Predictive factors of virological success to salvage regimens containing protease inhibitors in HIV-1 infected children.

BACKGROUND: The impact of HIV drug resistance mutations in salvage therapy has been widely investigated in adults. By contrast, data available of predictive value of resistance mutations in pediatric population is scarce. METHODS: A multicenter, retrospective, observational study was conducted in children who received rescue salvage antiretroviral therapy after virologic failure. CD4 counts and viral load were determined at baseline and 6 months after rescue intervention. Genotypic HIV-1 resistance test and virtual phenotype were assessed at baseline. RESULTS: A total of 33 children met the inclusion criteria and were included in the analysis. The median viral load (VL) and median percentage of CD4+ at baseline was 4.0 HIV-RNA log copies/ml and 23.0% respectively. The median duration that children were taking the new rescue regimen was 24.3 weeks (23.8-30.6). Overall, 47% of the 33 children achieved virological response at 24 weeks. When we compared the group of children who achieved virological response with those who did not, we found out that mean number of PI related mutations among the group of responders was 3.8 vs. 5.4 (p = 0.115). Moreover, the mean number of susceptible drugs according to virtual phenotype clinical cut-off for maximal virologic response was 1.7 vs. 0.8 and mean number of susceptible drugs according to virtual phenotype cut-off for minimal virlologic response was 2.7 vs. 1.3 (p < 0.01 in all cases). Eighteen children were rescued with a regimen containing a boosted-PI and virological response was significantly higher in those subjects compared with the others (61.1% vs. 28.6%, p < 0.01). CONCLUSION: Salvage treatment containing ritonavir boosted-PIs in children with virological failure was very efficient. The use of new tools as virtual phenotype could help to improve virologic success in pediatric population.

Virological phenotype switches under salvage therapy with lopinavir-ritonavir in heavily pretreated HIV-1 vertically infected children.

OBJECTIVE: To investigate the effects of salvage therapy with lopinavir-ritonavir on HIV-1 phenotype in heavily antiretroviral experienced HIV-infected children. DESIGN: Twenty antiretroviral experienced HIV-infected children were studied during a mean of time of 16.1 months from initiation of the treatment with lopinavir-ritonavir. METHODS: Besides CD4 T cells, viral load and clinical status, we analyzed 91 serial viral isolates to study the phenotype, and biological clones derived from co-cultivation techniques. RESULTS: We observed an increase in CD4 T cells, a statistically significant decrease in viral load and clinical benefits from 3 months after treatment. Ninety per cent of children had SI/X4 bulk isolates in peripheral blood mononuclear cells at study entry. The viral phenotype changed to non syncitium-inducing (NSI)/R5 in 94% of the children after a mean of 5.7 months (95% confidence interval, 2.1-9.3 months) of salvage therapy. The remaining 10% of children had NSI/R5 isolates at entry and at all follow-up study. Similar results were found at the clonal level. Thus, at study entry in PBMC of three children with bulk syncitium-inducing (SI) phenotype, we recovered 65 biologic clones, 56 being SI and nine NSI. After salvage therapy bulk isolates changed to NSI and of 40 biologic clones recovered only five were SI and the rest were NSI. CONCLUSIONS: Our data suggest that lopinavir-ritonavir salvage therapy led not only to a viral load decrease but also to a phenotypic change. X4 virus appeared to be preferentially suppressed. Shifts in co-receptor usage may thereby contribute to the clinical efficacy of anti-HIV drugs in vertically infected infants.

Extensive implementation of highly active antiretroviral therapy shows great effect on survival and surrogate markers in vertically HIV-infected children.

We performed a retrospective observational study of 253 children vertically infected with human immunodeficiency virus (1994-2001) to assess the effectiveness of antiretroviral therapies (ARTs) on survival and surrogate markers at the population level. Children were divided into 3 groups according to the ART protocols used during the follow-up period: calendar period (CP) 1 (1994-1996) received combined therapy with 2 nucleoside reverse transcriptase inhibitors (NRTIs); CP2 (1997-1998) received implementation of highly active ART (HAART) with 3 drugs (NRTIs, protease inhibitors, and non-NRTIs); and CP3 (1999-2001) received extensive HAART. The children in the CP3 group had statistically significant longer survival periods, lower virus load (VL), highest undetectable VL proportion, and highest CD4+ T cell counts. HAART is effective at the population level at decreasing VL, increasing CD4+ T cells, and increasing the survival in a higher percentage of HIV-infected children.

Comparison of levels of antiretroviral drugs with efficacy in children with HIV infection.

