Clinical validation of saquinavir/ritonavir genotypic resistance score in protease-inhibitor-experienced patients.

OBJECTIVE: To identify a genotypic score for resistance to saquinavir boosted with ritonavir (SQV/r; 1,000/100 mg twice daily)-based regimens in protease inhibitor (PI)-experienced patients. METHODS: One-hundred and fifty-one PI-experienced patients receiving a SOV/r-containing regimen were enrolled retrospectively. The virological response (VR) was defined as the decrease in HIV RNA at months 3-5. The effect of each mutation in the protease gene on the VR to SQV/r regimen was assessed using non-parametric univariate analyses and then a step-by-step analysis was carried out using a Jonckheere-Tepstra (JT) nonparametric test to retain the group of mutations most strongly associated with VR. RESULTS: Among the 138 patients with detectable plasma SQV, the median VR was -1.48 [range: -4 to +1.2] log10 copies/ml. Changes at 12 codons were associated with a reduced VR to SQV/r: codons 10, 15, 20, 24, 46, 54, 62, 71, 73, 82, 84 and 90. The JT procedure led to selection of the following genotypic score, 10+15+20+ 24+62+73+82+84+90, as providing the strongest association with VR. In the 35 patients with none of the mutations in this score, the median decrease in HIV RNA was -2.24 log10 copies/ml and it was -1.88 (n=29), -1.43 (n=24), -0.52 (n=30), -0.18 (n=9), -0.11 (n=6) and -0.30 (n=5) log10 copies/ml in those with 1, 2, 3, 4, 5 and 6 mutations, respectively. CONCLUSION: With this resistance score to SQV/r, the isolates were classified as having no evidence of resistance (0-2), possible resistance (3) or resistance (> or =4) by grouping the number of mutations in samples for which the viral load reduction was similar.

Performance of six different ritonavir-boosted protease inhibitor-based regimens in heavily antiretroviral-experienced HIV-infected patients.

BACKGROUND: Regimens based on ritonavir-boosted protease inhibitors (PI/r) are often used as rescue interventions. It is unclear whether significant differences exist between distinct PI/r. METHOD: All HIV+ patients who had experienced PI failure at two HIV clinics and were rescued with a regimen based on saquinavir (SQV)/r 1000/100 mg bid, indinavir (IDV)/r 800/100 mg bid, lopinavir (LPV)/r 400/100 mg bid, amprenavir (APV)/r 600/100 mg bid, atazanavir (ATV)/r 300/100 mg qd, or tipranavir (TPV)/r 500/200 mg bid were retrospectively examined. A significant virological response (VR) was defined as >1 log reduction in plasma HIV-RNA or to <50 copies/mL at week 24. RESULTS: A total of 389 patients were included in the analysis: 139 on SQV/r, 35 on IDV/r, 129 on LPV/r, 35 on APV/r, 29 on ATV/r, and 22 on TPV/r. No significant differences in HIV-RNA and CD4 counts at baseline were recognized between groups. In a multivariate analysis, only the total number of protease resistance mutations was associated with a lower VR (odds ratio [OR] = 0.77, 95% CI 0.68-0.87, p < .001). The presence of <5 or > or =5 protease resistance mutations at baseline was the best threshold to discriminate the achievement of VR in any treatment group. In an intent-to-treat analysis, for individuals with 5 protease resistance mutations, the rates of VR were 64% with TPV/r, 47% with LPV/r, 46% with SQV/r, 33% with ATV/r, 25% with IDV/r, and 16% with APV/r. Adverse events leading to treatment withdrawal occurred more frequently using IDV/r (22.8%) than others (p = .03). CONCLUSION: The rate of VR in salvage therapy using PI/r-based regimens is relatively high in PI-experienced patients. The efficacy is greatly influenced by the number of baseline protease resistance mutations; 5 mutations is the best threshold to predict the chances of VR to any PI/r-based regimen.

Prevalence of the HIV-1 protease mutation I47A in clinical practice and association with lopinavir resistance.

Mutation proI47A has recently been associated with lopinavir/ritonavir (LPV/r) resistance. Only four out of 1859 specimens (0.2%) sent for drug resistance testing (219 drug-naive and 1650 antiretroviral-experienced) showed I47A. All belonged to patients failing LPV/r. The prevalence among protease inhibitor-experienced patients was 0.6%. Phenotypic testing showed that proI47A caused high-level lopinavir resistance (> 100-fold) and cross-resistance to amprenavir, whereas it caused hypersusceptibility to saquinavir. ProI47A should thus be considered the primary lopinavir resistance mutation.

Predictive value of drug levels, HIV genotyping, and the genotypic inhibitory quotient (GIQ) on response to saquinavir/ritonavir in antiretroviral-experienced HIV-infected patients.

