Primary resistance to integrase strand transfer inhibitors in Spain using ultrasensitive HIV-1 genotyping.

BACKGROUND: Transmission of resistance mutations to integrase strand transfer inhibitors (INSTIs) in HIV-infected patients may compromise the efficacy of first-line antiretroviral regimens currently recommended worldwide. Continued surveillance of transmitted drug resistance (TDR) is thus warranted. OBJECTIVES: We evaluated the rates and effects on virological outcomes of TDR in a 96 week prospective multicentre cohort study of ART-naive HIV-1-infected subjects initiating INSTI-based ART in Spain between April 2015 and December 2016. METHODS: Pre-ART plasma samples were genotyped for integrase, protease and reverse transcriptase resistance using Sanger population sequencing or MiSeq™ using a ≥ 20% mutant sensitivity cut-off. Those present at 1%-19% of the virus population were considered to be low-frequency variants. RESULTS: From a total of 214 available samples, 173 (80.8%), 210 (98.1%) and 214 (100.0%) were successfully amplified for integrase, reverse transcriptase and protease genes, respectively. Using a Sanger-like cut-off, the overall prevalence of any TDR, INSTI-, NRTI-, NNRTI- and protease inhibitor (PI)-associated mutations was 13.1%, 1.7%, 3.8%, 7.1% and 0.9%, respectively. Only three (1.7%) subjects had INSTI TDR (R263K, E138K and G163R), while minority variants with integrase TDR were detected in 9.6% of subjects. There were no virological failures during 96 weeks of follow-up in subjects harbouring TDR as majority variants. CONCLUSIONS: Transmitted INSTI resistance remains rare in Spain and, to date, is not associated with virological failure to first-line INSTI-based regimens.

Riesgo de enfermedad cardiovascular en pacientes con infección VIH en tratamiento antirretroviral / Risk of cardiovascular disease in patients with HIV infection undergoing antiretroviral therapy

ANTECEDENTES: La mayor supervivencia de los pacientes con infección por VIH gracias al tratamiento antirretroviral (TAR) se acompaña de una mayor frecuencia de enfermedad cardiovascular (ECV). Analizamos la prevalencia de los factores de riesgo cardiovascular (FRCV) y la estimación del riesgo de ECV en una cohorte de personas con infección por VIH en España. MÉTODOS: Estudio transversal, observacional de los FRCV en la cohorte española VACH de pacientes con infección por VIH que recibían TAR. RESULTADOS: Se evaluaron 15.559 pacientes con infección por VIH (76% varones; edad media: 46 años). Un 3,7% había experimentado al menos un evento de ECV. La prevalencia de FRCV era elevada: hiperlipidemia, 64%; tabaquismo, 47%; HTA, 22%; y diabetes, 16%. Según la escala Framingham, un 10,9% presentaba alto riesgo de ECV y un 28,8% riesgo moderado. De los pacientes con elevado riesgo de ECV, el 49% recibía inhibidores de proteasa y el 43% abacavir. Se usaron fármacos hipotensores en el 53% de los pacientes con diagnóstico de HTA, y fármacos antidiabéticos en el 2,6% de los pacientes con diabetes. CONCLUSIONES: Los FRCV tradicionales son frecuentes en los pacientes con infección por VIH con TAR en España, y una elevada proporción de ellos tiene riesgo moderado-alto de ECV. Por tanto, el control de los FRCV modificables en los pacientes con infección por VIH debería mejorarse y valorar el uso de fármacos con mejor perfil de riesgo cardiovascular