OBJECTIVE: To determine the prevalence of low and high antiretroviral (ARV) plasma levels and to analyze correlation between ARV concentrations and the appearance of therapeutic failure and toxicity. METHODS: The authors present here a study evaluating antiretroviral plasma concentrations in HIV infected children on nonnucleoside reverse transcriptase inhibitors and protease inhibitors based therapy. The authors carried out a multicentre, cross-sectional study, including HIV-infected children from five large Hospitals in Madrid, Spain. Clinical, haematological, biochemical and immuno-virological parameters were assessed. Antiretroviral plasma trough levels were performed using a validated high performance liquid chromatography method. RESULTS: Between April 2006 and April 2008, 129 children were enrolled in the present study, with median treatment duration of 39.2 months. 25.5% of the non-nucleoside reverse transcriptase inhibitors levels were low and 17.6%, high. 27.9% percent of the protease inhibitors levels were low and 12.5%, high. A correlation was found among adequate or high levels of antiretrovirals and normal CD4 percentage and low viral load. Lopinavir/ritonavir plasma levels were correlated with an increase in lipodystrophy. Patients with Tanner stage 1 presented the lowest ARV plasma levels. Full adherence was reported for all the participants by a questionnaire. CONCLUSION: Many HIV-infected children show ARV plasma levels out of the therapeutic range which demands a child-adjusted approach. However, larger studies are urgently needed in pediatric populations to define optimal reference values.

Mutations at codons 54 and 82 of HIV protease predict virological response of HIV-infected children on salvage lopinavir/ritonavir therapy.

BACKGROUND: Lopinavir/ritonavir is a protease inhibitor (PI) that has shown great effectiveness as salvage therapy in PI-experienced HIV-infected children. OBJECTIVES: To study whether mutations in the HIV-1 protease gene can reliably predict virological responses to salvage therapy with lopinavir/ritonavir in HIV-infected children. PATIENTS AND METHODS: We carried out a prospective study in 56 HIV-infected children. PI-associated resistance mutations were determined by genotypic testing and were scored according to the IAS-USA guidelines 2005. RESULTS: Children with a 'lopinavir mutation score' (LMS) > or = 6 had a negative association for achieving viral load (VL) control [undetectable viral load (uVL) < or = 400 copies/mL] and maintaining uVL for at least 6 months. Moreover, children with protease-associated mutations (PRAMs) > or = 2 had a negative association for achieving VL control but not for maintaining uVL for at least 6 months. The relative proportion (RP) to uVL was 0.32 (CI95%: 0.16; 0.33; P = 0.002) in children with I54V (46% of total) and 0.48 (CI95%: 0.24; 0.97; P = 0.041) in children with V82A/F (52% of total). Children with I54V and V82A/F had higher prevalence of lopinavir-associated resistance mutations and showed RP of 0.36 (CI95%: 0.17; 0.76; P = 0.007) for achieving uVL. CONCLUSIONS: LMS and PRAMs in HIV-infected children were associated with virological failure in pre-treated HIV-infected children on salvage therapy with lopinavir/ritonavir. Moreover, I54V and V82A/F led to the poorest virological response.

Low blood CD8+ T-lymphocytes and high circulating monocytes are predictors of HIV-1-associated progressive encephalopathy in children.

