CD4 count of 575 cells/uL. More patients in the DRV/r monotherapy arm had hepatitis C virus coinfection at baseline than in the control arm (18% vs. 12%, respectively). By week 144, the percentage of patients with HIV RNA < 50 copies/mL [intent to treat (ITT), TLOVR, switch=failure method] was 69% vs. 75% in the DRV/r monotherapy and triple therapy arms [difference= -5.9%; 95% confidence interval (CI) -16.9%, +5.1%]; by a strict ITT analysis (switches not considered failures), the percentage of patients with HIV RNA < 50 copies/mL was 84% vs. 83.5%, respectively (difference= +0.5%; 95% CI -8.7%, +9.7%). Twenty-one and 13 patients had two consecutive HIV RNA results above 50 copies/mL in the DRV/r monotherapy arm and triple therapy arm, respectively, of whom 18 of 21 (86%) and 10 of 13 (77%) had HIV RNA < 50 copies/mL at week 144.

CONCLUSIONS

In this study, for patients with HIV RNA < 50 copies/mL at baseline, switching to DRV/r monotherapy showed noninferior efficacy to DRV/r plus two NRTIs in a strict ITT (switches not considered failures) analysis, but not in a TLOVR switch equals failure analysis.

Polymorphic mutations associated with the emergence of the multinucleoside/tide resistance mutations 69 insertion and Q151M

BACKGROUND

We hypothesized that polymorphic mutations exist that are associated with the emergence of the multinucleoside resistance mutations (MNR), 69 insertion and Q151M.

METHODS

The Swiss HIV Cohort Study was screened, and the frequencies of polymorphic mutations in HIV-1 (subtype B) were compared between patients detected with the 69 insertion (n = 17), Q151M (n = 29), ≥2 thymidine analogue mutations (TAM) 1 (n = 400) or ≥2 TAM 2 (n = 249). Logistic regressions adjusted for the antiretroviral treatment history were performed to analyze the association of the polymorphic mutations with MNR.

RESULTS

The 69 insertion and TAM 1 were strongly associated and occurred in 94.1% (16 of 17) together. The 69 insertion seemed to emerge as a consequence of the TAM 1 pathway (median years until detection: 6.8 compared with 4.4 for ≥2 TAM 1, P Wilcoxon = 0.009). Frequencies of 8 polymorphic mutations (K43E, V60I, S68G, S162C, T165I, I202V, R211K, F214L) were significantly different between groups. Logistic regression showed that F214L and V60I were associated with the emergence of Q151M/TAM 2 opposed to 69 insertion/TAM 1. S68G, T165I, and I202V were associated with Q151M instead of TAM 2.

CONCLUSIONS

Besides antiretroviral therapy, polymorphic mutations may contribute to the emergence of specific MNR mutations.

Phase 2 double-blind, randomized trial of etravirine versus efavirenz in treatment-naive patients: 48-week results

BACKGROUND

The Study of Etravirine Neuropsychiatric Symptoms versus Efavirenz (SENSE) trial compared etravirine with efavirenz in treatment-naive patients. The primary endpoint was neuropsychiatric adverse events up to week 12; HIV RNA suppression at week 48 was a secondary endpoint.

METHODS

Patients with HIV RNA more than 5000  copies/ml were randomized to etravirine 400  mg once daily (n = 79) or efavirenz (n = 78), plus two nucleoside analogues. HIV RNA less than 50  copies/ml at week 48 was analysed using the time to loss of virological response (TLOVR) algorithm. Drug resistance at treatment failure and safety endpoints were also evaluated.

