Monotherapy with Lopinavir/Ritonavir as maintenance after HIV-1 viral suppression: results of a 96-week randomized, controlled, open-label, pilot trial (KalMo study)

Genital Human Immunodeficiency Virus-1 RNA and DNA Shedding in Virologically Suppressed Individuals Switching From Triple- to Dual- or Monotherapy: Pooled Results From 2 Randomized, Controlled Trials

BACKGROUND

Increasingly, people living with human immunodeficiency virus (HIV) benefit from lower drug regimens (LDRs). Exploring viral genital shedding during LDRs is crucial to ensure their safety.

METHODS

We pooled genital sub-studies from 2 clinical trials in this area. Patients were randomized 1:1 to continue abacavir/lamivudine/dolutegravir or switch to dolutegravir (MONCAY trial), or to continue tenofovir/emtricitabine + a third agent or switch to tenofovir/emtricitabine (TRULIGHT trial). Participants whose plasma HIV-RNA remained <50 copies/mL had sperm or cervicovaginal lavage collected between Weeks 24 and 48. HIV-RNA and HIV-DNA were amplified by ultrasensitive polymerase chain reaction. The main objective was to measure the proportion of participants who had no detectable HIV in genital fluids, both according to each strategy and then in an aggregated analysis (LDR versus triple therapies).

RESULTS

There were 64 participants (35 males, 29 females) included: 16 received dual therapies and 16 received triple therapies in TRULIGHT; and 16 received monotherapies and 16 received triple therapies in MONCAY. In TRULIGHT, 13/15 (87%) of evaluable participants on dual therapy had no detectable HIV in their genital fluid, versus 14/15 (93%) under triple therapy (P = 1.0). In MONCAY, these figures were 12/15 (80%) on monotherapy versus 13/16 (81%) on triple therapy (P = 1.0). In the pooled analysis, a similar proportion of participants in the LDR and triple therapy groups had no detectable HIV: 25/30 (83%) and 27/31 (87%), respectively (P = .73).

CONCLUSIONS

There was no evidence of increased HIV-RNA and/or -DNA shedding in the genital fluids of people who maintained undetectable plasma HIV-RNA during LDRs.

CLINICAL TRIALS REGISTRATION

NCT02302547 and NCT02596334.

HIV Viral Dynamics of Lopinavir/Ritonavir Monotherapy as Second-Line Treatment: A Prospective, Single-Arm Trial

Background:

Characterizing viral response to lopinavir/ritonavir (LPV/r) monotherapy as second-line treatment may guide recommendations for resource-limited settings (RLS).

Methods:

We conducted a 48-week prospective, single-arm study of LPV/r monotherapy in patients failing first-line therapy in Nigeria. The primary outcome was sustained HIV-1 viral load (VL) <400 copies/mL at 48 weeks.

Results:

Of 30 enrolled patients, 28 (93%) achieved viral suppression on LPV/r, while 29 (96%) experienced low-level viremia. At 48 weeks, 9 (30%) met the primary outcome of sustained viral suppression; 14 (47%) patients were suppressed on LPV/r in a snapshot analysis. Detectable VLs at 12 and 24 weeks were strongly associated with treatment failure at 48 weeks. New resistance mutations were not detected. The trial was stopped early due to treatment failure.

Conclusion:

In this study, the rate of virologic failure among patients on a second-line lopinavir monotherapy regimen was relatively high and predicted by early detectable viremia. However, no LPV/r-associated resistance mutations were detected despite fluctuating low-level viremia, demonstrating the high genetic barrier to resistance of the protease inhibitor class which could be useful in RLS.

High quality of life, treatment tolerability, safety and efficacy in HIV patients switching from triple therapy to lopinavir/ritonavir monotherapy: A randomized clinical trial

Trial design

The QoLKAMON study evaluated quality of life, efficacy and treatment safety in HIV patients receiving lopinavir/ritonavir in monotherapy (MT) versus continuing combined antiretroviral triple treatment with a boosted protease inhibitor (TT).

Methods

This was a 24-week, open-label, multicentre study in virologically-suppressed HIV-infected participants (N = 225) with a 2:1 randomization: 146 patients who switched to MT were compared with 79 patients who remained on a TT regimen. The primary endpoint was change in patient-reported outcomes in quality of life as measured by the MOS-HIV and EQ-5D questionnaires. Secondary endpoints included treatment adherence, patient satisfaction, incidence of adverse events and differences in plasma HIV-1 RNA viral load (VL) and CD4 cell counts.

Results

Baseline quality of life, measured with the MOS-HIV score, was very good (overall score of 83 ± 10.5 in the MT arm and 82.3 ± 11.3 in the TT arm) and suffered no change during the study in any of the arms (at week 24, 83.5 ± 12.2 in MT arm and 81.9 ± 12.7 in TT arm), without statistically significant differences when compared. In regards to adherence to therapy and patient satisfaction, some aspects (number of doses forgotten in the last week and satisfaction of treatment measured with the CESTA score, dimension 1) improved significantly with MT. There were also no differences in the incidence and severity of adverse events, even though 22.8% of those in the MT arm switched their treatment when they were included in the study. Moreover, there was also no significant difference between the immunological and virological evolution of MT and TT. In the MT arm, the VL was always undetectable in 83% of patients (vs 90.7% in the TT arm) and there were only 6.7% of virological failures with VL > 50 copies/mL (vs 2.3% in the TT arm), without resistance mutations and with resuppression of VL after switching back to TT.

Conclusions

In a new clinical trial, monotherapy as a treatment simplification strategy in HIV-1 infected patients with sustained viral suppression has demonstrated quality of life, safety and efficacy profiles comparable to those of conventional triple therapy regimens.

The Protease Inhibitor Monotherapy Versus Ongoing Triple Therapy (PIVOT) trial: a randomised controlled trial of a protease inhibitor monotherapy strategy for long-term management of human immunodeficiency virus infection

BACKGROUND

Standard-of-care antiretroviral therapy (ART) for human immunodeficiency virus (HIV) infection uses a combination of drugs, until now considered essential to minimise treatment failure and development of drug resistance. Protease inhibitors (PIs) are potent with a high genetic barrier to resistance and have the potential for use as monotherapy after viral load (VL) suppression achieved on combination therapy. However, longer-term resistance and toxicity risks are uncertain.

