Salvage antiretroviral therapy in HIV infection

Positioning of darunavir/cobicistat-containing antiretroviral regimens in real life: results from a large multicentre observational prospective cohort (SCOLTA)

Background

Study aim was to evaluate the safety and durability of darunavir/cobicistat (DRV/c) in a real life setting.

Methods

Multicentre prospective cohort study performed in the context of SCOLTA (Surveillance Cohort Long-Term Toxicity Antiretrovirals). Patients were evaluated at baseline, week 24 and 48. Changes were evaluated using the paired t test or signed rank test. The multivariable analysis was performed using a general linear model, after ranking of not normally distributed variables.

Results

A total of 249 patients were included, 72 (29%) were in DRV/c-based dual therapies (DT). Hypercholesterolemia, HC, (total cholesterol (TC) ≥ 200 mg/dL or low density-C (LDL-C) ≥ 130 or statin use) was present in 121 (48.6%) and hypertriglyceridemia, (triglycerides (TG) ≥ 200 mg/dl or fibrate use) in 41 (16.5%) patients. Blood lipid profile did not change significantly in either the global population or patients with HC. After a median observation of 17 months (IQR 13–20), 59 (25.3%) patients discontinued DRV/c, of which 13 were in DT. The durability DT resulted higher than that of triple therapy (log-rank test p = 0.01). Main reasons for stopping DRV/c were simplification (15 patients), adverse events (13 patients), planned discontinuation for treatment initiation with DAA (4 patients), treatment failure (2 patients); death (2 patients), other causes (10 patients). Twenty-six were lost to follow-up.

Conclusions

DRV/c was safe and well tolerated. Dual therapies showed a better profile of tolerability and a longer durability compared to triple therapies.

Clinical Impact of Double Protease Inhibitor Boosting with Lopinavir/Ritonavir and Amprenavir as Part of Salvage Antiretroviral Therapy

PURPOSE

Double protease inhibitor (PI) boosting is being explored as a new strategy in salvage antiretroviral (ARV) therapy. However, if a negative drug interaction leads to decreased drug levels of either or both PIs, double PI boosting could lead to decreased virologic response. A negative drug interaction has been described between amprenavir (APV) and lopinavir/ritonavir (LPV/r). This observational cohort study assessed the virologic impact of the addition of APV to a salvage ARV regimen, which also contains LPV/r, compared to a regimen containing LPV/r alone.

METHOD

Patients initiated on a salvage ARV regimen that included LPV/r obtained from the expanded access program in Toronto, Canada, were evaluated. APV (600-1,200 mg bid) was added at the discretion of the treating physician.

RESULTS

Using multivariate Cox proportional hazards models, we found that the addition of APV to a LPV/r-containing salvage regimen was not significantly associated with time to virologic suppression (< 50 copies/mL; adjusted hazard ratio [HR] = 0.75, p =.12) or with time to virologic rebound (adjusted HR = 1.46, p =.34). Those patients who received higher doses of APV had an increased chance of virologic suppression (p =.03). In a subset of 27 patients, the median LPV C(trough) was significantly lower in patients receiving APV (p =.04), and the median APV C(trough) was reduced compared to reported controls.

CONCLUSION

Our data do not support an additional benefit in virologic reduction of double boosting with APV and LPV/r relative to LPV/r alone in salvage ARV therapy. Our study's limitations include its retrospective nature and the imbalance between the two groups potentially confounding the results. Although these factors were adjusted for in the multivariate analysis, a prospective randomized controlled trial is warranted to confirm our findings.

Meta-Analysis of Interventions for Reducing Number of Sexual Partners and Drug and Alcohol Abuse among People Living with HIV/AIDS

OBJECTIVE

To perform a systematic review and meta-analysis of the efficacy of risk reduction interventions on HIV-related risk behaviors among people living with HIV/AIDS (PLWHA).