RESULTS

At baseline, the median CD4 cell count was 302  cells/μl and HIV RNA was 4.8 log10  copies/ml. In the intent to treat TLOVR analysis at week 48, 60 of 79 (76%) patients on etravirine versus 58 of 78 (74%) on efavirenz had HIV RNA less than 50  copies/ml. In the on-treatment analysis, 60 of 65 (92%) taking etravirine had HIV RNA les than 50 copies/ml versus 58 of 65 (89%) for efavirenz: etravirine showed noninferior efficacy versus efavirenz in both analyses (P < 0.05). Four patients had virological failure in the etravirine arm: none developed resistance to nucleoside analogues or nonnucleosides. Seven patients had virological failure in the efavirenz arm: three developed treatment-emergent resistance to nucleoside analogues and/or nonnucleosides. At the week 48 visit, the percentage with ongoing neuropsychiatric adverse events was 6.3% for etravirine and 21.5% for efavirenz (P = 0.011).

CONCLUSION

First-line treatment with etravirine 400 mg once daily and two nucleoside reverse transcriptase inhibitors (NRTIs) led to similar rates of HIV RNA suppression, compared with efavirenz and two NRTIs. None of the patients with virological failure in the etravirine arm developed resistance to nonnucleosides.

Statistical methods in recent HIV noninferiority trials: reanalysis of 11 trials

BACKGROUND

In recent years the "noninferiority" trial has emerged as the new standard design for HIV drug development among antiretroviral patients often with a primary endpoint based on the difference in success rates between the two treatment groups. Different statistical methods have been introduced to provide confidence intervals for that difference. The main objective is to investigate whether the choice of the statistical method changes the conclusion of the trials.

METHODS

We presented 11 trials published in 2010 using a difference in proportions as the primary endpoint. In these trials, 5 different statistical methods have been used to estimate such confidence intervals. The five methods are described and applied to data from the 11 trials. The noninferiority of the new treatment is not demonstrated if the prespecified noninferiority margin it includes in the confidence interval of the treatment difference.

RESULTS

Results indicated that confidence intervals can be quite different according to the method used. In many situations, however, conclusions of the trials are not altered because point estimates of the treatment difference were too far from the prespecified noninferiority margins. Nevertheless, in few trials the use of different statistical methods led to different conclusions. In particular the use of "exact" methods can be very confusing.

CONCLUSION

Statistical methods used to estimate confidence intervals in noninferiority trials have a strong impact on the conclusion of such trials.

Monitoring of HIV viral loads, CD4 cell counts, and clinical assessments versus clinical monitoring alone for antiretroviral therapy in rural district hospitals in Cameroon (Stratall ANRS 12110/ESTHER): a randomised non-inferiority trial

BACKGROUND

Scaling up of antiretroviral therapy in low-resource countries is done on the basis of decentralised, integrated HIV care in rural facilities; however, laboratory monitoring is generally unavailable. We aimed to assess the effectiveness and safety of clinical monitoring alone (CLIN) in terms of non-inferiority to laboratory and clinical monitoring (LAB).

METHODS

We did a randomised, open-label, non-inferiority trial in nine rural district hospitals in Cameroon. Eligible participants were adults (≥18 years) infected with HIV-1 group M (WHO disease stage 3-4) who had not previously received antiretroviral therapy, and were followed-up for 2 years by health-care workers in routine activities. We randomly assigned participants (1:1) to CLIN or LAB (counts of HIV viral load and CD4 cell every 6 months) groups with a computer-generated list. The primary outcome was non-inferiority of CLIN to LAB in terms of increase in CD4 cell count with a non-inferiority margin of 25%. We did all analyses in participants who attended at least one follow-up visit. This trial is registered with ClinicalTrials.gov, number NCT00301561.

