Left Atrial Appendage Occlusion Versus Direct Oral Anticoagulants in the Prevention of Ischaemic Stroke in Patients with Atrial Fibrillation.

Introduction Existing randomised controlled trials assessing the safety and efficacy of left atrial appendage occlusion (LAAO) in atrial fibrillation (AF) were of relatively small sample size, or included patients who could receive oral anticoagulant treatment after device implantation. We compared the outcomes of patients with newly diagnosed AF who received percutaneous LAAO or direct oral anticoagulants (DOAC) treatment, in a large population from a global federated health network (TriNetX). Methods Patients with AF treated with percutaneous LAAO were matched with those treated with DOAC between 1st December 2010 and 1st October 2018. Outcomes were all-cause mortality, ischaemic stroke and intracranial haemorrhage (ICH) at 5 years. Results We included 200 patients with AF, who received either LAAO or DOAC. The risk of all-cause mortality, ischaemic stroke and ICH at 5 years was not significantly different between the two groups (Risk Ratio [RR] for all-cause mortality: 1.52, 95% confidence interval (CI): 0.97- 2.38, RR for ischaemic stroke: 1.09, 95% CI: 0.51- 2.36, and RR for ICH: 1.0, 95% CI: 0.44- 2.30). Conclusion Patients newly diagnosed with AF, eligible for DOAC, showed similar 5-year risk of death, ischemic stroke, and ICH when comparing those who underwent percutaneous LAAO to those receiving DOAC. Future randomised controlled trials are needed to confirm the findings and advise changes in guidelines.

Structures of carboxylic acid reductase reveal domain dynamics underlying catalysis.

Carboxylic acid reductase (CAR) catalyzes the ATP- and NADPH-dependent reduction of carboxylic acids to the corresponding aldehydes. The enzyme is related to the nonribosomal peptide synthetases, consisting of an adenylation domain fused via a peptidyl carrier protein (PCP) to a reductase termination domain. Crystal structures of the CAR adenylation-PCP didomain demonstrate that large-scale domain motions occur between the adenylation and thiolation states. Crystal structures of the PCP-reductase didomain reveal that phosphopantetheine binding alters the orientation of a key Asp, resulting in a productive orientation of the bound nicotinamide. This ensures that further reduction of the aldehyde product does not occur. Combining crystallography with small-angle X-ray scattering (SAXS), we propose that molecular interactions between initiation and termination domains are limited to competing PCP docking sites. This theory is supported by the fact that (R)-pantetheine can support CAR activity for mixtures of the isolated domains. Our model suggests directions for further development of CAR as a biocatalyst.

Standard-dose versus double-dose dolutegravir in HIV-associated tuberculosis in South Africa (RADIANT-TB): a phase 2, non-comparative, randomised controlled trial.

BACKGROUND: The drug-drug interaction between rifampicin and dolutegravir can be overcome by supplemental dolutegravir dosing, which is difficult to implement in high-burden settings. We aimed to test whether virological outcomes with standard-dose dolutegravir-based antiretroviral therapy (ART) are acceptable in people with HIV on rifampicin-based antituberculosis therapy. METHODS: RADIANT-TB was a phase 2b, randomised, double-blind, non-comparative, placebo-controlled trial at a single site in Khayelitsha, Cape Town, South Africa. Participants were older than 18 years of age, with plasma HIV-1 RNA greater than 1000 copies per mL, CD4 count greater than 100 cells per µL, ART-naive or first-line ART interrupted, and on rifampicin-based antituberculosis therapy for less than 3 months. By use of permuted block (block size of 6) randomisation, participants were assigned (1:1) to receive either tenofovir disoproxil fumarate, lamivudine, and dolutegravir plus supplemental 50 mg dolutegravir 12 h later or tenofovir disoproxil fumarate, lamivudine, and dolutegravir plus matched placebo 12 h later. Participants received standard antituberculosis therapy (rifampicin, isoniazid, pyrazinamide, and ethambutol for the first 2 months followed by isoniazid and rifampicin for 4 months). The primary outcome was the proportion of participants with virological suppression (HIV-1 RNA <50 copies per mL) at week 24 analysed in the modified intention-to-treat population. This study is registered with ClinicalTrials.gov, NCT03851588. FINDINGS: Between Nov 28, 2019, and July 23, 2021, 108 participants (38 female, median age 35 years [IQR 31-40]) were randomly assigned to supplemental dolutegravir (n=53) or placebo (n=55). Median baseline CD4 count was 188 cells per µL (IQR 145-316) and median HIV-1 RNA was 5·2 log10 copies per mL (4·6-5·7). At week 24, 43 (83%, 95% CI 70-92) of 52 participants in the supplemental dolutegravir arm and 44 (83%, 95% CI 70-92) of 53 participants in the placebo arm had virological suppression. No treatment-emergent dolutegravir resistance mutations were detected up to week 48 in the 19 participants with study-defined virological failure. Grade 3 and 4 adverse events were similarly distributed between the study arms. The most frequent grade 3 and 4 adverse events were weight loss (4/108 [4%]), insomnia (3/108 [3%]), and pneumonia (3/108 [3%]). INTERPRETATION: Our findings suggest that twice-daily dolutegravir might be unnecessary in people with HIV-associated tuberculosis. FUNDING: Wellcome Trust.

