Abacavir Hypersensitivity Reaction Reporting Rates During a Decade of HLA-B*5701 Screening as a Risk-Mitigation Measure.

INTRODUCTION: Human leukocyte antigen (HLA)-B*5701 screening identifies patients at increased risk for abacavir (ABC) hypersensitivity reaction (HSR). Screening was adopted in GlaxoSmithKline and ViiV Healthcare clinical trials in 2007 and human immunodeficiency virus treatment guidelines in 2008. Company meta-analyses of trials pre-HLA-B*5701 screening reported HSR rates of 4-8%. We analyzed the effectiveness of HLA-B*5701 screening on reducing HSR rates using clinical trial, Observational Pharmaco-Epidemiology Research & Analysis (OPERA) cohort, and spontaneous reporting data. METHODS: A meta-analysis examined 12 trials in 3063 HLA-B*5701-negative patients receiving an ABC-containing regimen from April 9, 2007, to September 22, 2015. Potential cases were identified using prespecified Medical Dictionary for Regulatory Activities (MedDRA) preferred terms (drug hypersensitivity, hypersensitivity, anaphylactic reaction, anaphylaxis) and adjudicated against a Company ABC HSR case definition. Investigator-diagnosed cases were identified and rates were calculated. In the OPERA cohort, 9619 patients initiating their first ABC-containing regimen from January 1, 1999, to January 1, 2016, were identified. Patients were observed from regimen start until the earliest-following censoring event: ABC discontinuation, loss to follow-up, death, or study end (July 31, 2016). OPERA physicians evaluated events against OPERA definitions for definite/probable cases of ABC HSR; rates were calculated pre- and post-2008. The Company case definition was used to identify spontaneously reported cases for four marketed ABC-containing products; reporting rates were calculated using estimated exposure from sales data, through December 31, 2016. RESULTS: Suspected ABC HSR rates were 1.3% or less in the meta-analysis. In the OPERA cohort, the rate was 0.4% among patients initiating ABC post-2008 versus 1.3% pre-2008 (p<0.0001). Spontaneous reporting rates were low post-2008 (54 to 22 cases per 100,000 patient-years exposure [PYE]) versus pre-2008 (618 to 55 cases per 100,000 PYE). CONCLUSIONS: Clinically suspected ABC HSR rates were 1.3% or less in HLA-B*5701-negative patients. Recognizing their limitations, data from the OPERA cohort and spontaneous reporting indicate that HLA-B*5701 screening has reduced reporting rates of suspected HSR in clinical practice. Where screening for HLA-B*5701 is standard care, patients should be confirmed negative for this allele before starting ABC treatment.

Response by gender of HIV-1-infected subjects treated with abacavir/lamivudine plus atazanavir, with or without ritonavir, for 144 weeks.

PURPOSE: The 144-week results of the open-label, multicenter Atazanavir/Ritonavir Induction with Epzicom Study (ARIES) were stratified by gender to compare treatment responses. METHODS: A total of 369 HIV-infected, antiretroviral-naïve subjects receiving once-daily abacavir/lamivudine + atazanavir/ritonavir (ATV/r) whose HIV-1 RNA was <50 copies/mL by week 30 were randomized 1:1 at week 36 to maintain or discontinue ritonavir for 108 subsequent weeks. Between- and within-treatment gender-related efficacy and safety differences were analyzed. RESULTS: Subjects were 85% male; 64% white; and had a mean age of 39 years, baseline median HIV-1 RNA of 114,815 copies/mL, and median CD4+ cell count of 198 cells/mm3. Gender (ATV [n=189]: 29 females/160 males; ATV/r [n=180]: 25 females/155 males) and most other demographics were similar between groups; more females than males were black (65% vs 25%) and fewer females had baseline HIV-1 RNA ≥100,000 copies/mL (41% vs 58%). At week 144, no significant differences between genders were observed in proportion maintaining HIV-1 RNA <50 copies/mL (ATV, 79% vs 77%; ATV/r, 60% vs 75%) or <400 copies/mL (ATV, 83% vs 84%; ATV/r, 68% vs 82%) (intent-to-treat-exposed: time to loss of virologic response analysis); median CD4+ change from baseline (ATV, +365 vs +300 cells/mm3; ATV/r, +344 vs +301 cells/mm3); proportion with treatment-related grade 2-4 adverse events (baseline to week 144: ATV, 41% vs 31%; ATV/r, 36% vs 43%; weeks 36 to 144: ATV, 14% vs 13%; ATV/r, 24% vs 23%); or proportion developing fasting lipid changes. Female and male virologic failure rates (ATV, 0 vs 5; ATV/r, 2 vs 4) and proportions completing the study were similar during the extension phase. Primary withdrawal reasons were loss to follow-up and pregnancy for females and loss to follow-up and other for males. CONCLUSION: Over 144 weeks, no significant gender differences were observed in efficacy, safety, or fasting lipid changes with abacavir/lamivudine +ATV or abacavir/lamivudine +ATV/r.