METHODS

Studies included in the meta-analysis were randomized clinical trials (RCTs) of risk reduction interventions, which targeted PLWHA aged 18 year or older and assessed the changes of number of sexual partners, drug use, needle sharing, and/or alcohol abuse between pre- and post-intervention. The standardized mean differences (SMD) between study arms as well as between baseline and post-intervention, defined as the effect sizes (ES), were calculated in random effects models. Heterogeneity of studies was estimated by the I2 statistic.

RESULTS

Twelve RCTs involving 3993 PLWHA were included in our analysis: seven reported impacts on the number of sexual partners, and three reported impacts on drug use, needle sharing, and alcohol abuse, respectively. There were no statistically significant impacts of risk reduction interventions on the number of total sexual partners (mean ES, -0.10; 95% confidence interval [CI], -0.26, 0.06; P=0.22) or on the subset of HIV-negative or unknown-status sexual partners (mean ES, 0.003; 95% CI, -0.54, 0.54; P=0.99). Overall, risk reduction intervention studies documented a reduction of drug abuse (mean ES: -0.26; 95% CI: -0.51, -0.01; P=0.04) among HIV-infected drug users, but this impact was mainly attributable to one study. Risk reduction interventions did not show a reduction of needle sharing (mean ES, -0.15; 95% CI, -0.43, 0.13; P=0.29) or of alcohol abuse (mean ES, -0.10; 95% CI, -0.36, 0.17; P=0.47). No heterogeneity or publication bias was found across individual studies.

CONCLUSIONS

Our meta-analysis did not find a positive impacts of risk reduction interventions on number of sexual partners, drug use, needle sharing, or alcohol abuse among PLWHA, but the small number of studies meeting our review criteria limits these findings.

Developments in virus-like particle-based vaccines for HIV

Virus-like particles (VLPs) hold great promise for the development of effective and affordable vaccines. VLPs, indeed, are suitable for presentation and efficient delivery to antigen-presenting cells of linear as well as conformational antigens. This will ultimately result in a crosspresentation with both MHC class I and II molecules to prime CD4(+) T-helper and CD8(+) cytotoxic T cells. This review describes an update on the development and use of VLPs as vaccine approaches for HIV.

Progress towards development of an HIV vaccine: report of the AIDS Vaccine 2009 Conference

The search for an HIV/AIDS vaccine is steadily moving ahead, generating and validating new concepts in terms of novel vectors for antigen delivery and presentation, new vaccine and adjuvant strategies, alternative approaches to design HIV-1 antigens for eliciting protective cross-neutralising antibodies, and identification of key mechanisms in HIV infection and modulation of the immune system. All these different perspectives are contributing to the unprecedented challenge of developing a protective HIV-1 vaccine. The high scientific value of this massive effort is its great impact on vaccinology as a whole, providing invaluable scientific information for the current and future development of new preventive vaccine as well as therapeutic knowledge-based infectious-disease and cancer vaccines.

Two cases of multidrug-resistant human immunodeficiency virus infection treated with atazanavir and lopinavir/ritonavir combination therapy

The combination of atazanavir (ATV) and lopinavir/ritonavir (LPV/RTV) with nucleoside reverse transcriptase inhibitors (NRTI) has been used as a salvage regimen for human immunodeficiency virus (HIV)-positive patients. In this paper, we discuss two cases of HIV-positive patients who had long histories of virological failure following a heavy treatment of antiretroviral drugs, but then achieved virological suppression with double-boosted protease inhibitor (PI) regimens. In patients with multiple genotypic resistance to PIs and NRTIs, virological suppression can be achieved with a combination of ATV plus LPV/RTV with an NRTI backbone. The two cases in this report suggest that a combination of ATV plus LPV/RTV could be a useful salvage regimen for the subset of HIV-positive patients with limited treatment options.

