To evaluate the relationship between plasma and intracellular darunavir (DRV) concentrations and virological efficacy in HIV-infected patients on DRV/rtv monotherapy.

Treatment of HIV infection requires the combination of multiple antiretroviral drugs, known as highly active antiretroviral therapy (HAART); however, up to 84% of patients experience adverse drug effects that lead to discontinuation within first months of treatment. Skin manifestations are reported to 22% of patients. The severity of these is variable, such as erythema multiforme, rash, hives and severe skin reactions at less than 2%. Mild rashes, usually transient and self-limiting, while severe reactions require immediately remove the drug involved to prevent progression of the reaction. Only in those cases where the offending drug does not have another alternative and documented the reaction is mediated type I hypersensitivity mechanisms, can be performed desensitization protocol.

INTRODUCTION:

When darunavir (DRV) 800 mg is boosted with 150 mg cobicistat (DRVcobi ), DRV trough concentration (Ctrough ) is about 30% lower as compared to 100 mg ritonavir (DRVrtv ). DRVcobi shows similar virological efficacy as DRVrtv when combined with two nucleos(t)ide analogue reverse-transcriptase inhibitors, but it is unknown whether a lower DRV Ctrough would undermine the effectiveness of DRVcobi when given as monotherapy (mtDRVcobi ).

METHODS:

Prospective observational study on virologically suppressed HIV-infected subjects who switched to mtDRVcobi . Virological failure was defined as two consecutive HIV-RNA >200 copies/mL. Efficacy was evaluated by intention-to-treat (ITT) and on-treatment (OT) analyses, and compared with data from a previous cohort of subjects on mtDRVrtv conducted at our centre. Plasma DRV Ctrough was measured using LC-MS/MS.

RESULTS:

A total of 234 subjects were enrolled. At week 96, the efficacy rates were 67.8% (CI95 , 61.8 to 73.7) by ITT and 86.9% (CI95 , 78.0 to 87.7) by OT analyses. The corresponding rates in our historical DRVrtv controls were 67.6% (CI95 , 60.0 to 75.2) and 83.6% (CI95 : 77.2 to 90.0). A total of 135 DRV determinations were performed in 83 subjects throughout the follow-up period, with a median plasma DRV Ctrough of 1305 ng/mL (range, 150 to 5895) compared with 1710 ng/mL (range, 200 to 3838) in subjects on monotherapy with DRVrtv (p = 0.05).

CONCLUSIONS:

DRV Ctrough was lower in HIV-infected subjects receiving DRVcobi than with DRVrtv . However, this did not appear to influence the efficacy of DRVcobi , when administered as monotherapy.

This trial evaluates options for second‐line antiretroviral therapy in patients failing on a non‐nucleoside reverse transcriptase inhibitor (NNRTI) and tenofovir (TDF)‐based first‐line regimen in the setting of the public health approach in sub‐Saharan Africa (with assumed substantial nucleoside reverse transcriptase inhibitor (NRTI) cross‐resistance). The trial tests two hypotheses. Firstly that a regimen of dolutegravir (DTG) with two NRTIs is non‐inferior to a regimen of ritonavir‐boosted darunavir (DRV/r) with two NRTIs. Secondly that continuing an NRTI regimen of TDF and lamivudine (3TC) is non‐inferior to switching to zidovudine (ZDV) and 3TC. The trial is a parallel group, open‐label, multi‐centre, factorial (2X2) randomised, controlled trial. Patients will be randomised to either DTG or DRV/r with a second randomisation to ZDV and 3TC or TDF and 3TC. Treatment efficacy will be monitored by testing viral load (VL). Analyses will compare DRV/r with DTG; and ZDV/3TC with TDF/3TC by intention to treat analysis on the primary outcome parameter of plasma VL below 400 copies/ml at 48 weeks. Trial follow‐up will continue to 96 weeks.

BACKGROUND:

This study aimed to evaluate whether low darunavir (DRV) minimum plasma concentration (Cmin) values contribute to virological outcomes during DRV/ritonavir monotherapy (mtDRV/rtv).

METHODS:

This was a prospective observational single-arm 96-week efficacy study in virologically suppressed subjects on triple therapy switched to mtDRV/rtv (800/100 mg every 24 h). Previous virological failures (VF) on protease-inhibitor-based regimens were allowed if the historical resistance tests showed no major resistance mutation to DRV/rtv. VF was defined as two consecutive HIV RNA measurements of >200 copies/ml. Efficacy was analysed by per-protocol and by intention-to-treat analyses. Plasma DRV Cmin values were measured by LC-MS/MS.

RESULTS:

A total of 150 subjects were included. At week 96, the efficacy rate on treatment was 83.6% (95% CI 77.2%, 90.0%) by per-protocol analysis and 67.6% (95% CI 60.0%, 75.2%) by intention-to-treat. In the whole cohort the median (IQR) DRV Cmin was significantly higher during the periods of undetectable than of detectable viraemia (1.82 µg/ml [1.47-2.46] versus 1.56 µg/ml [0.93-2.32]; P=0.006) as well as in the subjects with blips and VF. However, a cutoff point sufficiently sensitive and specific could not be found.