OBJECTIVE

To compare the effectiveness, toxicity profile and cost-effectiveness of PI monotherapy with those of standard-of-care triple therapy in a pragmatic long-term clinical trial.

DESIGN

Open-label, parallel-group, randomised controlled trial.

SETTING

Forty-three HIV clinical centres in the UK NHS.

PARTICIPANTS

HIV-positive adults taking standard combination ART with a suppressed VL for ≥ 6 months.

INTERVENTIONS

Patients were randomised to maintain ongoing triple therapy (OT) or switch to a strategy of physician-selected ritonavir-boosted PI monotherapy (PI-mono), with prompt return to combination therapy in the event of VL rebound.

MAIN OUTCOME MEASURES

The primary outcome was reduction of future drug options, defined as new intermediate-/high-level resistance to one or more drugs to which the patient's virus was considered to be sensitive at trial entry (non-inferiority comparison, 10% margin). Secondary outcomes included confirmed virological rebound, serious drug- or disease-related complications, total grade 3 or 4 adverse events (AEs), neurocognitive function change, cluster of differentiation 4 (CD4) cell count change, change in health-related quality of life, cardiovascular risk change, health-care costs and health economic analysis.

RESULTS

In total, 587 participants were randomised (77% male, 68% white) to OT (n = 291) or PI-mono (n = 296) and followed for a median of 44 months, of whom 2.7% withdrew/were lost to follow-up. One or more episodes of confirmed VL rebound were observed in eight patients (Kaplan-Meier estimate 3.2%) in the OT group and 95 patients (35.0%) in the PI-mono group [absolute risk difference 31.8%, 95% confidence interval (CI) 24.6% to 39.0%; p < 0.001]. PI-mono patients who changed to ART after VL rebound all resuppressed (median 3.5 weeks). The proportions with loss of a future drug option at 3 years were 0.7% in the OT group and 2.1% in the PI-mono group (difference 1.4%, (95% CI -0.4% to 3.4%); non-inferiority demonstrated). There were no significant differences in serious disease complications between groups or in the frequency of grade 3 or 4 clinical AEs (16.8% OT group vs. 22% PI-mono group; absolute risk difference 5.1%, 95% CI -1.3% to 11.5%; p = 0.12). Overall, the PI-mono strategy was shown to be cost-effective compared with OT under most scenarios explored. PI-mono was cost saving because of the large savings in ART drug costs while being no less effective in terms of quality-adjusted life-years in the within-trial analysis and only marginally less effective when extrapolated to lifetime outcomes.

CONCLUSIONS

PI monotherapy, with prompt reintroduction of combination therapy for VL rebound, was non-inferior to combination therapy in preserving future treatment options and is an acceptable and cost-effective alternative for long-term management of HIV infection.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN04857074.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 21. See the NIHR Journals Library website for further project information.

Virological efficacy of PI monotherapy for HIV-1 in clinical practice

BACKGROUND

Clinical trials of PI monotherapy indicate that most participants maintain viral suppression and emergent protease resistance is rare. However, outcomes among patients receiving PI monotherapy for clinical reasons, such as toxicity or adherence issues, are less well studied.

METHODS

An observational study of patients attending an HIV treatment centre in London, UK, who had received PI monotherapy between 2004 and 2013, was conducted using prospectively collected clinical data and genotypic resistance reports. Survival analysis techniques were used to examine the times to virological failure and treatment discontinuation.

RESULTS

Ninety-five patients had PI monotherapy treatment for a median duration of 126 weeks. Virological failure occurred during 64% of episodes and 8% of patients developed emergent protease mutations. We estimate failure occurs in half of episodes within 2 years following initiation. Where PI monotherapy was continued following virological failure, 68% of patients achieved viral re-suppression. Despite a high incidence of virological failure, many patients continued PI monotherapy and 79% of episodes were ongoing at the end of the study. The type of PI used, the presence of baseline protease mutations and the plasma HIV RNA at initiation did not have a significant impact on treatment outcomes.

CONCLUSIONS

There was a higher incidence of virological failure and emerging resistance in our UK clinical setting than described in PI monotherapy clinical trials and other European observational studies. Despite this, many patients continued PI monotherapy and regained viral suppression, indicating this strategy remains a viable option in certain individuals following careful clinical evaluation.

HIV-1 replication in central nervous system increases over time on only protease inhibitor therapy

There are concerns about central nervous system (CNS)-replication of HIV-1 in patients on boosted protease inhibitors. Purpose of this study was to compare HIV-1 viral loads (VLs) from patients treated with only boosted dual protease inhibitor (bdPI), versus combination antiretroviral therapy (cART group), containing two nucleoside analogue reverse transcriptase inhibitors (NRTI) and a third partner. All patients from a large German HIV-treatment cohort with available medication, clinical and demographic data, including results from simultaneous HIV-1 viral load (VL) assessments in cerebrospinal fluid (CSF) and blood plasma, were retrospectively evaluated as controlled cross-sectional study. CSF had been obtained from patients with variable neurological symptoms during 2005-2014. Statistical analysis comprised nonparametric tests, regression and correlation techniques accounting for undetectable quantifications. Statistical analysis comprised nonparametric tests, regression and correlation techniques accounting for undetectable quantifications. Overall, 155 patients were evaluable (bdPI: 24; cART: 131). At time of CSF-collection, both groups were comparable in age, gender, CD4-cell counts, or primary HIV-transmission risks, though bdPI patients were clinically more advanced. The proportion of patients with undetectable HIV-1 (<50 copies/ml) in CSF was lower for bdPI group (25 vs 49.6 %; p = 0.026), but similar in plasma (46 vs 41 %). Median CSF-VL was higher in bdPI group (600 vs 50 copies/ml; p = 0.027) and similar in plasma. Mean VL CSF/plasma ratio was 342.91 for bdPI- and 54.48 for cART patients (p < 0.001). Pearson's regression analysis revealed a trend for an elevated VL-ratio over time within bdPI group. HIV-1 replication was higher and more frequently detectable in CSF from bdPI patients, indicating a worse CNS penetration effectiveness of used boosted PI. Within bdPI group, measured CNS-viral replication was increasing over time, suggesting an over time impaired HIV-1 suppression in CSF.

