Ritonavir boosted indinavir treatment as a simplified maintenance "mono"-therapy for HIV infection

Late treatment failures in cerebrospinal fluid in patients on long-term maintenance ART with ritonavir-boosted protease PI monotherapy

BACKGROUND

Antiretroviral treatment (ART) with ritonavir-boosted protease inhibitor monotherapy (rb-PMT) remains a potentially attractive strategy for treatment simplification in HIV-infected individuals. However, long-term follow-up in particular with respect to HIV-RNA suppression in cerebrospinal fluids (CSF) is still lacking.

METHODS

Patients who participated in one of the three monotherapy trials [indinavir/r, ATARITMO (atazanavir/r), MOST (lopinavir/r)] at our HIV clinic and remained successfully suppressed during the entire trial (plasma < 50 copies/mL, CSF < 100 copies/mL) were offered to continue their monotherapy under close monitoring. While on rb-PMT, patients were asked to provide CSF samples in yearly or 2-yearly intervals. All patients fully suppressed in plasma and CSF for at least 12 months were included in the analysis. Patients demonstrating any failure in plasma or CSF resumed triple combined ART.

RESULTS

A total of 27 patients (5 women and 22 men) fulfilled the entry criteria. The median follow-up time was 4.8 (1.1-10.9) years with an overall experience of 139 patient-years on monotherapy. Eleven of 27 (41 %) patients (2 women and 9 men) developed virologic failure (1 in plasma only, 4 in CSF only, 4 both in plasma and CSF and 2 in plasma with CSF not available). Plasma failure occurred in 7 patients after a median follow-up of 25 (13-32) months, and CSF failure in 8 patients after a median follow-up of 30 (14-64) months. Seven patients are still on rb-PMT with atazanavir/r. Failure was associated with shorter duration of fully suppressed plasma viral load prior to starting (p < 0.022).

CONCLUSION

For selected patients, rb-PMT might be a valid long-term treatment strategy. Nevertheless, even after 12 months of full HIV-RNA suppression, more than 1/3 of patients may still develop failure in either plasma or CSF. Given the observation of isolated CSF failure, treatment monitoring with regular lumbar puncture should be recommended in rb-PMT. Only monotherapy with atazanavir/r was successful beyond 39 months. Monotherapy failure was significantly associated with a shorter duration of complete HIV-RNA suppression in plasma prior to rb-PMT start. Further investigation is needed to better identify predictors for patients that will qualify for successful long-term rb-PMT.

Baseline natural killer and T cell populations correlation with virologic outcome after regimen simplification to atazanavir/ritonavir alone (ACTG 5201)

Objectives

Simplified maintenance therapy with ritonavir-boosted atazanavir (ATV/r) provides an alternative treatment option for HIV-1 infection that spares nucleoside analogs (NRTI) for future use and decreased toxicity. We hypothesized that the level of immune activation (IA) and recovery of lymphocyte populations could influence virologic outcomes after regimen simplification.

Methods

Thirty-four participants with virologic suppression ≥48 weeks on antiretroviral therapy (2 NRTI plus protease inhibitor) were switched to ATV/r alone in the context of the ACTG 5201 clinical trial. Flow cytometric analyses were performed on PBMC isolated from 25 patients with available samples, of which 24 had lymphocyte recovery sufficient for this study. Assessments included enumeration of T-cells (CD4/CD8), natural killer (NK) (CD3⁺CD56⁺CD16⁺) cells and cell-associated markers (HLA-DR, CD's 38/69/94/95/158/279).

Results

Eight of the 24 patients had at least one plasma HIV-1 RNA level (VL) >50 copies/mL during the study. NK cell levels below the group median of 7.1% at study entry were associated with development of VL >50 copies/mL following simplification by regression and survival analyses (p = 0.043 and 0.023), with an odds ratio of 10.3 (95% CI: 1.92–55.3). Simplification was associated with transient increases in naïve and CD25⁺ CD4⁺ T-cells, and had no impact on IA levels.