CONCLUSIONS:

The DRV Cmin values are related to viral control during mtDRV/rtv, but therapeutic drug monitoring cannot be recommended routinely as a precise cutoff point is unknown. Adherence is a key success factor on this regimen.

OBJECTIVES:

Darunavir/ritonavir (DRV/r) in mono or dual therapy has proven efficacy in selected patients. The aim of this study was to evaluate the efficacy of switching from DRV/r to DRV/cobicistat (DRV/c) in patients under mono or dual therapy.

METHODS:

This was a prospective multicenter cohort study of patients using DRV/r under mono or dual therapy plus lamivudine who changed to DRV/c maintaining the previous regimen. All patients had a controlled HIV viral load (<50 copies/ml) when switched and were examined every 12 weeks. The primary end-point was the percentage of participants without virological failure (VF) at week 48 in the intent-to-treat analysis. The CD4 cell count and concentrations of cholesterol, triglyceride, and creatinine were measured from baseline to week 48.

RESULTS:

A total of 162 patients were included: 68.5% were men, and their mean age was 46 ± 12 years. Seventy (43.2%) patients were treated with DRV/r monotherapy, and 92 (56.8%) were treated with DRV/r plus lamivudine. The efficacy at week 48 was 95.1% (95% CI.: 90.6%-97.5%) in the intent-to-treat analysis and 98.7% (95.5-99.6%) in the on-treatment analysis. Two VFs were documented but without development of resistance mutations. No significant changes were found in the lipid profile. Creatinine concentration increased significantly by 0.07 mg/dl (0.04-0.10, P < 0.001).

CONCLUSIONS:

Switching from DRV/r to DRV/c in patients under mono or dual therapy is safe and effective.

Darunavir is an oral nonpeptidic HIV-1 protease inhibitor (PI) that is used, together with a low boosting dose of ritonavir, as part of an antiretroviral therapy (ART) regimen in treatment-experienced and -naive patients with HIV-1 infection. Compared with early-generation PIs, boosted darunavir has a high genetic barrier to resistance and is active against multidrug-resistant HIV isolates. In clinical trials in treatment-experienced patients with HIV-1 infection receiving an optimized background regimen (OBR), twice-daily boosted darunavir was more effective than investigator-selected ritonavir-boosted control PIs (CPIs) or ritonavir-boosted lopinavir. In clinical trials in treatment-naive patients with HIV-1 infection receiving a fixed background regimen, once-daily boosted darunavir was noninferior to boosted lopinavir at 48 weeks and more effective than boosted lopinavir at 96weeks. Boosted darunavir was generally well tolerated in patients with HIV-1 infection in clinical trials. It was associated with a lower incidence of diarrhoea than CPIs or lopinavir in treatment-experienced or -naive patients, and fewer lipid abnormalities than lopinavir in treatment-naive patients. Thus, for the management of treatment-experienced or -naive patients with HIV-1 infection, a ritonavir-boosted darunavir-based ART regimen is a valuable treatment option.

PHARMACOLOGICAL PROPERTIES:

Darunavir is an oral nonpeptidic HIV-1 PI that selectively inhibits the cleavage of HIV gag and gag-pol polyproteins, thereby preventing viral maturation. Darunavir is highly potent against laboratory strains and clinical isolates of wild-type and multidrug-resistant HIV and has limited cytotoxicity. In an in vitro study in MT-2 cells, the potency of darunavir was greater than that of saquinavir, amprenavir, nelfinavir, indinavir, lopinavir and ritonavir. Darunavir binds with high affinity to HIV-1 protease, including multidrug-resistant proteases, and retains potency against multidrug-resistant HIV-1 strains. Although some potential may exist for cross-resistance with amprenavir, darunavir did not display cross-resistance with other PIs in vitro. In a 24-week analysis of pooled data from the POWER 1 and 2 studies in treatment-experienced patients, 11 protease mutations associated with a reduced response to boosted darunavir were identified (V11I, V32I, L33F, I47V, I50V, I54L/M, G73S, L76V, I84V and L89V). The presence of at least three darunavir resistance-associated mutations (prevalent in approximately 7-9% of treatment-experienced patients) together with a high number of protease resistance-associated mutations were required to confer darunavir resistance. In the 48-week analysis of treatment-experienced patients with virological failure in the the TITAN study, fewer in the boosted darunavir group than in the boosted lopinavir group developed additional mutations or lost susceptibility to PIs compared with baseline. In treatment-naive patients, no primary PI-resistance-associated mutations developed in patients with an available genotype at baseline and endpoint during 96 weeks of treatment with boosted darunavir or boosted lopinavir. Oral darunavir, boosted with low-dose ritonavir, is rapidly absorbed, generally reaching peak plasma concentrations within 2.5-4 hours. The bioavailability of oral darunavir is increased by about 30% when taken with food. Darunavir is primarily metabolized by the hepatic cytochrome P450 (CYP) enzymes, primarily CYP3A. The 'boosting' dose of ritonavir acts an an inhibitor of CYP3A, thereby increasing darunavir bioavailability. Drug interactions can result when darunavir is coadministered with other drugs that are inducers or inhibitors of, or act as substrates for, CYP3A. The mean elimination half-life of boosted darunavir is approximately 15 hours.