BACKGROUND: The increased survival of patients with HIV infection thanks to antiretroviral therapy (ART) is accompanied by a higher rate of cardiovascular disease (CVD). We analysed the prevalence of the cardiovascular risk factors (CRFs) and estimated the risk of CVD in a cohort of patients with HIV in Spain. METHODS: We conducted a cross-sectional, observational study of CRFs in the Spanish VACH cohort of patients with HIV who undergo ART. RESULTS: The study assessed 15,559 patients with HIV (76% men; mean age, 46 years). Some 3.7% had experienced at least 1 CVD event. The prevalence of CRFs was high (hyperlipidaemia, 64%; tobacco use, 47%; arterial hypertension, 22%; and diabetes, 16%). According to the Framingham scale, 10.9% of the patients presented a high CVD risk, and 28.8% presented a moderate risk. Of the patients with a high CVD risk, 49% took protease inhibitors and 43% took abacavir. Fifty-three percent of the patients diagnosed with arterial hypertension took antihypertensive drugs, and 2.6% of the patients with diabetes took antidiabetic agents. CONCLUSIONS: Classical CRFs are common in patients with HIV undergoing ART in Spain, and a large proportion of them have a moderate-high risk of CVD. Therefore, controlling the modifiable CRFs in patients with HIV should be improved, and the use of drugs with a better cardiovascular risk profile should be assessed

Risk of cardiovascular disease in patients with HIV infection undergoing antiretroviral therapy. / Riesgo de enfermedad cardiovascular en pacientes con infección VIH en tratamiento antirretroviral.

BACKGROUND: The increased survival of patients with HIV infection thanks to antiretroviral therapy (ART) is accompanied by a higher rate of cardiovascular disease (CVD). We analysed the prevalence of the cardiovascular risk factors (CRFs) and estimated the risk of CVD in a cohort of patients with HIV in Spain. METHODS: We conducted a cross-sectional, observational study of CRFs in the Spanish VACH cohort of patients with HIV who undergo ART. RESULTS: The study assessed 15,559 patients with HIV (76% men; mean age, 46 years). Some 3.7% had experienced at least 1 CVD event. The prevalence of CRFs was high (hyperlipidaemia, 64%; tobacco use, 47%; arterial hypertension, 22%; and diabetes, 16%). According to the Framingham scale, 10.9% of the patients presented a high CVD risk, and 28.8% presented a moderate risk. Of the patients with a high CVD risk, 49% took protease inhibitors and 43% took abacavir. Fifty-three percent of the patients diagnosed with arterial hypertension took antihypertensive drugs, and 2.6% of the patients with diabetes took antidiabetic agents. CONCLUSIONS: Classical CRFs are common in patients with HIV undergoing ART in Spain, and a large proportion of them have a moderate-high risk of CVD. Therefore, controlling the modifiable CRFs in patients with HIV should be improved, and the use of drugs with a better cardiovascular risk profile should be assessed.

Real World Patient-reported Outcomes in HIV-infected Adults Switching to EVIPLERA®, Because of a Previous Intolerance to cART. PRO-STR Study.

BACKGROUND: To investigate the impact of switching from stable Combined Antiretroviral Therapy (cART) to single-tablet regimen (RPV/FTC/TDF=EVIPLERA® /COMPLERA®) on patient- reported outcomes in HIV-infected adults who cannot tolerate previous cART, in a real-world setting. METHODS: PRO-STR is a 48-week observational, prospective, multicenter study. Presence and magnitude of symptoms (main endpoint), health-related quality-of-life (HRQoL), adherence, satisfaction with treatment and patient preferences were assessed. RESULTS: Three hundred patients with 48-week follow-up, who switched to EVIPLERA® (mean age: 46.6 years; male: 74.0%; 74.7% switched from a non-nucleoside reverse-transcriptase-inhibitor, 25.3% from a protease inhibitor + ritonavir) were included. There was no statistical difference in median CD4+ cell count (baseline: 678.5 cells/mm3; 48-week: 683.0 cells/mm3) neither in virological suppression (≤50 copies/mL) (baseline: 98.3%; 48-week: 95.3%). The most frequent reasons for switching were neuropsychiatric (62.3%), gastrointestinal (19.3%) and biochemical/metabolic (19.3%) events. Only 7.7% of patients permanently discontinued therapy. At 48-week, all outcomes showed an improvement compared to baseline. Overall, there was a significant decrease (pvalue≤ 0.05) in number and magnitude of symptoms, while HRQoL, satisfaction and adherence improved significantly. Most patients prefered EVIPLERA® than previous cART. According to the type of intolerance, HRQoL was improved, but only significantly in patients with neuropsychiatric and gastrointestinal symptoms. Adherence improved significantly in patients with metabolic disturbances and satisfaction with EVIPLERA® was higher in the three groups. CONCLUSION: Switching to EVIPLERA® from non-nucleoside reverse-transcriptase-inhibitor or protease inhibitor-based regimens due to toxicity, improved the presence/magnitude of symptoms, HRQoL, and preference with treatment. EVIPLERA® maintained a virological response, CD4+ cell count and maintained or improved adherence.