FINDINGS

238 (93%) of 256 participants assigned to CLIN and 221 (93%) of 237 assigned to LAB were eligible for analysis. CLIN was not non-inferior to LAB; the mean increase in CD4 cell count was 175 cells per μL (SD 190, 95% CI 151-200) with CLIN and 206 (190, 181-231) with LAB (difference -31 [-63 to 2] and non-inferiority margin -52 [-58 to -45]). Furthermore, in the predefined secondary outcome of treatment changes, 13 participants (6%) in the LAB group switched to second-line regimens whereas no participants in the CLIN group did so (p<0·0001). By contrast, other predefined secondary outcomes were much the same in both groups-viral suppression (<40 copies per mL; 465 [49%] of 952 measurements in CLIN vs 456 [52%] of 884 in LAB), HIV resistance (23 [10%] of 238 participants vs 22 [10%] of 219 participants), mortality (44 [18%] of 238 vs 32 [14%] of 221), disease progression (85 [36%] of 238 vs 64 [29%] of 221), adherence (672 [63%] of 1067 measurements vs 621 [61%] of 1011), loss to follow-up (21 [9%] of 238 vs 17 [8%] of 221), and toxic effects (46 [19%] of 238 vs 56 [25%] of 221).

INTERPRETATION

Our findings support WHO's recommendation for laboratory monitoring of antiretroviral therapy. However, the small differences that we noted between the strategies suggest that clinical monitoring alone could be used, at least temporarily, to expand antiretroviral therapy in low-resource settings.

FUNDING

French National Agency for Research on AIDS (ANRS) and Ensemble pour une Solidarité Thérapeutique Hospitalière En Réseau (ESTHER).

Effectiveness of protease inhibitor monotherapy versus combination antiretroviral maintenance therapy: a meta-analysis

BACKGROUND

The unparalleled success of combination antiretroviral therapy (cART) is based on the combination of three drugs from two classes. There is insufficient evidence whether simplification to ritonavir boosted protease inhibitor (PI/r) monotherapy in virologically suppressed HIV-infected patients is effective and safe to reduce cART side effects and costs.

METHODS

We systematically searched Medline, Embase, the Cochrane Library, conference proceedings and trial registries to identify all randomised controlled trials comparing PI/r monotherapy to cART in suppressed patients. We calculated in an intention to treat (loss-of follow-up, discontinuation of assigned drugs equals failure) and per-protocol analysis (exclusion of protocol violators following randomisation) and based on three different definitions for virological failure pooled risk ratios for remaining virologically suppressed.

FINDINGS

We identified 10 trials comparing 3 different PIs with cART based on a PI/r plus 2 reverse transcriptase inhibitors in 1189 patients. With the most conservative approach (viral load <50 copies/ml on two consecutive measurements), the risk ratios for viral suppression at 48 weeks of PI/r monotherapy compared to cART were in the ITT analysis 0.94 8 (95% CI 0.89 to 1.00) p = 0.06; risk difference -0.06 (95%CI -0.11 to 0) p = 0.05, p for heterogeneity  = 0.08, I(2) = 43.1%) and in the PP analysis 0.93 ((95%CI 0.90 to 0.97) p<0.001; risk difference -0.07 (95%CI -0.10 to -0.03) p<0.001, p for heterogeneity  = 0.44, I(2) = 0%). Reintroduction of cART in 44 patients with virological failure led in 93% to de-novo viral suppression.

INTERPRETATION

Virologically well suppressed HIV-infected patients have a lower chance to maintain viral suppression when switching from cART to PI/r monotherapy. Failing patients achieve high rates of de-novo viral suppression following reintroduction of reverse transcriptase inhibitors.

96 week results from the MONET trial: a randomized comparison of darunavir/ritonavir with versus without nucleoside analogues, for patients with HIV RNA <50 copies/mL at baseline

BACKGROUND

In virologically suppressed patients, switching to darunavir/ritonavir monotherapy could avoid resistance and adverse events from continuing nucleoside analogues.

