Indinavir/ritonavir-based therapy in HIV-1-infected antiretroviral therapy-naive patients: comparison of 800/100 mg and 400/100 mg twice daily

A target safety assessment of the potential toxicological risks of targeting plasmepsin IX/X for the treatment of malaria

The aspartic proteases plasmepsin IX/X are important antimalarial drug targets due to their specificity to the malaria parasite and their vital role as mediators of disease progression. Focusing on parasite-specific targets where no human homologue exists reduces the possibility of on-target drug toxicity. However, there is a risk of toxicity driven by inadequate selectivity for plasmepsins IX/X in Plasmodium over related mammalian aspartic proteases. Of these, CatD/E may be of most toxicological relevance as CatD is a ubiquitous lysosomal enzyme present in most cell types and CatE is found in the gut and in erythrocytes, the clinically significant site of malarial infection. Based on mammalian aspartic protease physiology and adverse drug reactions (ADRs) to FDA-approved human immunodeficiency virus (HIV) aspartic protease inhibitors, we predicted several potential toxicities including β-cell and congenital abnormalities, hypotension, hypopigmentation, hyperlipidaemia, increased infection risk and respiratory, renal, gastrointestinal, dermatological, and other epithelial tissue toxicities. These ADRs to the HIV treatments are likely to be a result of host aspartic protease inhibition due a lack of specificity for the HIV protease; plasmepsins are much more closely related to human CatD than to HIV proteinase. Plasmepsin IX/X inhibition presents an opportunity to specifically target Plasmodium as an effective antimalarial treatment, providing adequate selectivity can be obtained. Potential plasmepsin IX/X inhibitors should be assayed for inhibitory activity against the main human aspartic proteases and particularly CatD/E. An investigative rodent study conducted early in drug discovery would serve as an initial risk assessment of the potential hazards identified.

Adverse effects of chronic treatment with the Main subclasses of highly active antiretroviral therapy: a systematic review

OBJECTIVES

The aim of the review was to elucidate the adverse effects of chronic treatment with the main subclasses of highly active antiretroviral therapy (HAART).

METHODS

A systematic review was carried out using the methods recommended in the Preferred Reporting Items for Systematic Review and Meta-analysis Protocols (PRISMA-P). Searches of articles in MEDLINE, SCIELO, Web of Science and LILACS were conducted from January to October 2018 based on the following descriptors and keywords: 'HIV' [AND]; 'AIDS' [OR]; 'HAART' [AND]; 'Highly Active Antiretroviral Therapy' [OR]; 'Adverse Effects' [AND]. All articles selected described the biochemical changes produced by, and the main adverse effects of, using one or more of the following HAART subclasses: nucleoside reverse transcriptase inhibitors (NRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs) and other new drugs. The selected articles included patients living with HIV (PLWH) initiating or continuing any type of HAART. The results are presented qualitatively and discussed.

RESULTS

Twenty-one articles found in the searches were selected for the review, and they included a total of 5626 participants. Seven of the studies investigated mainly NRTIs, three studies mainly NNRTIs, eight studies predominantly PIs, and three studies other antiretroviral drugs as the main treatment. The most common adverse effects on biochemical parameters were the emergence of anaemia for NRTIs as well as NNRTIs and PIs, and plasma lipid alterations caused by their prolonged use. In general, it was found that biological differences among individuals can cause differences in adverse effects, such as virological and treatment failure.

CONCLUSIONS

One or more occurrences of adverse effects of the chronic utilization of drugs were found for all subclasses of HAART, and certain combinations of drugs from different subclasses were also found to be associated with adverse events.

Evaluation of universal versus genotype-guided efavirenz dose reduction in pregnant women using population pharmacokinetic modelling

Objectives

Lack of data on the pharmacokinetics of efavirenz in pregnant women at the 400 mg reduced dose currently prevents universal roll-out. Population pharmacokinetic modelling was used to explore pharmacokinetic endpoints at 200, 400 and 600 mg daily doses in pregnant women stratified by CYP2B6 metabolic status.

Methods

The analysis was based on 252 plasma efavirenz concentrations from 77 pregnant women (77 sparse, 175 intensive) who received antiretroviral regimens containing 600 mg of efavirenz. The model was developed using NONMEM®. The effect of genetics was investigated and concentration-time courses at steady-state were simulated for individuals (n = 1000 each) classified as CYP2B6 slow, intermediate and fast metabolizers at 200, 400 and 600 mg daily doses.

Results

At a 400 mg reduced dose, predicted mean (90% CI) mid-dose efavirenz concentration (C12) was 2.24 μg/mL (0.89-4.18) in pregnant women classified as slow metabolizers, compared with 0.87 μg/mL (0.34-1.64) in intermediate metabolizers and 0.78 μg/mL (0.30-1.47) in fast metabolizers. C12 was below the 0.47 μg/mL threshold determined within the ENCORE 1 trial in 10% at 400 mg, 4.6% at 600 mg and 3.4% with genotype-guided dosing. The 4.0 μg/mL toxicity threshold was exceeded in 4.6% at 400 mg, 13.5% at 600 mg and 5.2% with genotype-guided dosing.