Conclusions

Lower NK cell levels prior to regimen simplification were predictive of virologic rebound after discontinuation of nucleoside analogs. Regimen simplification did not have a sustained impact on markers of IA or T lymphocyte populations in 48 weeks of clinical monitoring.

Trial Registration

ClinicalTrials.gov NCT00084019

Evaluation of four tenofovir-containing regimens as first-line treatments in Cameroon and Senegal: the ANRS 12115 DAYANA Trial

BACKGROUND

The aim of the present study was to determine appropriate tenofovir-based regimens meriting evaluation in large-scale randomized trials among sub-Saharan African patients.

METHODS

This was a randomized open-label 96-week prospective pilot study evaluating four first-line regimens: tenofovir/emtricitabine/nevirapine (group 1), tenofovir/lopinavir/ritonavir (group 2), tenofovir/emtricitabine/zidovudine (group 3) and tenofovir/emtricitabine/efavirenz (group 4) in antiretroviral-naive, HIV-1-infected patients in Senegal and Cameroon. The primary end point was defined as an HIV-1 RNA viral load <50 copies/ml (study detection limit) at week 16 in ≥50% of patients using intention-to-treat analysis.

RESULTS

At baseline, 119 patients included were 34% male, had a median plasma viral load of 5.4 log10 copies/ml and median CD4(+) T-cell count of 200 cells/mm(3) (range 53-358). The primary end point was achieved for groups 1, 3 and 4 (58% [n=31], 62% [n=29] and 53% [n=30], respectively), but not for group 2 (38% [n=29]). At week 96, undetectable HIV-1 RNA had been achieved in 74% of patients in group 1, 38% in group 2, 72% in group 3 and 73% in group 4. Patients with detectable HIV-1 RNA at week 16 were more likely to have baseline HIV-1 RNA≥100,000 copies/ml (adjusted OR 5.56, 95% CI 1.72, 16.67). HIV mutations associated with protease inhibitor resistance emerged in three patients, all of whom were in group 2. Anaemia occurred in two group 3 patients and was the only serious treatment-related adverse event.

CONCLUSIONS

Three efficient and safe tenofovir-based triple regimens were identified; the two-drug regimen (tenofovir/lopinavir/ritonavir) did not achieve the protocol-defined virological threshold of efficacy.

Randomized controlled study demonstrating failure of LPV/r monotherapy in HIV: the role of compartment and CD4-nadir

BACKGROUND

Long-term side-effects and cost of HIV treatment motivate the development of simplified maintenance. Monotherapy with ritonavir-boosted lopinavir (LPV/r-MT) is the most widely studied strategy. However, efficacy of LPV/r-MT in compartments remains to be shown.

METHODS

Randomized controlled open-label trial comparing LPV/r-MT with continued treatment for 48 weeks in treated patients with fully suppressed viral load. The primary endpoint was treatment failure in the central nervous system [cerebrospinal fluid (CSF)] and/or genital tract. Treatment failure in blood was defined as two consecutive HIV RNA levels more than 400 copies/ml.

RESULTS

The trial was prematurely stopped when six patients on monotherapy (none in continued treatment-arm) demonstrated a viral failure in blood. At study termination, 60 patients were included, 29 randomized to monotherapy and 13 additional patients switched from continued treatment to monotherapy after 48 weeks. All failures occurred in patients with a nadir CD4 cell count below 200/microl and within the first 24 weeks of monotherapy. Among failing patients, all five patients with a lumbar puncture had an elevated HIV RNA load in CSF and four of six had neurological symptoms. Viral load was fully resuppressed in all failing patients after resumption of the original combination therapy. No drug resistant virus was found. The only predictor of failure was low nadir CD4 cell count (P < 0.02).

CONCLUSION

Maintenance of HIV therapy with LPV/r alone should not be recommended as a standard strategy; particularly not in patients with a CD4 cell count nadir less than 200/microl. Further studies are warranted to elucidate the role of the central nervous system compartment in monotherapy-failure.