Enzymatic and structural analysis of the I47A mutation contributing to the reduced susceptibility to HIV protease inhibitor lopinavir

Lopinavir (LPV) is a second-generation HIV protease inhibitor (PI) designed to overcome resistance development in patients undergoing long-term antiviral therapy. The mutation of isoleucine at position 47 of the HIV protease (PR) to alanine is associated with a high level of resistance to LPV. In this study, we show that recombinant PR containing a single I47A substitution has the inhibition constant (K(i) ) value for lopinavir by two orders of magnitude higher than for the wild-type PR. The addition of the I47A substitution to the background of a multiply mutated PR species from an AIDS patient showed a three-order-of-magnitude increase in K(i) in vitro relative to the patient PR without the I47A mutation. The crystal structure of I47A PR in complex with LPV showed the loss of van der Waals interactions in the S2/S2' subsites. This is caused by the loss of three side-chain methyl groups due to the I47A substitution and by structural changes in the A47 main chain that lead to structural changes in the flap antiparallel beta-strand. Furthermore, we analyzed possible interaction of the I47A mutation with secondary mutations V32I and I54V. We show that both mutations in combination with I47A synergistically increase the relative resistance to LPV in vitro. The crystal structure of the I47A/I54V PR double mutant in complex with LPV shows that the I54V mutation leads to a compaction of the flap, and molecular modeling suggests that the introduction of the I54V mutation indirectly affects the strain of the bound inhibitor in the PR binding cleft.

Successful treatment with atazanavir and lopinavir/ritonavir combination therapy in protease inhibitor-susceptible and protease inhibitor-resistant HIV-infected patients

The combination of atazanavir (ATV) plus lopinavir/ritonavir (LPV/r) has been used in practice. However, clinical data supporting its use are limited. The objective of this study was to evaluate the efficacy and tolerability of regimens with ATV + LPV/r in protease inhibitor (PI)-susceptible and PI-resistant patients. A retrospective review of 2703 charts was performed to identify all patients who received ATV + LPV/r. From June 2003 to January 2005, 33 patients received ATV + LPV/r with nucleoside reverse transcriptase inhibitors (NRTIs) for 3 months or more. Virologic success (HIV-RNA < 400 copies per milliliter) was achieved in 30 patients (91%) in a median of 10 weeks (range, 2-68). Nineteen of the 23 patients (83%) who had ultrasensitive viral load (VL) assays were nondetectable. Among patients with 6 or more protease resistance (PR) mutations (PI-resistant), 11 of 14 (79%) achieved virologic success. Eleven of those received phenotypic testing (10 Virtual Phenotype, VircoLab, Baltimore, MD). Despite predicted phenotypic resistance to ATV (6 patients) and LPV/r (7 patients), virologic success was achieved in 4 of 6 (67%) and 4 of 7 (57%), respectively. The 3 PI-resistant patients who were virologic failures had extensive prior LPV/r use, 8-11 PR mutations, and predicted phenotypic resistance to LPV/r, but 2 of 3 had CD4 increases with ATV + LPV/r. Overall, 28 patients (85%) continue to tolerate ATV + LPV/r for a median of 32 weeks follow-up (range, 12-76). Combination ATV + LPV/r with NRTIs appears safe, tolerable, and efficacious in PI-resistant patients (>/=6 PR mutations) and predicted phenotypic resistance to ATV and LPV/r. Further studies of ATV + LPV/r in HIV-treatment are warranted.

Cost-effectiveness of enfuvirtide in HIV therapy for treatment-experienced patients in the United States

Enfuvirtide (ENF) is the first of a new class of antiretrovirals (ARVs) known as the HIV fusion inhibitors. Two phase III studies of ENF, TORO 1 and TORO 2, demonstrated that ENF given in combination with optimized background (OB) therapy significantly improved virological response, increased the time to virological failure, and increased CD4-cell count compared with OB alone among highly treatment-experienced patients. The present study investigated the long-term clinical outcomes, costs, and cost-effectiveness of ENF. Outcomes, costs, and cost-effectiveness were estimated using a Markov model. Viral suppression and immune reconstitution were determined from the outcomes of the clinical trials. Time to immunological failure, time to AIDS-defining event (ADE), and time to death were estimated based on published mathematical models of disease progression. Costs were based on published estimates of the use and costs of ARVs, cost of managing ADEs, and cost of laboratory and other outpatient services. Cost-effectiveness was calculated as the incremental cost per year of life gained, adjusted for quality of life. The combined effects of an increase in CD4 count and delayed time to virological and immunological failure with ENF + OB were predicted to produce a mean life expectancy of 7.4 years from initiation of therapy, which was 1.8 years (1.5 quality-adjusted lifeyears [QALYs]) greater than the life expectancy associated with OB alone. The incremental cost-effectiveness of ENF + OB was estimated to be Dollars 24,604 per QALY. ENF is projected to increase time to immunological failure, delay onset of new AIDS-defining events, and increase life expectancy by more than 1.5 years among treatment-experienced HIV-infected patients. The cost-effectiveness of ENF is comparable to many existing treatment and prevention management strategies for HIV.

