Barry M. Bernstein

Low-level viremia persists for at least 7 years in patients on suppressive antiretroviral therapy

Residual viremia can be detected in most HIV-1-infected patients on antiretroviral therapy despite suppression of plasma RNA to <50 copies per ml, but the source and duration of this viremia is currently unknown. Therefore, we analyzed longitudinal plasma samples from 40 patients enrolled in the Abbott M97-720 trial at baseline (pretherapy) and weeks 60 to 384 by using an HIV-1 RNA assay with single-copy sensitivity. All patients were on therapy (lopinavir/ritonavir, stavudine, and lamivudine) with plasma HIV RNA <50 copies per ml by week 96 of the study and thereafter. Single-copy assay results revealed that 77% of the patient samples had detectable low-level viremia (≥1 copy per ml), and all patients had at least one sample with detectable viremia. A nonlinear mixed effects model revealed a biphasic decline in plasma RNA levels occurring over weeks 60 to 384: an initial phase of decay with a half-life of 39 weeks and a subsequent phase with no perceptible decay. The level of pretherapy viremia extrapolated for each phase of decay was significantly correlated with total baseline viremia for each patient (R2 = 0.27, P = 0.001 and R2 = 0.19, P < 0.005, respectively), supporting a biological link between the extent of overall baseline viral infection and the infection of long-lived reservoirs. These data suggest that low-level persistent viremia appears to arise from at least two cell compartments, one in which viral production decays over time and a second in which viral production remains stable for at least 7 years.

Exploratory Study of Oral Combination Antiviral Therapy for Hepatitis C

BACKGROUND There is a need for interferon-free treatment regimens for hepatitis C virus (HCV) infection. The goal of this study was to evaluate ABT-450, a potent HCV NS3 protease inhibitor, combined with low-dose ritonavir (ABT-450/r), in addition to ABT-333, a nonnucleoside NS5B polymerase inhibitor, and ribavirin, for the treatment of HCV infection. METHODS We conducted a 12-week, phase 2a, open-label study involving patients who had HCV genotype 1 infection without cirrhosis. All patients received ABT-333 (400 mg twice daily) and ribavirin (1000 to 1200 mg per day) and one of two daily doses of ABT-450/r. Groups 1 and 2 included previously untreated patients; group 1 received 250 mg of ABT-450 and 100 mg of ritonavir, and group 2 received 150 mg and 100 mg, respectively. Group 3, which included patients who had had a null or partial response to previous therapy with peginterferon and ribavirin, received daily doses of 150 mg of ABT-450 and 100 mg of ritonavir. The primary end point was an undetectable level of HCV RNA from week 4 through week 12 (extended rapid virologic response). RESULTS A total of 17 of the 19 patients in group 1 (89%) and 11 of the 14 in group 2 (79%) had an extended rapid virologic response; a sustained virologic response 12 weeks after the end of treatment was achieved in 95% and 93% of the patients, respectively. In group 3, 10 of 17 patients (59%) had an extended rapid virologic response, and 8 (47%) had a sustained virologic response 12 weeks after therapy; 6 patients had virologic breakthrough, and 3 had a relapse. Adverse events included abnormalities in liver-function tests, fatigue, nausea, headache, dizziness, insomnia, pruritus, rash, and vomiting. CONCLUSIONS This preliminary study suggests that 12 weeks of therapy with a combination of a protease inhibitor, a nonnucleoside polymerase inhibitor, and ribavirin may be effective for treatment of HCV genotype 1 infection. (Funded by Abbott; ClinicalTrials.gov number, NCT01306617.).

Loss of bone mineral density after antiretroviral therapy initiation, independent of antiretroviral regimen