Simplification to dual therapy (atazanavir/ritonavir + lamivudine) versus standard triple therapy [atazanavir/ritonavir + two nucleos(t)ides] in virologically stable patients on antiretroviral therapy: 96 week results from an open-label, non-inferiority, randomized clinical trial (SALT study).

OBJECTIVES: We evaluated whether maintenance therapy with atazanavir/ritonavir plus lamivudine (ATV/r + 3TC) was non-inferior to ATV/r plus two nucleosides (ATV/r + 2NUCs) at 96 weeks of follow-up. METHODS: SALT is a multicentre, open-label, non-inferiority clinical trial in HIV-1-infected virologically suppressed patients. Hepatitis B virus surface antigen-negative subjects with no previous treatment failure/resistance mutations and HIV-1-RNA <50 copies/mL for ≥6 months were randomized (1 : 1) to ATV/r + 3TC or ATV/r + 2NUCs. The primary endpoint was HIV-1-RNA <50 copies/mL in the PP population. Non-inferiority was demonstrated if the lower bound of the 95% CI for the difference was not below -12%. RESULTS: Some 286 patients were analysed. At week 96, 74.4% had HIV-1-RNA <50 copies/mL in the ATV/r + 3TC arm versus 73.9% in the ATV/r + 2NUCs arm (95% CI for the difference, -9.9%-11.0%). In both groups, similar values were observed for patients with confirmed virological failure in ATV/r + 3TC versus ATV/r + 2NUCs (9 versus 5), death (1 versus 0), discontinuation due to ART-related toxicity (7 versus 11), withdrawal from the study (7 versus 9) and loss to follow-up (6 versus 6). One patient taking ATV/r + 2NUCs developed resistance mutations (M184V and L63P). Similar values were obtained for change in mean CD4 count [19 versus 18 cells/mm3 (95% CI for the difference, -49.3-50.7), grade 3-4 adverse events (70.7% versus 70.2%) and changes in the global deficit score, -0.3 (95% CI, -0.5 to -0.1) for ATV/r + 3TC, versus -0.2 (95% CI, -0.4 to -0.1) for ATV/r + 2NUCs]. CONCLUSIONS: The long-term results of switching to ATV/r + 3TC show that this strategy is effective, safe and non-inferior to ATV + 2NUCs in virologically suppressed HIV-infected patients.

The role of tenofovir alafenamide in future HIV management.

HIV infection has become a chronic condition rather than an acute life-threatening disease in developed countries, thanks to consistent innovation and evolution of effective interventions. This has altered HIV management and created new challenges. People living with HIV (PLWHIV) are living longer and so encounter comorbidities linked not only with their disease, but also with ageing, lifestyle and chronic exposure to antiretroviral therapy (ART). Although longevity, viral suppression and the prevention of viral transmission remain key goals, more needs to be achieved to encompass the vision of attaining an optimum level of overall health. Treatment choices and management practices should ensure patients' long-term health with minimal comorbidity. Treatments that balance optimal efficacy with the potential for improved long-term safety are needed for all patients. In this review, we consider the evolution and development of tenofovir alafenamide (TAF), a novel prodrug of tenofovir which offers high antiviral efficacy at doses over ten times lower than that of tenofovir disoproxil fumarate (TDF). Emerging clinical data suggest that elvitegravir, cobicistat, emtricitabine and TAF (E/C/F/TAF) as a single-tablet regimen offers highly effective viral suppression in treatment-naïve and treatment-experienced patients with an improved renal and bone safety profile compared with TDF, this having been demonstrated in diverse groups including patients with existing renal impairment and adolescents. The profile of TAF identifies it as an agent with a promising role within future ART regimens that aim to deliver the vision of undetectable viral load, while requiring less monitoring and having a safety profile designed to minimize comorbid risks while supporting good long-term health.