Steady-state pharmacokinetics, cord blood concentrations, and safety of ritonavir-boosted fosamprenavir in pregnancy.

Steady-state pharmacokinetics in pregnant women prescribed ritonavir-boosted fosamprenavir (FPV) to prevent HIV transmission were assessed in the second trimester, third trimester, and postpartum. Compared with postpartum, geometric mean amprenavir (APV, FPVs active metabolite) area under the plasma concentration-time curves were 35% lower in the second trimester and 25% lower in the third trimester. Maternal APV concentrations were 9- to 15-fold above the mean APV protein-adjusted 50% inhibitory concentration for wild-type HIV. Median ratio of cord blood/maternal APV levels was 0.27, and all infants were HIV negative. FPV/ritonavir during pregnancy was well tolerated and led to virologic suppression.

Inflammatory biomarker changes and their correlation with Framingham cardiovascular risk and lipid changes in antiretroviral-naive HIV-infected patients treated for 144 weeks with abacavir/lamivudine/atazanavir with or without ritonavir in ARIES.

Propensity for developing coronary heart disease (CHD) is linked with Framingham-defined cardiovascular risk factors and elevated inflammatory biomarkers. Cardiovascular risk and inflammatory biomarkers were evaluated in ARIES, a Phase IIIb/IV clinical trial in which 515 antiretroviral-naive HIV-infected subjects initially received abacavir/lamivudine + atazanavir/ritonavir for 36 weeks. Subjects who were virologically suppressed by week 30 were randomized 1:1 at week 36 to either maintain or discontinue ritonavir for an additional 108 weeks. Framingham 10-year CHD risk scores (FRS) and risk category of <6% or ≥6%, lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), interleukin-6 (IL-6), and high-sensitivity C-reactive protein (hsCRP) were assessed at baseline, week 84, and week 144. Biomarkers were stratified by FRS category. When ritonavir-boosted/nonboosted treatment groups were combined, median hsCRP did not change significantly between baseline (1.6 mg/liter) and week 144 (1.4 mg/liter) in subjects with FRS <6% (p=0.535) or with FRS ≥6% (1.9 mg/liter vs. 2.0 mg/liter, respectively; p=0.102). Median IL-6 was similar for subjects with FRS <6% (p=0.267) at baseline (1.6 pg/ml) and week 144 (1.4 pg/ml) and for FRS ≥6% (2.0 pg/ml vs. 2.2 pg/ml, respectively; p=0.099). Median Lp-PLA(2) decreased significantly (p<0.001) between baseline (197 nmol/min/ml) and week 144 (168 nmol/min/ml) in subjects with FRS <6% and with FRS ≥6% (238 nmol/min/ml vs. 175 nmol/min/ml, respectively; p<0.001). In conclusion, in antiretroviral-naive subjects treated with abacavir-based therapy for 144 weeks, median inflammatory biomarker levels for hsCRP and IL-6 generally remained stable with no significant difference between baseline and week 144 for subjects with either FRS <6% or FRS ≥6%. Lp-PLA(2) median values declined significantly over 144 weeks for subjects in either FRS stratum.

Impact of comorbidities and drug therapy on development of renal impairment in a predominantly African American and Hispanic HIV clinic population.