Effect of Monotherapy with Darunavir/Ritonavir on Viral Load in Seminal Fluid, and Quality Parameters of Semen in HIV-1-Positive Patients

Patients with human immunodeficiency virus type 1 (HIV-1) who receive antiretroviral therapy (ART) often achieve increased survival and improved quality of life. In this respect, monotherapy with darunavir/ritonavir (mDRV/r) can be a useful treatment strategy. This prospective study analyses the effect of mDRV/r on sperm quality and viral load in a group of 28 patients who had previously been given conventional ART and who had recorded a viral load <20 copies/mL for at least six months. These patients were given mDRV/r at a dose of 800/100 mg for 48 weeks. At baseline (V0), CD4, CD8, FSH, LH and testosterone levels were measured, together with HIV-1 viral load in plasma and semen. In addition, seminal fluid quality was studied before mDRV/r treatment was prescribed. At week 48 (V1), HIV-1 viral load in plasma and semen and the quality of the seminal fluid were again measured. The results obtained indicate that at V0, 10% of the patients with ART had a positive viral load in seminal fluid (>20 copies/ml), and that at V1, after mDRV/r treatment, this figure had fallen to 3%. The quality of seminal fluid was close to normal in 57% of patients at V0 and in 62% at V1. We conclude that, similar to ART, mDRV/r maintains HIV-1 viral load in most patients, and that there is no worsening in seminal fluid quality.

Atazanavir/ritonavir monotherapy: 96 week efficacy, safety and bone mineral density from the MODAt randomized trial

OBJECTIVES

To report the 96 week results on efficacy, safety and bone mineral density (BMD) in subjects with HIV-1 that were virologically suppressed and treated with atazanavir/ritonavir monotherapy versus atazanavir/ritonavir triple therapy.

METHODS

MODAt is a prospective, multicentre, open-label, non-inferiority, randomized, 96 week trial (NCT01511809) comparing efficacy of atazanavir/ritonavir monotherapy versus atazanavir/ritonavir triple therapy. Treatment success was defined as no occurrence of confirmed viral rebound (two consecutive HIV-RNA >50 copies/mL) or discontinuation for any cause of the ongoing regimen.

RESULTS

The 96 week treatment success was 64% in the atazanavir/ritonavir monotherapy arm and 63% in the triple-therapy arm (difference 1.3%, 95% CI: -17.5 to 20.1). In the atazanavir/ritonavir monotherapy arm, no PI- or NRTI-associated resistance mutations were observed at virological failure and all patients re-suppressed after re-intensification. In the monotherapy arm, treatment failure was more frequent in patients coinfected with hepatitis C virus [64% versus 28% (difference 35.4%, 95% CI: 3.7-67.2)]. Drug-related adverse events leading to discontinuation were 3 (6%) in the atazanavir/ritonavir monotherapy arm and 11 (21.5%) in the triple-therapy arm (P = 0.041). The 96 week adjusted mean percentage change in total proximal femur (not at lumbar spine) BMD was +1.16% and -1.64% in the atazanavir/ritonavir monotherapy arm and the triple-therapy arm, respectively (P = 0.012).

CONCLUSIONS

The 96 week analyses suggested that long-term efficacy of atazanavir/ritonavir monotherapy was inferior as compared with atazanavir/ritonavir triple therapy, particularly when administered in subjects coinfected with hepatitis C virus. In the atazanavir/ritonavir monotherapy arm, reintroduction of nucleosides, as needed, was always effective with no new resistance mutation; monotherapy was also associated with a lower incidence of adverse events and improvement in femur BMD.

Efficacy of protease inhibitor monotherapy vs. triple therapy: meta-analysis of data from 2303 patients in 13 randomized trials

OBJECTIVES

The aim of this analysis was to review the evidence and update a meta-analysis evaluating the efficacy and safety results from randomized controlled trials of ritonavir-boosted protease inhibitor (PI/r) monotherapy.

METHODS

A PubMed/EMBASE search was conducted to find randomized trials of PI/r monotherapy vs. triple therapy in patients with HIV-1 RNA suppression at baseline (<50 HIV-1 RNA copies/mL). Rates of virological suppression were analysed using switch-equals-failure and intensification-included endpoints [intent-to-treat (ITT)]. The rate of treatment-emergent resistance mutations, neurocognitive function endpoints, and cerebrospinal fluid (CSF) HIV-1 RNA were also analysed by treatment arm.

RESULTS

There were 2303 patients from 13 different randomized clinical trials of darunavir/r monotherapy (n = 784: MONET, MONOI, Monarch and PROTEA), lopinavir/r monotherapy (n = 829: OK pilot, OK-04, KalMo, KALESOLO, KRETA, MOST and DREAM), atazanavir/r monotherapy (n = 103: MODAT), or all three (n = 587: PIVOT). HIV-1 RNA plasma suppression was lower in the PI/r monotherapy arm compared with the triple therapy arm in the switch-equals-failure analysis [difference -8.3%; 95% confidence interval (CI) -11.9 to -4.8%], but not when intensification was included (difference 0.5%; 95% CI -2.5 to 3.6%). Rates of resistance mutations were similar between arms, as was overall neurocognitive function.

CONCLUSIONS

PI/r monotherapy showed a higher risk of plasma HIV-1 RNA elevations. However, there was no increased risk of treatment-emergent drug resistance, neurocognitive endpoints did not differ, and HIV-1 RNA suppression rates after intensification were similar between PI/r monotherapy and triple therapy.

Protease inhibitor monotherapy is effective in controlling human immunodeficiency virus 1 shedding in the male genital tract

Cross-sectional study comparing seminal human immunodeficiency virus type 1 (HIV-1) shedding in patients receiving boosted protease inhibitor monotherapy (mtPI/rtv) (n = 66) versus triple therapy (TT) (n = 61). Seminal HIV-1 shedding rates in patients with undetectable plasma HIV-RNA were 16.0% on mtPI/rtv compared with 28.6% on TT (p 0.173). Aviraemic status and time on viral suppression were independently associated with lack of seminal HIV-1 shedding. During TT, non PI/rtv-based regimens were associated with a better control of HIV infection in semen despite similar time on viral suppression. The use of mtPI/rtv in well-controlled patients is not associated with increased seminal HIV excretion compared with TT.