[Prognostic factors of virological response in patients treated with lopinavir/ritonavir monotherapy]

Nine clinical trials have analyzed whether the use of lopinavir-ritonavir (LPV/r) monotherapy could be a valid alternative to triple antiretroviral therapy. Four of these clinical trials included an analysis of risk factors for virological failure. The MONARK study evaluated monotherapy in treatment-naïve patients. The M03-613 trial evaluated monotherapy after a period of induction therapy with triple combination antiretroviral therapy. The study by Sprinz et al and the OK studies evaluated monotherapy as maintenance of virological suppression. The efficacy of monotherapy varied according to the scenario. In the scenario of induction-maintenance, the factors related to virological failure were suboptimal adherence and low baseline CD4 counts. In the scenario of maintenance, the factors related to virological failure were suboptimal adherence, nadir CD4 count and low hemoglobin. In treatment-naive patients, the risk of virological failure increased in patients who did not achieve a viral load of less than 400 copies/ml 4 weeks after initiating treatment and in those infected with non-B subtypes (a factor that was probably also related to suboptimal adherence).

Regimen simplification to atazanavir-ritonavir alone as maintenance antiretroviral therapy: final 48-week clinical and virologic outcomes

BACKGROUND

Simplified maintenance therapy with ritonavir-boosted atazanavir (ATV/RTV) alone is attractive because of nucleoside reverse-transcriptase inhibitor (NRTI)-sparing benefits, low pill burden, once-daily dosage, and safety.

METHODS

Subjects with virologic suppression after > or = 48 weeks of initial antiretroviral therapy with 2 NRTIs and a protease inhibitor (PI) were enrolled. Subjects switched to ATV/RTV at entry and discontinued NRTIs after 6 weeks. The primary end point was time to virologic failure (confirmed HIV-1 RNA level > or = 200 copies/mL). Drug resistance at virologic failure was evaluated by standard genotyping and single-genome sequencing (SGS). Residual viremia (1.1-49 copies/mL) was measured by single-copy assay.

RESULTS

Thirty-four subjects simplified to ATV/RTV alone, of whom 30 (88%) did not experience virologic failure by 48 weeks after simplification. Residual viremia did not change significantly after NRTI discontinuation among those without virologic failure but did increase 4-12 weeks before confirmed virologic failure. No major PI-resistance mutations were identified at virologic failure by standard genotyping or SGS.

CONCLUSIONS

In this pilot study, simplified maintenance therapy with ATV/RTV alone maintained viral suppression in most subjects through 48 weeks. PI resistance was not detected among subjects experiencing virologic failure. Larger, randomized trials are warranted to further define the efficacy and safety of this strategy.

HIV monotherapy with ritonavir-boosted protease inhibitors: a systematic review

OBJECTIVE

To assess the efficacy of ritonavir-boosted protease inhibitor monotherapy.

DESIGN AND METHODS

Systematic review of all protease inhibitor-monotherapy studies published in peer-reviewed journals or presented at conferences to date. Data of randomized controlled trials were pooled to yield common odds ratios.

RESULTS

Twenty-two protease inhibitor-monotherapy studies were identified. In the intent-to-treat analysis, 395 out of 582 (67.9%) patients had undetectable HIV-RNA at the end of follow-up. In the six randomized controlled trials (all lopinavir/ritonavir monotherapy), the risk of therapy failure was greater on monotherapy: 121 out of 364 (33.2%) patients on monotherapy against 64 out of 280 (22.9%) patients on HAART [pooled odds ratio 1.48 (95% confidence interval 1.02-2.13, P = 0.037)]. Regarding patients with successfully resuppressed HIV-RNA upon (re-)introducing nucleoside reverse transcriptase inhibitors (NRTIs) as nonfailures, the risk of therapy failure was comparable: 98 out of 364 (26.9%) against 64 out of 280 (22.9%) patients [odds ratio 1.05 (95% confidence interval 0.72-1.53, P = 0.81)].