PURPOSE: Renal impairment in human immunodeficiency virus (HIV)-infected patients could potentially be caused by many factors. HIV-related renal impairment risks have been little studied in African Americans and Hispanics. We investigated the impact of HIV itself, highly active antiretroviral therapy (HAART), comorbidities, and non-HIV-related drug treatment on glomerular filtration rate in a predominantly African American/Hispanic HIV-infected population who had received HAART for at least one year. This study was a retrospective electronic medical record database evaluation of renal impairment risks in a largely African American/Hispanic HIV population obtaining medical care at an HIV clinic in Dallas, Texas. METHODS: Proportional hazards models were used to investigate an association between an estimated glomerular filtration rate decrease >25% from baseline (ie, renal impairment) and demographics, antiretroviral/nonantiretroviral medications, comorbidities (hypertension, diabetes mellitus, hepatitis C virus [HCV] infection, hepatitis B virus [HBV] infection), CD4+ counts, viral load, and duration patients were monitored at the clinic (time on study). RESULTS: In total, 323 patients were evaluated: 82% males; 61% African American/12% Hispanic/19% Caucasian; mean age 37.9 years (standard deviation [SD] 8.5); 6% HBV-positive; 34% HCV-positive; 29% hypertensive; 3% diabetic; 52% tenofovir-treated; mean weight 75.4 kg (SD, 15.4); mean estimated glomerular filtration 114.5 mL/min/1.73 m(2) (SD, 36.7) using the Modification of Diet in Renal Disease (MDRD) calculation method; mean creatinine clearance (from which estimated glomerular filtration was extrapolated) by the Cockcroft-Gault calculation method 120.6 mL/min/1.73 m(2) (SD, 41.2); mean time on study 2.7 years (SD, 1.0 year). An estimated glomerular filtration rate decrease of >25% from baseline was significantly associated with time on study (P = 0.0017; hazards ratio [HR] = 0.999) and hypertension (HR = 1.706; P = 0.0158) by the MDRD method, and with age (HR = 1.039; P = 0.0077), weight (HR = 0.987; P = 0.0023), and time on study (HR = 0.999; P = 0.0043) by extrapolation of Cockcroft-Gault creatinine clearance calculation. No specific HAART agent was associated with significant renal impairment risk by the definition used in this study. CONCLUSION: This retrospective database study showed time on study, hypertension, weight, and age to be the only significant predictors of an estimated glomerular filtration rate decrease >25% from baseline.

Characteristics of foot fractures in HIV-infected patients previously treated with tenofovir versus non-tenofovir-containing highly active antiretroviral therapy.

In a retrospective case series study, medical records were evaluated for all male patients infected with human immunodeficiency virus (HIV) diagnosed over a one-year period with foot fractures (n = 30) confirmed by magnetic resonance imaging at a Los Angeles outpatient private practice rheumatology clinic. Proportionally more patients had received tenofovir prefracture (17 [57%]) than those who had not (13 [43%]). At fracture diagnosis, these two groups were similar in median age (49 versus 48 years), HIV-1 RNA (both 1.7 log(10) copies/mL), CD4 count (300 versus 364/mm(3)), time between HIV diagnosis and foot fracture (both 17 years), family history of degenerative bone disease (24% versus 23%), prevalence of malabsorption syndrome, renal failure, calcium deficiency, or vitamin D deficiency, and concurrent use of bisphosphonates, calcitonin, and diuretics. However, more tenofovir-treated patients had osteoporosis (35% versus 8%), stress-type fractures (53% versus 31%), concurrent fractures (12% versus 0%), wasting syndrome (29% versus 15%), truncal obesity (18% versus 8%), smoked cigarettes (more than one pack/day for more than one year; 35% versus 8%), dual energy X-ray absorptiometry (DEXA) T scores < -2.4 (denoting osteoporosis) at the femur (24% versus 9%) and spine (47% versus 36%), and had received protease inhibitors (71% versus 46%), non-nucleoside reverse transcriptase inhibitors (24% versus 0%), prednisone (24% versus 0%), testosterone (47% versus 23%), and teriparatide (29% versus 8%). Median time from tenofovir initiation until fracture was 2.57 (range 1.17-5.69) years. In conclusion, more foot fractures were observed in tenofovir-treated patients than in non-tenofovir-treated patients with HIV infection. Comorbidities and/or coadministered drugs may have been contributory.

Impact of low abundance HIV variants on response to ritonavir-boosted atazanavir or fosamprenavir given once daily with tenofovir/emtricitabine in antiretroviral-naive HIV-infected patients.

Population genotyping (PG) can underestimate resistance if resistance-containing low abundance variants go undetected. PG and clonal analysis (CA) results were compared in virologic failures (VFs) from a 48-week clinical trial that evaluated once-daily fosamprenavir/ritonavir (FPV/r) 1400 mg/100 mg or atazanavir/ritonavir (ATV/r) 300 mg/100 mg, each combined with tenofovir/emtricitabine, in antiretroviral-naive patients. VF was defined as confirmed HIV-1 RNA > or =400 copies/ml at > or =24 weeks or viral rebound >400 copies/ml any time following viral suppression. All patients had baseline PG. One hundred and six patients enrolled (53/arm). Baseline resistance mutations were more prevalent in patients receiving FPV/r (10/53) than ATV/r (3/53). Seven patients (7%) were VFs-four on FPV/r and three on ATV/r. In the four FPV/r-treated VFs, baseline HIV TAMs combinations and/or PI mutations were detected in one by PG at VF (RT: L210W + T215C; PR: M46I + L76V) and three others by CA alone (RT: L210W + T215Y; RT: M41L; RT: K65R + K70R; PR: I47V); all four had study drug-associated mutations (CA detecting more HIV-1 resistance mutations than PG). In the three ATV/r VFs, no baseline drug-associated mutations were detected by PG; for one patient CA detected RT: K65R; PR: I84V. Phylogenetic analysis revealed tight clustering for FPV/r-treated VFs with highly related clones, whereas HIV-1 from ATV/r-treated VFs had no outgrowth from baseline of low abundance resistance-containing variants. In conclusion, low-abundance HIV resistance-containing variants were detected in baseline samples from patients with VF. The archived viruses that reemerged under selection pressure and acquired additional mutations were found primarily in patients in the FPV/r arm. Despite this and a baseline resistance imbalance between the two arms, FPV/r and ATV/r provided similar virologic suppression through 48 weeks; however, these findings highlight the necessity for the development of quick and inexpensive methods for detection of minority species to better guide therapy selection.