Plasma levels of HIV protease inhibitors (PI) are often close to IC50 values of wild-type viruses when administered without ritonavir boosting. The impact of drug levels, resistance mutations, and the genotypic inhibitory quotient (GIQ) were examined on the response to saquinavir/ritonavir (SQV/r)-based salvage therapy. Patients with prior exposure to PI other than SQV and currently failing virologically were recruited prospectively in a multicenter trial. All patients began SQV/r 1000/100 mg bid plus another two antiretrovirals. A total of 139 patients was enrolled. At month 12, virological response (VR), defined as plasma HIV-RNA decline >1 log, was recorded in 68.2% of patients on treatment (41.7% in the intent-to-treat analysis). The median baseline number of protease resistance mutations was three. The VR was significantly lower in patients with >5 protease resistance mutations and in those with plasma SQV Cmin<0.1 microg/ml. At week 48, the VR was seen in 77.1% of patients with a GIQ>0.04 compared to 18.2% of those with a lower GIQ (P=0.001). In the multivariate analysis, 0.1 microg/ml were independently associated with VR. Interestingly, drug levels had their highest predictive value of the VR at week 12, since low SQV plasma levels often permitted ruling out poorly adherent patients. In contrast, the number of protease resistance mutations had the highest impact on the VR at week 24, suggesting that for those taking the drugs, the VR is highly dependent of the presence of resistance mutations. At any time, nevertheless, the GIQ provided the most accurate prediction of the VR.

Predictors of selection of K65R: tenofovir use and lack of thymidine analogue mutations.

Over the past 5 years, 1846 HIV-infected patients underwent drug resistance testing at our institution. None out of 216 drug-naive subjects showed K65R. However, it was recognized in 53 out of 1630 antiretroviral-experienced patients (3.3%), of whom 10 had never been exposed to tenofovir. The rate of K65R increased from 0.6% in 1999 to 11.5% in 2004. The recognition of K65R correlated negatively with the presence of thymidine analogue mutations but positively with Q151M.

Failure to detect human immunodeficiency virus type 1 superinfection in 28 HIV-seroconcordant individuals with high risk of reexposure to the virus.

We have examined the occurrence of HIV-1 superinfection in 14 HIV-seroconcordant couples (i.e., partners were independently infected with different HIV-1 strains) with high risk of reexposure to the virus. Phylogenetic analyses based on pol and env global sequences obtained from more than 100 longitudinal plasma samples (corresponding to a period of 1-4 years) failed to detect HIV-1 superinfection in this cohort of patients. Our results suggest that despite recent reports of HIV-1 reinfection, chronic HIV infection seems to confer protection against superinfection with a second HIV-1 strain.

Predictors of virological response to atazanavir in protease inhibitor-experienced patients.

BACKGROUND: Atazanavir (ATV) is the latest approved HIV protease inhibitor (PI). Even though it is very convenient (only two capsules once a day), concerns have risen about its potency. METHOD: The clinical performance of ATV 400 mg once a day was examined in all PI-experienced patients who were included in the ATV expanded access program conducted in a single institution. The predictive value of baseline drug resistance HIV genotypes, ATV plasma trough levels, and the genotypic inhibitory quotient (GIQ) on the virological response at week 24 was assessed. RESULTS: Data from 92 patients were analyzed. ATV was prescribed as part of a rescue intervention (45%), a simplification strategy (11%), or an attempt to ameliorate hyperlipidemias (23%) or other toxicities (16%). Tenofovir (TDF) was concomitantly used with ATV in 78% of patients. None received ritonavir boosting. In patients with detectable viremia at baseline (65%), the median HIV RNA drop was 0.7 logs. The median ATV Cmin was 0.12 microg/mL (IQR, 0.05-0.22 microg/mL), which is clearly above the IC90 (90% inhibitory concentration) for ATV in wild-type viruses. The virological response did not correlate significantly with ATV Cmin. The median number of protease resistance mutations was lower in patients showing virological response than in nonresponders (1 vs. 5; p=.07). A higher HIV RNA drop was associated with a higher GIQ (p=.02; beta=-5.4; 95% CI, -10 to -1). Only 4 patients (4%) discontinued treatment due to ATV-related toxicities (hyperbilirubinemia in 1). Bilirubin levels were associated with ATV plasma concentrations (p=.05; beta=3.2; 95% CI, -0.1 to 6.5). The rate of hypertriglyceridemia and hypercholesterolemia declined significantly with respect to baseline. CONCLUSION: ATV is relatively safe and provides significant virological response in PI-experienced patients, mainly among those with a low number of protease resistance mutations. The GIQ predicts accurately the virological response in patients receiving ATV. Hyperbilirubinemia is associated with higher ATV plasma levels.

