Cost Effectiveness of Protease Inhibitor Monotherapy Versus Standard Triple Therapy in the Long-Term Management of HIV Patients: Analysis Using Evidence from the PIVOT Trial

BACKGROUND: Protease inhibitor (PI) monotherapy can maintain virological suppression in the majority of patients once it has been established on triple therapy and may also have the potential for substantial cost savings arising from the use of fewer drugs. However, the cost effectiveness of PI monotherapy has yet to be demonstrated. OBJECTIVES: In this study we examine the cost effectiveness of PI monotherapy with prompt return to combination therapy in the event of viral load rebound compared with ongoing triple therapy (OT) in patients with suppressed viral load on combination antiretroviral therapy (ART) in the UK. METHODS: The analysis used data from the PIVOT trial in which HIV-positive adults with suppressed viral load for ≥24 weeks on combination ART were randomised to maintain OT or to a strategy of PI monotherapy with prompt return to combination therapy if viral load rebounded. A cost-effectiveness analysis including long-term modelling was conducted. Main outcomes included UK National Health Service (NHS) costs and quality-adjusted life-years (QALYs) with comparative results presented as incremental cost-effectiveness ratios. RESULTS: PI monotherapy was cost saving as a result of large savings in ART drug costs while being no less effective in terms of QALYs in the within-trial analysis and marginally less effective with lifetime modelling. In the base-case analysis over 3 years, the incremental total cost per patient was -£6424.11 (95 % confidence interval -7418.84 to -5429.38) and incremental QALYs were 0.0051 (95 % CI -0.0479 to 0.0582), resulting in PI monotherapy 'dominating' OT. Multiple scenario analyses found that PI monotherapy was cost saving with no marked differences in QALYs. Modelling of lifetime costs and QALYs showed that PI monotherapy was associated with significant cost savings and was marginally less effective; PI monotherapy was cost effective at accepted cost-effectiveness thresholds in all but one scenario analysis. CONCLUSIONS: Under most assumptions, PI monotherapy appears to be a cost-effective treatment strategy compared with OT for HIV-infected patients who have achieved sustained virological suppression

Next generation sequencing of HIV-1 protease in the PIVOT trial of protease inhibitor monotherapy

BACKGROUND: The PIVOT trial examined whether patients with suppressed viral load on combination antiretroviral therapy could be safely switched long-term to ritonavir-boosted protease inhibitor (PI) monotherapy. The main trial publication reported that only one of 296 patients allocated to PI monotherapy experienced a loss of drug options due to protease mutations (identified by local Sanger sequencing resistance tests) likely selected by study drug. OBJECTIVES: To assess if we had missed low frequency mutations, using a more sensitive methodology. STUDY DESIGN: We performed next generation sequencing (NGS) on all available frozen plasma samples with VL >1000 copies/ml from patients who were randomised to PI monotherapy. Assays were performed at Public Health England laboratories using a previously described method. Median coverage depth was 76,000 and the threshold for detection of minority variants was 2%. Drug susceptibility was predicted using the Stanford HIVdb algorithm. RESULTS: 17 of 26 potential samples, all from different patients, were identified and successfully tested. The median viral load was 6780 copies/ml and the median time since randomisation was 43 weeks. NGS revealed previously unidentified minority variant protease mutations (G73D, I54T, L89V) in three samples, at frequencies ranging between 2% and 10%. None of these mutations predicted intermediate or high level resistance, the trial primary outcome. DISCUSSION: This report adds to the body of evidence that ritonavir-boosted PI monotherapy, when used as a switch strategy with prompt detection of viral load rebound and early re-introduction of combination therapy, rarely leads to the development of clinically important protease resistance mutations

Peripheral neuropathy in HIV patients in sub-Saharan Africa failing first-line therapy and the response to second-line ART in the EARNEST trial.