CONCLUSION

The overall efficacy of ritonavir-boosted protease inhibitor monotherapy is inferior to HAART. The efficacy improves in patients started on monotherapy after suppressed HIV-RNA for at least 6 months. Ten percent of patients have viral rebound with HIV-RNA levels between 50 and 500 copies/ml. Possible explanations are lack of HIV suppression in particular cells or compartments, alternative resistance mechanisms, and nonadherence. Once proven that reintroduction of NRTIs, in patients with loss of viral suppression, is safe and effective, a broader use of simplification of HAART to protease inhibitor monotherapy might be justified. This review supports that the majority of patients with prolonged viral suppression on HAART can successfully be treated with protease inhibitor monotherapy. Arguments for this strategy are NRTI/NNRTI side effects, NRTI/NNRTI resistance, and costs.

Simplification Strategies to Reduce Antiretroviral drug Exposure: Progress and Prospects

Current US guidelines for initial therapy of HIV type-1 (HIV-1) infection recommend daily, lifelong treatment with a combination of three antiretroviral drugs consisting of two nucleoside analogue reverse transcriptase inhibitors and a non-nucleoside reverse transcriptase inhibitor or a protease inhibitor. Although this approach has been successful in reducing morbidity and mortality from HIV-1 infection, concerns remain about adverse events from chronic drug exposure, the requirement for daily medication adherence, the risk of HIV-1 drug resistance and high treatment costs. The availability of antiretrovirals that are coformulated and dosed once daily have reduced pill burden and have simplified dosing schedules, but have not lowered drug exposure or cost. These limitations have stimulated research into drug-sparing strategies including intermittent therapy and simplified maintenance regimens. Randomized clinical trials have shown greater mortality with intermittent therapy compared with continuous therapy leading to rejection of this strategy. Pilot studies of simplified maintenance therapy with a ritonavir-boosted protease inhibitor alone have shown more promise, although concerns remain. This article reviews progress in the simplification of antiretroviral therapy, recent clinical trial results and prospects for the future.

Prognostic factors for virological response in antiretroviral therapy-naive patients in the MONARK Trial randomized to ritonavir-boosted lopinavir alone

Background

MONARK is a pilot randomized trial comparing the safety and efficacy of lopinavir/ritonavir (LPV/r) monotherapy to a standard triple-drug regimen as initial therapy. The primary endpoint was virological response (VR) defined as viral load (VL)<400 copies/ml at week 24 and VL<50 copies/ml at week 48. The objective of this study was to determine prognostic factors of VR in patients receiving LPV/r monotherapy.

Methods

Baseline characteristics, including demographics, HIV type-1 (HIV-1) subtype (B versus non-B), early VR up to week 4, LPV trough concentrations and compliance were investigated as prognostic factors for VR in patients receiving LPV/r monotherapy. Logistic regression was used to search for variables significantly associated with the occurrence of VR.

Results

VR was achieved in 53 out of 83 patients randomized to the LPV/r arm. The on-treatment analysis, using a multivariate model, indicated that having VL<400 copies/ml at week 4 and harbouring HIV-1 subtype B were independently associated with an increased probability of VR. No difference in early VL reduction was evidenced between patients harbouring B or non-B subtypes. The latter patients had more difficulty in adherence to therapy than the former patients. The intention-to-treat analysis showed similar results.

Conclusions

HIV-1 RNA measured at baseline or at week 4 and HIV-1 subtype (B versus non-B) were independent predictive factors of VR in patients starting therapy with LPV/r alone. Although based on a small sample size, results of this study showed that adherence to therapy is lower in patients harbouring non-B subtypes and appears to be a key factor of VR in the context of protease inhibitor monotherapy.

Lopinavir/ritonavir monotherapy or plus zidovudine and lamivudine in antiretroviral-naive HIV-infected patients

BACKGROUND

Guidelines for the use of antiretroviral agents for HIV-1 infection recommend combining at least three agents. The toxicity, cost, and complexity of such regimens warrant the search for other options.