Interpreting the reasons for the choice and changing of two drug regimens in an observational cohort: comparison of a ritonavir-boosted protease inhibitor-based versus a nonnucleoside reverse transcriptase inhibitor-based first-line regimen.

OBJECTIVES: We compared reasons for the choice of regimen, time to and reasons for third drug modification, virological response and change in CD4 T-cell counts in patients started on atazanavir/ritonavir (ATV/r)- vs. efavirenz (EFV)-based first-line regimens. METHODS: We included patients from the Cohort of the Spanish HIV Research Network (CoRIS), a multicentre cohort of HIV-positive treatment-naïve subjects, in the study. We used logistic regression to assess factors associated with choosing ATV/r vs. EFV, proportional hazards models on the subdistribution hazard to estimate subdistribution hazard ratios (sHRs) for third drug modification, logistic regression to estimate odds ratios (ORs) for virological response and linear regression to assess mean differences in CD4 T-cell count increase from baseline. RESULTS: Of 2167 patients, 10.7% started on ATV/r. ATV/r was more likely than EFV to be prescribed in injecting drug users [adjusted OR 1.85; 95% confidence interval (CI) 1.03-3.33], in 2009-2010 (adjusted OR 1.63; 95% CI 1.08-2.47) and combined with abacavir plus lamivudine (adjusted OR 1.53; 95% CI 0.98-2.43). Multivariate analyses showed no differences, comparing ATV/r vs. EFV, in the risk of third drug modification (sHR 1.04; 95% CI 0.74-1.46) or in virological response (OR 0.81; 95% CI 0.46-1.41); differences in mean CD4 T-cell count increase from baseline were at the limit of statistical significance (mean difference 29.8 cells/µL; 95% CI -4.1 to 63.6 cells/µL). In patients changing from EFV, 48% of changes were attributable to toxicity/adverse events, 16% to treatment failure/resistance, 3% to simplification, and 8 and 12%, respectively, to patients' and physicians' decisions; these percentages were 24, 6, 12, 14 and 24%, respectively, in those changing from ATV/r. CONCLUSIONS: ATV/r- and EFV-based regimens meet the requirements of both efficacy and safety for initial combination antiretroviral regimen, which relate to better durability.

Late initiation of HAART among HIV-infected patients in Spain is frequent and related to a higher rate of virological failure but not to immigrant status.

PURPOSE: To determine whether immigrant status is associated with late initiation of highly active antiretroviral treatment (HAART) and/or poor response to antiretrovirals. METHODS: GESIDA 5808 is a multicenter, retrospective cohort study (inclusion period January 2005 through December 2006) of treatment-naïve patients initiating HAART that compares HIV-infected patients who are immigrants with Spanish-born patients. A late starter (LS) was defined as any patient starting HAART with a CD4+ lymphocyte count <200 cells/µL and/or diagnosis of an AIDS-defining illness before or at the start of therapy. The primary endpoint was time to treatment failure (TTF), defined as virological failure (VF), death, opportunistic infection, treatment discontinuation/switch (D/S), or missing patient. Secondary endpoints were time to treatment failure as observed data (TTO; censoring missing patients) and time to virological failure (TVF; censoring missing patients and D/S not due to VF). RESULTS: LS accounted for 56% of the patients. Lower educational and socioeconomic level and intravenous drug use (IVDU) were associated with categorization as LS, but immigrant status was not. Cox regression analysis (hazard ratio [HR]; 95% CI) between LS and non-LS patients showed no differences in TTF (0.97; 0.78-1.20) or TTO (1.18; 0.88-1.58), although it did reveal a difference in TVF (1.97; 1.18-3.29). CD4+ lymphocyte recovery was equivalent for both LS and non-LS patients (159 vs 173). CONCLUSIONS: In our cohort, immigrant status was not shown to be related to late initiation of HAART. Although LS patients did not have a longer TTF for any reason, TVF was significantly shorter. Despite universal free access to HAART in Spain, measures to ensure early diagnosis and treatment of HIV infection are necessary.