Atrial Fibrillation and Stroke.

Atrial fibrillation (AF) is the most common cardiac arrythmia and a major cause of stroke, heart failure, sudden death, and cardiovascular morbidity. AF increases risk of thromboembolic stroke via stasis in the left atrium and subsequent embolization to the brain. In patients with acute ischemic stroke, it is essential that clinicians undertake careful investigation to search for AF. In these patients, up to 23.7% eventually are found to have underlying AF. Oral anticoagulation is effective in prevention of strokes secondary to AF, reducing overall stroke numbers by approximately 64%. Left atrial appendage occlusion is promising for prevention of stroke in AF.

Review of safety and minimum pricing of nitazoxanide for potential treatment of COVID-19.

BACKGROUND: Many treatments are being assessed for repurposing to treat coronavirus disease 2019 (COVID-19). One drug that has shown promising results in vitro is nitazoxanide. Unlike other postulated drugs, nitazoxanide shows a high ratio of maximum plasma concentration (Cmax), after 1 day of 500 mg twice daily (BD), to the concentration required to inhibit 50% replication (EC50) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Cmax : EC50 roughly equal to 14:1). As such, it is important to investigate the safety of nitazoxanide for further trials. Furthermore, treatments for COVID-19 should be cheap to promote global access, but prices of many drugs are far higher than the costs of production. We aimed to conduct a review of the safety of nitazoxanide for any prior indication and calculate its minimum costs of production. METHODS: A review of nitazoxanide clinical research was conducted using EMBASE and MEDLINE databases, supplemented by ClinicalTrials.gov. We searched for phase 2 or 3 randomised controlled trials (RCTs) comparing nitazoxanide with placebo or active control for 5-14 days in participants experiencing acute infections of any kind. Data extracted were grade 1-4 and serious adverse events (AEs). Data were also extracted on gastrointestinal (GI) AEs, as well as hepatorenal and cardiovascular effects.Active pharmaceutical ingredient cost data from 2016 to 2019 were extracted from the Panjiva database and adjusted for 5% loss during production, costs of excipients, formulation, a 10% profit margin and tax. Two dosages, at 500 mg BD and a higher dose of 1100 mg three times daily (TDS), were considered. Our estimated costs were compared with publicly available list prices from a selection of countries. RESULTS: Nine RCTs of nitazoxanide were identified for inclusion. These RCTs accounted for 1514 participants and an estimated 95.3 person-years-of-follow-up. No significant differences were found in any of the AE endpoints assessed, across all trials or on subgroup analyses of active- or placebo-controlled trials. Mild GI AEs increased with dose. No hepatorenal or cardiovascular concerns were raised, but few appropriate metrics were reported. There were no teratogenic concerns, but the evidence base was very limited.Based on a weighted-mean cost of US $61/kg, a 14-day course of treatment with nitazoxanide 500 mg BD would cost $1.41. The daily cost would therefore be $0.10. The same 14-day course could cost $3944 in US commercial pharmacies, and $3 per course in Pakistan, India and Bangladesh. At a higher dose of 1100 mg TDS, our estimated cost was $4.08 per 14-day course, equivalent to $0.29 per day. CONCLUSION: Nitazoxanide demonstrates a good safety profile at approved doses. However, further evidence is required regarding hepatorenal and cardiovascular effects, as well as teratogenicity. We estimate that it would be possible to manufacture nitazoxanide as generic for $1.41 for a 14-day treatment course at 500 mg BD, up to $4.08 at 1100 mg TDS. Further trials in COVID-19 patients should be initiated. If efficacy against SARS-CoV-2 is demonstrated in clinical studies, nitazoxanide may represent a safe and affordable treatment in the ongoing pandemic.