Sensory peripheral neuropathy (PN) remains a common complication in HIV-positive patients despite effective combination anti-retroviral therapy (ART). Data on PN on second-line ART is scarce. We assessed PN using a standard tool in patients failing first-line ART and for 96 weeks following a switch to PI-based second-line ART in a large Randomised Clinical Trial in Sub-Saharan Africa. Factors associated with PN were investigated using logistic regression. Symptomatic PN (SPN) prevalence was 22 % at entry (N = 1,251) and was associated (p < 0.05) with older age (OR = 1.04 per year), female gender (OR = 1.64), Tuberculosis (TB; OR = 1.86), smoking (OR = 1.60), higher plasma creatinine (OR = 1.09 per 0.1 mg/dl increase), CD4 count (OR = 0.83 per doubling) and not consuming alcohol (OR = 0.55). SPN prevalence decreased to 17 % by week 96 (p = 0.0002) following similar trends in all study groups (p = 0.30). Asymptomatic PN (APN) increased over the same period from 21 to 29 % (p = 0.0002). Signs suggestive of PN (regardless of symptoms) returned to baseline levels by week 96. At weeks 48 and 96, after adjusting for time-updated associations above and baseline CD4 count and viral load, SPN was strongly associated with TB (p < 0.0001). In summary, SPN prevalence was significantly reduced with PI-based second-line therapy across all treatment groups, but we did not find any advantage to the NRTI-free regimens. The increase of APN and stability of PN-signs regardless of symptoms suggest an underlying trend of neuropathy progression that may be masked by reduction of symptoms accompanying general health improvement induced by second-line ART. SPN was strongly associated with isoniazid given for TB treatment

Detecting solar g-modes with ASTROD

We present an up-to-date estimate for the prospect of using the Astrodynamical Space Test of Relativity using Optical Devices (ASTROD) for an unambiguous detection of solar g modes (f < 400 micro Hertz) through their gravitational signature. There are currently two major efforts to detect low-frequency gravitational effects, ASTROD and the Laser Interferometer Space Antenna (LISA). Using the most recent g mode surface amplitude estimates, both observational and theoretical, it is unclear whether LISA will be capable of successfully detecting these modes. The ASTROD project may be better suited for detection as its sensitivity curve is shifted towards lower frequencies with the best sensitivity occurring in the range 100-300 micro Hertz.Comment: HELAS II international conference "Helioseismology, asteroseismology and MHD connections", 20-24 August 2007, Goettingen, German

Evolution of protease inhibitor resistance in HIV-1-infected patients failing protease inhibitor monotherapy as second-line therapy in low-income countries: an observational analysis within the EARNEST randomised trial

BACKGROUND: Limited viral load (VL) testing in HIV-infected individuals on treatment in low-income countries often results in late detection of treatment failure. The impact of remaining on failing second-line, protease inhibitor (PI) containing regimens is unclear. METHODS: We retrospectively tested VL from 2,164 stored plasma samples from 386 patients randomised to receive PI-monotherapy (ritonavir-boosted lopinavir, after initial PI+raltegravir induction) in the EARNEST trial. Protease genotypic resistance testing was performed in samples with VL>1000 copies/ml. We assessed evolution of drug resistance mutations from virological failure (confirmed VL>1000 copies/ml) until discontinuation of PI-monotherapy and examined associations using Poisson and linear mixed-effects models. RESULTS: 118 patients had a median 68(IQR 48-88) weeks on PI-monotherapy post-failure. At failure, 21/107(20%) had intermediate/high resistance to lopinavir. 40-48 weeks post-failure, 49/72(68%) and 36/71(51%) had intermediate/high-level resistance to lopinavir and atazanavir. Most remained susceptible to darunavir (12/72[17%] intermediate, no high resistance). Common PI mutations were M46I, I54V, and V82A. On average, 1.7(95% CI 1.5,2.0) PI mutations developed per year; this increased after the first mutation developed, but decreased with subsequent mutations (p<0.0001). Modest VL changes were mainly driven by non-adherence (p=0.006) and PI mutation development. I47A was associated with a larger increase in log₁₀ VL(+0.53[+0.18,+0.87], p=0.003) than other PI mutations (+0.15[+0.07,+0.23] p<0.001; heterogeneity p=0.05). CONCLUSION: Most develop intermediate/high-level lopinavir resistance within one year when lopinavir/ritonavir is exposed to sustained VL replication without protection from other drugs. Even in this extreme situation, annual VL testing (current WHO recommendation) would identify failure when most would still benefit from switching to darunavir

