Martin S. Rhee

Antiviral activity, safety, and pharmacokinetics/pharmacodynamics of tenofovir alafenamide as 10-day monotherapy in HIV-1-positive adults.

Objective: To evaluate the antiviral activity, safety, pharmacokinetics, and pharmacokinetics/pharmacodynamics of short-term monotherapy with tenofovir alafenamide (TAF), a next-generation tenofovir (TFV) prodrug. Design: A phase 1b, randomized, partially blinded, active- and placebo-controlled, dose-ranging study. Methods: Treatment-naive and experienced HIV-1–positive adults currently off antiretroviral therapy were randomized to receive 8, 25, or 40 mg TAF, 300 mg tenofovir disoproxil fumarate (TDF), or placebo, each once daily for 10 days. Results: Thirty-eight subjects were enrolled. Baseline characteristics were similar across dose groups. Significant reductions in plasma HIV-1 RNA from baseline to day 11 were observed for all TAF dose groups compared with placebo (P < 0.01), with a median decrease of 1.08–1.73 log10 copies per milliliter, including a dose–response relationship for viral load decrease up to 25 mg. At steady state, 8, 25, and 40 mg TAF yielded mean TFV plasma exposures [area under the plasma concentration–time curve (AUCtau)] of 97%, 86%, and 79% lower, respectively, as compared with the TFV exposures observed with 300 mg TDF. For 25 and 40 mg TAF, the mean intracellular peripheral blood mononuclear cell tenofovir diphosphate AUCtau was ∼7-fold and ∼25-fold higher, relative to 300 mg TDF. Conclusions: Compared with 300 mg TDF, TAF demonstrated more potent antiviral activity, higher peripheral blood mononuclear cell intracellular tenofovir diphosphate levels, and lower plasma TFV exposures, at approximately 1/10th of the dose. This may translate into greater antiviral efficacy, a higher barrier to resistance, and an improved safety profile relative to TDF, supporting further investigation of TAF dosed once daily in HIV-infected patients.

A randomized double-blind comparison of coformulated elvitegravir/ cobicistat/emtricitabine/tenofovir disoproxil fumarate versus efavirenz/emtricitabine/tenofovir disoproxil fumarate for initial treatment of HIV-1 infection: Analysis of week 96 results

Abstract:We report week 96 results from a phase 3 trial of elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate (EVG/COBI/FTC/TDF, n = 348) vs efavirenz/emtricitabine/tenofovir disoproxil fumarate (EFV/FTC/TDF, n = 352). At week 48, EVG/COBI/FTC/TDF was noninferior to EFV/FTC/TDF (88% vs 84%, difference +3.6%, 95% confidence interval: −1.6% to 8.8%). Virologic success (HIV-1 RNA <50 copies/mL) was maintained at week 96 (84% vs 82%, difference +2.7%, 95% CI: −2.9% to 8.3%). Discontinuation due to adverse events was low (5% vs 7%). Median changes in serum creatinine (mg/dL) at week 96 were similar to week 48. These results support the durable efficacy and long-term safety of EVG/COBI/FTC/TDF.

Cobicistat versus ritonavir as a pharmacoenhancer of atazanavir plus emtricitabine/tenofovir disoproxil fumarate in treatment-naive HIV type 1-infected patients: week 48 results.

BACKGROUND  Cobicistat (COBI) is a pharmacoenhancer with no antiretroviral activity in vitro. METHODS  An international, randomized, double-blind, double-dummy, active-controlled trial was conducted to evaluate the efficacy and safety of COBI versus ritonavir (RTV) as a pharmacoenhancer of atazanavir (ATV) in combination with emtricitabine (FTC)/tenofovir disoproxil fumarate (TDF) in treatment-naive patients. The primary end point was a human immunodeficiency virus type 1 (HIV-1) RNA load of <50 copies/mL at week 48 by the Food and Drug Administration snapshot algorithm; the noninferiority margin was 12%. RESULTS  A total of 692 patients were randomly assigned to a treatment arm and received study drug (344 in the COBI group vs 348 in the RTV group). At week 48, virologic success was achieved in 85% of COBI recipients and 87% of RTV recipients (difference, -2.2% [95% confidence interval, -7.4% to 3.0%]); among patients with a baseline HIV-1 RNA load of >100 000 copies/mL, rates were similar (86% vs 86%). Similar percentages of patients in both groups had serious adverse events (10% of COBI recipients vs 7% of RTV recipients) and adverse events leading to discontinuation of treatment with the study drug (7% vs 7%). Median increases in the serum creatinine level were 0.13 and 0.09 mg/dL, respectively, for COBI and RTV recipients. CONCLUSIONS  COBI was noninferior to RTV in combination with ATV plus FTC/TDF at week 48. Both regimens achieved high rates of virologic success. Safety and tolerability profiles of the 2 regimens were comparable. Once-daily COBI is a safe and effective pharmacoenhancer of the protease inhibitor ATV.