Conclusions

These data provide context for the ongoing debate about reduction in efavirenz dose to 400 mg during pregnancy and should be interpreted alongside the lower toxicity expected with the lower dose. Additional research is required to investigate genotype-guided dose reduction in pregnant women.

Protease inhibitor therapy in resource-limited settings

PURPOSE OF REVIEW

The use of protease inhibitors in resource-limited settings will increase in coming years as HIV treatment cohorts mature. We review data available to guide the expanded use of protease inhibitors in these settings.

RECENT FINDINGS

The safety and effectiveness of protease inhibitors may be affected by the context of their use, yet limited data exist regarding the use of these agents in resource-limited settings in either first or subsequent regimens. Critically, data are needed regarding optimal regimens at time of first-line nonnucleoside reverse transcriptase inhibitor-based regimen failure. A number of alternative strategies are being investigated, including dual-boosting, monotherapy and dose reduction. Despite recent progress cost, storage requirements, drug interactions and formulation continue to hinder the use of protease inhibitors, particularly for children.

SUMMARY

Protease inhibitors are the core component of second-line therapy in resource-limited settings and are used in specific situations in first-line therapy. Use of second-line regimens has been more diverse than first line, but WHO has recently prioritized regimens containing lopinavir/ritonavir or ritonavir-boosted atazanavir. As use of protease inhibitors in resource-limited settings increases evidence needs to be accrued to guide further expanded use.

Adult combination antiretroviral therapy in sub-Saharan Africa: lessons from Botswana and future challenges

Numerous national public initiatives offering first-line combination antiretroviral therapy (cART) for HIV infection have commenced in sub-Saharan Africa since 2002. Presently, 2.1 million of an estimated seven million Africans in need of cART are receiving treatment. Analyses from the region report favorable clinical/treatment outcomes and impressive declines in AIDS-related mortality among HIV-1-infected adults and children receiving cART. While immunologic recovery, virologic suppression and cART adherence rates are on par with resource-rich settings, loss to follow-up and high mortality rates, especially within the first 6 months of treatment, remain a significant problem. Over the next decade, cART coverage rates are expected to improve across the region, with attendant increases in healthcare utilization for HIV- and non-HIV-related complications and the need for expanded laboratory and clinical services. Planned and in-progress trials will evaluate the use of cART to prevent primary HIV-1 infection with so-called 'test and treat' expansions of coverage and treatment. Education and training programs as well as patient-retention strategies will need to be strengthened as national cART programs are expanded and more people require lifelong monitoring and care.

Low prevalence of transmitted antiretroviral drug resistance in a large UK HIV-1 cohort

OBJECTIVES

To describe current practice in testing for transmitted antiretroviral drug resistance (TDR) and the prevalence of TDR in a large UK HIV-1 cohort.

METHODS

The study includes a retrospective analysis of newly diagnosed HIV-1-infected patients presenting to eight HIV clinics in the north of England between March 2005 and March 2007. Resistance mutations were defined by IAS-USA. Predicted phenotypes were calculated by the Stanford University database.

RESULTS

Five hundred and fifty-eight patients were studied, of whom 394 (70.6%) had heterosexually acquired HIV and 377 (67.6%) were infected outside the UK. TDR testing was performed in 406 patients (72.8%). Thirteen of 392 viral resistance profiles (3.3%) showed genotypic TDR. There was no significant association between TDR and any demographic or risk factor or baseline CD4 count. In particular, rates of TDR were similar in white British (6/147, 4.1%) and black African (7/224, 3.1%) patients. The numbers of patients with TDR to individual drug classes were: nucleoside reverse transcriptase inhibitors, 2 (0.5%); non-nucleoside reverse transcriptase inhibitors, 7 (1.8%); and protease inhibitors, 4 (1.0%). No patients had multi-class resistance detected. Eleven patients (2.8%) were predicted to have significant phenotypic resistance to at least one drug.

CONCLUSIONS

In a large unselected UK cohort, with high coverage of TDR testing, the prevalence of TDR was low and is in accordance with recent data, showing a decrease in the prevalence of TDR in the UK. Differences in population mix did not appear to explain this low rate.

Maintenance of indinavir by dose adjustment in HIV-1-infected patients with indinavir-related toxicity

OBJECTIVE

Treatment with indinavir/ritonavir (IDV/RTV) is very effective but hampered by frequent development of IDV-associated adverse events (mainly nephrotoxicity and skin changes). We tested whether dose reduction of IDV guided by therapeutic drug monitoring resulted in improved tolerability without compromising antiviral efficacy.