Ritonavir-boosted lopinavir as maintenance monotherapy in HIV-infected patients who achieved viral suppression during a second-line protease inhibitor-based regimen: a pilot randomized trial (BIDI-MONO)

Eligibility criteria were (I) having previously failed first-line nonnucleoside reverse transcriptase inhibitor-based regimens and (2) having achieved virologic suppression >6 months while receiving a protease inhibitor (PI)-based regimen as second-line treatment. Eligible participants were randomized to receive either (I) ritonavir-boosted lopinavir (LPV/r) monotherapy (n = 29) or (2) LPV/r with optimized background regimens (OBRs; n = 31). Median duration of viral suppression before randomization was 45 months. At week 48, viral suppression during LPV/r monotherapy was 86.2% and did not differ from the suppression achieved with LPV/r with OBRs (87.1%, P = 1.000). However, persistent viremia during LPV/r monotherapy tended to be higher than during LPV/r with OBRs (10.3% versus 3.2%, P = .346). History of viral blip during virologic suppression with second-line PI-based regimen is a predictor of achieving viral suppression at all visits (adjusted relative risk 0.255 [95% confidence interval 0.080-0.821], P = .022). Use of LPV/r monotherapy as maintenance regimen in this study produced persistent viremia that tended to be higher than LPV/r monotherapy with OBRs.

Simplification to atazanavir/ritonavir monotherapy for HIV-1 treated individuals on virological suppression: 48-week efficacy and safety results

OBJECTIVES

The objective of this study was to assess the 48-week virological efficacy of atazanavir/ritonavir (ATV/r) monotherapy vs. ATV/r along with two nucleoside reverse transcriptase (NRTIs) in HIV-1 treated individuals with HIV-RNA less than 50 copies/ml.

METHODS

A multicentre, randomized, open-label, noninferiority trial. HIV-1 treated individuals on ATV/r 300/100 mg along with two NRTIs were randomized to receive ATV/r monotherapy or to maintain their antiretroviral regimen. The primary endpoint was the confirmed viral rebound (CVR: two consecutive HIV-RNA >50 copies/ml) or treatment discontinuation for any reason. Individuals who experienced CVR on ATV/r monotherapy reintroduced NRTIs and discontinued the study if HIV-RNA was more than 50 copies/ml after 12 weeks since reintensification.

RESULTS

One hundred and three patients enrolled. By week 48, 11 patients in ATV/r arm and two in ATV/r along with two NRTIs experienced CVR; four (8%) patients in ATV/r and eight (15%) in ATV/r along with two NRTIs discontinued. At the 48-week primary efficacy analysis (re-intensification = failure), treatment success was 73% in ATV/r arm and 85% in ATV/r along with two NRTIs [difference -12.1%, 95% confidence interval (95% CI) -27.8 to 2.1]. According to the analysis considering re-intensification is equal to success, treatment success was 92% in ATV/r arm and 85% in the ATV/r along with two NRTIs arm (difference 7.5%, 95% CI -4.7 to 19.8). At CVR, no mutation was observed in ATV/r arm and reintensification with NRTIs was effective in all individuals. Overall, Grade 3-4 (P = 0.003) and grade 3-4 drug-related (P = 0.027) adverse events were less frequent in ATV/r arm. A significant increase in total and low-density lipoprotein (LDL)-cholesterol was observed as well as a significant improvement in high-density lipoprotein (HDL)-cholesterol, fasting glucose, liver fibrosis and alkaline phosphatase was observed in ATV/r monotherapy in comparison with ATV/r along with two NRTIs.

CONCLUSION

ATV/r monotherapy treatment simplification showed lower virological efficacy in comparison with maintaining triple therapy; NRTIs reintroduction was effective in all the individuals.

Is there a higher risk of CNS adverse events for PI monotherapy versus triple therapy? A review of results from randomized clinical trials

BACKGROUND

Protease inhibitor (PI) monotherapy for treatment could avoid the adverse events, drug resistance, and additional costs associated with other antiretrovirals that are normally used, particularly the nucleoside analogues. PI monotherapy has mainly been compared with standard triple therapy in randomized clinical trials of patients who have HIV RNA suppression at screening and no history of virological failure.

METHODS

This review included 11 randomized clinical trials of darunavir/ritonavir (DRV/r) or lopinavir/ritonavir (LPV/r) monotherapy versus triple therapy in 1,267 patients with HIV RNA suppression at baseline who were studied between 48 and 144 weeks.

RESULTS

There was no clear difference in the risk of central nervous system (CNS) adverse events between PI monotherapy (either DRV/r or LPV/r) and standard triple drug treatment. There were 2 clinical trials - MONOI (DRV/r) and MOST (LPV/r) - that showed CNS symptoms and detectable HIV RNA levels in the cerebrospinal fluid in a small number of individuals taking PI monotherapy.

CONCLUSIONS

There was no consistent evidence from the randomized trials currently available for an additional risk of HIV CNS disease during monotherapy with either LPV/r or DRV/r versus standard triple drug therapy. However, the information on CNS adverse events has not been reported using standardized definitions in the studies. In addition, few randomized studies included detailed analysis of neurocognitive function or detection of HIV RNA in the cerebrospinal fluid.

Immune activation throughout a boosted darunavir monotherapy simplification strategy

Our aim was to assess the evolution and the impact that blips, intermittent low-level viraemia and virological failure (VF) episodes have on patients' immune activation (IA) profiles during ritonavir-boosted darunavir monotherapy (mtDRV/rtv). A prospective cohort of human immunodeficiency virus-1-infected patients who switched to mtDRV/rtv was followed for 2 years. Cellular IA was assessed according to HLA-DR and CD38 expression in CD4(+) and CD8(+) T-cells and their naïve, effector memory and central memory subpopulations, and systemic IA was evaluated according to sCD14 and D-dimer levels. Seventy-five patients from the MonDAR cohort were selected for this substudy, and classified according to viral outcome as having continuous undetectable viraemia (n = 19), blips (n = 19), intermittent viraemia (n = 21), and VF (n = 16). The IA profile was closely linked to viral behaviour. Patients on viral suppression for 24 months showed a significant decrease in CD4(+) and CD8(+) T-cell activation and sCD14 and D-dimer levels. Patients with transient low-level viraemia episodes (blips and intermittent viraemia) showed cellular and systemic IA similar to baseline values. In contrast, significant increases in T-cell activation and sCD14 and D-dimer levels were observed in patients with VF. Baseline levels of HLA-DR(+)CD38(+)CD8(+) T-cells of >6.4% were independently associated with the emergence of VF. Therefore, mtDRV/rtv might be considered as a safe simplification strategy, on the basis of the IA results, whenever viral replication is under medium-term and long-term control. Transient low-level viraemia episodes do not affect patients' IA status. Moreover, HLA-DR(+)CD38(+)CD8(+) T-cell baseline levels should be considered when patients are switched to mtDRV/rtv.