METHODS

Two hundred and fifty-six patients with HIV RNA <50 copies/mL on current antiretrovirals were switched to darunavir/ritonavir 800/100 mg once daily, either as monotherapy (n = 127) or with two nucleoside analogues (n = 129). Treatment failure was defined as two consecutive HIV RNA levels at least 50 copies/mL by week 96, or discontinuation of study drugs. The trial had 80% power to show non-inferiority (δ = -12%) at week 48. Results Patients were 81% male, 91% Caucasian, and had a median baseline CD4 count of 575 cells/mm(3). There were more patients with hepatitis C co-infection at baseline in the monotherapy arm (18%) compared with the triple therapy arm (12%). In the efficacy analysis, HIV RNA <50 copies/mL by week 96 (per protocol, time to loss of virological response, switch equals failure) was 78% versus 82% in the monotherapy and triple therapy arms [difference -4.2%, 95% confidence interval (CI) -14.3% to +5.8%]; in a switch included analysis, HIV RNA <50 copies/mL was 93% versus 92% (difference +1.6%, 95% CI -5.0% to +8.1%). The percentage of patients with HIV RNA <5 copies/mL (optical density from the sample equal to the negative control) remained constant over time in both treatment arms. Conclusions In the week 96 analysis of the MONotherapy in Europe with TMC114 (MONET) trial, switching to darunavir/ritonavir monotherapy showed non-inferior efficacy to darunavir/ritonavir plus two nucleoside analogues in the switch included and observed failure analyses, but not in the main switch equals failure analysis.

A comparison of neuropsychiatric adverse events during 12 weeks of treatment with etravirine and efavirenz in a treatment-naive, HIV-1-infected population

BACKGROUND

Although efavirenz is a universally recommended treatment for naive HIV-infected individuals, neuropsychiatric adverse events are common.

METHODS

The Study of Efavirenz NeuropSychiatric Events versus Etravirine (SENSE) trial is a double-blind, placebo-controlled study in which 157 treatment-naive individuals with HIV-RNA higher than 5000 copies/ml were randomized to etravirine 400 mg once daily (n = 79) or to efavirenz 600 mg once daily (n = 78), with two investigator-selected nucleoside reverse transcriptase inhibitors (NRTIs). The primary end point was the percentage of patients with grade 1-4 drug-related treatment-emergent neuropsychiatric adverse events up to week 12.

RESULTS

The study population were 81% men and 85% whites, with a median age of 36 years, baseline CD4 cell counts of 302 cells/μl and HIV-RNA of 4.8 log10 copies/ml. In the intent-to-treat analysis, 13 of 79 individuals (16.5%) in the etravirine arm and 36 of 78 individuals (46.2%) in the efavirenz arm showed at least one grade 1-4 drug-related treatment-emergent neuropsychiatric adverse event (P < 0.001). The number with at least one grade 2-4 drug-related treatment-emergent neuropsychiatric adverse event was four of 79 individuals (5.1%) in the etravirine arm and 13 of 78 individuals (16.7%) in the efavirenz arm (P = 0.019). The change in HIV-RNA to week 12 was -2.9 log10 in both treatment arms. The median rise in CD4 cell counts was 146 cells/μl in the etravirine arm and 121 cells/μl in the efavirenz arm.

CONCLUSIONS

After 12 weeks, first-line treatment with etravirine 400 mg once daily with two NRTIs was associated with significantly fewer neuropsychiatric adverse events when compared with efavirenz with two NRTIs. The virological and immunological efficacy profile was similar between the two arms.

Methodological issues in the use of composite endpoints in clinical trials: examples from the HIV field

BACKGROUND

In many fields, the choice of a primary endpoint for a trial is not always the ultimate clinical endpoint of interest, but rather some surrogate endpoint believed to be relevant for predicting the effect of the intervention on the clinical endpoint. The classic example of such a field is clinical HIV treatment research, where a variety of primary endpoints are used to evaluate the efficacy of new antiretroviral drugs or new combinations of existing drugs. The choice of endpoint reflects either the goal of therapy as recommended by treatment guidelines (e.g. rapid virological suppression) or the licensing requirements of official drug approval organizations (e.g. time to loss of virological response [TLOVR]).

PURPOSE

To review the diversity of endpoints used in recent clinical trials in HIV infection and highlight the methodological issues.

METHODS

We identified articles relating to antiretroviral therapy by searching PubMed and through hand searches of relevant conference abstracts. We restricted the search to randomized controlled trials conducted in HIV-infected adults published/presented from January 2005 until March 2008.