A Randomized, Double-Blind Comparison of Single-Tablet Regimen Elvitegravir/Cobicistat/Emtricitabine/Tenofovir DF Versus Single-Tablet Regimen Efavirenz/Emtricitabine/Tenofovir DF for Initial Treatment of HIV-1 Infection: Analysis of Week 144 Results

INTRODUCTION The first integrase inhibitor-based single-tablet regimen combines elvitegravir (an integrase inhibitor), cobicistat (a pharmacoenhancer), emtricitabine (FTC), and tenofovir DF (TDF) (EVG/ COBI/FTC/TDF). In 2 phase 3 randomized trials, EVG/COBI/FTC/TDF demonstrated noninferior efficacy at week 48 to efavirenz (EFV)/FTC/TDF (study 102) and to ritonavir-boosted atazanavir ATV + RTV + FTC/TDF (study 103) with durable efficacy through week 96. We present week 144 data from study 102. METHODS A full description of the methods has been published. A brief description is provided below.

Efficacy and safety of tenofovir alafenamide versus tenofovir disoproxil fumarate given as fixed-dose combinations containing emtricitabine as backbones for treatment of HIV-1 infection in virologically suppressed adults: A randomised, double-blind, active-controlled phase 3 trial

BACKGROUND Emtricitabine with tenofovir disoproxil fumarate is a standard-of-care nucleoside reverse transcriptase inhibitor (NRTI) backbone. However, tenofovir disoproxil fumarate is associated with renal and bone toxic effects; the novel prodrug tenofovir alafenamide achieves 90% lower plasma tenofovir concentrations. We aimed to further assess safety and efficacy of fixed-dose combination emtricitabine with tenofovir alafenamide in patients switched from emtricitabine with tenofovir disoproxil fumarate. METHODS In this controlled, double-blind, multicentre phase 3 study, we recruited virologically suppressed (HIV RNA <50 copies per mL) patients with HIV aged 18 years and older receiving regimens containing fixed-dose combination emtricitabine with tenofovir disoproxil fumartate from 78 sites in North America and Europe. Patients were randomly assigned (1:1) to switch to fixed-dose 200 mg emtricitabine with 10 mg or 25 mg tenofovir alafenamide or to continue 200 mg emtricitabine with 200 mg or 300 mg tenofovir disoproxil fumarate, while remaining on the same third agent for 96 weeks. Randomisation was done by a computer-generated allocation sequence and was stratified by the third agent (boosted protease inhibitor vs other agent). Investigators, patients, and study staff giving treatment, assessing outcomes, and collecting data were masked to treatment group. The primary outcome was the proportion of patients with plasma HIV-1 RNA less than 50 copies per mL at week 48 as defined by the US Food and Drug Administration snapshot algorithm with a prespecified non-inferiority margin of 10%. The primary efficacy endpoint was analysed with the per-protocol analysis set, whereas the safety analysis included all randomly assigned patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, number NCT02121795. FINDINGS We recruited patients between May 6, 2011, and Sept 11, 2014; 780 were screened and 668 were randomly assigned to receive either tenofovir alafenamide (n=333) or tenofovir disoproxil fumarate (n=330). Through week 48, virological success (HIV-1 RNA <50 copies per mL) was maintained in 314 (94%) of patients in the tenofovir alafenamide group compared with 307 (93%) in the tenofovir disoproxil fumarate group (difference 1·3%, 95% CI -2·5 to 5·1), showing non-inferiority of tenofovir alafenamide to tenofovir disproxil fumarate. Seven patients in the tenofovir alafenamide (2%) and three (1%) in the tenofovir disoproxil fumarate group discontinued due to adverse events. There were no cases of proximal renal tubulopathy in either group. INTERPRETATION In patients switching from emtricitabine with tenofovir disoproxil fumarate to emtricitabine with tenofovir alafenamide, high rates of virological suppression were maintained. With its safety advantages, fixed-dose emtricitabine with tenofovir alafenamide has the potential to become an important NRTI backbone. FUNDING Gilead Sciences.