Prediction of virological response to lopinavir/ritonavir using the genotypic inhibitory quotient.

The predictive value of virological response to lopinavir (LPV)/ritonavir (r) was assessed in 126 HIV-infected patients who failed antiretroviral therapy and had begun a rescue intervention based on LPV/r. At 3 months, subjects with < or =6 protease (PRO) resistance mutations showed a higher rate of virological response (HIV-RNA drop > 1 log or to <50 copies/ml) than patients with >6 PRO resistance mutations (77% versus 48%; p = 0.01). On the other hand, virological responders had greater mean LPV plasma trough levels than nonresponders (6.4 versus 3.9 microg/ml; p = 0.02). A positive correlation was found between LPV trough concentration and viral load reductions at 3 months under LPV/r (r = 0.23; p = 0.017). Overall, virological response was seen in 80.8% of patients with LPV trough levels >4.8 microg/ml while in only 52.5% of patients with lower LPV trough concentrations (p = 0.002). In the multivariate analysis, both < or =6 PRO resistance mutations and LPV trough levels >4.8 microg/ml were independent predictors of virological response to salvage therapy with LPV/r. A genotypic inhibitory quotient (GIQ) was estimated for each patient based on the ratio between LPV trough levels and the number of PRO resistance mutations. A positive strong correlation was found between GIQ and viral load reductions (r = 0.42; p = 0.002). Virological response was seen in 78% of patients with a GIQ >0.7 but only in 41.6% of those with lower GIQ (p = 0.004). When LPV trough levels >4.8 microg/ml, PRO resistance mutations < or =6, and GIQ >0.7 were all included in a stepwise multivariate analysis, GIQ remained as the main independent predictor of response to LPV/r.

Impact of drug levels and baseline genotype and phenotype on the virologic response to amprenavir/ritonavir-based salvage regimens.

Coadministration of amprenavir (APV) with small doses of ritonavir (RTV) results in a significant increase in APV plasma concentrations. Viruses showing resistance to other protease inhibitors (PI) may remain susceptible to APV, supporting a role for this drug in salvage therapy. We enrolled 35 patients who began a rescue intervention based on APV/RTV 600/100 mg twice daily. Their median viral load before beginning APV/RTV was 4.15 logs and their median CD4 count was 247 cells per microliter. The median prior PI exposure was of 43 months. At baseline, the median number of PI resistance mutations was 7. A significant virologic response (VR) (>1 log drop in plasma HIV-RNA and/or to <50 copies per milliliter) was recorded in 21.7% (5/23) of treated patients at week 48 (14.3% in the intent-to-treat analysis). The VR was significantly more frequent among subjects with less than 5 PI resistance mutations (66.6% vs. 5.8%; p = 0.008). Patients with prior exposure to lopinavir showed VR significantly less frequently than those not exposed to that drug (11% versus 60%; p < 0.05). The mean APV plasma trough concentration at week 12 was 1.3 microg/mL, and did not differ significantly comparing subjects having or not having VR. A trend toward a higher VR rate at week 48 was noticed among subjects with high genotypic inhibitory quotients (GIQ). In summary, HIV genotyping but not drug levels might be helpful to predict which patients would benefit from a rescue intervention based on APV/RTV 600/100 twice daily.

Long-term outcome of HIV-infected patients with multinucleoside-resistant genotypes.

BACKGROUND: Multiple resistance to nucleoside analogs mediated by the Q151M complex and/or codon 67-69 inserts/deletions represents a growing problem among HIV-infected persons, most of whom have been exposed to sequential therapies for long periods of time. PATIENTS AND METHOD: All plasma samples collected from HIV-infected patients failing antiretroviral therapy and referred for HIV genotyping to our institution during the last 3 years were examined. Genetic analysis of the reverse transcriptase (RT) and protease (PR) genes was performed using an automatic sequencer. RESULTS: Multinucleoside-resistance (MNR) genotypes were recognized in 22 (2.9%) of 761 participants. Twelve of them carried the Q151M complex and 9 harbored different codon 67-69 inserts. One participant carried a deletion at codon 67 of the RT gene. All patients with MNR viruses had been exposed to nucleoside analogs for a median of 54 months (range, 19-96). The mean plasma HIV RNA at the time MNR was first identified was 4.62 log and the mean CD4 count was 227 cells/microL. All patients with MNR viruses except two began salvage therapies based on protease inhibitors (PIs). Overall, 54.5% (12/22) of participants showed a significant virologic response (defined as >1 log reduction in plasma HIV RNA). Seven of them reached <50 copies/mL and remained with undetectable viremia for a median of 17 months (range, 8-50). No differences were found when patients with Q151M and codon 67-69 rearrangements were compared. The only predictor of response was the inclusion of ritonavir-boosted PI in the salvage regimen. In all patients with virologic failure, MNR genotypes have persisted over time. CONCLUSION: The prevalence of viruses with MNR genotypes is currently low (approximately 3%) among HIV-infected patients failing antiretroviral therapy. The expected poor prognosis of patients harboring MNR viruses may often be overcome using rescue interventions based on potent ritonavir-boosted PI combinations.