Background:Decreased bone mineral density (BMD) has been described in HIV-infected patients initiating antiretroviral therapy (ART), but the contributions of ART and immunologic and/or virologic factors remain unclear. Methods:We compared total BMD changes over 96 weeks in 106 ART-naive HIV-infected subjects who were randomized to receive efavirenz (EFV) + zidovudine/lamivudine (n = 32) or lopinavir/ritonavir (LPV/r) + zidovudine/lamivudine induction (n = 74) for 24-48 weeks followed by LPV/r monotherapy. We also sought to identify factors associated with BMD loss, including markers of systemic inflammation [soluble tumor necrosis factor-α receptors (sTNFR I and II)]. Results:After 96 weeks, the mean percent change from baseline in total BMD was −2.5% (LPV/r) and −2.3% (EFV) (P < 0.01 for within-group changes in either arm; P = 0.86 for between-group differences). No alteration in the rate of BMD change was observed upon simplification to LPV/r monotherapy. Although soluble tumor necrosis factor-α receptor II concentrations at baseline and 24 weeks were at least marginally associated with subsequent changes in BMD (P = 0.06 and P = 0.028, respectively), these associations were no longer significant after adjustment for CD4+ T cell count. Subjects with lower baseline CD4+ T cell count, non-black race, and higher baseline glucose demonstrated a higher risk for >5% decrease in BMD. Conclusions:Similar decreases in BMD over 96 weeks occurred in ART-naive subjects receiving either EFV-based regimen or LPV/r-based regimen, which was not altered by simplification to LPV/r monotherapy and was unrelated to markers of tumor necrosis factor-α activity.

Incidence of Resistance in a Double-Blind Study Comparing Lopinavir/Ritonavir Plus Stavudine and Lamivudine to Nelfinavir plus Stavudine and Lamivudine

Study M98-863 was a double-blind, randomized, phase 3 study that compared lopinavir/ritonavir with nelfinavir, each coadministered with stavudine and lamivudine, in 653 antiretroviral therapy-naive human immunodeficiency virus (HIV) type 1-infected subjects. The incidence of HIV drug resistance was analyzed using baseline and rebound virus isolates from subjects with plasma HIV RNA >400 copies/mL from weeks 24 to 108 of therapy. No evidence of genotypic or phenotypic resistance to lopinavir/ritonavir, defined as any active site or primary mutation in HIV protease, was detected in virus isolates from 51 lopinavir/ritonavir-treated subjects with available genotypes. Primary mutations related to nelfinavir resistance (D30N and/or L90M) were observed in 43 (45%) of 96 nelfinavir-treated subjects. Resistance to lamivudine and stavudine was also significantly higher in nelfinavir-treated versus lopinavir/ritonavir-treated subjects. These differences suggest substantially different genetic and pharmacological barriers to resistance for these 2 protease inhibitors and may have implications for strategies for initiating antiretroviral therapy.

Identification of Genotypic Changes in Human Immunodeficiency Virus Protease That Correlate with Reduced Susceptibility to the Protease Inhibitor Lopinavir among Viral Isolates from Protease Inhibitor-Experienced Patients

ABSTRACT The association of genotypic changes in human immunodeficiency virus (HIV) protease with reduced in vitro susceptibility to the new protease inhibitor lopinavir (previously ABT-378) was explored using a panel of viral isolates from subjects failing therapy with other protease inhibitors. Two statistical tests showed that specific mutations at 11 amino acid positions in protease (L10F/I/R/V, K20M/R, L24I, M46I/L, F53L, I54L/T/V, L63P, A71I/L/T/V, V82A/F/T, I84V, and L90M) were associated with reduced susceptibility. Mutations at positions 82, 54, 10, 63, 71, and 84 were most closely associated with relatively modest (4- and 10-fold) changes in phenotype, while the K20M/R and F53L mutations, in conjunction with multiple other mutations, were associated with >20- and >40-fold-reduced susceptibility, respectively. The median 50% inhibitory concentrations (IC50) of lopinavir against isolates with 0 to 3, 4 or 5, 6 or 7, and 8 to 10 of the above 11 mutations were 0.8-, 2.7-, 13.5-, and 44.0-fold higher, respectively, than the IC50 against wild-type HIV. On average, the IC50 of lopinavir increased by 1.74-fold per mutation in isolates containing three or more mutations. Each of the 16 viruses that displayed a >20-fold change in susceptibility contained mutations at residues 10, 54, 63, and 82 and/or 84, along with a median of three mutations at residues 20, 24, 46, 53, 71, and 90. The number of protease mutations from the 11 identified in these analyses (the lopinavir mutation score) may be useful for the interpretation of HIV genotypic resistance testing with respect to lopinavir-ritonavir (Kaletra) regimens and may provide insight into the genetic barrier to resistance to lopinavir-ritonavir in both antiretroviral therapy-naive and protease inhibitor-experienced patients.