RESULTS

We identified 28 trials in antiretroviral-naive patients (i.e. patients who were starting antiretroviral therapy for the first time at the time of randomization) and 23 trials in antiretroviral-experienced patients. Most trials were performed for purposes of drug licensing, but others were focused on strategies of using approved drugs. Most trials (40 of 51) used a composite primary endpoint (TLOVR in 13). Of note, 22 of these 40 studies reported that they had used a purely virological efficacy endpoint, but the primary endpoint was actually a composite one due to the way in which missing data and treatment switches were considered as failures.

LIMITATIONS

Examples are restricted to HIV clinical trials.

CONCLUSIONS

Whilst most current HIV clinical trials use composite primary endpoints, there are substantial differences in the components that make up these endpoints. In HIV and other fields where precise definitions are variable, guidelines for standardization of definition and reporting would greatly improve the ability to compare trial results.

Regulatory issues in developing new HIV protease inhibitors: risks and benefits

PURPOSE OF REVIEW

To provide a regulatory perspective on developing new HIV protease inhibitors. The present review highlights the risks and benefits of certain design aspects for studies in treatment-naïve and treatment-experienced patients, including timing of studies, study design options, choice of control arms, and duration of treatment.

RECENT FINDINGS

The present review highlights published studies to illustrate the need for new therapies and highlights potential historical data to help design future HIV clinical trials better.

SUMMARY

New antiretroviral agents for patients with multidrug resistance, including safer, more convenient therapies without significant drug-drug interactions, are still needed for all patients. The goals of therapy have evolved and the expectation for treatment regimens is that the majority of patients, including treatment-experienced patients, will achieve undetectable HIV RNA. New study designs, particularly for treatment-experienced patients, are needed to help identify potential risks and benefits of new treatments.

Identification of new genotypic cut-off levels to predict the efficacy of lopinavir/ritonavir and darunavir/ritonavir in the TITAN trial

BACKGROUND

Genotypic algorithms used to predict the clinical efficacy of lopinavir/ritonavir (LPV/r) have included a range of mutation lists and efficacy endpoints. Normally, HIV clinical trials are powered to detect a difference between treatment arms of 10-12% for the endpoint of viral load suppression <50 HIV-1 RNA copies/mL. The TITAN trial evaluated LPV/r vs. darunavir/ritonavir (DRV/r) in treatment-experienced patients with viral load >1000 copies/mL. This analysis aimed to re-evaluate resistance algorithms for LPV/r in the TITAN trial.

METHODS

Baseline genotype data were classified using seven genotypic resistance algorithms: International AIDS Society USA (IAS-USA) LPV mutations (current cut-off=6), Abbott 2007 mutation list (cut-off=3), ANRS mutations (cut-off=4), FDA mutations (cut-off=3), Stanford, REGA and IAS-USA major protease inhibitor (PI) mutations. Efficacy in the TITAN trial (HIV-1 RNA <50 copies/mL at week 48) was correlated with the number of mutations from each list, to show the 'efficacy advantage cut-off level': the number of mutations from each list associated with a difference in efficacy between treatment arms of at least 12%.

RESULTS

Multivariate logistic regression analysis identified lower genotypic cut-off levels than previously reported where there was at least 12% lower efficacy for LPV/r vs. DRV/r. These efficacy advantage cut-off levels were: IAS-USA LPV mutations, cut-off=3; Abbott 2007, cut-off=2; ANRS LPV, cut-off=3; FDA LPV mutations, cut-off=2; major IAS-USA PI mutations, cut-off=1; Stanford algorithm, cut-off=low-level LPV resistance; REGA algorithm, cut-off=intermediate-level LPV resistance. There were linear falls in HIV-1 RNA suppression rates with rising mutation counts in the TITAN, French LPV ATU, BMS-045 and RESIST trials.

CONCLUSIONS

The analysis identified more sensitive cut-off levels for LPV genotypic algorithms, below those currently used.