Virologic response to tipranavir-ritonavir or darunavir-ritonavir based regimens in antiretroviral therapy experienced HIV-1 patients: a meta-analysis and meta-regression of randomized controlled clinical trials

Virologic Effectiveness of Abacavir/Lamivudine with Darunavir/Ritonavir Versus Other Protease Inhibitors in Treatment-Experienced HIV-Infected Patients in Clinical Practice

Background and Objectives

The standard of care for HIV treatment is a three-drug regimen consisting of two nucleoside reverse transcriptase inhibitors (NRTIs) and either a non-nucleoside reverse transcriptase inhibitor, a protease inhibitor (PI) or an integrase strand transfer inhibitor. Darunavir boosted with ritonavir (DRV/r) is the only preferred PI in the US Department of Health and Human Services (DHHS) HIV treatment guidelines for antiretroviral-naïve patients, recommended in combination with tenofovir/emtricitabine for antiretroviral-naïve patients. For treatment-experienced and certain antiretroviral-naïve patients, abacavir and lamivudine (ABC/3TC) in combination with DRV/r is considered an effective and tolerable alternative, despite limited research on the effectiveness of this particular combination. This study evaluated virologic outcomes in treatment-experienced patients taking ABC/3TC + DRV/r compared to treatment-experienced patients taking ABC/3TC with any other PI.

Methods

Treatment-experienced HIV-infected patients initiating their first regimen containing ABC/3TC in combination with any PI in the year 2005 or later were selected from the Observational Pharmaco-Epidemiology Research and Analysis (OPERA^®) cohort, a prospective observational cohort reflecting routine medical care. Viral load measurements taken during follow-up were compared between patients taking ABC/3TC + DRV/r and ABC/3TC with a PI other than DRV/r. Logistic regression models were fit to assess the association between regimen exposure and viral load suppression.

Results

A total of 151 patients initiating ABC/3TC + DRV/r and 525 patients initiating ABC/3TC + a non-darunavir PI were included. Patients in both treatment groups had comparable clinical indicators (viral load, CD4) at baseline. A regimen of ABC/3TC + DRV/r was more likely to be prescribed in the later years of the study period, leading to a shorter median follow-up in the DRV/r treatment group (as-treated analysis: 14 vs. 17 months, p = 0.04; intent-to-treat analysis: 33 vs. 68 months, p < 0.001). Multivariable logistic regression models accounting for year of regimen initiation, among other factors, indicated no statistically significant differences in achieving an undetectable viral load for patients taking DRV/r with ABC/3TC compared with other PIs, both in the as-treated (odds ratio [95 % confidence interval]: 0.84 [0.53–1.34]) and intent-to-treat analyses (0.82 [0.48–1.40]). Patients in both treatment groups also showed similar reductions in viral load (median darunavir vs. non-darunavir: −23.0 vs. −23.0 copies/mL; p = 0.72) and gains in CD4 T cell counts (median darunavir vs. non-darunavir: 106 vs. 108 cells/mm³; p = 0.59] while being treated with the regimen of interest.

Conclusions

Patients receiving ABC/3TC + DRV/r appear to experience similar treatment benefit to patients taking ABC/3TC with other PIs in terms of achieving suppression, as well as absolute reductions in viral load and CD4 lymphocyte gains.

Effectiveness, durability, and safety of darunavir/ritonavir in HIV-1-infected patients in routine clinical practice in Italy: a postauthorization noninterventional study

