Several new antiretroviral (ARV) agents for treatment experienced HIV-infected patients have been approved since June 2006, including darunavir (DRV) and raltegravir (RAL). While efficacious in clinical trials, the effectiveness, durability, and tolerability of these new ARVs remains understudied in the context of routine clinical care. The Darunavir Outcomes Study is a prospective cohort study of three-class ARV-experienced patients changing regimens at the 1917 Clinic after 1/7/2006. All treatment decisions were at the discretion of primary providers. Multivariate (MV) logistic regression for 48 week VL < 400c/ml and Cox models for regimen durability were completed. Propensity score methods controlled for sociodemographics. Among 108 patients, mean age of 46, 48% were white, 80% male, with prior exposure to a mean 10.5 ARVs. Overall, 64% of patients achieved 48-week VL < 400 c/ml. In MV modeling DRV/rll (OR = 5.77;95%CI = 1.62-20.58) and RAL (OR = 3.84;95%CI = 1.23-11.95) use increased odds of 48-week suppression. Use of these agents exhibited a trend towards prolonged regimen durability in Cox models. Among those highly ARV-experienced, regimens containing DRV/r and/or RAL were more likely to achieve 48-week VL < 400 c/ml and exhibited a trend towards prolonged durability. New agents have transformed the treatment landscape for ARV-experienced patients, with effectiveness in routine clinical care mirroring efficacy in clinical trials.

OBJECTIVE:

ODIN (Once-daily Darunavir In treatment-experieNced patients) was a phase III, 48-week, open-label study comparing once-daily vs. twice-daily darunavir/ritonavir (DRV/r) in treatment-experienced patients with no DRV resistance-associated mutations (RAMs) at screening.

METHODS:

Patients with no DRV RAMs and receiving stable HAART for at least 12 weeks were stratified by HIV-1 RNA (≤ or > 50 000 copies/ml) and randomized to once-daily DRV/r 800/100 mg or twice-daily DRV/r 600/100 mg and an optimized background regimen (≥2 nucleoside reverse transcriptase inhibitors). Primary objective was to demonstrate noninferiority of once-daily vs. twice-daily DRV/r in confirmed virologic response (HIV-1 RNA < 50 copies/ml) at week 48.

RESULTS:

Five hundred and ninety patients received once-daily (n = 294) or twice-daily (n = 296) DRV/r. Mean baseline HIV-1 RNA was 4.16 log10 copies/ml; median CD4 cell count was 228 cells/μl; and 53.9% had previously used at least one protease inhibitor. At week 48, 72.1% of once-daily and 70.9% of twice-daily patients achieved HIV-1 RNA less than 50 copies/ml (intent-to-treat/time-to-loss of virologic response). The difference in response between once-daily and twice-daily arms was 1.2% (95% confidence interval -6.1 to 8.5%; P < 0.001), establishing noninferiority of once-daily DRV/r versus twice-daily DRV/r. Median CD4 cell count increase was 100 (once-daily) and 94 cells/μl (twice-daily). Virologic failure rate was low and similar for both arms; only one patient (once-daily arm) developed primary protease inhibitor mutations. Once-daily DRV/r had a lower incidence of grade 2-4 triglyceride increases (5.2 vs. 11.0%, P < 0.05).

CONCLUSION:

Once-daily DRV/r 800/100 mg was noninferior in virologic response to twice-daily DRV/r 600/100 mg at 48 weeks in treatment-experienced patients with no DRV RAMs, and with a more favorable lipid profile. These findings support use of once-daily DRV/r in this population.

Background: Long-term (96-week) efficacy and safety of the protease inhibitor (PI) darunavir coadministered with low-dose ritonavir (DRV/r) was evaluated in HIV type-1 (HIV-1)-infected patients with extensive prior treatment experience in the POWER 1, 2 and 3 trials. Methods: Patients with HIV-1 RNA≥1,000 copies/ml and ≥1 primary PI mutation were randomized to receive either DRV/r 600/100 mg twice daily plus an optimized background regimen (OBR), or an investigator-selected control PI (CPI) plus OBR (POWER 3 was a DRV/r 600/100 mg twice daily single-arm study). The proportion of patients with HIV-1 RNA<50 copies/ml at week 96 was assessed (intent-to-treat [ITT], time-to-loss of virological response algorithm). Results: In total, 467 patients received DRV/r 600/100 mg twice daily; 124 patients received CPI(s). At week 96, 39% of DRV/r patients in POWER 1 and 2 (pooled analysis) versus 9% of CPI patients achieved HIV-1 RNA<50 copies/ ml (ITT, time-to-loss of virological response algorithm; P<0.001). A similar proportion of DRV/r patients (42%) in POWER 3 achieved HIV-1 RNA<50 copies/ml at week 96. Mean absolute CD4+ T-cell count increase for DRV/r at 96 weeks was 133 cells/mm3 in POWER 1 and 2 and 103 cells/mm3 in POWER 3. Grade 2-4 treatmentemergent adverse events at least possibly related to DRV/r (≥2% incidence, excluding laboratory abnormalities) were diarrhoea (3%), vomiting (3%), nausea (2%) and headache (2%). Conclusions: Treatment with DRV/r 600/100 mg twice daily was well tolerated and led to sustained virological and immunological responses in treatment-experienced HIV-1-infected patients over 96 weeks. ©2009 International Medical Press.