Tuberculous hepatic abscess appearing after liver transplantation in a patient with human immunodeficiency virus and hepatitis B and C virus co-infection.

Tuberculosis infection occurs relatively frequently in solid organ transplant recipients, although the occurrence of tuberculous hepatic abscesses is uncommon. Anti-tuberculous therapy has several concerns in transplant recipients, including an increased risk of cellular rejection and potential hepatotoxicity. We present the case of a human immunodeficiency virus-infected liver transplant patient who developed multiple tuberculous liver abscesses. Treatment with isoniazid, ethambutol, pyrazinamide, and moxifloxacin was efficacious, well tolerated, and safe.

Effect of food on the antiviral activity of didanosine enteric-coated capsules: a pilot comparative study.

OBJECTIVES: To determine the effect of food on the antiviral activity of enteric-coated (EC) capsules of didanosine (ddI). METHODS: We conducted a pilot, randomized, open-label study of 28-day ddI-EC capsules monotherapy-administered in a fasted state (group 1, n=11) or with food (group 2, n=10) to treatment-naïve chronically HIV-1-infected individuals. To assess the antiviral efficacy, HIV-1 RNA was determined at baseline, day 3, day 7 and weekly thereafter. The area under the HIV-1 RNA curve minus baseline weighted by time (AUCMB/day) was calculated. RESULTS: Mean baseline HIV-1 RNA was 4.2 log(10) copies/mL in group 1 and 3.8 log(10) copies/mL in group 2. After 28 days, the mean HIV-1 RNA reduction was 0.99 log(10) copies/mL [95% confidence interval (CI) 0.45-1.53] for group 1 and 0.89 log(10) copies/mL (95% CI 0.38-1.40) for group 2. AUCMB/day values were 0.775 log(10) copies/mL (95% CI 0.33-1.22) and 0.774 log(10) copies/mL (95% CI 0.48-1.07), respectively, showing no difference in the rate of decrease of HIV-1 RNA (P=0.995). Mean ddI plasma levels at day 28 were 0.0234 mg/L for group 1 and 0.0227 mg/L for group 2 (P=0.96). CONCLUSIONS: In this pilot study, the administration of food did not have any significant effect on the antiviral activity of ddI-EC capsules.

Limitations of a simplification antiretroviral strategy for HIV-infected patients with decreasing adherence to a protease inhibitor regimen.

PURPOSE: To determine the long-term efficacy of a simplification strategy in the clinical setting when used to improve adherence. METHOD: Prospective study of 70 patients included in a regimen with ddI plus 3TC plus an NNRTI, after viral suppression with a PI-containing regimen, due to decreasing adherence. Adherence to PI was calculated as the percentage of doses taken last week before inclusion, and patients were stratified as high and low adherence (95% and <95% of doses). RESULTS: Overall, 19 patients (27%) related adherence to PI <95% at inclusion (6 patients [9%], with adherence <80%). Mean adherence improved, with only 8% of patients presenting values <95%. At 104 weeks, 88% of patients on therapy had viral load suppression, but only 43% by ITT analysis. The main cause of therapy change or withdrawal was toxicity or drug interactions (26%). Notably, 16% of patients were lost to follow-up or left therapy, especially in the group of initially low adherent (26% vs. 12%, p = .02). CONCLUSION: The use of a simplification strategy could be associated with long-term high risk of treatment failure, when used to improve adherence in the clinical setting.