Estimation of cost-based prices for injectable medicines in the WHO Essential Medicines List.

OBJECTIVES: Challenges remain in ensuring universal access to affordable essential medicines. We previously estimated the expected generic prices based on cost of production for medicines in solid oral formulations (ie, capsules or tablets) on the WHO Model List of Essential Medicines (EML). The objectives of this analysis were to estimate cost-based prices for injectable medicines on the EML and to compare these to lowest current prices in England, South Africa, and India. DESIGN: Data on the cost of active pharmaceutical ingredients (APIs) exported from India were extracted from an online database of customs declarations (www.infodriveindia.com). A formula was designed to use API price data to estimate a cost-based price, by adding the costs of converting API to a finished pharmaceutical product, including the cost of formulation in vials or ampoules, transportation and an average profit margin. RESULTS: For injectable formulations on the WHO EML, medicines had prices above the estimated cost-based price in 77% of comparisons in England (median ratio 2.54), and 62% in South Africa (median ratio 1.48), while 85% of medicines in India had prices below estimated cost-based price (median ratio 0.30). 19% of injectable medicines in England, 9% in South Africa, and 5% in India had prices more than 10 times the estimated cost-based price. Medicines that appeared in the top 20 by ratio of lowest current price to estimated cost-based price for more than one country included numerous oncology medicines-irinotecan, leuprorelin, ifosfamide, daunorubicin, filgrastim and mesna-as well as valproic acid and ciclosporin. CONCLUSIONS: Estimating manufacturing costs can identify cases in which profit margins for medicines may be set significantly higher than average.

Global access of rifabutin for the treatment of tuberculosis - why should we prioritize this?

INTRODUCTION: Rifabutin, a rifamycin of equivalent potency to rifampicin, has several advantages in its pharmacokinetic and toxicity profile, particularly in HIV co-infected patients on combined antiretroviral therapy (cART). In this commentary, we evaluate evidence supporting increased global use of rifabutin and highlight key recommendations for action. DISCUSSION: Although extrapolation of data from HIV uninfected patients would suggest non-inferiority, there has been no randomized controlled study comparing rifabutin versus rifampicin in the outcomes of relapse-free cure, in drug susceptible tuberculosis (TB), in HIV co-infected patients on currently utilized cART regimens or in paediatric populations. An important advantage of rifabutin is that compared to the dose adjustments required with rifampicin, it can be co-administered with the integrase strand transfer inhibitors raltegravir or dolutegravir without the need for dose adjustments. This strategy would be easier to implement in a programmatic setting and would save costs. We have assessed cost incentives to utilize rifabutin and have estimated generic costs for a range of rifabutin dosage scenarios. Where facilities are present for drug re-challenge and monitoring for drug toxicity and cross-reactivity, rifabutin offers a switch alternative for adverse drug reactions (ADR)s attributed to rifampicin. This would negate the need to prolong treatment in the absence of a rifamycin as part of short-course multidrug therapy. There is evidence of incomplete cross-resistance to rifampicin and rifabutin. Rifabutin may be useful in rifampicin-resistant TB, in an estimated 20% of cases, based on phenotypic or genotypic rifabutin susceptibility testing. CONCLUSIONS: Rifabutin should be available globally as a first-line rifamycin in HIV co-infected individuals and as a switch option in cases of rifampicin associated ADRs. Further studies are needed to ascertain the utility of rifabutin in rifampicin-resistant rifabutin-susceptible TB.

Estimated costs of production and potential prices for the WHO Essential Medicines List.

INTRODUCTION: There are persistent gaps in access to affordable medicines. The WHO Model List of Essential Medicines (EML) includes medicines considered necessary for functional health systems. METHODS: A generic price estimation formula was developed by reviewing published analyses of cost of production for medicines and assuming manufacture in India, which included costs of formulation, packaging, taxation and a 10% profit margin. Data on per-kilogram prices of active pharmaceutical ingredient exported from India were retrieved from an online database. Estimated prices were compared with the lowest globally available prices for HIV/AIDS, tuberculosis (TB) and malaria medicines, and current prices in the UK, South Africa and India. RESULTS: The estimation formula had good predictive accuracy for HIV/AIDS, TB and malaria medicines. Estimated generic prices ranged from US$0.01 to US$1.45 per unit, with most in the lower end of this range. Lowest available prices were greater than estimated generic prices for 214/277 (77%) comparable items in the UK, 142/212 (67%) in South Africa and 118/298 (40%) in India. Lowest available prices were more than three times above estimated generic price for 47% of cases compared in the UK and 22% in South Africa. CONCLUSION: A wide range of medicines in the EML can be profitably manufactured at very low cost. Most EML medicines are sold in the UK and South Africa at prices significantly higher than those estimated from production costs. Generic price estimation and international price comparisons could empower government price negotiations and support cost-effectiveness calculations.