Cellular HIV reservoir replenishment is not affected by blip or intermittent viremia episodes during darunavir/ritonavir monotherapy

OBJECTIVE

To assess the impact of blips and persistent viremia episodes on cell-associated HIV-DNA reservoir in extensively pretreated patients receiving ritonavir-boosted darunavir monotherapy (MtDRV/rtv) for 24 months.

DESIGN AND METHODS

Patients from the MonDAR prospective study (NCT01606722) who received at least 6 months of MtDRV/rtv and had at least two available peripheral blood mononuclear cells (PBMCs) samples were selected and classified according to the viral outcome as continuous undetectable viremia (cUV; n = 40), blips (n = 31), intermittent viremia (IV; n = 23), and virological failure (VF, two consecutive viral loads >200 copies/ml; n = 20). Proviral HIV-DNA was quantified by real-time PCR in PBMCs samples at baseline, and months 6, 12, 18 and 24. Additionally, HIV-DNA levels were exhaustively analyzed at virological failure and blip episodes.

RESULTS

The HIV-DNA levels remained constant during the 24 months in every group. Neither blips nor intermittent viremia influenced the HIV-DNA levels at short-term or at middle term. By contrast, virological failure episodes gave rise to a significant increase in proviral DNA (2.15 vs. 2.32 log10 HIV-DNA copies/10 PBMCs; P = 0.042). Basal proviral DNA levels more than 2 log10 copies/10 PBMCs predicted the time to viral rebound at any given cut-off point (>20, >50, and >200 copies/ml. HR: 3.02, 2.61, and 3.02, respectively; P ≤ 0.03. Besides, an adherence less than 95% was also strongly associated with virological failure (HR, 3.17; P = 0.021).

CONCLUSION

Blip episodes and intermittent viremia did not affect the cellular HIV reservoir dynamic during MtDRV/rtv. Higher adherence and an HIV-DNA levels less than 2 log10 copies/10 PBMCs at baseline were associated with a lower risk of virological failure.

[Consensus Statement by GeSIDA/National AIDS Plan Secretariat on antiretroviral treatment in adults infected by the human immunodeficiency virus (Updated January 2013)]

OBJECTIVE

This consensus document is an update of combined antiretroviral therapy (cART) guidelines for HIV-1 infected adult patients.

METHODS

To formulate these recommendations a panel composed of members of the GeSIDA/National AIDS Plan Secretariat (Grupo de Estudio de Sida and the Secretaría del Plan Nacional sobre el Sida) reviewed the efficacy and safety advances in clinical trials, cohort and pharmacokinetic studies published in medical journals (PubMed and Embase) or presented in medical scientific meetings. The strength of the recommendations and the evidence which support them are based on a modification of the criteria of Infectious Diseases Society of America.

RESULTS

cART is recommended in patients with symptoms of HIV infection, in pregnant women, in serodiscordant couples with high risk of transmission, in hepatitisB co-infection requiring treatment, and in HIV nephropathy. cART is recommended in asymptomatic patients if CD4 is <500cells/μl. If CD4 are >500cells/μl cART should be considered in the case of chronic hepatitisC, cirrhosis, high cardiovascular risk, plasma viral load >100.000 copies/ml, proportion of CD4 cells <14%, neurocognitive deficits, and in people aged >55years. The objective of cART is to achieve an undetectable viral load. The first cART should include 2 reverse transcriptase inhibitors (RTI) nucleoside analogs and a third drug (a non-analog RTI, a ritonavir boosted protease inhibitor, or an integrase inhibitor). The panel has consensually selected some drug combinations, for the first cART and specific criteria for cART in acute HIV infection, in tuberculosis and other HIV related opportunistic infections, for the women and in pregnancy, in hepatitisB or C co-infection, in HIV-2 infection, and in post-exposure prophylaxis.

CONCLUSIONS

These new guidelines update previous recommendations related to first cART (when to begin and what drugs should be used), how to monitor, and what to do in case of viral failure or adverse drug reactions. cART specific criteria in comorbid patients and special situations are similarly updated.

Lopinavir plasma concentrations and virological outcome with lopinavir-ritonavir monotherapy in HIV-1-infected patients

There is significant intra- and intersubject variability in lopinavir (LPV) plasma concentrations after standard dosing; thus, this prospective study was conducted to determine whether low plasma LPV concentrations could be associated with virological outcome throughout lopinavir-ritonavir maintenance monotherapy (mtLPVr) in the clinical practice setting. If this hypothesis would be confirmed, LPV drug monitoring could improve the efficacy of mtLPVr regimens. Patients with previous virological failure (VF) on protease inhibitor-based regimens were also included if the genotypic resistance tests showed no major resistance mutation associated with reduced susceptibility to lopinavir-ritonavir. VF was defined as 2 consecutive determinations of HIV RNA levels of >200 copies/ml. Efficacy was analyzed by per-protocol analysis. Plasma LPV trough concentrations were measured by high-performance liquid chromatography using a UV detector. A total of 127 patients were included (22% with previous failure on protease inhibitors). After 96 weeks, the efficacy rate was 82.3% (95% confidence interval [CI(95)], 75.3 to 89.3%). Virological efficacy was independent of LPV plasma concentrations even when LPVr was given once daily. An adherence of <90% (HR, 4.4 [CI(95), 1.78 to 10.8; P = 0.001]) and the presence of blips in the preceding 12 months (HR, 3.06 [CI(95), 1.17 to 8.01; P = 0.022]) were the only variables independently associated with time to VF. These findings suggest that the LPV concentrations achieved with the standard doses of LPVr are sufficient to maintain virological control during monotherapy and that measurement of LPV concentrations is not useful for predicting virological outcome. Tight control of viral replication in the previous months and strict adherence throughout the mtLPVr regimen could improve the virological efficacy of this maintenance regimen.