Steady-state amprenavir, tenofovir, and emtricitabine pharmacokinetics before and after reducing ritonavir boosting of a fosamprenavir/tenofovir/emtricitabine regimen from 200 mg to 100 mg once daily (TELEX II).

PURPOSE: Evaluate how reducing ritonavir (RTV) boosting from 200 mg to 100 mg once daily (QD) affects steady-state pharmacokinetics of components of a fosamprenavir (FPV)-based regimen. METHODS: Prospective, open-label, pharmacokinetic study in 12 HIV-infected patients stabilized on FPV/RTV 1400 mg/200 mg + tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) 300 mg/200 mg QD (TELEX II). Pharmacokinetics were assessed by noncompartmental analysis at baseline and 4 weeks after RTV reduction to 100 mg QD. RESULTS: Baseline median minimum plasma concentration (Cmin) and area under the plasma concentration-time curve over 24 hours post dose (AUC24h) were as follows: APV: 1,708 ng/mL, 84,260 h * ng/mL; tenofovir: 53 ng/mL, 2,420 h * ng/mL; FTC: 58 ng/mL, 9,190 h * ng/mL; RTV: 80 ng/mL, 10,230 h * ng/mL. Four weeks after reducing RTV, changes in Cmin and AUC24h were: APV: +26%, +0.6%; tenofovir: +77%, +30%; FTC: +188%, +13%; RTV -64%, -79%. Component plasma concentration ranges were consistent with historical values. Median APV Cmin was 14.7-fold above the protein-binding-adjusted 50% inhibitory concentration of wild-type HIV. Four weeks after RTV reduction, HIV-1 RNA levels remained <50 copies/mL in all patients, median CD4+ count increased from 465 to 495 cells/mm3, and favorable lipid changes and no adverse events were observed. CONCLUSION: Reducing RTV boosting from 200 to 100 mg QD of FPV/TDF/FTC QD conferred no detrimental effect on APV, tenofovir, FTC, or RTV pharmacokinetics and maintained virologic suppression.

Predictive value of pharmacokinetics-adjusted phenotypic susceptibility on response to ritonavir-enhanced protease inhibitors (PIs) in human immunodeficiency virus-infected subjects failing prior PI therapy.

The activities of protease inhibitors in vivo may depend on plasma concentrations and viral susceptibility. This nonrandomized, open-label study evaluated the relationship of the inhibitory quotient (IQ [the ratio of drug exposure to viral phenotypic susceptibility]) to the human immunodeficiency virus type 1 (HIV-1) viral load (VL) change for ritonavir-enhanced protease inhibitors (PIs). Subjects on PI-based regimens replaced their PIs with ritonavir-enhanced indinavir (IDV/r) 800/200 mg, fosamprenavir (FPV/r) 700/100 mg, or lopinavir (LPV/r) 400/200 mg twice daily. Pharmacokinetics were assessed at day 14; follow-up lasted 24 weeks. Associations between IQ and VL changes were examined. Fifty-three subjects enrolled, 12 on IDV/r, 33 on FPV/r, and 8 on LPV/r. Median changes (n-fold) (FC) of 50% inhibitory concentrations (IC(50)s) to the study PI were high. Median 2-week VL changes were -0.7, -0.1, and -1.0 log(10) for IDV/r, FPV/r, and LPV/r. With FPV/r, correlations between the IQ and the 2-week change in VL were significant (Spearman's r range, -0.39 to -0.50; P < or = 0.029). The strongest correlation with response to FPV/r was the IC(50) FC (r = 0.57; P = 0.001), which improved when only adherent subjects were included (r = 0.68; P = 0.001). In multivariable analyses of the FPV/r arm that included FC, one measure of the drug concentration, corresponding IQ, baseline VL, and CD4, the FC to FPV was the only significant predictor of VL decline (P < 0.001). In exploratory analyses of all arms, the area under the concentration-time curve IQ was correlated with the week 2 VL change (r = -0.72; P < 0.001). In conclusion, in PI-experienced subjects with highly resistant HIV-1, short-term VL responses to RTV-enhanced FPV/r correlated best with baseline susceptibility. The IQ improved correlation in analyses of all arms where a greater range of virologic responses was observed.