[HIV superinfection: clinical and biological implications]. / Superinfección por el virus de la inmunodeficiencia humana: implicaciones clínicas y biológicas.

The recognition of HIV-1 particles including recombinant virus sequences suggests that a single individual has been infected with more than one HIV subtype. This circumstance may result from superinfection or coinfection. In the first case, the new infection occurs in subjects already carrying HIV-1, whereas coinfection refers to a concomitant exposure to diverse HIV-1 variants. The demonstration of superinfection represents an indirect evidence against protective immunity for HIV-1 and, therefore, against the success of vaccines.

Comparison of the efficacy, safety and predictive value of HIV genotyping using distinct ritonavir-boosted protease inhibitors.

The pharmacokinetic profile of protease inhibitors (PI) is improved significantly by adding low doses of ritonavir (rit). The use of rit-boosted PI allows the reduction of pill burden, improves dosing schedules and enhances drug exposure, all factors that have been associated with a greater benefit of antiretroviral therapy. All patients receiving rit 100 mg bid together with saquinavir (SQV) soft gel 1000 mg bid, indinavir (IDV) 800 mg bid or lopinavir (LPV) 400 mg bid, as part of a salvage regimen, were retrospectively analyzed in a reference institution. Only subjects who had failed all three antiretroviral drug families in the past were included. A total of 299 patients were included in the study (121 on SQV, 62 on IDV and 116 on LPV). Mean plasma HIV-RNA and CD4 lymphocyte counts at baseline were less favourable in the LPV group (4.4 logs, 275 cells/microl) with respect to SQV (4.3 logs, 355 cells/microl) and IDV (3.7 logs, 409 cells/microl) groups (P < 0.05). The proportion of subjects experiencing virological success (attainment of either < 500 HIV-RNA copies/ml or > 1 log reduction) in an intent-to-treat analysis at 24 weeks was 61% with LPV, 49% with SQV and 48% with IDV. The CD4 count increased 48% with SQV, 45% with IDV and 37% with LPV. The proportion of subjects discontinuing therapy due to adverse events was higher using IDV (27%) than using either SQV (11%) or LPV (6%) (P < 0.05). The presence of < 5 or > 5 PI resistance mutations at baseline discriminated significantly better who would respond to therapy in all instances: 90 vs. 48% with LPV, 95 vs. 21% with SQV and 90 vs. 23% with IDV. The efficacy of rit-boosted PI combinations is greatly influenced by the extent of baseline PI resistance. Differences, not only in potency, but mainly in tolerance may favour the selection of one dual PI combination over others.

Resistance mutations in HIV-infected patients experiencing early failure with nelfinavir-containing triple combinations.

BACKGROUND: The purpose of our study was to assess the presence of nelfinavir (NFV)-associated resistance mutations at the time of early virological failure in subjects receiving NFV as part of a first protease inhibitor (PI)-based triple regimen. MATERIAL/METHODS: Subjects failing their first PI-based NFV-containing triple regimen were identified in six Spanish hospitals. HIV genotyping was carried out in plasma samples collected at the time of the first viral rebound. RESULTS: Upon initiation of NFV-based therapy, 19 of the 30 subjects (63%) were naïve; 11 (37%) had been exposed to nucleoside analogues. Median HIV-RNA at the time of viral rebound was 4, 180 copies/ml. PCR-amplified products were obtained in 22 subjects (73%). These products were sequenced and primary PI resistance mutations were recognized in 6 patients (27%). All six individuals harbored the D30N mutation, and none presented the L90M mutation. Other PI resistance mutations were present in 5 subjects (at codons 36, 63, 71, 77, 82 and/or 88). Secondary PI resistance mutations were present in another 9 subjects. By contrast, mutations conferring resistance to reverse transcriptase inhibitors were present in 50% of the patients, and the M184V substitution was the most frequently seen. CONCLUSIONS: Nearly 75% of patients failing their first PI-based triple regimen containing NFV do not harbor PI resistance mutations. The D30N substitution, rather than L90M, is the most frequently recognized, which does not challenge the efficacy of further rescue interventions with other PIs. This observation supports the use of nelfinavir as first protease inhibitor.