A comparison of 18F-FDG PET/MR with PET/CT in pulmonary tuberculosis

PURPOSE: PET/computed tomography (CT) has been shown to detect lesions in patients with pulmonary tuberculosis (PTB) and may be useful for assessing PTB disease in clinical research studies. However, radiation dose is of concern for clinical research in individuals with an underlying curable disease. This study aimed to determine whether PET/MR is equivalent to PET/CT in PTB. MATERIALS AND METHODS: Ten patients with microbiologically confirmed PTB were recruited. Patients received 129.0±4.1 MBq of fluorine-18-fluorodeoxyglucose. Five of the 10 patients underwent a PET/MR scan, followed by PET/CT. The remaining five were first imaged on the PET/CT, followed by the PET/MRI. PET acquisition began at 66.7±14.4 min (mean±SD) after injection when performing PET/MR first (PET/CT: 117.2±5.6 min) and 92.4±7.6 min when patients were imaged on PET/MR second (PET/CT: 61.1±3.9 min). PET data were reconstructed iteratively with Ordinary-Poisson Ordered-Subset Expectation-Maximization and reconstruction parameters were matched across the two scanners. A visual lesion detection task and a standardized uptake value (SUV) analysis were carried out. The CT Hounsfield unit values of PTB lesions were also compared with MR-based attenuation correction mu-map tissue classes. RESULTS: A total of 108 PTB lesions were detected on PET/MR and 112 on PET/CT. SUV analysis was carried out on 50 of these lesions that were observed with both modalities. Mean standardized uptake value (SUVmean) and maximum standardized uptake value (SUVmax) were significantly lower on PET/MR (SUVmean: 2.6±1.4; SUVmax: 4.3±2.5) than PET/CT (SUVmean: 3.5±1.5; SUVmax: 5.3±2.4). CONCLUSION: PET/MR visual performance was shown to be comparable to PET/CT in terms of the number of PTB lesions detected. SUVs were significantly lower on PET/MR. Dixon-based attenuation correction underestimates the linear attenuation coefficient of PTB lesions, resulting in lower SUVs compared with PET/CT. However, the use of PET/MR to measure the response of lung lesions to assess response to treatment in research studies is unlikely to be affected by these differences in quantification

Protease inhibitor monotherapy for long-term management of HIV infection: a randomised, controlled, open-label, non-inferiority trial

BACKGROUND: Standard-of-care antiretroviral therapy (ART) uses a combination of drugs deemed essential to minimise treatment failure and drug resistance. Protease inhibitors are potent, with a high genetic barrier to resistance, and have potential use as monotherapy after viral load suppression is achieved with combination treatment. We aimed to assess clinical risks and benefits of protease inhibitor monotherapy in long-term clinical use: in particular, the effect on drug resistance and future treatment options. METHODS: In this pragmatic, parallel-group, randomised, controlled, open-label, non-inferiority trial, we enrolled adults (≥18 years of age) positive for HIV attending 43 public sector treatment centres in the UK who had suppressed viral load (<50 copies per mL) for at least 24 weeks on combination ART with no change in the previous 12 weeks and a CD4 count of more than 100 cells per μL. Participants were randomly allocated (1:1) to maintain ongoing triple therapy (OT) or to switch to a strategy of physician-selected ritonavir-boosted protease inhibitor monotherapy (PI-mono); we recommended ritonavir (100 mg)-boosted darunavir (800 mg) once daily or ritonavir (100 mg)-boosted lopinavir (400 mg) twice daily, with prompt return to combination treatment if viral load rebounded. All treatments were oral. Randomisation was with permuted blocks of varying size and stratified by centre and baseline ART; we used a computer-generated, sequentially numbered randomisation list. The primary outcome was loss of future drug options, defined as new intermediate-level or high-level resistance to one or more drugs to which the patient's virus was deemed sensitive at trial entry (assessed at 3 years; non-inferiority margin of 10%). We estimated probability of rebound and resistance with Kaplan-Meier analysis. Analyses were by intention to treat. This trial is registered with the International Standard Randomised Controlled Trial Number registry, number ISRCTN04857074. FINDINGS: Between Nov 4, 2008, and July 28, 2010, we randomly allocated 587 participants to OT (291) or PI-mono (296). At 3 years, one or more future drug options had been lost in two participants (Kaplan-Meier estimate 0·7%) in the OT group and six (2·1%) in the PI-mono group: difference 1·4% (-0·4 to 3·4); non-inferiority shown. 49 (16·8%) participants in the OT group and 65 (22·0%) in the PI-mono group had grade 3 or 4 clinical adverse events (difference 5·1% [95% CI -1·3 to 11·5]; p=0·12); 45 (six treatment related) and 56 (three treatment related) had serious adverse events. INTERPRETATION: Protease inhibitor monotherapy, with regular viral load monitoring and prompt reintroduction of combination treatment for rebound, preserved future treatment options and did not change overall clinical outcomes or frequency of toxic effects. Protease inhibitor monotherapy is an acceptable alternative for long-term clinical management of HIV infection. FUNDING: National Institute for Health Research