Pharmacologic Consideration for the Use of Antiretroviral Agents in the Elderly

The prevalence of human immunodeficiency virus (HIV) infection among people older than 50 years is increasing. HIV‐infected patients require lifelong treatment with antiretroviral agents to suppress viral replication and maintain immune function. The use of antiretroviral agents in the elderly can be complicated by multiple chronic comorbidities and coadministered non‐HIV medications. The pharmacokinetics of antiretroviral agents may be altered due to age‐related decrements in hepatic and renal function. The elderly may be more sensitive than younger people to antiretroviral drug toxicity. A better understanding of the pharmacokinetics of antiretroviral agents in the elderly is of importance for the successful management of complex antiretroviral regimens in this population.

A randomized study of tenofovir disoproxil fumarate in treatment-experienced HIV-1 infected adolescents.

Background: There are few data on the safety and antiviral activity of tenofovir disoproxil fumarate (TDF) in HIV-1 infected adolescents. Methods: A randomized, double-blinded, placebo-controlled study was conducted. Ninety adolescents (12 to <18 years) who were viremic while receiving antiretroviral treatment were randomized to receive TDF 300 mg (mean, 216.8 mg/m2) or placebo in combination with an optimized background regimen (OBR) for 48 weeks. The primary efficacy endpoint was time-weighted average change in plasma HIV-1 RNA from baseline at week 24 Results: Eighty-seven subjects (45 TDF, 42 placebo) received the study drug. Through week 24, the median time-weighted average change in plasma HIV-1 RNA was not different between the TDF and placebo groups (−1.6 versus −1.6 log10copies/mL, P = 0.55). The percentages of subjects who achieved HIV-1 RNA <400 copies/mL were similar at week 24 (40.9 versus 41.5%). One fourth of subjects in the TDF and placebo groups (24.4 versus 28.6%) had at least 3 active agents in the OBR. Many subjects in both groups had baseline genotypic resistance to TDF (48.9 versus 33.3%). TDF was generally safe and well tolerated. There were no statistically significant differences in changes of renal function and bone mineral density between the 2 groups. Conclusion: This study of TDF in combination with an OBR in antiretroviral-experienced adolescents did not meet its primary or secondary efficacy endpoints. The effectiveness of the OBR and baseline genotypic resistance to TDF in both groups may have confounded the efficacy findings. No clinically relevant TDF-related renal or bone toxicities were observed in this adolescent population.

Week 144 resistance analysis of elvitegravir/cobicistat/emtricitabine/tenofovir DF versus efavirenz/emtricitabine/tenofovir DF in antiretroviral-naive patients.

BACKGROUND Here, the baseline and emergent resistance to elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate (EVG/COBI/FTC/TDF) versus efavirenz (EFV)/FTC/TDF in HIV-1-infected antiretroviral-naive adults through 144 weeks from the randomized, ongoing, Phase III study GS-US-236-0102 is described. METHODS HIV-1 protease (PR) and reverse transcriptase (RT) were sequenced at screening; patients with HIV-1 resistant to EFV, FTC or TDF were excluded. Genotypic/phenotypic analyses were performed at virological failure confirmation and baseline for PR, RT and integrase (IN) for patients with virological failure and for patients with HIV-1 RNA≥400 copies/ml at weeks 48, 96, 144 or early study drug discontinuation. Retrospective, baseline, IN genotyping was conducted for EVG/COBI/FTC/TDF patients. RESULTS In the EVG/COBI/FTC/TDF group through week 144, HIV-1 from 10 patients (2.9%; 10/348 treated patients) developed primary IN strand transfer inhibitor (n=9) and/or nucleoside RT inhibitor resistance substitutions (n=10). The emergence of resistance decreased over time with 8, 2 and 0 patients developing HIV-1 resistance through week 48, post-week 48-96 and post-week 96-144, respectively. Emergent substitutions were E92Q (n=7), N155H (n=3), Q148R (n=1) and T66I (n=1) in IN, and M184V/I (n=10) and K65R (n=4) in RT. All 10 isolates had reduced susceptibility to EVG, FTC or TDF. Virus with EVG phenotypic resistance had cross-resistance to raltegravir. In the EFV/FTC/TDF group, virus from 14 patients (4.0%; 14/352 treated patients; 4 during weeks 96-144) developed a resistance substitution to EFV (n=14; K103N: n=13), FTC (M184V/I: n=4) or TDF (K65R: n=3). CONCLUSIONS Resistance development to EVG/COBI/FTC/TDF was infrequent through 144 weeks of therapy and decreased over time, consistent with durable efficacy.