PATIENTS

HIV-infected patients with any IDV/RTV regimen who suffer from IDV-related adverse events were included. Viral load had to be adequately controlled for at least 2 months prior to inclusion. Dose reduction from 800 mg to 600 or 400 mg IDV b.i.d. followed a specified protocol. IDV-related toxicity and IDV plasma concentrations were monitored for 24 weeks. IDV concentrations were quantified with a validated high performance liquid chromatography method.

RESULTS

Twenty patients were included. Reasons for inclusion were: skin abnormalities 11, nephrotoxicity five, metabolic disturbances three, and hypertension one. IDV dose could be lowered to 400 mg b.i.d. in 13, to 600 mg b.i.d. in two patients. Five patients discontinued the treatment. Overall tolerability improved with respect to incidence and severity of adverse events. Median trough concentrations decreased from 1.02 mg/l (range 0.08-7.1) at baseline to 0.48 mg/l (0.11-1.4) after 24 weeks (p = 0.03) and remained above the critical threshold of 0.1 mg/l at any time after dose reduction. There was no change of CD4 cell counts or viral suppression. There were no significant changes in other laboratory parameters (creatinine, bilirubin, triglycerides, cholesterol, blood count, and urinalysis).

CONCLUSION

Dose reduction of IDV improved tolerability of IDV-containing highly active antiretroviral treatment (HAART). Sufficient IDV trough concentrations were maintained in all patients as was virologic control.

Second-line combination antiretroviral therapy in resource-limited settings: facing the challenges through clinical research

Combination antiretroviral therapy (ART) has dramatically altered the prognosis of individuals infected with HIV. In the past 5 years there has been a concerted effort to increase access to ART in the developing world. The evidence to date suggests that adherence to therapy and clinical outcomes in developing world programmes are at least the equal of those observed in developed countries. Although access to first-line therapy is reasonably well established, there is a substantial and unacceptable mortality rate in the first 6 months after initiation of ART, particularly in those with low CD4 cell counts and late-stage disease. Failure of first-line ART is inevitable in a proportion of patients. Access to second-line ART regimens in developing countries is problematic, mainly because of the expense of HIV protease inhibitors (PIs). Access to second-line ART may be facilitated by novel strategies using the existing recommended agents or by the use of new agents or classes. Refinement of programmes in the developing world must be underpinned by the same rigorous scientific research effort that has characterized the success of the effort in the developed world. Therefore, the funding bodies responsible for the roll-out of antiretroviral access across the globe must mandate, incorporate and fund clinical research as an intrinsic aspect of combination ART roll-out programmes.

Indinavir: the forgotten HIV-protease inhibitor. Does it still have a role?

Indinavir is one of four first-generation HIV-protease inhibitors and was the most popular amongst them in the late 1990s. It was initially licensed for use alone, given three times daily, administered away from meals and together with at least 1.5 litres of fluid per day. In clinical practice, it became common for clinicians to prescribe it with a ritonavir pharmacokinetic 'boost' to remove the food restriction, reduce the pill burden and enable a more convenient twice-daily dosing schedule. However, at a ritonavir-boosted dosing schedule of indinavir/ritonavir 800/100 mg b.i.d., the regimen proved toxic and poorly tolerable, and its use diminished as newer, better tolerated PIs became available. Recent research has suggested that ritonavir-boosted indinavir administered at lower doses, particularly indinavir/ritonavir 400/100 mg b.i.d., retains potency and is considerably less toxic. As a result, there is interest in its application in resource-constrained settings.

Lack of indinavir-associated nephrological complications in HIV-infected adults (predominantly women) with high indinavir plasma concentration in Abidjan, Côte d'Ivoire

To report the tolerance of indinavir combined with ritonavir (IDV/r 800/100 mg) twice daily (bid) in sub-Saharan African HIV-infected adults. HAART-naives patients started zidovudine plus lamivudine plus IDV/r 800/100 mg bid. Follow-up included standardized documentation of morbidity, CD4(+) cell count, creatininemia, plasma HIV-1 RNA, and IDV minimal plasma concentration (C(min)) measurements at month 1 (M1), M3, and M6. Seventy HIV-1-infected adults (68 women, median CD4 235/mm(3)) started HAART. At M6, 63% had undetectable viral load, and the median gain in CD4 since baseline was +128/mm(3). During the first 6 months, 21 patients experimented with 23 treatment modifications (reduction in IDV/r 400/100 mg bid, n = 11; switch to efavirenz, n = 11; zidovudine replaced by stavudine, n = 1), including 22 for digestive intolerance and 1 for severe anemia. At M1, M3, and M6, 67, 59, and 48 patients were still receiving IDV/r 800/100 mg bid, of whom 70%, 72%, and 60% had IDV Cmin above 5 ng/ml, respectively. In these patients, at M1, M3, and M6, the mean (+/- SD) IDV C(min) were 3431 +/- 3835 ng/ml, 2288 +/- 2116 ng/ml, and 1543 +/- 2398 ng/ml, respectively. There was no renal insufficiency of any grade, and no symptoms of urinary stones. The IDV/r 800/100 mg bid-containing regimen led to high IDV Cmin and a high rate of digestive intolerance. There was a surprising lack of nephrological side effects during the 6 months of follow-up, supporting the hypothesis that nephrological tolerance of IDV might be higher in sub-Saharan African individuals than in Americans or Europeans.