Boosted protease inhibitor monotherapy in HIV-infected adults: outputs from a pan-European expert panel meeting

While the introduction of combination highly active antiretroviral therapy (HAART) regimens represents an important advance in the management of human immunodeficiency virus (HIV)-infected patients, tolerability can be an issue and the use of several different agents may produce problems. The switch of combination HAART to ritonavir-boosted protease inhibitor (PI) monotherapy may offer the opportunity to maintain antiviral efficacy while reducing treatment complexity and the risks of toxicity. Current European AIDS Clinical Society (EACS) guidelines recognise ritonavir-boosted PI monotherapy with twice-daily lopinavir/ritonavir or once-daily darunavir/ritonavir as a possible option in patients who have intolerance to nucleoside reverse transcriptase inhibitors, or for treatment simplification. Clinical trials data for PI boosted monotherapy are encouraging, showing substantial efficacy in the majority of patients; however, further data are required before this approach can be recommended as a routine treatment. Available data indicate that the most suitable candidates for the use of boosted PI monotherapy are long-term virologically suppressed patients who have demonstrated good adherence to antiretroviral therapy, who do not have chronic hepatitis B, have no history of treatment failure on PIs and are able to tolerate low-dose ritonavir.

Boosted protease inhibitor monotherapy as a maintenance strategy: an observational study

OBJECTIVES

We aimed to determine the effectiveness of boosted protease inhibitor monotherapy (BPIMT) initiated as a maintenance strategy in routine care and identify predictive factors of failure.

DESIGN

Observational study in the FHDH-ANRS CO4 cohort.

METHODS

Five hundred and twenty-nine virologically suppressed individuals switched to BPIMT in the period 2006-2010, 75% had at least 12 and 49% at least 24 months of follow-up. Virological failure (two consecutive HIV-RNA > 50 copies/ml or one HIV-RNA > 50 copies/ml followed by BPIMT discontinuation) and treatment failure (virological failure, antiretroviral reintensification or death) were analysed separately.

RESULTS

At baseline, 11% were protease inhibitor-naive, median duration on combined antiretroviral therapy was 84 months and median duration of suppressed viremia was 38 months. Nine percent had a history of virological failure, while on a protease inhibitor-containing regimen, and rates of virological failure were higher among those individuals [adjusted hazard ratio, 1.6; 95% confidence interval (CI), 0.9-2.9]. Compared to individuals with less than 1 year of sustained virological suppression before the switch to BPIMT, those with longer duration were less likely to experience virological failure [hazard ratio, 0.7; (95% CI, 0.4-1.2) and 0.6 (95%CI, 0.4-0.9)] for a duration of 12-23 months and 24 months or more, respectively. Rates of failure were similar for BPIMT with lopinavir-ritonavir (RTV) or darunavir-RTV, but increased for BPIMT with atazanavir-RTV. Same risk factors were associated with treatment failure.

CONCLUSION

The safety and efficacy of a maintenance strategy with BPIMT in a routine care setting matched the results of randomized clinical trials. A longer duration since last virological rebound before switching to BPIMT was associated with a decreased risk of subsequent failure.

[Consensus document of Gesida and Spanish Secretariat for the National Plan on AIDS (SPNS) regarding combined antiretroviral treatment in adults infected by the human immunodeficiency virus (January 2012)]

This consensus document has been prepared by a panel consisting of members of the AIDS Study Group (Gesida) and the Spanish Secretariat for the National Plan on AIDS (SPNS) after reviewing the efficacy and safety results of clinical trials, cohort and pharmacokinetic studies published in medical journals, or presented in medical scientific meetings. Gesida has prepared an objective and structured method to prioritise combined antiretroviral treatment (cART) in naïve patients. Recommendations strength (A, B, C) and the evidence which supports them (I, II, III) are based on a modification of the Infectious Diseases Society of America criteria. The current antiretroviral treatment (ART) of choice for chronic HIV infection is the combination of three drugs. ART is recommended in patients with symptomatic HIV infection, in pregnancy, in serodiscordant couples with high transmission risk, hepatitis B fulfilling treatment criteria, and HIV nephropathy. Guidelines on ART treatment in patients with concurrent diagnosis of HIV infection and an opportunistic type C infection are included. In asymptomatic patients ART is recommended on the basis of CD4 lymphocyte counts, plasma viral load and patient co-morbidities, as follows: 1) therapy should be started in patients with CD4 counts <350 cells/μL; 2) when CD4 counts are between 350 and 500 cells/μL, therapy will be recommended and only delayed if patient is reluctant to take it, the CD4 are stabilised, and the plasma viral load is low; 3) therapy could be deferred when CD4 counts are above 500 cells/μL, but should be considered in cases of cirrhosis, chronic hepatitis C, high cardiovascular risk, plasma viral load >10(5) copies/mL, proportion of CD4 cells <14%, and in people aged >55 years. ART should include 2 reverse transcriptase inhibitors nucleoside analogues and a third drug (non-analogue reverse transcriptase inhibitor, ritonavir boosted protease inhibitor or integrase inhibitor). The panel has consensually selected and given priority to using the Gesida score for some drug combinations, some of them co-formulated. The objective of ART is to achieve an undetectable viral load. Adherence to therapy plays an essential role in maintaining antiviral response. Therapeutic options are limited after ART failures, but an undetectable viral load may be possible nowadays. Adverse events are a fading problem of ART. Guidelines in acute HIV infection, in women, in pregnancy, and to prevent mother-to-child transmission and pre- and post-exposition prophylaxis are commented upon. Management of hepatitis B or C co-infection, other co-morbidities, and the characteristics of ART in HIV-2 infection are included.

Long-term treatment outcomes of ritonavir-boosted lopinavir monotherapy among HIV-infected patients who experienced NRTI and NNRTI failure

Background

We continue the previously described prospective cohort study of ritonovir-boosted lopinavir (LPV/r) monotherapy for second-line therapy in HIV-infected patients with prior failure and extensive resistance to nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs), with the objective being to determine the three-year treatment responses.

Findings

There were 40 patients with a mean ± SD age of 37 ± 8 years. Median (IQR) baseline CD4 was 123 (37-245) cells/mm³ and median (IQR) HIV-1 RNA was 55,800 (9,670-100,000) copies/mL. All patients received twice daily LPV/r 400/100 mg and recycled lamivudine 150 mg. By intend-to-treat analysis at 144 weeks, 26 (65%) and 22 (56%) patients achieved HIV-1 RNA at < 400 and < 50 copies/mL, respectively. In as-treated analysis, the corresponding rates were 26 of 28 (93%) and 22 of 28 (78%), respectively. Low-level viral rebound (HIV-1 RNA 50-400 copies/mL) was found in 6 (15%), 6 (15%), and 4 (10%) patients at week 48, 96 and week 144, respectively. Medians CD4 at week 48, 96, and 144 were 351, 481, and 584 cells/mm³ and significantly changed from baseline (all, P < 0.05). There were increments of mean triglycerides at 48 weeks and 144 weeks from baseline (P < 0.05). No major protease resistance-associated mutations emerged after virologic failure.