Viral kinetics and early prediction of nonresponse to peg-IFN-alpha-2b plus ribavirin in HCV genotypes 1/4 according to HIV serostatus.

To evaluate, among 70 hepatitis C virus (HCV)-monoinfected and 36 human immunodeficiency virus (HIV)-coinfected naïve patients with genotypes 1/4 receiving weight-adjusted pegylated interferon-alpha-2b/ribavirin, viral kinetics and the feasibility to predict treatment failure measuring early HCV-RNA decreases. HCV-RNA was assessed at baseline, weeks 4, 12 and 24. Receiver operating characteristic (ROC) curves were calculated to determine the most sensitive cut-off values of viral decrease at week 4 predicting treatment failure. Baseline predictors of failure were evaluated by univariate and multivariate analyses. Despite similar baseline HCV-RNA (5.75 vs 5.72 log(10)IU/ml, P = 0.6), HCV monoinfection led to significantly lower HCV-RNA values at weeks 4 (3.7 vs 4.3 log(10)IU/ml, P = 0.01), 12 (2.3 vs 3.5 log(10)IU/ml, P = 0.01) and 24 (1.4 vs 3.3 log(10)IU/ml, P = 0.001) and a higher rates of viral clearance at weeks 24 (60%vs 36%, P = 0.02), 48 (46%vs 25%, P = 0.03) and 72 (37%vs 17%). The lack of achieving an HCV-RNA decrease of at least 1 log(10) at week 4 was highly predictive of treatment failure for HCV-monoinfected patients (Se 100%, Sp 50%, positive predictive value (PPV) 57%, negative predictive value (NPV) 100%, ROC curve area, 0.86 [95% confidence interval (CI) 0.77-0.95], but not for HCV/HIV-coinfected patients (cut-off, 0 log(10), Se 100%, Sp 27%, PPV 21%, NPV 100%, ROC curve area, 0.71 (95% CI 0.49-0.93). HIV coinfection was independently associated with failure (odds ratio 2.95, 95% CI 1.08-8.04, P = 0.01). Thus the magnitude of HCV-RNA decreases at week 4 correlated with treatment response. Significant differences in viral kinetics and cut-off values predicting nonresponse suggest a slower HCV clearance rate in HIV coinfection, which was independently associated with treatment failure.

Once-daily antiretroviral therapy: Spanish Consensus Statement.

BACKGROUND: Administration of antiretroviral therapy (ART) once daily is creating extraordinary interest among the members of the scientific community and also among those who receive the therapy. However, in clinical practice, some doubts remain about its use. OBJECTIVES: This document examines the characteristics and possibilities of treatment administered once daily. METHODS: Consensus of 248 Spanish experts in the field. RESULTS: Once-daily dosing is considered an added value which could favour adherence and, therefore, efficacy, as well as the quality of life of certain patients, however, the objective of adequate adherence in the long term is often difficult to achieve regardless of the treatment used. In theory, any patient can receive once-daily therapy, although some patients could particularly benefit from it, e.g. those with unfavourable social or personal circumstances, including drug users, patients whose treatment must be supervised, patients receiving multiple medications, or those who need rescue therapy after multiple treatment failures. At present, it is possible to design once-daily ART using some of the combinations of drugs considered as first-choice in national and international recommendations for antiretroviral therapy, but the options are still limited. The marketing of new drugs with this characteristic could allow us to increase the number and types of patient who can benefit from once-daily regimens, including those patients who need rescue therapy. CONCLUSIONS: Once-daily ART is a good alternative to regimens administered several times each day when a potent combination of active drugs is available.

Relapsing visceral leishmaniasis in HIV-infected patients undergoing successful protease inhibitor therapy.