Response of HIV positive patients to the long-term salvage therapy by lopinavir/ritonavir

BACKGROUND

The cohort of 19 patients on LPV/r salvage regimen was followed for the period of up to 37.5 months. Patient's virologic response was evaluated with regard to the various baseline characteristics.

RESULTS

A 73.7% of patients (14 out of 19) achieved viral suppression during the first three months of treatment, either complete (47.4%) or partial (26.3%). This effect was only transient in five cases (virologic rebound emerged after 9 months of treatment on average) and in nine cases the treatment was successful in the long-term analysis (HIV RNA plasma level still undetectable at 31st month of the therapy on average with maximum of 36 months). We analyzed the link between the virologic response and possible predictive factors of treatment efficiency, such as lopinavir mutation score, various individual mutations, previous PI exposure, etc. We also describe changes in the PR sequence associated with poor response to the salvage therapy to LPV/r.

CONCLUSIONS

The results of LPV/r salvage therapy were encouraging. About 47% of patients from our study achieved stable suppression of viral replication for 31 months on average. LPV/r proved to be potent inhibitor despite unfavourable prognosis.

Simplifying the treatment of HIV infection with ritonavir-boosted protease inhibitors in antiretroviral-experienced patients

PURPOSE

The rationale, advantages, and disadvantages of attempting to enhance the efficacy of a primary protease inhibitor (PI) with ritonavir in the management of HIV infection, especially in patients who have previously undergone highly active antiretroviral therapy (HAART), are discussed.

SUMMARY

PIs are pivotal components of the HAART regimens used to fight HIV infection. Long-term viral suppression remains a major clinical challenge. Certain pharmacologic features of many PIs, such as their limited oral bioavailability, necessitate burdensome dosage schedules, creating a barrier to patient adherence. Compliance may be further compromised by adverse events. Any factors that undermine adherence may increase the risk that plasma drug concentrations will be suboptimal and that viral resistance and subsequent treatment failure will develop. The pharmacokinetic enhancement, or "boosting," of PI levels with low-dose ritonavir may increase PI potency and efficacy, as well as decrease the emergence of viral resistance, reduce the pill burden, and simplify administration. A number of clinical studies suggest that PI-boosted regimens are safe and effective in HIV-infected patients who have been previously treated with antiretroviral agents, but more research is needed.

CONCLUSION

PI boosting with ritonavir can improve PI pharmacokinetics so that potency and efficacy are increased and regimens are simplified, thereby potentially reducing antiretroviral resistance and promoting patient adherence.

Induction of systemic and mucosal cross-clade neutralizing antibodies in BALB/c mice immunized with human immunodeficiency virus type 1 clade A virus-like particles administered by different routes of inoculation

We have recently developed a candidate human immunodeficiency virus type 1 (HIV-1) vaccine model, based on virus-like particles (VLPs) expressing gp120 from a Ugandan HIV-1 isolate of clade A (HIV-VLP(A)s), which shows the induction of neutralizing antibodies as well as cytotoxic T lymphocytes (CTL) in BALB/c mice by intraperitoneal (i.p.) administration. In the present study, immunization experiments based on a multiple-dose regimen have been performed with BALB/c mice to compare different routes of administration. i.p. and intranasal (i.n.), but not oral, administration induce systemic as well as mucosal (vaginal and intestinal) immunoglobulin G (IgG) and IgA responses. These immune sera exhibit >50% ex vivo neutralizing activity against both autologous and heterologous primary isolates. Furthermore, the administration of HIV-VLP(A)s by the i.n. immunization route induces a specific CTL activity, although at lower efficiency than the i.p. route. The HIV-VLP(A)s represent an efficient strategy to stimulate both arms of immunity; furthermore, the induction of specific humoral immunity at mucosal sites, which nowadays represent the main port of entry for HIV-1 infection, is of great interest. All these properties, and the possible cross-clade in vivo protection, could make these HIV-VLP(A)s a good candidate for a mono- and multicomponent worldwide preventive vaccine approach not restricted to high-priority regions, such as sub-Saharan countries.