THERAPEUTIC EFFICACY:

In treatment-experienced patients with HIV-1 infection, the therapeutic efficacy of oral twice-daily darunavir 600 mg, boosted with ritonavir 100 mg, versus that of investigator selected boosted CPIs (POWER studies) or versus twice-daily boosted lopinavir (administered as a fixed dose combination of lopinavir/ritonavir 400/100 mg) [TITAN study] has been evaluated in phase IIb and III studies. All patients received concurrent treatment with an OBR. Significantly more patients receiving boosted darunavir achieved a viral load reduction from baseline of >or=1 log(10) copies/mL (primary endpoint) than boosted CPI recipients at all timepoints, up to and including the final efficacy analysis at 144 weeks, in the combined analyses of POWER 1 and 2. The efficacy of boosted darunavir was noninferior to that of boosted lopinavir at 48 weeks, and was significantly better than boosted lopinavir at 48 and 96 weeks in the TITAN study, as determined by significantly more patients in the darunavir group than in the lopinavir group achieving a viral load of <400 copies/mL (primary endpoint). In the ARTEMIS study in treatment-naive patients with HIV-1 infection receiving a fixed background regimen of tenofovir and emtricitabine, once-daily boosted darunavir 800 mg was noninferior to boosted lopinavir 800 mg/day at 48 weeks. At 96 weeks, boosted darunavir was found to be more effective than boosted lopinavir, as determined by significantly more patients in the darunavir group than in the lopinavir group achieving a confirmed plasma viral load of <50 copies/mL (primary endpoint).

TOLERABILITY:

Boosted darunavir was generally well tolerated in patients with HIV-1 infection in clinical trials, with most events being mild to moderate in severity. At 48-week analyses, the most common adverse events associated with once- or twice-daily boosted darunavir in treatment-experienced or -naive patients were diarrhoea, nausea, headache, upper respiratory tract infection and nasopharyngitis. The most common boosted darunavir-related grade 2-4 laboratory abnormalities in treatment-experienced patients included increased triglycerides and increased total cholesterol. Overall, boosted darunavir was associated with less diarrhoea than CPIs or boosted lopinavir in treatment-experienced and -naive patients, and a lower incidence of grade 2-4 elevations in triglycerides and total cholesterol than boosted lopinavir in treatment-naive patients. Treatment discontinuation because of adverse events occurred in 3% of boosted darunavir recipients and 7% of boosted lopinavir recipients during 48 weeks of therapy in treatment-naive patients.

PHARMACOECONOMIC CONSIDERATIONS:

Healthcare costs in the UK and US were estimated to be lower with boosted darunavir than with investigator-selected CPIs in treatment-experienced patients with HIV-1 infection in two 1-year cost analyses conducted from the perspective of a healthcare provider and using predicted costs based on CD4+ cell counts and clinical data from the POWER studies. The higher acquisition cost of boosted darunavir compared with CPIs was more than offset by the better efficacy of darunavir. In modelled cost-effectiveness analyses, boosted darunavir was predicted to be cost effective compared with other boosted CPIs in heavily pretreated adults from a healthcare payer perspective in Europe and from a societal perspective in the US. In a further model of a subgroup of patients with at least one primary International AIDS Society-USA PI mutation, boosted darunavir was predicted to be cost effective compared with boosted lopinavir from a healthcare payer perspective in Europe. The incremental costs per quality-adjusted life-year gained were within commonly accepted thresholds in all cost-effectiveness analyses.

The purpose of this study is to compare the safety and efficacy of a combination of a QD regimen consisting on ritonavir boosted darunavir (FDC) and lamivudine versus ritonavir boosted darunavir (FDC) plus co-formulated tenofovir and emtricitabine or co-formulated tenofovir/lamivudine in naïve HIV-1 infected patients. Subjects will be ARV-naïve HIV-1-infected patients eligible to start ARV therapy according to current guidelines.Subjects will be adults ≥ 18 years of age who meet all of the inclusion criteria and none of the exclusion criteria.

Retrospective cohort of virologically suppressed HIV-infected patients who received the combination of Raltegravir plus Darunavir boosted with cobicistat or ritonavir, as dual therapy, because or toxicity or intolerance to nucleoside analogues

This is a phase I, open-label, controlled drug interaction study to determine the effects of darunavir plus ritonavir on the pharmacokinetics of the hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, rosuvastatin, in HIV-1-seronegative subjects.