Conclusion

LPV/r monotherapy with recycled lamivudine can maintain long-term virologic suppression in a relatively small proportion of patients failing NNRTI-based regimen and having limit option for active NRTI. More antiretroviral classes are needed be accessible in resource-limited countries.

Single genome sequencing of HIV-1 gag and protease resistance mutations at virologic failure during the OK04 trial of simplified versus standard maintenance therapy

BACKGROUND

Ritonavir-boosted lopinavir (LPV/RTV) alone has been evaluated as simplified maintenance therapy for HIV-1 infection, but there are concerns about greater potential for emergence of protease inhibitor (PI) resistance. The OK04 trial evaluated maintenance therapy with LPV/RTV alone versus standard therapy (ST) with two NRTIs plus LPV/RTV in 205 patients, of whom 15 had virological rebound by week 48 (11 versus 4 patients, respectively). We developed a single genome sequencing (SGS) assay of HIV-1 gag and protease to assess the emergence of low frequency drug-resistant variants during virological rebound.

METHODS

Plasma samples from 15 subjects at virological rebound were analysed by SGS of HIV-1 gag and protease genes. A total of 45 SGS sequences were planned per sample, providing 90% power to detect variants comprising >5% of the virus population.

RESULTS

Overall, 521 single sequences obtained from 13 patients (range 4-48 sequences/patient) revealed similar frequencies of major protease resistance mutations in samples from the LPV/RTV alone (3/11) and ST (3/4) arms (P=0.10), with a median number of minor protease resistance mutations of 3.0 versus 3.5, respectively (P=0.23). Median number of gag PI resistance mutations were similar between the LPV/RTV alone and ST arms at cleavage sites (3.0 versus 2.5; P=0.83), non-cleavage sites (21 versus 16.5; P=0.71) and the transframe protein-p6 pol region cleavage sites (4.0 versus 3.0; P=0.6).

CONCLUSIONS

Although more subjects with simplified maintenance therapy with LPV/RTV alone had virological rebound compared to the ST arm, this was not associated with more frequent emergence of variants encoding PI resistance mutations in gag or protease detected by SGS.

[New strategies in the optimisation of lopinavir/ritonavir doses in human immunodeficiency virus-infected patients]

Lopinavir/ritonavir (LPV/r) has demonstrated virological and immunological efficacy in the combined antiretroviral treatment (cART), in both naïve and experienced patients. Furthermore, LPV/r showed a high barrier to the development of resistance. Although generally well tolerated, adverse gastrointestinal side effects and metabolic disorders are frequent. The different tools used to optimise the cART with this drug combination in the daily clinical practice, emphasising the therapeutic drug monitoring (TDM) of LPV/r and the genetic analysis of the main enzymes responsible for the metabolism and transport, are reviewed. The relationship between phenotype and genotype, established through TDM, could be useful for the physician to improve the clinical management of the HIV infection, due to the possibility of individualising the dose with this drug. Monotherapy is also reviewed as a new strategy used in the simplification of the treatment with this drug, which could increase safety and reduce costs.

Simplification of antiretroviral therapy: a good choice for our patients and the sustainability of our health care system

OBJECTIVE

To describe the efficacy, safety, compliance and cost savings of lopinavir/ritonavir monotherapy.

METHOD

Observational, descriptive and retrospective study evaluating monotherapy. Adherence was calculated using an objective method. We estimated the direct costs of dispensing non-triple therapy.

RESULTS

We identified 17 patients. Interval adherence was > 95% in 9 patients, 90-95% in 2 patients, 90-85% in 2 patients, and less than 85% in 4 patients. Viral load was undetectable during weeks 12, 24, 36 and 48, except in 2 patients. The CD4 count in most analytical tests remained at > 350 cells/ml, only 1 patient had a lower figure. The average savings was 4819 Euros/patient/year (range 1116 to 8700).

CONCLUSIONS

In selected patients, monotherapy can be a cost-effective treatment option.

Pilot, randomized study assessing safety, tolerability and efficacy of simplified LPV/r maintenance therapy in HIV patients on the 1 PI-based regimen

OBJECTIVES

To compare the efficacy and safety of an individualized treatment-simplification strategy consisting of switching from a highly-active anti-retroviral treatment (HAART) with a ritonavir-boosted protease inhibitor (PI/r) and 2 nucleoside reverse-transcriptase inhibitors (NRTIs) to lopinavir/ritonavir (LPV/r) monotherapy, with intensification by 2 NRTIs if necessary, to that of continuing their HAART.

METHODS

This is a one-year, randomized, open-label, multi-center study in virologically-suppressed HIV-1-infected adults on their first PI/r-containing treatment, randomized to either LPV/r-monotherapy or continue their current treatment. Treatment efficacy was determined by plasma HIV-1 RNA viral load (VL), time-to-virologic rebound, patient-reported outcomes (PROs) and CD4+T-cell-count changes. Safety was assessed with the incidence of treatment-emergent adverse events (AE).

RESULTS

Forty-one patients were randomized to LPV/r and 39 to continue their HAART. No statistically-significant differences between the two study groups in demographics and baseline characteristics were observed. At day-360, 71(39:LPV/r;32:HAART) patients completed treatment, while 9(2:LPV/r;7:HAART) discontinued. In a Last Observation Carried Forward Intent-to-Treat analysis, 40(98%) patients on LPV/r and 37(95%) on HAART had VL<200 copies/mL (P = 0.61). Time-to-virologic rebound, changes in PROs, CD4+ T-cell-count and VL from baseline, also exhibited no statistically-significant between-group differences. Most frequent AEs were diarrhea (19%), headache (18%) and influenza (16%). Four (10%) patients on LPV/r were intensified with 2 NRTIs, all regaining virologic control. Eight serious AEs were reported by 5(2:LPV/r;3:HAART) patients.

CONCLUSION

At day-360, virologic efficacy and safety of LPV/r appears comparable to that of a PI+2NRTIs HAART. These results suggest that our individualized, simplified maintenance strategy with LPV/r-monotherapy and protocol-mandated NRTI re-introduction upon viral rebound, in virologically-suppressed patients merits further prospective long-term evaluation.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00159224.