Comparison of once-daily fosamprenavir boosted with either 100 or 200 mg of ritonavir, in combination with abacavir/lamivudine: 96-week results from COL100758.

The long-term efficacy of once-daily (qd) fosamprenavir (FPV) 1400 mg boosted by ritonavir 100 mg (FPV/r100) has not been evaluated previously. A 96-week open-label, randomized, multicenter study compared the efficacy/safety of FPV/r100 with FPV 1400 mg boosted by ritonavir 200 mg qd (FPV/r200), plus abacavir/lamivudine 600 mg/300 mg qd, in antiretroviral-naive, HIV-infected patients with viral load (VL)> or =1000 copies/ml. Primary endpoints were proportion of patients achieving VL <400 copies/ml or discontinuing for drug-related reasons. In the intent-to-treat:exposed (ITT-E) population, missing = failure (M = F), and observed approaches were used to assess between-arm differences in VL responses by Cochran-Mantel-Haenszel test and CD4(+) count by Wilcoxon rank-sum test. One hundred and fifteen (115) patients enrolled, with 58 on FPV/r100 (median VL 4.7 log(10) copies/ml; CD4(+) count 259 cells/mm(3)) and 57 on FPV/r200 (median VL 4.9 log(10) copies/ml; CD4(+) count 179 cells/mm(3)). Fewer FPV/r100-treated patients discontinued treatment prematurely (12 vs. 24) and experienced virologic failure (5 vs. 8, none developing major protease inhibitor resistance mutations). At week 96, more FPV/r100-treated patients had VL <400 copies/ml [ITT-E,M = F: 78% (45/58) vs. 53% (30/57), p = 0.006; observed: 98% (45/46) vs. 94% (30/32)] and VL<50 copies/ml [ITT-E,M = F: 66% (38/58) vs. 53% (30/57); observed: 83% (38/46) vs. 94% (30/32)]. The FPV/r100 and FPV/r200 arms were similar at week 96 regarding median change from baseline in CD4(+) count (+265 vs. +260 cells/mm(3)) and total cholesterol (+33 vs. +35 mg/dl), and in total-cholesterol:HDL-cholesterol ratio (4.0 vs. 4.1) and type/frequency of treatment-related grade 2-4 adverse events, although FPV/r100 was associated with a lower elevation in triglycerides (+27 vs. +48 mg/dl). In conclusion, through 96 weeks, FPV/r100 was more effective and prompted less elevation in triglycerides than FPV/r200.

A review of the pharmacokinetics of abacavir.

Abacavir is a carbocyclic 2'-deoxyguanosine nucleoside reverse transcriptase inhibitor that is used as either a 600-mg once-daily or 300-mg twice-daily regimen exclusively in the treatment of HIV infection. Abacavir is rapidly absorbed after oral administration, with peak concentrations occurring 0.63-1 hour after dosing. The absolute bioavailability of abacavir is approximately 83%. Abacavir pharmacokinetics are linear and dose-proportional over the range of 300-1200 mg/day. To date, one study has assessed the steady-state pharmacokinetics of abacavir following a 600-mg once-daily regimen, and reported a geometric mean steady-state abacavir peak concentration of 3.85 microg/mL. Although this concentration is higher than the steady-state abacavir peak concentration reported following a 300-mg twice-daily regimen (0.88-3.19 microg/mL, depending on the study), the geometric mean steady-state abacavir exposure over 24 hours was similar following these regimens. Coadministration with food has no significant effect on abacavir exposure; therefore, abacavir may be administered with or without food.The apparent volume of distribution of abacavir after intravenous administration is approximately 0.86 +/- 0.15 L/kg, suggesting that abacavir is distributed to extravascular spaces. Binding to plasma proteins is about 50% and is independent of the plasma abacavir concentration. Abacavir is extensively metabolized by the liver; less than 2% is excreted as unchanged drug in the urine. Abacavir is primarily metabolized via two pathways, uridine diphosphate glucuronyltransferase and alcohol dehydrogenase, resulting in the inactive glucuronide metabolite (361W94, ~36% of the dose recovered in the urine) and the inactive carboxylate metabolite (2269W93, approximately 30% of the dose recovered in the urine). The remaining 15% of abacavir equivalents found in the urine are minor metabolites, each less than 2% of the total dose. Faecal elimination accounts for about 16% of the dose. The terminal elimination half-life of abacavir is approximately 1.5 hours. The antiviral effect of abacavir is due to its intracellular anabolite, carbovir-triphosphate (CBV-TP). When assessed by validated high-performance liquid chromatography electrospray ionization tandem mass spectrometry, CBV-TP has been shown to have a long elimination half-life (>20 hours), supporting once-daily dosing. The mean CBV-TP trough concentrations do not differ following abacavir 600-mg once-daily and 300-mg twice-daily regimens. Limited data are available for abacavir in subjects with renal dysfunction or hepatic impairment. Abacavir pharmacokinetics in HIV-infected subjects with end-stage renal disease were found to be no different from those observed in healthy adults; this finding was consistent with the kidney being a minor route of abacavir elimination. A study of abacavir pharmacokinetics in hepatically impaired adults (Child-Pugh score of 5-6) showed that the abacavir area under the plasma concentration-time curve and elimination half-life were 89% and 58% greater, respectively, suggesting that the daily dose of abacavir should be reduced in patients with mild hepatic impairment (Child-Pugh score of 5-6). Abacavir pharmacokinetics have not been studied in patients with higher Child-Pugh scores. Abacavir is not significantly metabolized by cytochrome P450 (CYP) enzymes, nor does it inhibit these enzymes. Therefore, clinically significant drug interactions between abacavir and drugs metabolized by CYP enzymes are unlikely. The potential for drug interactions is no different when abacavir is used as a once-daily regimen versus a twice-daily regimen. No clinically significant drug interactions have been observed between recommended doses of abacavir and lamivudine, zidovudine, alcohol (ethanol) or methadone.