Pharmacokinetic-Pharmacodynamic Analysis of Lopinavir-Ritonavir in Combination with Efavirenz and Two Nucleoside Reverse Transcriptase Inhibitors in Extensively Pretreated Human Immunodeficiency Virus-Infected Patients

ABSTRACT The steady-state pharmacokinetics and pharmacodynamics of two oral doses of lopinavir-ritonavir (lopinavir/r; 400/100 and 533/133 mg) twice daily (BID) when dosed in combination with efavirenz, plus two nucleoside reverse transcriptase inhibitors, were assessed in a phase II, open-label, randomized, parallel arm study in 57 multiple protease inhibitor-experienced but non-nucleoside reverse transcriptase inhibitor-naive human immunodeficiency virus (HIV)-infected subjects. All subjects began dosing of lopinavir/r at 400/100 mg BID; subjects in one arm increased the lopinavir/r dose to 533/133 mg BID on day 14. When codosed with efavirenz, the lopinavir/r 400/100 mg BID regimen resulted in lower lopinavir concentrations in plasma, particularly Cmin, than were observed in previous studies of lopinavir/r administered without efavirenz. Increasing the lopinavir/r dose to 533/133 mg increased the lopinavir area under the concentration-time curve over a 12-h dosing interval (AUC12), Cpredose, and Cmin by 46, 70, and 141%, respectively. The increase in lopinavir Cmax (33%,) did not reach statistical significance. Ritonavir AUC12, Cmax, Cpredose, and Cmin values were increased 46 to 63%. The lopinavir predose concentrations achieved with the 533/133-mg BID dose were similar to those observed with lopinavir/r 400/100 mg BID in the absence of efavirenz. Results from univariate logistic regression analyses identified lopinavir and efavirenz inhibitory quotient (IQ) parameters, as well as the baseline lopinavir phenotypic susceptibility, as predictors of antiviral response (HIV RNA < 400 copies/ml at week 24); however, no lopinavir or efavirenz concentration parameter was identified as a predictor. Multiple stepwise logistic regressions confirmed the significance of the IQ parameters, as well as other baseline characteristics, in predicting virologic response at 24 weeks in this patient population.

Once-Daily versus Twice-Daily Lopinavir/Ritonavir in Antiretroviral-Naive HIV-Positive Patients: A 48-Week Randomized Clinical Trial

The safety, pharmacokinetics, and antiviral activity of lopinavir, a human immunodeficiency virus (HIV) protease inhibitor, coformulated with ritonavir as a pharmacokinetic enhancer were evaluated in 38 antiretroviral-naive patients randomized 1:1 to receive open-label lopinavir/ritonavir at a dose of 800/200 mg once daily or 400/100 mg twice daily, each in combination with stavudine and lamivudine twice daily, for 48 weeks. Over the course of 48 weeks, median predose concentrations of lopinavir exceeded the protein-binding corrected concentration required to inhibit replication of wild-type HIV by 50% in vitro by 40- and 84-fold in the once- and twice-daily groups, respectively. Predose concentrations of lopinavir were more variable in the once-daily group (mean +/- SD, 3.62+/-3.38 microg/mL for the once-daily group and 7.13+/-2.93 microg/mL for the twice-daily group). At week 48, in an intent-to-treat (missing = failure) analysis, 74% of patients in the once-daily group and 79% of patients in the twice-daily group had HIV RNA levels of <50 copies/mL (P=.70). Study drug-related discontinuations occurred in 1 patient in each treatment group. Genotypic resistance testing of 4 patients with HIV RNA levels >400 copies/mL between weeks 24 and 48 demonstrated no protease inhibitor-resistance mutations.

A 96-Week Comparison of Lopinavir-Ritonavir Combination Therapy Followed by Lopinavir-Ritonavir Monotherapy versus Efavirenz Combination Therapy

Antiretroviral-naive HIV-1-infected volunteers received zidovudine/lamivudine plus either lopinavir/ritonavir (n=104) or efavirenz (n=51). Lopinavir/ritonavir-treated subjects demonstrating 3 consecutive monthly HIV-1 RNA levels <50 copies/mL started lopinavir/ritonavir monotherapy. In previous-failure=failure analysis, 48% (lopinavir/ritonavir) and 61% (efavirenz) maintained HIV-1 RNA at <50 copies/mL through week 96, (P= .17; 95% confidence interval [CI] for the difference, -29% to 4%); in noncompletion=failure analysis, 60% (lopinavir/ritonavir) and 63% (efavirenz) maintained HIV-1 RNA at <50 copies/mL at week 96 (P= .73; 95% CI for the difference, -19% to 13%). Significant sparing of peripheral lipoatrophy was noted in the lopinavir/ritonavir simplification strategy. This study has provided important information for future studies using treatment simplified to lopinavir/ritonavir monotherapy.