Boosted versus Unboosted Indinavir with Zidovudine and Lamivudine in Nucleoside Pre-Treated Patients: A Randomized, Open-Label Trial with 112 Weeks of Follow-Up (HIV-Nat 005)

Introduction

The use of HIV protease inhibitors (PIs) in a ritonavir (RTV)-boosted form is now common. However, randomized data comparing boosted with unboosted PI strategies are scarce.

Methods

This randomized, open-label trial compared indinavir (IDV) 800 mg three times daily with IDV/RTV 800/100 mg twice daily, both given with zidovudine (AZT)/lamivudine (3TC) twice daily in individuals with at least 3 months previous AZT experience. The primary endpoint was the time-weighted average change in HIV RNA from baseline. Designed as a 48-week study, follow-up continued until week 112. Primary analysis is by intention to treat.

Results

One hundred and three patients commenced therapy and are included in the analysis. Patients had a median of 29 months past nucleoside reverse transcriptase inhibitor (NRTI) exposure. Baseline median (interquartile range) log10 HIV RNA was 4.0 (3.3–4.5) and CD4+T-cell count 166 (40–323) cells/μl. After 112-weeks of study there was no significant difference observed between arms in the mean (sd) change in time-weighted average HIV RNA from baseline (-1.6 [1.1] HIV RNA copies/week/ml three times daily arm; -1.4 [1.1] HIV RNA copies/week/ml twice daily arm; P=0.3). Both arms were associated with substantial toxicity expressed as serious adverse events and study drug interruptions. The twice daily arm experienced greater dyslipidaemia. Mean (sd) changes in time-weighted CD4+ T-cell count from baseline were similar [88 (84) cells/week/μl three times daily arm; 70 [109] cells/week/μl twice daily arm; P=0.3).

Conclusions

RTV-boosted IDV 800/100 mg twice daily demonstrated comparable efficacy to unboosted IDV 800mg three times daily dosing. Both regimens were associated with substantial toxicity. Use of lower doses of RTV-boosted IDV may result in better tolerability without loss of efficacy and warrant further research.

Efficacy and Safety of Indinavir/Ritonavir 400/100 mg Twice Daily plus Two Nucleoside Analogues in Treatment-Naive HIV-1-Infected Patients with CD4+ T-cell Counts <200 cells/mm3: 96-Week Outcomes

Objective

To evaluate the efficacy and safety of indinavir/ritonavir 400/100 mg plus stavudine and lamivudine twice daily in antiretroviral-therapy-naive Thai HIV-1-infected patients.

Methods

This was an open-label, non-randomized single arm study. Antiretroviral-naive patients ( n=80) with CD4+ cell count <200x106/l were started on stavudine and lamivudine plus indinavir/ritonavir 400/100mg twice daily. CD4+ cell count and HIV RNA were determined at week 0, 12, 24, 48 and 96. HIV RNA was measured to a level of 50 copies/ml by RT-PCR assay. Primary analysis was statistically performed as intent to treat. The primary endpoint was the percentage of patients with plasma HIV RNA below 50 copies/ml at week 96.

Result

Eighty antiretroviral-therapy-naive patients with median CD4+ cell count 19x106/l (range: 2-197x106/l) and median baseline plasma HIV RNA of 174,000 copies/ml (range 16,800–750,000 copies/ml) were enrolled. In the intent-to-treat analysis at week 96, the proportion of patients with HIV RNA of <50 copies/ml was 68.8% (95% confidence interval [CI]: 68.3-69.3), whereas it was 88.7% (95% CI: 88.1-89.3) in the on-treatment analysis at week 96. The regimen was well tolerated. Hyperglycaemia, hypercholesterolaemia and hypertriglyceridaemia were found in 8.3, 33.3 and 37.0% of the patients, respectively. Treatment was stopped in 18 patients; two from intolerance, two switched therapy, four as a result of serious adverse event-related death, and ten were lost to follow-up.

Conclusion

Our study demonstrates that indinavir/ritonavir 400/100 mg plus stavudine and lamivudine twice daily, the least expensive boosted protease inhibitor, appears to be effective and safe up to 96 weeks despite high baseline viraemia and low CD4+ cell count in antiretroviral-naive patients.