Current antiretroviral (ARV) therapy for the treatment of human immunodeficiency virus (HIV-1)-infected patients provides long-term control of viral load (VL). Darunavir (DRV) is a nonpeptidomimetic protease inhibitor approved for use with a ritonavir booster (DRV/r). This study evaluated the effectiveness of DRV/r in combination with other ARV agents in routine clinical practice in Italy. In this descriptive observational study, data on utilization of DRV/r, under the conditions described in the marketing authorization, were collected from June 2009 to December 2012. Effectiveness (VL <50 copies/mL), tolerability, and durability in four patient groups (two DRV/r-experienced, one ARV-experienced DRV/r-naïve, and one ARV-naïve) were analyzed. Secondary objectives included immunological response, safety, and persistence/discontinuation rates. In total, 875 of 883 enrolled patients were included in the analysis: of these, 662 (75.7%) completed the follow-up until the end of 2012 and 213 (24.3%) withdrew from the study earlier. Initial DRV dose was 600 mg twice daily (67.1%) or 800 mg once daily (32.9%). Only 16 patients (1.8%) withdrew from the study due to virological failure. Virological response proportions were higher in patients virologically suppressed at study entry versus patients with baseline VL ≥50 copies/mL in each ARV-experienced group, while there was no consistent difference across study groups and baseline VL strata according to baseline CD4⁺ cell count. CD4⁺ cell count increased from study entry to last study visit in all the four groups. DRV/r was well tolerated, with few discontinuations due to study-emergent nonfatal adverse events (3.0% overall, including 2.1% drug-related) or deaths (3.0% overall, all non-drug-related); 35.3% of patients reported ≥1 adverse events. These observational data show that DRV/r was effective and well tolerated in the whole patient population described here. The DRV/r-containing regimen provided viral suppression in a high percentage of patients in all groups, with low rates of discontinuation due to virological failure.

The role of mutations at codons 32, 47, 54, and 90 in HIV-1 protease flap dynamics

Treatment of Human Immunodeficiency Virus remains challenging due to the emergence of drug resistant strains under the selective pressure produced by standard anti-retroviral therapy. To explore the structural mechanisms of drug resistance, we performed 40 ns molecular dynamics simulations on three multi-drug resistant HIV-1 protease clinical isolates from patients attending an infectious diseases clinic in Detroit, MI. We identify a novel structural role for the I47V, V32I, I54M and L90M major resistance mutations in flap opening and closure of MDR-PR isolates. Our studies suggest I47V is involved in flap opening and the interaction between I47V and V32I tethers the flaps to the active site. Also, I54M and L90M may be responsible for asymmetric movement of the protease flaps. These findings can be utilized to improve drug design strategies against MDR HIV-1 PR variants.

Liver enzyme elevation during darunavir-based antiretroviral treatment in HIV-1-infected patients with or without hepatitis C coinfection: data from the ICONA foundation cohort

OBJECTIVES

To investigate differences in liver enzyme elevation (LEE) between HIV-infected patients with and without HCV coinfection who start a darunavir/ritonavir-containing regimen.

METHODS

HIV-infected patients enrolled in the Italian Cohort of Naïve to Antiretrovirals (ICONA) Foundation Study were included if they started darunavir/ritonavir for the first time. Patients were classified as not HCV coinfected, HCV active coinfected (HCV RNA positive), and HCV nonactive coinfected (HCV-Ab positive/HCV RNA negative). Time to LEE endpoint was defined using the ACTG toxicity scale, based on changes relative to baseline. Kaplan-Meier was used to estimate 1-year and 2-year probability of LEE. The incidence rate ratios (IRRs) of LEEs were estimated until the last follow-up (intention-to-treat analysis [ITT]) and up to darunavir/ritonavir discontinuation (on-treatment analysis [OT]).

RESULTS

Overall, 703 patients were included. Ninety-one were HCV-Ab positive; of those, 68 (9.7%) had active HCV coinfection. In 879 person-years of follow-up, 101 LEEs occurred (ITT). No severe hepatotoxicity event was registered in active HCV coinfected patients. HCV active coinfection was predictive of LEE in the overall population (OT: adjusted incidence rate ratio (IRR), 2.25; 95% CI, 0.70-7.24; P = .17; ITT: adjusted IRR, 3.62; 95% CI, 1.67-7.83; P < .001) and in naïve patients (OT: adjusted IRR, 6.29; 95% CI, 2.54-15.55; P = .00; ITT: adjusted IRR, 3.87; 95% CI, 0.99-15.16; P = .05).

CONCLUSIONS

No grade 3-4 LEEs occurred in HCV active coinfected patients. HCV active coinfected patients experienced low grade LEEs more frequently than HCV-Ab negative patients. Darunavir/ritonavir seems to be safe whatever the HCV status, when liver enzymes are carefully monitored.