METHODS

MONARK is a prospective, open-label, randomized, 96-week trial comparing the safety and efficacy of lopinavir/ritonavir monotherapy with a standard lopinavir/ritonavir plus zidovudine and lamivudine regimen as an initial treatment regimen in HIV-infected patients with HIV-RNA levels less than 100,000 copies/ml. The primary endpoint was the proportion of patients with HIV-1-RNA levels below 400 copies/ml at week 24 and below 50 copies/ml at week 48.

RESULTS

Eight-three and 53 patients were randomly assigned and exposed in the monotherapy and triple-drug groups, respectively. At week 48, by an intent-to-treat analysis, 53 of 83 patients (64%) in the monotherapy group and 40 of 53 patients (75%) in the triple-drug group achieved the primary endpoint (P = 0.19). The on-treatment analysis indicates that 80 and 95% of patients reached the primary endpoint in the monotherapy and triple-drug groups, respectively (P = 0.02). In the monotherapy arm, protease inhibitor-associated resistance mutations were seen in three of the 21 patients qualifying for genotypic resistance testing, with a modest impact on lopinavir susceptibility. None of the serious reported adverse events were considered to be related to study treatment.

CONCLUSION

Our results suggest that lopinavir/ritonavir monotherapy demonstrates lower rates of virological suppression when compared with lopinavir/ritonavir triple therapy and therefore should not be considered as a preferred treatment option for widespread use in antiretroviral-naive patients.

Potential risks and benefits of HIV treatment simplification: a simulation model of a proposed clinical trial

BACKGROUND

In recent studies, subjects who had achieved suppression of the human immunodeficiency virus (HIV) RNA level while receiving an initial 3-drug antiretroviral regimen successfully maintained suppression while receiving treatment with a "boosted" protease inhibitor (PI) alone. We projected the long-term outcomes of this treatment simplification strategy to inform the design of a proposed multicenter, randomized clinical trial.

METHODS

We used published studies to estimate the efficacy, adverse effects, and cost of a sequence of HIV drug regimens for the simplification strategy, compared with those outcomes for the current standard-of-care (SOC) strategy. Using a published simulation model of HIV disease, we projected life expectancy, discounted quality-adjusted life expectancy (QALE), and discounted lifetime medical costs for each strategy.

RESULTS

Subjects who have not developed PI-resistant HIV infection at the time of failure of the simplification regimen have a greater life expectancy (27.9 vs. 27.1 years) and QALE (14.9 vs. 14.7 years), compared with SOC subjects, because they receive an additional line of therapy without negative consequences for future treatment options. The QALE for the simplification strategy remains higher than that for the SOC, unless a large proportion of patients experiencing virologic failure while receiving the simplification regimen develop PI resistance. Depending on the probability of simplification regimen failure, the advantage is maintained even if HIV develops PI resistance in 42%-70% of subjects. Projected lifetime costs are $26,500-$72,400 per person lower for the simplification strategy than for the SOC strategy.

CONCLUSIONS

An HIV treatment simplification strategy involving use of a boosted PI alone may lead to longer survival overall at lower cost, compared with the SOC combination therapy, because the simplification strategy potentially adds an additional line of therapy. The risk of emergence of PI resistance during treatment with a simplified regimen is a critical determinant of the viability of this strategy.

Efficacy of boosted protease inhibitor monotherapy in patients with complex medical problems

The efficacy of boosted protease inhibitor monotherapy (BPIm) in HIV-positive patients with complex medical problems was assessed in ten patients. With BPIm, median (range) HIV viral load reduction was log10 2.15 (1.62-3.1) by 4-8 weeks; in four patients, viral load was < 400 copies/ml. During follow-up, at median (range) = 50 (8-156) weeks, no patient had an opportunistic illness; one patient developed new PI mutations after 48 weeks. These very preliminary data need further confirmation on a larger scale.