Randomized study of dual versus single ritonavir-enhanced protease inhibitors for protease inhibitor-experienced patients with HIV.

PURPOSE: To compare activity and safety of a regimen containing lopinavir/ritonavir (LPV/r) + fosamprenavir (FPV) to regimens with LPV/r or FPV + r and to test the hypothesis that a ritonavir-enhanced dual protease inhibitor (PI) regimen has better antiviral activity. METHOD: This study was a multicenter, open-label, randomized study. HIV-infected adults with prior PI failure were selectively randomized based on prior PI experience to either LPV/r, FPV + r, or LPV/r + FPV. All patients received tenofovir DF and 1 to 2 nucleoside reverse transcriptase inhibitors. RESULTS: Baseline characteristics were similar across arms. Study enrollment and follow-up were stopped early (N = 56) because pharmacokinetic analyses showed significantly lower LPV and FPV exposures in the dual-PI arm. At Week 24, proportions achieving >1 log10 decline in HIV RNA or <50 copies/mL in the dual-PI versus single-PI arms combined were 75% vs. 61% in intent-to-treat (ITT, p = .17) and 100% vs. 64% in as-treated (AT) analyses (p = .02), respectively. Median CD4+ T cell/mm3 increases were 81 vs. 41 (ITT, p = .4) and 114 vs. 43 (AT, p = .08), respectively. Clinical events and toxicity rates were not different between arms. CONCLUSION: The trial was unable to show a difference between dual versus single PIs in ITT analyses but favored dual PIs in AT analyses.

Fosamprenavir or atazanavir once daily boosted with ritonavir 100 mg, plus tenofovir/emtricitabine, for the initial treatment of HIV infection: 48-week results of ALERT.

BACKGROUND: Once-daily (QD) ritonavir 100 mg-boosted fosamprenavir 1400 mg (FPV/r100) or atazanavir 300 mg (ATV/r100), plus tenofovir/emtricitabine (TDF/FTC) 300 mg/200 mg, have not been compared as initial antiretroviral treatment. To address this data gap, we conducted an open-label, multicenter 48-week study (ALERT) in 106 antiretroviral-naïve, HIV-infected patients (median HIV-1 RNA 4.9 log10 copies/mL; CD4+ count 191 cells/mm3) randomly assigned to the FPV/r100 or ATV/r100 regimens. RESULTS: At baseline, the FPV/r100 or ATV/r100 arms were well-matched for HIV-1 RNA (median, 4.9 log10 copies/mL [both]), CD4+ count (mean, 176 vs 205 cells/mm3). At week 48, intent-to-treat: missing/discontinuation = failure analysis showed similar responses to FPV/r100 and ATV/r100 (HIV-1 RNA < 50 copies/mL: 75% (40/53) vs 83% (44/53), p = 0.34 [Cochran-Mantel-Haenszel test]); mean CD4+ count change-from-baseline: +170 vs +183 cells/mm3, p = 0.398 [Wilcoxon rank sum test]). Fasting total/LDL/HDL-cholesterol changes-from-baseline were also similar, although week 48 median fasting triglycerides were higher with FPV/r100 (150 vs 131 mg/dL). FPV/r100-treated patients experienced fewer treatment-related grade 2-4 adverse events (15% vs 57%), with differences driven by ATV-related hyperbilirubinemia. Three patients discontinued TDF/FTC because their GFR decreased to <50 mL/min. CONCLUSION: The all-QD regimens of FPV/r100 and ATV/r100, plus TDF/FTC, provided similar virologic, CD4+ response, and fasting total/LDL/HDL-cholesterol changes through 48 weeks. Fewer FPV/r100-treated patients experienced treatment-related grade 2-4 adverse events.