A Once-Daily Lopinavir/Ritonavir-Based Regimen Is Noninferior to Twice-Daily Dosing and Results in Similar Safety and Tolerability in Antiretroviral-Naive Subjects Through 48 Weeks

Background:Lopinavir/ritonavir (LPV/r)-dosed twice daily has demonstrated durable efficacy in antiretroviral-naive and protease inhibitor (PI) -experienced patients. Study M05-730 compared LPV/r tablets dosed once daily vs. twice daily in antiretroviral-naive subjects. Methods:Six hundred sixty-four subjects were randomized to LPV/r soft gel capsules (SGCs) once daily, SGC twice daily, tablets once daily, and tablets twice daily, all with tenofovir and emtricitabine once daily. At week 8, all SGC-treated subjects were switched to tablets, maintaining randomized dose frequency. The primary efficacy analysis used an intent-to-treat, noncompleter = failure approach to assess noninferiority of the LPV/r once-daily group compared with the twice-daily group. Results:At week 48, 77% of once-daily-dosed subjects vs. 76% of twice-daily-dosed subjects had HIV-1 RNA <50 copies per milliliter (P = 0.715; 95% confidence interval for difference: 5% to 8%). Response rates were numerically similar between the once-daily and twice-daily groups among subjects with baseline HIV-1 RNA ≥100,000 copies per milliliter (75% once daily vs. 74.6% twice daily; P > 0.999) or when analyzed by baseline CD4+ T-cell count (<50, 50 to <200, and ≥200 cells/mm3). Rates of discontinuation and adverse events, including diarrhea, were similar between arms. Among subjects with protocol-defined virologic rebound through week 48, no new PI resistance mutations were detected. Conclusions:At 48 weeks, the antiviral response in the LPV/r once-daily group was noninferior to the twice-daily group when coadministered with tenofovir and emtricitabine in antiretroviral-naive subjects. Efficacy was comparable between the once-daily and twice-daily groups regardless of baseline HIV-1 RNA or CD4+ T-cell count. Safety and tolerability of once-daily and twice-daily dosing was also comparable. No new PI resistance mutations were detected upon virologic rebound.

A phase 2a trial of 12-week interferon-free therapy with two direct-acting antivirals (ABT-450/r, ABT-072) and ribavirin in IL28B C/C patients with chronic hepatitis C genotype 1.

BACKGROUND & AIMS ABT-450 (combined with low-dose ritonavir, ABT-450/r) is a potent HCV NS3 protease inhibitor, and ABT-072 is a non-nucleoside NS5B polymerase inhibitor. The goal of this study was to evaluate the safety, tolerability, and efficacy of the peginterferon-free combination of ABT-450/r and ABT-072 with ribavirin in treatment-naïve patients with IL28B CC genotype, infected with HCV genotype 1. METHODS This was a phase 2a, multicenter, open-label, single-arm study in 11 treatment-naïve, non-cirrhotic HCV GT1-infected patients with IL28B rs12979860 genotype CC. Patients received ABT-450/r 150/100 mg once daily and ABT-072 400 mg once daily with weight-based ribavirin 1000-1200 mg/day dosed twice daily for 12 weeks. RESULTS Eight (73%) patients were male, 9 (82%) were Caucasian (including 3 who self-identified as Hispanic); mean baseline HCV RNA was 6.9 log₁₀ IU/ml (range 6.5-7.3 log₁₀ IU/ml). All 11 patients completed 12 weeks of treatment and maintained HCV RNA <25 IU/ml from weeks 4 through 12 of treatment. Ten patients (91%) achieved sustained virologic response 24 weeks post-treatment, with a second patient relapsing 36 weeks post-treatment. There were no deaths, serious or severe adverse events, or premature discontinuations. Adverse events were mostly mild and the most frequent were headache, fatigue, nausea, and dry skin. CONCLUSIONS A 12-week regimen of ABT-450/r and ABT-072 with ribavirin was well tolerated with 9/11 patients achieving sustained virologic response through 36 weeks of post-treatment observation. These findings suggest that peginterferon-free regimens may have the potential to cure a high proportion of HCV genotype 1-infected patients.