Early virologic rebound in a pilot trial of ritonavir-boosted atazanavir as maintenance monotherapy

OBJECTIVE

To investigate the feasibility of ritonavir-boosted atazanavir monotherapy in HIV-1-infected patients with stable antiretroviral therapy (ART).

DESIGN

Single-armed single-center pilot trial.

METHODS

Adult HIV-1-infected patients, without protease inhibitor (PI) experience, were eligible if they had maintained a viral load <20 copies/mL for a minimum of 12 months on conventional ART. The trial regimen was atazanavir/ritonavir at a dose of 300/100 mg once daily. The atazanavir dose could be adjusted if plasma concentrations showed a low exposure. The study was intended to recruit 30 patients to be followed over 72 weeks. If 5 cases of virologic failure occurred during this period, the study was to be terminated.

RESULTS

The study was terminated according to protocol when 15 of the planned 30 patients had been recruited, because 5 cases of virologic failure had occurred. In patients failing therapy, viral rebound was seen at weeks 12 through 16. Plasma atazanavir concentrations were not associated with the outcome. The median serum bilirubin concentration was significantly lower in the patients failing therapy, however. No PI resistance was found in samples from patients failing therapy.

CONCLUSIONS

Ritonavir-boosted atazanavir as maintenance monotherapy in HIV-1 infection might not be as potent as conventional ART. Serum bilirubin should be further studied as a biomarker of adequate atazanavir exposure.

Second-line combination antiretroviral therapy in resource-limited settings: facing the challenges through clinical research

Combination antiretroviral therapy (ART) has dramatically altered the prognosis of individuals infected with HIV. In the past 5 years there has been a concerted effort to increase access to ART in the developing world. The evidence to date suggests that adherence to therapy and clinical outcomes in developing world programmes are at least the equal of those observed in developed countries. Although access to first-line therapy is reasonably well established, there is a substantial and unacceptable mortality rate in the first 6 months after initiation of ART, particularly in those with low CD4 cell counts and late-stage disease. Failure of first-line ART is inevitable in a proportion of patients. Access to second-line ART regimens in developing countries is problematic, mainly because of the expense of HIV protease inhibitors (PIs). Access to second-line ART may be facilitated by novel strategies using the existing recommended agents or by the use of new agents or classes. Refinement of programmes in the developing world must be underpinned by the same rigorous scientific research effort that has characterized the success of the effort in the developed world. Therefore, the funding bodies responsible for the roll-out of antiretroviral access across the globe must mandate, incorporate and fund clinical research as an intrinsic aspect of combination ART roll-out programmes.

The role of compartment penetration in PI-monotherapy: the Atazanavir-Ritonavir Monomaintenance (ATARITMO) Trial

OBJECTIVES

To limit exposure to anti-HIV drugs and minimize risk of long-term side effects, studies have looked at the possibility of simplified maintenance strategies. Ritonavir-boosted protease-inhibitor (PI)-monotherapies are an attractive alternative, but limited compartmental penetration of PI remains a concern.

DESIGN

Non-comparative 24-week pilot study.

METHOD

Ritonavir-boosted atazanavir (ATV/r) monotherapy administered to fully suppressed patients (>3 month HIV RNA < 50 copies/ml). Plasma was obtained every 4 weeks and cerebrospinal fluid (CSF) and semen at W24.

RESULTS

Two patients (7%) failed ATV/r monotherapy. One patient was subsequently identified as a protocol violator since he had a previous history of treatment failure under indinavir. The second patient deliberately decided to stop treatment after W20. Excluding failing patients, individual measurements of HIV RNA in patients having occasional viral 'blips' was found in five patients. At W24, 3/20 patients had elevated viral loads in CSF (HIV RNA > 100 copies/ml), and 2/15 in semen, despite viral suppression in plasma (< 50 copies/ml). Samples with elevated HIV RNA (> 500 copies/ml) in CSF were all wild type. The mean ATV drug concentration ratio (CSF/blood, n = 22) was 0.9%. Indicators of altered immune activation (CD8CD38 C-reactive protein) remained unchanged.