Is hepatitis C virus elimination possible among people living with HIV and what will it take to achieve it?

INTRODUCTION: The World Health Organization targets for hepatitis C virus (HCV) elimination include a 90% reduction in new infections by 2030. Our objective is to review the modelling evidence and cost data surrounding feasibility of HCV elimination among people living with HIV (PLWH), and identify likely components for elimination. We also discuss the real-world experience of HCV direct acting antiviral (DAA) scale-up and elimination efforts in the Netherlands. METHODS: We review modelling evidence of what intervention scale-up is required to achieve WHO HCV elimination targets among HIV-infected (HIV+) people who inject drugs (PWID) and men who have sex with men (MSM), review cost-effectiveness of HCV therapy among PLWH and discuss economic implications of elimination. We additionally use the real-world experience of DAA scale-up in the Netherlands to illustrate the promise and potential challenges of HCV elimination strategies in MSM. Finally, we summarize key components of the HCV elimination response among PWLH. RESULTS AND DISCUSSION: Modelling indicates HCV elimination among HIV+ MSM and PWID is potentially achievable but requires combination treatment and either harm reduction or behavioural risk reductions. Preliminary modelling indicates elimination among HIV+ PWID will require elimination efforts among PWID more broadly. Treatment for PLWH and high-risk populations (PWID and MSM) is cost-effective in high-income countries, but costs of DAAs remain a barrier to scale-up worldwide despite the potential low production price ($50 per 12 week course). In the Netherlands, universal DAA availability led to rapid uptake among HIV+ MSM in 2015/16, and a 50% reduction in acute HCV incidence among HIV+ MSM from 2014 to 2016 was observed. In addition to HCV treatment, elimination among PLWH globally also likely requires regular HCV testing, development of low-cost accurate HCV diagnostics, reduced costs of DAA therapy, broad treatment access without restrictions, close monitoring for HCV reinfection and retreatment, and harm reduction and/or behavioural interventions. CONCLUSIONS: Achieving WHO HCV Elimination targets is potentially achievable among HIV-infected populations. Among HIV+ PWID, it likely requires HCV treatment scale-up combined with harm reduction for both HIV+ and HIV- populations. Among HIV+ MSM, elimination likely requires both HCV treatment and behaviour risk reduction among the HIV+ MSM population, the latter of which to date has not been observed. Lower HCV diagnostic and treatment costs will be key to ensuring scale-up of HCV testing and treatment without restriction, enabling elimination.

Risks of cardiovascular or central nervous system adverse events and immune reconstitution inflammatory syndrome, for dolutegravir versus other antiretrovirals: meta-analysis of randomized trials.

PURPOSE OF REVIEW: Results from nonrandomized cohort studies suggest higher risks of CNS adverse events for dolutegravir, versus other ARVs. There have been two case reports of myocarditis on dolutegravir. Integrase inhibitors have been associated with IRIS in two cohort studies. Meta-analysis of randomized trials can be used to cross-check potential safety signals. This systematic review of drug safety used an EMBASE and MEDLINE search combined with serious adverse event (SAE) reports on the website www.clinicaltrials.gov. Cardiovascular, CNS or IRIS-associated adverse events were analysed for dolutegravir versus other ARVs. Relative risks for the comparison between dolutegravir and other antiretrovirals were calculated for each adverse event. Meta-analyses applied Mantel-Haenszel random-effects models. RECENT FINDINGS: There was a higher risk of Grade 1-4 insomnia adverse events for DTG (6.1%) versus other ARVs (4.5%; P = 0.02). There was no significant difference between DTG and other ARVs in the risk of cardiovascular serious adverse events. In the SINGLE and SPRING-1 trials comparing DTG with efavirenz, there were 5/465 patients with reported suicidality SAEs on DTG (1.1%) versus 6/469 (1.3%) on EFV. In other studies, serious adverse events of suicidality were reported for 15/2250 patients on DTG (0.7%) versus 9/2257 patients on other ARVs (0.4%). Risks of IRIS were low, but event rates were low and the main trials excluded CDC stage C disease. SUMMARY: In this meta-analysis, there was no significant effect of dolutegravir on the risk of cardiac, IRIS or suicide-related serious adverse events. There was a higher risk of insomnia for DTG. Other completed randomized trials should be included in new evaluations of DTG safety. Continued pharmacovigilance, with regular meta-analyses, should be used to monitor safety.

