Changes in darunavir/r resistance score after previous failure to tipranavir/r in HIV-1-infected multidrug-resistant patients.

OBJECTIVES: To evaluate changes in resistance to tipranavir/r (TPV/r) and darunavir/r (DRV/r) in patients who had failed a TPV/r-including regimen. METHODS: HIV genotypes obtained both at baseline and at tipranavir/r failure (TPVF) were analyzed in 47 HIV-infected patients failing a TPV/r-including regimen. Genotypes were evaluated through the Stanford mutation score: patients were ranked for TPV/r and DRV/r resistance as susceptible (class 1), potential low-level (class 2), low-level (class 3), intermediate-level (class 4), and high-level resistance (class 5). Values are expressed as median (interquartile range) or as frequency (%). RESULTS: Forty-seven patients were eligible. At baseline (tipranavir initiation), the scoring for TPV/r was: class 3 = 4 (8.5%); class 4 = 31 (66%); and class 5 = 12 (25.5%). Corresponding scores for DRV/r were: class 2 = 1 (2%), class 3 = 12 (25.5%), class 4 = 32 (68%), and class 5 = 2 (4.5%). At TPVF, a shift toward a higher TPV/r scoring class was seen in 16 (34.1%) patients (P = 0.001), whereas a shift toward a higher DRV/r scoring class was observed in 9 (19.2%) patients (P = 0.2381). After TPVF, 25/47 patients (53%) were treated with a DRV/r-containing regimen. After 24 weeks (on-treatment analysis), the median HIV RNA decrease was 3.04 (2.13-3.45) log10 copies per milliliter in DRV/r group versus -0.04 (-0.44; 0.50) log10 copies per milliliter in patients not treated with a DRV/r-containing regimen (P < 0.0001); CD4 increase was 126 (70-169) cells per cubic millimeter in DRV/r group versus -42 (-121; 42) (P < 0.0001). DISCUSSION: Treatment with TPV/r did not significantly increase the resistance score to DRV/r and did not preclude the efficacy of subsequent treatment with DRV/r.

Steady-state pharmacokinetics of atazanavir given alone or in combination with saquinavir hard-gel capsules or amprenavir in HIV-1-infected patients.

OBJECTIVE: The aim of this pilot study was to examine the pharmacokinetics of atazanavir (ATV) when given in combination with amprenavir (APV) or saquinavir hard-gel capsules (SQV) to human immunodeficiency virus (HIV)-positive patients. METHODS: Included in the study were 34 HIV-infected patients enrolled in the ATV Early Access Program, who were treated with unboosted ATV alone (group 1) or with the double protease inhibitor combinations, ATV plus APV (group 2) or ATV plus SQV (group 3). ATV was given at a daily dose of 400 mg q.d. with the morning meal with SQV 1200 mg per day or APV 1200 mg per day. Serial blood samples for steady-state ATV pharmacokinetics were collected before the morning dose and at 1, 2, 3, 6, 8 and 24 h post-dosing. ATV plasma concentrations were measured using a high-performance liquid chromatography method with ultraviolet detection. RESULTS: Of the patients, 12 received ATV as a single protease inhibitor; 12 received ATV in combination with APV; and 10 in combination with SQV. Geometric mean (coefficient of variation) ATV C(trough) was 110 ng/ml (2.38), 86 ng/ml (0.84) and 149 ng/ml (2.01) in groups 1, 2 and 3, respectively. ATV C(trough) in both double protease inhibitor combination regimens was not significantly different from that as a single protease inhibitor [geometric mean ratio (GMR): 0.77; 95% confidence interval (CI): 0.38-1.58, P=not significant for group 2 versus group 1 and 1.34, 0.40-4.49, P=not significant, for group 3 versus group 1). Patients treated with ATV plus APV had a 40.2% lower ATV C(max) and a 30.8% smaller ATV AUC than the reference group treated with unboosted ATV alone: both these differences were statistically significant (GMR, 95% CI: 0.59, 0.41-0.85, P=0.005 and 0.69, 0.48-0.99, P=0.056, respectively). No difference was observed for either C(max) or AUC between the group treated with ATV plus SQV and the reference group (GMR, 95% CI: 0.78, 0.47-1.30, P=not significant and 1.24, 0.73-2.10, P=not significant, respectively). CONCLUSION: ATV pharmacokinetics does not seem to be influenced by the concomitant administration of SQV, whereas APV significantly lowers plasma ATV levels.