Effectiveness of protease inhibitor monotherapy versus combination antiretroviral maintenance therapy: a meta-analysis

BACKGROUND

The unparalleled success of combination antiretroviral therapy (cART) is based on the combination of three drugs from two classes. There is insufficient evidence whether simplification to ritonavir boosted protease inhibitor (PI/r) monotherapy in virologically suppressed HIV-infected patients is effective and safe to reduce cART side effects and costs.

METHODS

We systematically searched Medline, Embase, the Cochrane Library, conference proceedings and trial registries to identify all randomised controlled trials comparing PI/r monotherapy to cART in suppressed patients. We calculated in an intention to treat (loss-of follow-up, discontinuation of assigned drugs equals failure) and per-protocol analysis (exclusion of protocol violators following randomisation) and based on three different definitions for virological failure pooled risk ratios for remaining virologically suppressed.

FINDINGS

We identified 10 trials comparing 3 different PIs with cART based on a PI/r plus 2 reverse transcriptase inhibitors in 1189 patients. With the most conservative approach (viral load <50 copies/ml on two consecutive measurements), the risk ratios for viral suppression at 48 weeks of PI/r monotherapy compared to cART were in the ITT analysis 0.94 8 (95% CI 0.89 to 1.00) p = 0.06; risk difference -0.06 (95%CI -0.11 to 0) p = 0.05, p for heterogeneity  = 0.08, I(2) = 43.1%) and in the PP analysis 0.93 ((95%CI 0.90 to 0.97) p<0.001; risk difference -0.07 (95%CI -0.10 to -0.03) p<0.001, p for heterogeneity  = 0.44, I(2) = 0%). Reintroduction of cART in 44 patients with virological failure led in 93% to de-novo viral suppression.

INTERPRETATION

Virologically well suppressed HIV-infected patients have a lower chance to maintain viral suppression when switching from cART to PI/r monotherapy. Failing patients achieve high rates of de-novo viral suppression following reintroduction of reverse transcriptase inhibitors.

HIV protease inhibitors: present and future

Antiretroviral therapy offers many options, largely based on the next-generation protease inhibitors (PIs). Early PI-based treatments involve high pill burdens and dosing schedules, and concerns of long-term toxicities are well established. In patients who have already achieved viral suppression, novel agents and strategies should be used to simplify the dosing treatment, reduce adverse events or preserve drug options. In experienced patients, drug escalation between PIs and different associations between classes allow virological suppression to be reached in the majority of patients. Therefore, there is a persistent clinical need for the discovery and development of new protease inhibitors. Several firms are trying to develop new types of PIs that will not be cross-resistant with existing drugs and will not require ritonavir boosting. This article aims to offer an overview on present drug options recommended for treatment in naive and experienced patients, new strategies currently undergoing clinical evaluation and new compounds in the pipeline.

Lopinavir: the old champion

Lopinavir/ritonavir approval for use in antiretroviral treatment 10 years ago was very important for the recognition of boosted protease inhibitor (PI)-based therapy as an attractive option for first-line therapy. Being coformulated with ritonavir and having less toxicity than former PIs it allowed for effective and durable virologic suppression with less impact on quality of life. It soon became the standard of care for salvage therapy in its class. Since then, however, its central role has been challenged by new PIs with a more favorable impact on lipid profile, better gastrointestinal tolerability or that are more active in the setting of multidrug resistance. This article summarizes the main clinical studies with lopinavir and discusses its particular characteristics as well as its possible current role in antiretroviral therapy.

Lopinavir/ritonavir monotherapy versus current treatment continuation for maintenance therapy of HIV-1 infection: the KALESOLO trial

OBJECTIVES

We evaluated a monotherapy maintenance regimen with lopinavir/ritonavir versus continuing current combined antiretroviral treatment (cART) in HIV patients with suppressed plasma HIV-1 RNA.

PATIENTS AND METHODS

This was an open-label, non-inferiority, multicentre trial in 23 sites in France. Adults were randomized if they had no history of virological failure while receiving a protease inhibitor, maintained HIV-1 RNA <50 copies/mL for at least 6 months and did not change cART during the last 3 months. The primary endpoint was the proportion of patients with HIV-1 RNA <50 copies/mL at Week 48 (non-inferiority margin set at -12%) with missing data and treatment modification considered as failure. The trial has been registered in ClinicalTrials.gov under the identifier NCT00140751.

RESULTS

At Week 48, 84% (73/87) of patients in the lopinavir/ritonavir monotherapy group met the primary endpoint compared with 88% (87/99) in the cART group [difference, -4.0%, lower limit of 90% two-sided confidence interval (CI) for difference, -12.4%]. In secondary analysis with success defined as plasma HIV-1 RNA <400 copies/mL, 87% (76/87) of patients in the lopinavir/ritonavir monotherapy group were virologically suppressed compared with 88% (87/99) in the cART group (difference, -0.5%, lower limit of 90% two-sided CI for difference, -8.5%). If antiretroviral treatment intensification was taken into account, 91% (79/87) of patients in the lopinavir/ritonavir monotherapy group met the primary endpoint compared with 88% (87/99) in the cART group (difference, +2.9%, lower limit of 90% two-sided CI for difference, -4.5%). Failures of lopinavir/ritonavir monotherapy did not show acquired resistance mutations in the protease gene.

CONCLUSIONS

Lopinavir/ritonavir monotherapy did not achieve non-inferiority versus cART for maintaining plasma HIV-1 RNA <50 copies/mL. Nevertheless, the incidence of virological failure was low (mostly with HIV-1 RNA <400 copies/mL) and easily managed by treatment intensification.

Antiretroviral drug concentrations in the male and female genital tract: implications for the sexual transmission of HIV

PURPOSE OF REVIEW

To summarize the recent literature (2008-2010) on antiretroviral (ARV) drug disposition into the male and female genital tract.

RECENT FINDINGS

Recent studies have confirmed that penetration of antiretroviral agents into the male and female genital tracts are both drug and sex specific. Concentrations achieved vary considerably depending on the class of drug studied, the sampling techniques used and the times samples are obtained.

SUMMARY

There appear to be several patterns of drug penetration into the male and female genital tract. In addition there appear to be different patterns of genital shedding under the influence of antiretroviral therapy. What effect these factors will have on the sexual transmission of HIV or the evolution and transmission of resistant HIV remains to be seen.