Analysis of treatment costs for HIV RNA reductions and CD4 increases for darunavir versus other antiretrovirals in treatment-experienced, HIV-infected patients.

BACKGROUND: For patients with preexisting HIV drug resistance, a wide range of antiretrovirals are used, with differences in efficacy and cost. The additional cost per incremental 25 cell rise in CD4 count, or 0.5 log reduction in HIV RNA, was calculated for 8 antiretrovirals using pivotal clinical trials data. METHOD: For approved antiretrovirals in HIV therapy--experienced patients, 24-week efficacy (benefit over control in HIV RNA and CD4 count) was extracted from pivotal trials in published reports and compared with the additional treatment cost versus the control arm of each trial (2006 US wholesale acquisition costs). Treatment costs in the POWER trials were calculated directly from the treatment use database. RESULTS: Data were available from 11 clinical trials in more than 4,000 antiretroviral treatment--experienced patients: Gilead 907 (TDF vs. placebo), TORO1/2 (T-20/OBR vs. OBR), RESIST-1/2 (TPV/r vs. control PI), BMS-045 (ATV/r vs. LPV/r), CONTEXT (fAPV/r vs. LPV/r), CAESAR (3TC vs. placebo), CNA3002 (ABC vs. placebo), and POWER 1/2 (DRV/r vs. control PI). Additional cost per 0.5 log reduction in HIV RNA was $152 for ritonavir-boosted darunavir (DRV/r), $4,453 for lamivudine (3TC), $4,274 for abacavir (ABC), $4,641 for tenofovir (TDF), and $13,217 for enfuvirtide (T-20). Cost per 25 cell rise in CD4 ranged from $132 for darunavir/r to $16,464 for T-20. CONCLUSION: There is a wide range of costs associated with efficacy improvements across the classes of antiretrovirals used for antiretroviral treatment--experienced patients. This analysis does not account for differences in toxicity, use of concomitant medications, or long-term adherence, which could also influence value assessments.

The road to elimination of hepatitis C: analysis of cures versus new infections in 91 countries.

BACKGROUND: Hepatitis C (HCV) can only be eradicated if annual rates of cure (SVR) are consistently and significantly higher than new HCV infections, across many countries. In 2016, the WHO called for a 90% reduction in new HCV infection by 2030. Direct-acting antivirals (DAA) can cure the majority of those treated, at around 90% in most populations, at potentially very low prices. We compared the net annual change in epidemic size across 91 countries using data on SVR, new HCV infections, and deaths. In a further 109 countries, we projected this figure using regional averages of epidemic size. METHODS: Epidemiological data for 2016 were extracted from national reports, publications and the Polaris Observatory. There were 91/210 countries with data on SVR, HCV-related deaths and new infections available for analysis; 109 countries had net change in epidemic size projected from the regional prevalence of HCV, extrapolated to their population size. 'Net cure' was defined as the number of people with SVR, minus new HCV infections, plus HCV-related deaths in 2016. RESULTS: For the 91 countries analysed, there were 57.3 million people with chronic HCV infection in 2016. In the remaining 109 countries, the projected epidemic size was 12.2 million, giving a global epidemic size of 69.6 million. Across the 91 countries, there was a fall from 57.3 to 56.9 million people in 2017, a 0.7% reduction. The projected global net change was from 69.6 to 69.3 million, a 0.4% reduction. Ten countries had at least five times more people reaching SVR than new HCV infections, including Egypt and USA. In 47/91 countries, there were more HCV infections than SVR in 2016. CONCLUSION: Very few countries are on target to achieve elimination of HCV as a public health problem by 2030. While the North American, North African/Middle East and Western European regions have shown small declines in prevalence, the epidemic is growing in sub-Saharan Africa and Eastern Europe. Far higher rates of DAA treatment are required for worldwide elimination of HCV.

When could new antiretrovirals be recommended for national treatment programmes in low-income and middle-income countries: results of a WHO Think Tank.