BACKGROUND:

The protease inhibitor darunavir has been shown to be efficacious in highly treatment-experienced patients with HIV infection, but needs to be assessed in patients with a broader range of treatment experience. We did a randomised, controlled, phase III trial (TITAN) to compare 48-week efficacy and safety of darunavir-ritonavir with that of lopinavir-ritonavir in treatment-experienced, lopinavir-naive patients.

METHODS:

Patients received optimised background regimen plus non-blinded treatment with darunavir-ritonavir 600/100 mg twice daily or lopinavir-ritonavir 400/100 mg twice daily. The primary endpoint was non-inferiority (95% CI lower limit for the difference in treatment response -12% or greater) for HIV RNA of less than 400 copies per mL in plasma at week 48 (per-protocol analysis). TITAN (TMC114-C214) is registered with ClinicalTrials.gov, number NCT00110877.

FINDINGS:

Of 595 patients randomised and treated, 187 (31%) were protease inhibitor naive; 476 of 582 (82%) were susceptible to four or more protease inhibitors. At week 48, significantly more darunavir-ritonavir than lopinavir-ritonavir patients had HIV RNA of less than 400 copies per mL (77% [220 of 286] vs 68% [199 of 293]; estimated difference 9%, 95% CI 2-16). Fewer virological failures treated with darunavir-ritonavir than with lopinavir-ritonavir developed primary protease inhibitor mutations (21% [n=6] vs 36% [n=20]) and nucleoside analogue-associated mutations (14% [n=4] vs 27% [n=15]). Safety data were generally similar between the groups; grade 3 or 4 adverse events occurred in 80 (27%) darunavir-ritonavir and 89 (30%) lopinavir-ritonavir patients.

INTERPRETATION:

In lopinavir-naive, treatment-experienced patients, darunavir-ritonavir was non-inferior to lopinavir-ritonavir treatment in terms of our virological endpoint, and should therefore be considered as a treatment option for this population.

Data from two Phase IIb trials, POWER 1 and 2 (TMC114-C213 and C202), were pooled to examine the effect of baseline viral susceptibility on response to control protease inhibitors [CPI(s)] compared with response to darunavir (TMC114) given with low-dose ritonavir (darunavir/r) in treatment-experienced HIV patients. POWER 1 and 2 were randomized, controlled Phase IIb trials with a similar design. Patients with one or more primary PI mutations and HIV-1 RNA >1000 copies/ml were randomized to receive an optimized background regimen plus darunavir/r or CPI(s). POWER 1 and 2 week 24 efficacy (intent-to-treat using time-to-loss of virologic response algorithm) data were pooled and analyzed according to baseline subgroups of susceptibility to the CPI regimen, fold-change (FC) in EC(50) to darunavir, and number of darunavir resistance-associated mutations (RAMs). In total, 131 patients received darunavir/r 600/100 mg twice daily; 124 received CPI(s) [lopinavir/r, 20%; saquinavir/r, 19%; (fos)-amprenavir/r, 24%; atazanavir/r, 11%; and 23% used dual-boosted CPI(s)]. At baseline, 72% of patients were resistant (defined as FC) to their investigator-selected CPIs. At week 24, darunavir/r 600/100 mg twice daily provided greater efficacy benefits over CPI(s), even when the virus was predicted to be fully susceptible to the CPI. The response to darunavir decreased when FC to darunavir at baseline was >40 or when three or more darunavir RAMs (in addition to other PI mutations) were present at baseline. Darunavir/r 600/100 mg twice daily showed efficacy benefits over CPI use regardless of viral susceptibility at baseline, FC to darunavir or boosting type in a population of treatment-experienced HIV-infected patients.

BACKGROUND:

The continuing, randomised, multinational, phase IIB POWER 1 and 2 studies aim to evaluate efficacy and safety of darunavir in combination with low-dose ritonavir in treatment-experienced HIV-1-infected patients. We did a pooled subgroup analysis to update results at week 48 for patients receiving the recommended dose of darunavir-ritonavir compared with those receiving other protease inhibitors (PIs).