The association of HIV viral load with indirect markers of liver injury

Summary.  This study assessed the association of HIV RNA with indirect markers of liver injury including FIB‐4 index, liver enzymes and platelet counts in a high‐risk Hispanic population. The data were derived from a prospective study that included 138 HIV/hepatitis C (HCV)‐coinfected and 68 HIV‐infected participants without hepatitis C or B co‐infection (mono‐infected). In unadjusted analyses, detectable HIV viral load (vs undetectable, <400 copies/mL) was associated with a 40% greater odds (OR 1.4, 95% CI: 1.1–1.9, P = 0.016) of FIB‐4 > 1.45 in the HIV/HCV‐coinfected group and 70% greater odds of FIB‐4 > 1.45 (OR 1.7, 95% CI: 1.0–2.8; P = 0.046) in the HIV‐mono‐infected group. In multivariable analyses, a 1 log10 increase in HIV RNA was associated with a median increase in FIB‐4 of 12% in the HIV/HCV‐coinfected group and 11% in the HIV‐mono‐infected group (P < 0.0001). Among the HIV/HCV‐coinfected group, the elevating effect of HIV RNA on FIB‐4 was strongest at low CD4 counts (P = 0.0037). Among the HIV‐mono‐infected group, the association between HIV RNA and FIB‐4 was independent of CD4 cell counts. HIV RNA was associated with alterations in both liver enzymes and platelet counts. HIV antiretroviral therapy was not associated with any measure of liver injury examined. This study suggests that HIV may have direct, injurious effects on the liver and that HIV viral load should be considered when these indirect markers are used to assess liver function.

Cobicistat-Boosted Protease Inhibitors in HIV-Infected Patients with Mild to Moderate Renal Impairment

Abstract Background: Cobicistat (COBI) is a pharmacoenhancer that optimizes systemic exposures of protease inhibitors (PIs) such as atazanavir (ATV) and darunavir (DRV). Objective: To evaluate the efficacy and safety of switching ritonavir (RTV) to COBI in patients with creatinine clearance (CrCl) 50 to 89 mL/min who are virologically suppressed on a stable regimen containing ritonavir (RTV)-boosted ATV or DRV. Other components of the regimen remained unchanged. Methods: A phase 3, non-comparative, open-label clinical trial. Results: Seventy-three patients were enrolled. At week 48, 82% maintained virologic suppression. No emergent resistance developed. Serious adverse events (AEs) occurred in 7%, and study drug discontinuation due to AEs occurred in 10% (7 patients). There were 2 renal discontinuations and no cases of proximal renal tubulopathy. Small reductions in CrCl (median [IQR]) were observed as early as week 2, after which they were nonprogressive through week 48 (-3.8 [-9 to 0.8]). Changes in CrCl by baseline CrCl (< 70 vs ≥ 70) were -1.1 [-6.5 to 6.3] versus -6.6 [-12.4 to -0.7], respectively. Conclusions: In HIV–1–infected patients with CrCl 50 to 89 mL/min switching from RTV to COBI, COBI-boosted PIs in combination with 2 nucleos(t)ide reverse transcriptase inhibitors were well-tolerated and effective in maintaining virologic suppression. The renal safety profile of COBI in this study was consistent with the long-term data in patients without renal impairment from the phase 3 studies of COBI-containing regimens.