PURPOSE OF REVIEW: To discuss barriers and opportunities for the introduction of new antiretrovirals into national treatment programmes in low-income and middle-income countries to support further treatment scale-up. Invitees to a WHO Think Tank in February 2017 evaluated recently published results. RECENT FINDINGS: There is not sufficient clinical experience of dolutegravir (DTG), tenofovir alafenamide (TAF) or efavirenz 400 mg (EFV400) to recommend their use in pregnancy. Outcomes from births and assessment of congenital anomalies need to be evaluated from several hundred pregnant women. Clinical experience of these treatments during rifampicin-based treatment for tuberculosis is also required. This could be difficult for TAF, which is currently contraindicated with TAF. Changes in second-line treatment from two nucleoside analogues + protease inhibitor plus ritonavir will require new randomized trials of alternative combinations. CONCLUSION: Additional safety and efficacy data on DTG, TAF and EFV400 in some subpopulations are needed before a large introduction in national treatment programmes. There is currently limited support for the introduction of TAF as part of first-line antiretroviral treatment in low-income and middle-income settings. There was an overall agreement for 6-monthly reviews of safety and efficacy data, in parallel with a phased introduction of the new antiretrovirals.

How can we achieve universal access to low-cost treatment for HIV?

Mass production of low-cost antiretrovirals (ARVs) has already allowed over 17 million individuals to access treatment for HIV infection, mainly in low-income countries. It is possible to manufacture combination ARVs for $110 per person-year, using tenofovir (TDF), lamivudine (3TC) and efavirenz (EFV). New combinations of ARVs costing as little as $60 per person-year will be available in the near future. Pre-exposure prophylaxis using TDF in combination with either 3TC or emtricitabine (FTC) could also be provided for less than $90 per person-year. Voluntary licensing allows people in the poorest countries to access new ARVs at prices close to manufacturing costs. Patents on several key ARVs will expire by 2018 and should allow worldwide access to high-quality, low-cost triple combination therapy, such as TDF/3TC/EFV. Several protease inhibitors will also become available as generics by 2018. However, ongoing patent restrictions will lead to sustained high prices for the most recently developed ARVs in most middle- and high-income countries. These include the nucleotide tenofovir alafenamide, the integrase strand inhibitor dolutegravir and several single combination tablet regimens. We suggest that as patents for ARVs expire, health authorities first need to rapidly import and introduce generic versions of drugs such as abacavir, 3TC, EFV and TDF. Once these low prices have been established for these generics, cost-effectiveness of patented ARVs needs to be re-evaluated. It may no longer be justified to pay high prices for these drugs. A strategy of low-cost generic ARVs for most people, with higher-cost patented alternatives used as switch options, could allow for an increased number of people to receive ARVs in the context of fixed health budgets.

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.

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.

Week 48 efficacy and central nervous system analysis of darunavir/ritonavir monotherapy versus darunavir/ritonavir with two nucleoside analogues.

BACKGROUND: In previous studies in virologically suppressed patients, protease inhibitor monotherapy has shown trends for more low-level elevations in HIV-1 RNA compared with triple therapy, but no increase in the risk of drug resistance. METHODS: A total of 273 patients with HIV-1 RNA less than 50 copies/ml on first-line antiretrovirals switched to darunavir/ritonavir (DRV/r) 800/100 mg once daily, either as monotherapy (n = 137) or as triple therapy with two nucleoside analogues (n = 136). Treatment failure was defined as HIV-1 RNA levels 50 copies/ml or above, or discontinuation of study treatment by week 48 (FDA Snapshot algorithm). RESULTS: Patients were 83% male and 88% white, with mean age 42 years. In the primary efficacy analysis, HIV-1 RNA less than 50 copies/ml by week 48 [intention-to-treat (ITT)] was 118 of 137 (86%) in the DRV/r monotherapy arm versus 129 of 136 (95%) in the triple therapy arm (difference = -8.7%, 95% confidence interval -15.50, -1.80). In a post-hoc analysis, for patients with nadir CD4 cell count 200 cells/µl or above, rates of HIV-1 RNA suppression were 91 of 96 (95%) in the DRV/r monotherapy arm and 100 of 106 (94%) in the triple therapy arm. There was no difference in neurocognitive function or the risk of neuropsychiatric adverse events between DRV/r monotherapy and triple therapy. Two patients in the monotherapy arm with CD4 nadir less than 200 cells/µl developed viraemia in both cerebrospinal fluid (CSF) and plasma, with one symptomatic case. CONCLUSIONS: In this study for patients with HIV-1 RNA less than 50 copies/ml at baseline, switching to DRV/r monotherapy showed lower efficacy versus triple therapy at week 48 in the primary ITT switch equals failure analysis, with two cases of viraemia in the CSF in the protease inhibitor monotherapy arm.