CONCLUSION

This study supports previous results indicating the potential use of PI-based mono-maintenance therapies. However, our results in CSF cautions against the uncontrolled use of PI-based monotherapies.

Lopinavir/ritonavir monotherapy as a simplification strategy in routine clinical practice

OBJECTIVES

The efficacy and safety of lopinavir/ritonavir monotherapy has been explored with promising results in well-controlled, randomized clinical trials. However, less information about its clinical usefulness in routine clinical practice is currently available. The objective of this study was to assess the effectiveness and safety of monotherapy with lopinavir/ritonavir as a treatment simplification strategy in HIV-infected patients with viral suppression outside a clinical trial setting.

METHODS

Fifty-one subjects who were switched to lopinavir/ritonavir monotherapy and whose HIV-1 RNA was <50 copies/mL were included in this retrospective study. Data were obtained from a prospectively compiled database. The primary endpoint was the percentage of subjects who maintained viral suppression after 48 weeks of follow-up. Secondary endpoints included the incidence of adverse events and changes in CD4+ T cell count and in lipid profile.

RESULTS

Two patients lost viral suppression, seven patients interrupted lopinavir/ritonavir monotherapy because of adverse events and four patients were lost before completing 48 weeks of follow-up. Thus, 38/40 (95.0%) patients maintained viral suppression when only subjects whose outcomes were available up to week 48 were considered and 38/51 (74.5%) patients maintained viral suppression when subjects who discontinued therapy or who were lost to follow-up were considered as treatment failures. The mean CD4+ T cell count significantly increased, from 541 (280) cells/mm3 at baseline to 609 (212) cells/mm3 at week 48 of follow-up (P=0.034). This increase was similar to that observed in the 48 weeks prior to lopinavir/ritonavir monotherapy (P=0.792). Although total cholesterol remained unchanged, there was a significant decrease in triglyceride levels during follow-up (P=0.029).

CONCLUSIONS

Monotherapy with lopinavir/ritonavir is safe and effective as a treatment simplification approach in HIV-1-infected patients with sustained viral suppression in routine clinical practice, particularly in those patients already receiving a lopinavir/ritonavir-based antiretroviral regimen.

The Safety, Efficacy, and Pharmacokinetic Profile of a Switch in Antiretroviral Therapy to Saquinavir, Ritonavir, and Atazanavir Alone for 48 Weeks and a Switch in the Saquinavir Formulation

BACKGROUND

Toxicities observed with current combination antiretroviral therapy (CART) warrant a search for novel options, such as class-sparing regimens. Ritonavir-boosted double-protease inhibitor (PI)-only regimens are such an option but are prone to pharmacokinetic interactions.

METHODS

This 48-week randomized study examined the safety and efficacy of a switch in CART to a once-daily regimen of saquinavir (SQV), ritonavir (RTV), and atazanavir (ATV) that did not include nucleoside reverse-transcriptase inhibitors (NRTIs). The study also assessed the pharmacokinetic profile of a change in the SQV formulation, from 200 mg to 500 mg, in 2 regimens (SQV-RTV twice per day plus NRTIs [arm 1] and SQV-RTV-ATV once per day without NRTIs [arm 2]) in human immunodeficiency virus type 1-infected subjects (plasma human immunodeficiency virus RNA level, <50 copies/mL). Patients underwent an initial SQV formulation change or a CART change to SQV-RTV-ATV with intense pharmacokinetic sampling. All patients were subsequently assigned to receive SQV-RTV-ATV (1500, 100, and 300 mg once per day, respectively) without NRTIs for 48 weeks. The primary end point was the percentage of patients who experienced virologic failure.