Antiretroviral resistance mutations in human immunodeficiency virus type 1 infected patients enrolled in genotype testing at the Central Public Health Laboratory, São Paulo, Brazil: preliminary results

Antiretroviral resistance mutations (ARM) are one of the major obstacles for pharmacological human immunodeficiency virus (HIV) suppression. Plasma HIV-1 RNA from 306 patients on antiretroviral therapy with virological failure was analyzed, most of them (60%) exposed to three or more regimens, and 28% of them have started therapy before 1997. The most common regimens in use at the time of genotype testing were AZT/3TC/nelfinavir, 3TC/D4T/nelfinavir and AZT/3TC/efavirenz. The majority of ARM occurred at protease (PR) gene at residue L90 (41%) and V82 (25%); at reverse transcriptase (RT) gene, mutations at residue M184 (V/I) were observed in 64%. One or more thymidine analogue mutations were detected in 73%. The number of ARM at PR gene increased from a mean of four mutations per patient who showed virological failure at the first ARV regimens to six mutations per patient exposed to six or more regimens; similar trend in RT was also observed. No differences in ARM at principal codon to the three drug classes for HIV-1 clades B or F were observed, but some polymorphisms in secondary codons showed significant differences. Strategies to improve the cost effectiveness of drug therapy and to optimize the sequencing and the rescue therapy are the major health priorities.

Salvage lopinavir-ritonavir therapy in human immunodeficiency virus-infected children

OBJECTIVE

To study the control of viral replication in human immunodeficiency virus (HIV)-infected children on different salvage therapies.

DESIGN AND SETTING

A retrospective observational study in 120 HIV-infected children was conducted. The children were divided into 3 groups according to their salvage therapies: (1) children receiving first line highly active antiretroviral therapy (HAART); (2) protease inhibitor-experienced children receiving second line HAART; (3) protease inhibitor-experienced children receiving HAART including lopinavir-ritonavir (LPV/r). The outcome variables examined were time to achieve viral load (VL) < or =400 copies/mL, success in achieving VL < or =400 copies/mL and time to virologic failure (VL >400 copies/mL).

METHODS

VL (HIV-RNA copies/mL) was quantified with reverse transcription-polymerase chain reaction molecular assay. For each protocol, survival analyses were conducted to determine the probability of achieving VL < or =400 copies/mL and rebound of VL.

RESULTS

VL < or =400 copies/mL was achieved by 52.4% of children receiving first line HAART, 48.3% receiving second line HAART and 71.5% receiving HAART including LPV/r. Children receiving HAART including LPV/r reached VL < or =400 copies/mL in a shorter time than children receiving second line HAART (P = 0.017), but quite similar to children receiving first line HAART. In terms of adjusted relative risk, children receiving HAART including LPV/r were 3.36 [95% confidence interval (95% CI), 1.59, 7.07] more likely to achieve VL < or =400 copies/mL than children receiving a different second line HAART. VL rebound occurred in 68.2% children receiving first line HAART, 73.4% receiving second line HAART and 32.4% receiving HAART including LPV/r. Children receiving HAART that includes LPV/r has less incidence of VL rebound (P=0.013) and 3.29 (95% CI 1.04, 10.3) times less risk to achieve a VL rebound than children receiving a different second line HAART.

CONCLUSIONS

HAART that includes LPV/r is able to control HIV replication more efficiently than other classic salvage antiretroviral therapies.