METHODS:

After 24-week dose-finding phases and primary efficacy analyses, patients randomised to receive darunavir-ritonavir were given 600/100 mg twice daily, and patients receiving control PIs continued on assigned treatment into the longer-term, open-label phase; all patients continued on optimised background regimen. We assessed patients who had reached week 48 or discontinued earlier at the time of analysis; for the darunavir-ritonavir group, only patients who received 600/100 mg twice daily from baseline were included. Analyses were intention-to-treat. The POWER 2 study (TMC114-C202) is registered with ClinicalTrials.gov (NCT00071097).

FINDINGS:

At week 48, 67 of 110 (61%) darunavir-ritonavir patients compared with 18 of 120 (15%) of control PI patients had viral load reductions of 1 log10 copies per mL or greater from baseline (primary endpoint; difference in response rates 46%, 95% CI 35%-57%, p<0.0001). Based on a logistic regression model including stratification factors (baseline number of primary PI mutations, use of enfuvirtide, baseline viral load) and study as covariates, the difference in response was 50% (odds ratio 11.72, 95% CI 5.75-23.89). In the darunavir-ritonavir group, rates of adverse events were mostly lower than or similar to those in the control group when corrected for treatment exposure. No unexpected safety concerns were identified.

INTERPRETATION:

Efficacy responses with darunavir-ritonavir 600/100 mg twice daily plus optimised background regimen were greater than those with control PI and were sustained to at least week 48, with favourable safety and tolerability in treatment-experienced patients. This regimen could expand the treatment options available for such patients.

Background and Objectives: Long-term use of antiretroviral therapy (ART) to treat HIV infection has been associated with dyslipidemia and metabolic and cardiovascular complications. Available options for patients at risk of cardiovascular disease include antiretroviral drugs with improved lipid profiles. Dolutegravir is one of a new generation of HIV integrase inhibitors recently incorporated into the US Department of Health and Human Services, German, Spanish, and Italian HIV treatment guidelines as a preferred first-line third agent in combination with dual nucleoside reverse transcriptase inhibitor (NRTI) backbone therapies. To understand the lipid profile of dolutegravir in the context of combination ART, we analyzed the lipid outcomes at 48 weeks in ART-naive participants in four phase IIb–IIIb clinical trials.Methods: Variables included in this analysis were total cholesterol (TC), low-density lipoprotein (LDL) cholesterol (LDL-C), high-density lipoprotein (HDL) cholesterol (HDL-C), TC/HDL ratio, and triglycerides at baseline and week 48.Results: In a comparative analysis, dolutegravir demonstrated a broadly neutral effect on lipids versus efavirenz or ritonavir-boosted darunavir; in both comparisons, patients taking dolutegravir exhibited smaller increases in TC, LDL-C, and triglyceride levels. In comparison with raltegravir, dolutegravir exhibited a similar lipid profile, including small increases in TC, LDL-C, and triglyceride levels for both agents. In the pooled dolutegravir analysis, minimal increases in LDL-C and triglycerides were observed but mean values at 48 weeks remained below National Cholesterol Education Program target levels. HDL-C levels increased at 48 weeks, and the mean TC/HDL-C ratio was 0.6 at 48 weeks; these values are associated with a lower risk of cardiovascular disease.Conclusions: Together, these data show that dolutegravir has a safer lipid profile in combination ART and provides an important treatment option for older patients who may have other risk factors for metabolic syndrome or cardiovascular disease.

Background: Clinical management of HIV patients co-infected with tuberculosis (TB) is hampered by drug-drug interactions (DDIs) that limit therapeutic options. Rifampicin (RIF), an important component of anti-TB treatment regimens, is a strong inducer of key metabolic enzymes, and thus can negatively affect antiretroviral bioavailability, clearance and efficacy. The aim of this study was to quantify DDIs between RIF and cobicistat (COBI)-boosted darunavir (DRV), and to compare this with DDIs between RIF and ritonavir (RTV)- boosted DRV (DRV/r) using an in vitro approach. Methods: Cryopreserved primary human hepatocytes plated on collagen-coated cell culture plates were overlaid with Geltrex™ matrix and were treated with RIF (10 μM) alone, or together with RTV (0.1-10 μM) or COBI (0.13-12.76 μM) in Williams' Medium E incubation medium, or were left untreated. Test compounds were replenished each day for a total of 72 hours, after which cells were treated with test compounds together with DRV (5 μM) for one hour. Resultant DRV concentrations were quantified using HPLC-UV. Apparent intrinsic clearance (CLint.app.) of DRV was calculated, and expressed as the mean ± SD (μl/min/106 hepatocytes) of a total of three biological replicates, using cells obtained from three separate donors. Results: Under control conditions where cells treated with DRV alone, DRV CLint.app. was 13.2 ± 1.5 μl/min, while following incubation with 10 μM RIF, DRV CLint.app. increased to 20.5 ± 4.7 μl/min (+55% compared to control). Inclusion of 1 μM RTV, or 1.28 μM COBI, was sufficient to overcome the effect of 10 μM RIF, reducing DRV CLint.app. by -15% and -3% compared to control, respectively. Using regression analysis, log10 RTV and COBI concentrations were found to be associated with percentage inhibition of DRV CLint.app. (β = 20.7, p = 0.001 and β = 11.3, p = 0.001, respectively; Figure 1). Conclusions: DDIs between RIF and both DRV/r and DRV/COBI were quantified using an in vitro human hepatocyte model. RIF-induced elevations in DRV CLint.app. were overcome by co-incubation with RTV or COBI. RTV- and COBI-mediated attenuation of RIF-enhanced DRV CLint.app. occurred in a concentration-dependent manner, but RTV reversed RIF induction more strongly than COBI. These results provide an insight into the relative effect of RTV and COBI as pharmacoenhancers in the presence of RIF, and can be used to inform pharmacokinetic models for optimising regimens in patients receiving concurrent antiretroviral and anti-TB therapy. (Figure Presented).