Amprenavir and lopinavir pharmacokinetics following coadministration of amprenavir or fosamprenavir with lopinavir/ritonavir, with or without efavirenz.

BACKGROUND: Amprenavir (APV), fosamprenavir (FPV), lopinavir (LPV), ritonavir (RTV) and efavirenz (EFV) are to varying degrees substrates, inducers and inhibitors of CYP3A4. Coadministration of these drugs might result in complex pharmacokinetic drug-drug interactions. METHODS: Two prospective, open-label, non-randomized studies evaluated APV and LPV steady-state pharmacokinetics in HIV-infected patients on APV 750 mg twice daily + LPV/RTV 533/133 mg twice daily with EFV (n=7) or without EFV (n=12) + background nucleosides (Study 1) and after switching FPV 1,400 mg twice daily for APV (n=10) (Study 2). RESULTS: In Study 1 EFV and non-EFV groups did not differ in APV minimum plasma concentration (Cmin; 1.10 versus 1.06 microg/ml, P = 0.89), area under the concentration-time curve (AUC; 17.46 versus 24.34 microg x h/ml, P = 0.22) or maximum concentration (Cmax; 2.61 versus 4.33 microg/ml, P = 0.08); for LPV there was no difference in Cmin, (median: 3.66 versus 6.18 microg/ml, P = 0.20), AUC (81.84 versus 93.75 microg x h/ml, P = 0.37) or Cmax (10.36 versus 10.93 microg/ml, P = 0.61). In Study 2, after switching from APV to FPV, APV Cmin increased by 58% (0.83 versus 1.30 microg/ml, P = 0.0001), AUC by 76% (19.41 versus 34.24 micorg x h/ml, P = 0.0001), and Cmax by 75% (3.50 versus 6.14, P = 0.001). Compared with historical controls, LPV and RTV pharmacokinetics were not changed. All treatment regimens were well tolerated. Seven of eight completers (88%) maintained HIV-1 RNA <400 copies/ml 12 weeks after the switch (1 lost to follow up). CONCLUSIONS: EFV did not appear to significantly alter APV and LPV pharmacokinetic parameters in HIV-infected patients taking APV 750 mg twice daily + LPV 533/133 mg twice daily. Switching FPV 1400 mg twice daily for APV 750 mg twice daily resulted in an increase in APV Cmin, AUC, and Cmax without changing LPV or RTV pharmacokinetics or overall tolerability.

Atovaquone plus cholestyramine in patients coinfected with Babesia microti and Borrelia burgdorferi refractory to other treatment.

Ten percent of US patients with Lyme disease are coinfected with Babesia microti. A double-blind, placebo-controlled, crossover trial enrolled 25 patients with confirmed Borrelia burgdorferi/B microti coinfection, abnormal visual contrast sensitivity (VCS), and persistent symptoms despite prior treatment with atovaquone and azithromycin. Patients were randomly assigned to atovaquone suspension or placebo plus cholestyramine for 3 weeks, were crossed over for 3 weeks, and then received open-label atovaquone and cholestyramine for 6 weeks. Symptoms and VCS scores were recorded at baseline and after weeks 3, 6, 9, and 12. Improvements in symptoms and VCS deficits were observed only after at least 9 weeks of treatment. At week 12, 5 patients were asymptomatic, and 16 had a notable reduction in the number of symptoms. The entire cohort demonstrated significant increases in VCS scores. Adverse effects were rare. Patients coinfected with B burgdorferi and B microti derive measurable clinical benefit from prolonged treatment with atovaquone and cholestyramine. Longer-term combination therapy may be indicated.

Abacavir, efavirenz, didanosine, with or without hydroxyurea, in HIV-infected adults failing initial nucleoside/protease inhibitor-containing regimens.