The aim of this study was to establish the evolution of visceral leishmaniasis (VL) in 10 consecutive patients coinfected with VL and HIV, taking into account the decline in the incidence of opportunistic infections after the introduction of protease inhibitor therapy. During a median follow-up of 31 months, 7 (70%) of 10 patients relapsed. The incidence of relapse was slightly lower than before institution of protease inhibitor therapy (20 vs. 13 patient-months), with a 31% probability that relapse would not have taken place within 2 years. VL relapses occurred even though increases in the CD4+ cell counts were observed and HIV loads were undetectable, suggesting that successful antiretroviral therapy is not sufficient to control the disease. Relapsing patients also had a lower increase in the CD4+ cell count.

Efficacy, tolerance, and pharmacokinetics of the combination of stavudine, nevirapine, nelfinavir, and saquinavir as salvage regimen after ritonavir or indinavir failure.

The high rate of protease inhibitor treatment failure in clinical cohorts makes it necessary to define novel salvage therapies. In a prospective study of 31 HIV-infected patients included in a salvage regimen with stavudine, nevirapine, nelfinavir, and saquinavir, viral load decreased a median of 1.65 log(10) and 1.95 log(10) after 6 and 12 months of treatment, respectively, and 35 and 56% of patients had an HIV RNA level below 50 copies/ml at the same time points. At baseline, the mean number of mutations in the protease gene was 10 (2-19), and the V82A and L90M mutations were present in 54 and 21% of patients. The presence of the V82A mutation did not affect significantly the rate of response (36 vs. 38%), whereas the L90M mutation was associated with treatment failure (0 vs. 43%). Plasma trough levels of nelfinavir (NFV) and saquinavir (SQV), in a twice daily dosing regimen, were above the protein-corrected IC(95) in most patients despite the addition of an enzymatic inducer such as nevirapine, and peak levels were 2- and 5-fold increased with respect to standard doses. However, pharmacokinetics of saquinavir-hard gel capsule (SQV-hgc) did not improve significantly in the three times daily dosing regimen. In conclusion, the combination of stavudine, nevirapine, nelfinavir, and saquinavir increased plasma drug levels and produced an adequate virological response in patients who had failed indinavir or ritonavir therapy. This degree of response is not significantly decreased in the presence of genotypic mutations associated with indinavir/ritonavir (IDV/RTV) resistance.

Phenotypic cross-resistance to nelfinavir: the role of prior antiretroviral therapy and the number of mutations in the protease gene.

Cross-resistance to nelfinavir (NFV) is observed in patients failing protease inhibitor (PI)-containing therapies. We performed a study with 111 patients who started an NFV-based salvage regimen after failing PI-based therapy to evaluate genotypic changes and to identify factors associated with resistance to NFV. Genotypic and phenotypic resistance data at entry (111 and 51 samples) and after NFV failure (74 and 31 samples) were available. Median CD4(+) cell count was 208 x 10(6)/liter, HIV RNA level was 4.6 log(10) copies/ml, and median number of mutations in the protease was 9. At baseline, 51 and 14% of viral isolates showed high or intermediate phenotypic resistance to NFV. Phenotypic data correlated with virological outcome, reaching undetectability at the third month in 40, 14, and 0% of those patients with susceptible, intermediate, or resistant viral isolates, respectively. Phenotypic resistance to NFV was associated with the presence of the L90M mutation: 46% for resistant vs. 6% in susceptible strains. The number of mutations in the protease correlated with the fold-increase in the IC(50)-NFV. The D30N mutation was detected in only 1 of 74 patients who failed. In a logistic regression analysis, the number of mutations in the protease was associated with NFV cross-resistance (RR, 2.09 per each additional mutation; 95% CI 1.23-3.55; p < 0.01). In conclusion, phenotypic cross-resistance to NFV for PI-experienced patients can be predicted by the number of mutations in the protease. The L90M mutation is significantly associated with the subsequent failure of NFV-containing regimens. The presence of the D30N mutation was rare and not useful in identifying NFV-resistant isolates.