Treatment of HIV-infected patients coinfected with Mycobacterium tuberculosis is challenging due to drug-drug interactions (DDIs) between antiretrovirals (ARVs) and antituberculosis (anti-TB) drugs. The aim of this study was to quantify the effect of cobicistat (COBI) or ritonavir (RTV) in modulating DDIs between darunavir (DRV) and rifampin (RIF) in a human hepatocyte-based in vitro model. Human primary hepatocyte cultures were incubated with RIF alone or in combination with either COBI or RTV for 3 days, followed by coincubation with DRV for 1 h. The resultant DRV concentrations were quantified by high-performance liquid chromatography with UV detection, and the apparent intrinsic clearance (CLint.app.) of DRV was calculated. Both RTV and COBI lowered the RIF-induced increases in CLint.app. in a concentration-dependent manner. Linear regression analysis showed that log10 RTV and log10 COBI concentrations were associated with the percent inhibition of RIF-induced elevations in DRV CLint.app., where β was equal to -234 (95% confidence interval [CI] = -275 to -193; P < 0.0001) and -73 (95% CI = -89 to -57; P < 0.0001), respectively. RTV was more effective in lowering 10 μM RIF-induced elevations in DRV CLint.app. (half-maximal [50%] inhibitory concentration [IC50] = 0.025 μM) than COBI (IC50 = 0.223 μM). Incubation of either RTV or COBI in combination with RIF was sufficient to overcome RIF-induced elevations in DRV CLint.app., with RTV being more potent than COBI. These data provide the first in vitro experimental insight into DDIs between RIF and COBI-boosted or RTV-boosted DRV and will be useful to inform physiologically based pharmacokinetic (PBPK) models to aid in optimizing dosing regimens for the treatment of patients coinfected with HIV and M. tuberculosis.

BACKGROUND:

Protease inhibitors were a major therapeutic breakthrough in the mid-1990s for the treatment of HIV infection, which resulted in improved life expectancy for patients who had failed previous therapies. With time and evolution of the virus, however, there is a new population of patients with treatment-resistant disease and few treatment options. Darunavir is a synthetic nonpeptidic analogue of amprenavir with enhanced activity against resistant virus that became available in 2006.

OBJECTIVES:

The purpose of this review was to describe the clinical pharmacology, pharmacokinetic and pharmacodynamic properties, and clinical efficacy of darunavir. Also discussed are the published clinical experience with darunavir, its adverse events, drug interactions, pharmacoeconomics, and dosing and administration.

METHODS:

A MEDLINE and EMBASE search (English-language only) was performed from January 1996 through April 2007 using the key words darunavir and TMC114. Abstracts from relevant scientific meetings were searched for the years 2000 through 2007. Additionally, the US Food and Drug Administration Web site was accessed to review the new drug application summary and data presented therein.

RESULTS:

Darunavir was found to maintain antiretroviral activity against HIV with protease inhibitor mutations in 6 studies. Clinical efficacy and safety data are limited to 4 controlled and 2 uncontrolled trials. In 2 large Phase IIb clinical studies, viral suppression at 48 weeks to undetectable levels in heavily pretreated patients was achieved in 45% of patients compared with 10% of patients in the control group (P < 0.001). The addition of enfuvirtide enhanced this response rate to 58% compared with 11% of the patients who did not receive enfuvirtide (P < 0.001). Gastrointestinal symptoms, nausea, and headache were the most commonly reported events.

CONCLUSIONS:

Darunavir has improved activity against resistant HIV isolates in patients with few treatment choices, particularly when enfuvirtide is added. The safety profile of darunavir is comparable to other protease inhibitors based on early data.