RESULTS

Of 25 subjects enrolled, scleral icterus was the most common adverse event (3 patients [12.5%]). Three subjects (12.5%) experienced virologic failure; and mean (+/- standard error of the mean) increase in the CD4(+) lymphocyte count was 63 +/- 36 cells/ mu L over 48 weeks (P=.012). The SQV geometric mean area under the time curve parameters were not significantly altered for the 2 SQV formulations (arm 1, 23.32 vs. 18.76 ngxh/mL [geometric mean ratio, 0.80] for the 200-mg vs. 500-mg formulations, respectively; arm 2, 50.31 vs. 44.79 ngxh/mL [geometric mean ratio, 0.88], for the 200-mg vs. 500-mg formulations, respectively).

CONCLUSIONS

A CART regimen of SQV-RTV-ATV alone demonstrated sustained virologic efficacy and was associated with significant increases in the CD4(+) lymphocyte count.

Lopinavir/ritonavir as single-drug therapy for maintenance of HIV-1 viral suppression: 48-week results of a randomized, controlled, open-label, proof-of-concept pilot clinical trial (OK Study)

OBJECTIVE

This study evaluated maintenance with lopinavir/ritonavir monotherapy vs. continuing lopinavir/ritonavir and 2 nucleosides in HIV-infected patients with suppressed HIV replication.

DESIGN

Randomized, controlled, open-label, multicenter, pilot clinical trial.

METHODS

Adult patients were eligible if they had no history of virologic failure while receiving a protease inhibitor, were receiving 2 nucleosides + lopinavir/ritonavir (400/100 mg b.i.d.) for >1 month and had maintained serum HIV RNA <50 copies/mL for >6 months prior to enrollment.

RESULTS

Forty-two patients were randomly assigned 1:1 to continue or stop the nucleosides. At baseline there were no significant differences between groups in median CD4 cells/muL (baseline or nadir), pre-HAART (highly active antiretroviral therapy) HIV log10 viremia, or time with HIV RNA <50 copies/mL prior to enrollment. After 48 weeks of follow-up, percentage of patients remaining at <50 HIV RNA copies/mL (intention to treat, M = F) was 81% for the monotherapy group (95% CI: 64% to 98%) vs. 95% for the triple-therapy group (95% CI: 86% to 100%); P = 0.34. Patients in whom monotherapy failed had significantly worse adherence than patients who remained virally suppressed on monotherapy. Monotherapy failures did not show primary resistance mutations in the protease gene and were successfully reinduced with prerandomization nucleosides. Mean change in CD4 cells/microL: +70 (monotherapy) and +8 (triple) (P = 0.27). Mean serum fasting lipids remained stable in both groups. No serious adverse events were observed.

CONCLUSION

Most of the patients maintained with lopinavir/ritonavir monotherapy remain with undetectable viral load after 48 weeks. Failures of lopinavir/ritonavir monotherapy were not associated with the development of primary resistance mutations in the protease gene and could be successfully reinduced adding back prior nucleosides.

Short-course induction with boosted saquinavir monotherapy for naive patients with late-stage infection

This study assessed the efficacy of short-course induction treatment with saquinavir/ritonavir as boosted protease inhibitor monotherapy in antiretroviral-naive patients, before switching to conventional highly active antiretroviral therapy. Twenty-eight patients were enrolled, with baseline CD4 cell counts of 26 cells/microl and HIV RNA 5.5 log10 copies/ml. There was a median 2.5 log10 reduction in HIV RNA and 115 cell increase in CD4 cell counts after 4-8 weeks of saquinavir/ritonavir monotherapy. This treatment strategy should be evaluated further.

Penetration of enfuvirtide, tenofovir, efavirenz, and protease inhibitors in the genital tract of HIV-1-infected men

One likely mechanism of virological failure is poor antiretroviral drug diffusion in sites of viral replication such as the genital tract. We measured antiretroviral drug concentrations in blood and semen in 13 HIV-infected men failing treatment. Enfuvirtide did not cross the blood-testis barrier, whereas tenofovir accumulated in semen. Unlike indinavir, semen concentrations of lopinavir, amprenavir, saquinavir and efavirenz were ineffective. These are worrying findings, because suboptimal semen drug concentrations may enhance the risk of sexually transmitted drug-resistant HIV variants.