Evaluation of atazanavir Ctrough, atazanavir genotypic inhibitory quotient, and baseline HIV genotype as predictors of a 24-week virological response in highly drug-experienced, HIV-infected patients treated with unboosted atazanavir.

The objective of this study was to evaluate virological and pharmacological determinants of a 24-week virological response to unboosted atazanavir (ATV) in highly drug-experienced HIV-infected patients. Among patients enrolled in the ATV Expanded Access Program, those with HIV-RNA >1000 copies/mL, a genotype performed within three months from the baseline (BL), and who completed 24 weeks of treatment, were included. They received at least three antiretrovirals, including ATV 400 mg once daily without boosting. ATV plasma levels were evaluated after four weeks of treatment by high performance liquid chromatography (HPLC). ATV genotypic inhibitory quotient (GIQ) was calculated as the ratio between ATV Ctrough and the number of the BL ATV-related protease resistance mutations (among the following: 10I/V/F, 20R/M/I, 24I, 331/F/V, 36I/L/V, 46I/L, 48V, 54V/L, 63P, 71V/T/I, 73C/S/T/A, 82A/F/S/T, 84V, and 90M). Thirty-five subjects were included. At baseline, median (interquartile range) CD4+ T-lymphocytes, HIV-RNA, and ATV resistance mutations were 232.5 (106-303)/microL, 4.7 (4.2-5.1) log10 copies/mL, 2 (1-6), respectively. Thirteen (37.1%) subjects were off-therapy and 11 (31.4%) showed no PI mutation at baseline. Median steady-state ATV Ctrough was 230 ng/mL (87-520), for an ATV GIQ of 86.5 (25.5-165.5). Median HIV-RNA changes from baseline at weeks 4, 12 and 24 were -1.76 (from -0.44 to -2.12), -1.41 (from -0.41 to -2.81) and -1.44 (from -0.42 to -2.71) log10, respectively. The HIV-RNA changes were correlated to the number of ATV resistance mutations at each time point (P < 0.05), whereas no correlation was found between ATV Ctrough or ATV GIQ and HIV-RNA changes. In conclusion, the number of ATV resistance mutations is the only correlate to virological response through 24 weeks of treatment with unboosted atazanavir 400 mg once daily.

Redistribution of human immunodeficiency virus type 1 variants resistant to protease inhibitors after a protease inhibitor-sparing regimen.

The redistribution of mutations related to protease inhibitor (PI) resistance after a PI-sparing regimen in human immunodeficiency virus (HIV)-infected, highly PI-experienced patients was prospectively assessed. Twenty-five patients failing a PI-including regimen were given PI-sparing antiretroviral therapy, and then followed for 24 weeks after PI resumption. Genotyping was performed by direct sequencing before and during the PI-sparing regimen. The median (interquartile range, IQR) baseline CD4+ T-lymphocyte count was 198 (120-255) cells/microl, and the median HIV-RNA level was 82,000 (41,000-300,000) copies/ml. Patients had experienced a median of 4.5 (4-5.25) PIs. The median number of PI mutations was eight (6-9). The PI-sparing regimen consisted of a median of three (3-4) drugs and lasted for a median of 53 (24-67) weeks. At the end of the study, the median number of PI mutations was 6.5 (6-9). The median change in the number of PI mutations was -1 (IQR from -1 to 0). A reduction from baseline was observed in 13 cases (52%); nine (36%) showed no change and three (12%) showed an increased number of PI substitutions. In highly PI-experienced patients, a PI-sparing regimen may lead to a reduction, no change, or increase in the number of PI mutations. The reduction is negligible in most cases.

Impact of a treatment including tenofovir plus didanosine on the selection of the 65R mutation in highly drug-experienced HIV-infected patients.

Data from 20 highly drug-experienced HIV-infected patients receiving tenofovir plus didanosine as part of a salvage regimen were analysed. At baseline, all but one patient harboured a virus bearing at least one nucleoside excision mutation (NEM); in 13 cases (65%) three or more NEM were detectable. After a median of 26 weeks of treatment, two patients (10%) selected the 65R mutation. These results support the hypothesis that NEM hinder the selection of this mutation.

Pharmacokinetics of amprenavir given once or twice a day when combined with atazanavir in heavily pre-treated HIV-positive patients.

We studied the pharmacokinetics of amprenavir at doses of 600 mg twice a day or 1200 mg once a day, when co-administered to HIV-positive patients with 400 mg a day of atazanavir without a ritonavir booster. Our preliminary results suggest that amprenavir and atazanavir could be coadministered and that amprenavir could be boosted by atazanavir without the need for ritonavir pharmaco-enhancement.