Long-term efficacy and safety of a treatment strategy for HIV infection using protease inhibitor monotherapy: 8-year routine clinical care follow-up from a randomised, controlled, open-label pragmatic trial (PIVOT).

BACKGROUND: Treatment-simplification strategies are important tools for patient-centred management. We evaluated long-term outcomes from a PI monotherapy switch strategy. METHODS: Eligible participants attending 43 UK treatment centres had a viral load (VL) below 50 copies/ml for at least 24 weeks on combination ART. Participants were randomised to maintain ongoing triple therapy (OT) or switch to a strategy of physician-selected PI monotherapy (PI-mono) with prompt return to combination therapy if VL rebounded. The primary outcome, previously reported, was loss of future drug options after 3 years, defined as new intermediate/high level resistance to at least one drug to which the participant's virus was considered sensitive at trial entry. Here we report resistance and disease outcomes after further extended follow-up in routine care. The study was registered as ISRCTN04857074. FINDINGS: We randomised 587 participants to OT (291) or PI-mono (296) between Nov 4, 2008, and July 28, 2010 and followed them for a median of more than 8 years (100 months) until 2018. At the end of this follow-up time, one or more future drug options had been lost in 7 participants in the OT group and 6 in the PI-mono group; estimated cumulative risk by 8 years of 2.7% and 2.1% respectively (difference -0.6%, 95% CI -3.2% to 2.0%). Only one PI-mono participant developed resistance to the protease inhibitor they were taking (atazanavir). Serious clinical events (death, serious AIDS, and serious non-AIDS) were infrequent; reported in a total of 12 (4.1%) participants in the OT group and 23 (7.8%) in the PI-mono group (P = 0.08) over the entire follow-up period. INTERPRETATION: A strategy of PI monotherapy, with regular VL monitoring and prompt reintroduction of combination treatment following rebound, preserved future treatment options. Findings confirm the high genetic barrier to resistance of the PI drug class that makes them well suited for creative, patient-centred, treatment-simplification approaches. The possibility of a small excess risk of serious clinical events with the PI monotherapy strategy cannot be excluded. FUNDING: The National Institute for Health Research Health Technology Assessment programme

HIV-1 viral load and resistance in genital secretions in patients taking protease-inhibitor-based second-line therapy in Africa

Background: HIV is transmitted primarily through sexual intercourse, and the objective of this study was therefore to assess whether there is occult viral replication and resistance in genital secretions in patients on protease inhibitor (PI)-based second-line therapy. Methods: HIV-infected adults taking ritonavir-boosted lopinavir with either two NRTIs, raltegravir, or as monotherapy for 96 weeks were enrolled at seven clinical sites in Uganda. Viral load (VL) was measured in cervico-vaginal secretions or semen and in a corresponding plasma sample. Genotypic resistance was assessed in genital secretion samples and plasma samples. Results were compared between compartments and with the plasma resistance profile at first-line failure. Results: Of the 111 participants enrolled (91 female, 20 male), 16 (14%) and 30 (27%) had VL >1000 and >40 copies/ml respectively in plasma; 3 (3%) and 23 (21%) had VL >1000 copies/ml and >40 copies/ml respectively in genital secretions. There was 74% agreement between plasma and genital secretion VL classification above/below 40 copies/ml threshold (kappa-statistic=0.29; p=0.001). RT mutations (both NRTI and NNRTI) were detected in genital secretions in 4 patients (similar profile to corresponding plasma sample at first-line failure) and PI mutations were detected in 2 (1 polymorphism with no impact on resistance; 1 with high-level PI resistance). Conclusions: High level (>1000 copies/ml) viral replication and development of new RT or PI resistance in the genital compartment were rare. The risks of transmission arising from resistance evolution in the genital compartment are likely to be low on PI-based second-line therapy