BACKGROUND: Hydroxyurea (HU) is an immunomodulatory agent that has been documented to enhance the antiretroviral activity of nucleoside reverse transcriptase inhibitors, such as abacavir (ABC) and didanosine (ddI), and would be expected to improve virologic efficacy. METHODS: A 48-week, phase IV, multicenter, open-label, proof-of-concept clinical trial was conducted to evaluate second-line, protease inhibitor (PI)-sparing therapy with ABC/efavirenz (EFV)/ddI plus HU or without HU in HIV-infected subjects failing to achieve HIV-1 RNA < or = 400 copies/mL after > or = 16 weeks of treatment with lamivudine/zidovudine or lamivudine/stavudine, plus 1 or 2 PIs. Subjects were assigned to ABC (300 mg twice daily)/ EFV (600 mg once daily)/ ddI (400 mg once daily) plus HU (500 mg twice daily) (n = 30) or this regimen without HU (n = 24). RESULTS: Baseline mean HIV-1 RNA was 3.86 log10 copies/mL and CD4+ cell count was 345 cells/mm3. A similar percentage of subjects in the non-HU arm (58%) and HU arm (53%) completed the study. Intent-to-treat: missing = failure analysis showed no differences in proportions of subjects in the non-HU and HU arms achieving undetectable plasma HIV-1 RNA levels at week 24 (< 400 copies/mL: 58% [14/24] vs 57% [17/30], P = 0.899; < 50 copies/mL (50% [12/24] vs 47% [14/30], P = 0.780). Median change from baseline in CD4+ cell count in the non-HU and HU arms at week 48 was +114 cells/mm3 and -63 cells/mm3 (P = 0.007), respectively. Both regimens were generally well tolerated, although more subjects in the HU arm withdrew prematurely from the study due to adverse events (23% vs 4%). Four cases of possible ABC-related hypersensitivity were observed. CONCLUSION: ABC/EFV/ddI was an effective and well-tolerated second-line regimen for nucleoside/PI-experienced HIV-infected subjects. The addition of HU blunted the CD4+ cell response, did not appear to enhance antiviral activity, and resulted in more treatment-limiting adverse events.

Substituting abacavir for hyperlipidemia-associated protease inhibitors in HAART regimens improves fasting lipid profiles, maintains virologic suppression, and simplifies treatment.

BACKGROUND: Hyperlipidemia secondary to protease inhibitors (PI) may abate by switching to anti-HIV medications without lipid effects. METHOD: An open-label, randomized pilot study compared changes in fasting lipids and HIV-1 RNA in 104 HIV-infected adults with PI-associated hyperlipidemia (fasting serum total cholesterol >200 mg/dL) who were randomized either to a regimen in which their PI was replaced by abacavir 300 mg twice daily (n = 52) or a regimen in which their PI was continued (n = 52) for 28 weeks. All patients had undetectable viral loads (HIV-1 RNA <50 copies/mL) at baseline and were naive to abacavir and non-nucleoside reverse transcriptase inhibitors. RESULTS: At baseline, the mean total cholesterol was 243 mg/dL, low density lipoprotein (LDL)-cholesterol 149 mg/dL, high density lipoprotein (HDL)-cholesterol 41 mg/dL, and triglycerides 310 mg/dL. Mean CD4+ cell counts were 551 and 531 cells/mm3 in the abacavir-switch and PI-continuation arms, respectively. At week 28, the abacavir-switch arm had significantly greater least square mean reduction from baseline in total cholesterol (-42 vs -10 mg/dL, P < 0.001), LDL-cholesterol (-14 vs +5 mg/dL, P = 0.016), and triglycerides (-134 vs -36 mg/dL, P = 0.019) than the PI-continuation arm, with no differences in HDL-cholesterol (+0.2 vs +1.3 mg/dL, P = 0.583). A higher proportion of patients in the abacavir-switch arm had decreases in protocol-defined total cholesterol and triglyceride toxicity grades, whereas a smaller proportion had increases in these toxicity grades. At week 28, an intent-to treat: missing = failure analysis showed that the abacavir-switch and PI-continuation arms did not differ significantly with respect to proportion of patients maintaining HIV-1 RNA <400 or <50 copies/mL or adjusted mean change from baseline in CD4+ cell count. Two possible abacavir-related hypersensitivity reactions were reported. No significant changes in glucose, insulin, insulin resistance, C-peptide, or waist-to-hip ratios were observed in either treatment arm, nor were differences in these parameters noted between treatments. CONCLUSION: In hyperlipidemic, antiretroviral-experienced patients with HIV-1 RNA levels <50 copies/mL and CD4+ cell counts >500 cells/mm3, substituting abacavir for hyperlipidemia-associated PIs in combination antiretroviral regimens improves lipid profiles and maintains virologic suppression over a 28-week period, and it simplifies treatment.