OBJECTIVE: Human immunodeficiency virus type 1 (HIV-1)-associated progressive encephalopathy (PE) is a common and devastating complication of HIV-1 infection in children, whose risk factors have not yet been clearly defined. Regardless of the age of presentation, PE shortens life expectancy. Paradoxically, as survival of patients has been prolonged as a result of the use of antiretroviral therapy, the prevalence of PE has increased. Therefore, a predictive marker of PE emergence is critical. The objective of this study was to determine in an observational study whether any immunologic (CD4(+) and CD8(+) T-lymphocyte counts, monocyte counts) or virologic (viral load [VL], biological characteristics of viral isolates) marker might be predictive of PE and whether any particular marker may be involved in the timing of clinical onset of PE. METHODS: A total of 189 children who were vertically infected with HIV-1 were studied retrospectively, 58 of whom fulfilled criteria of the American Academy of Neurology for PE. T-lymphocyte subsets and monocytes in peripheral blood were quantified by flow cytometry. HIV-1 RNA was measured in plasma using a quantitative reverse transcriptase polymerase chain reaction assay. Demographic, clinical, and viro-immunologic characteristics in infants were compared with control groups using logistic regression. Proportions were compared using the chi(2) test or Fisher exact test. For each child, immunologic and virologic markers were analyzed in parallel closely before clinical onset of PE and closely after PE onset and compared by using the Student t test for paired samples. RESULTS: Overall, mortality of 58 HIV-1-infected children who developed PE was significantly higher than of children who did not develop this complication. Blood CD8(+) T-lymphocytes <25% in the first months of life suggested a relative risk of progressing to PE 4-fold higher than those with CD8(+) >25% (95% confidence interval: 1.2-13.9) and remained statistically significant after adjustment for treatment. When we compared the PE-positive group with the acquired immunodeficiency syndrome (AIDS)/PE-negative group (children who developed clinical category C and without neurologic manifestations) in a cross-sectional study within 12 months before PE or AIDS diagnosis, respectively, the %CD8(+) T-lymphocytes were significantly lower in the PE-positive group. Normalized absolute counts of CD8(+) T-lymphocytes with respect to seroreverting children were significantly lower in the group of children with encephalopathy with respect to the AIDS/PE-negative group (data not shown). It is interesting that a statistically significant increase was observed in circulating monocyte percentages and absolute counts shortly before the first neurologic symptoms compared with values after PE was established and with those from HIV-1-infected controls. With respect to AIDS-related events, PE was strongly associated with anemia and lymphoid interstitial pneumonitis in the PE-positive group with respect to a group of children with AIDS but without PE. CONCLUSION: HIV-1 infection of the central nervous system (CNS) remains an important clinical concern. The first step toward PE prevention in HIV-1-infected children should be directed at predicting risk of PE and thus the prompt and reliable identification of infants who are at risk for CNS disease progression. Low blood CD8(+) T-lymphocytes is a strong early predictive marker of PE emergence in vertical HIV-1 infection. Indeed, among all of the immunologic and virologic variables assessed in this observational study, the only significant difference during the first months of life are the CD8(+) T-lymphocytes. A peak of significantly higher peripheral monocytes before the onset of PE with respect to established PE has not been previously described, and strengthens the growing evidence that an increased traffic of monocytes to the brain may be a key factor in triggering neurologic symptoms. The suppression of HIV-1 replication is dependent on the presence of a relatively small number of HIV-1-specifof HIV-1-specific CD8(+) T-lymphocytes, and it is possible that the duration of the neurologically asymptomatic phase for any given child may depend mostly on the magnitude of specific CD8(+) T-lymphocyte responses. Thus, a decrease of CD8(+) T-lymphocytes would diminish the host capacity to control viral infection, as reported in animal models, enabling infected macrophages to cross the blood-brain barrier. Our results advocate the use of CD8(+) T-lymphocyte and monocyte counts to follow-up HIV-1-infected children. We suggest that CD8(+) T-lymphocytes may be the nexus for many different aspects of the disease, namely loss of control of HIV-1 replication determining higher VL, increased traffic of activated and/or infected monocytes, spread of infection to immune sanctuaries, and finally clinical neurologic emergence of PE. Moreover, we suggest that CD8(+) T-lymphocytes or/and monocytes may be used as putative biological markers of neuropathogenicity. This might suggest their use in decision making of when to start more effective antiretroviral regimens for HIV-1 infection of the CNS and the need of new therapies either to preserve or to augment an adequate CD8(+) T-lymphocyte immune response. Early detection of children who are at risk for developing PE is particularly important because aggressive highly active antiretroviral therapy improves neurologic symptoms, allows possible use of neuroprotective treatment to prevent further development of encephalopathy, and emphasizes the relevance of developing therapies aimed to enhance CD8(+) T-lymphocyte function. In conclusion, the surrogate markers routinely used in clinical practice for HIV-1 infection (ie, CD4(+) T-lymphocyte counts and VL) seem to be insufficient to evaluate the clinical involvement of the CNS. Other systemic markers, as the recent proposed markers for PE evolution (cerebrospinal fluid VL by lumbar puncture and brain atrophy by cerebral magnetic resonance imaging) are undoubtedly more invasive than measuring CD8(+) T-lymphocyte and monocyte counts, when the neurologic manifestations of PE are still preventable.

Positive virological outcome after lopinavir/ritonavir salvage therapy in protease inhibitor-experienced HIV-1-infected children: a prospective cohort study.

BACKGROUND: Lopinavir/ritonavir has demonstrated antiviral activity in the HIV-infected patient. OBJECTIVE: To analyse virological response to lopinavir/ritonavir therapy in previously protease inhibitor (PI)-experienced HIV-1-infected children. MATERIALS AND METHODS: Sixty-seven HIV-1-children on lopinavir/ritonavir were studied in a multicentre prospective cohort observational study. The outcome variables were undetectable viral load (uVL; VL < or =400 copies/mL) and virological failure after uVL with a rebound of VL >400 copies/mL. VL and genotype of HIV-1-isolates were measured using standard assays. RESULTS: 83.5% of children had a 1 log10 VL decrease including 65.6% who reached uVL. Children with >2 changes of antiretroviral therapy (ART) or >5 drugs needed a median time of 3-4 months higher than children with < or =2 changes of ART or < or =5 drugs previous to lopinavir/ritonavir, to reach those values, and the relative proportions (RP) were 2.2 (P =0.038) and 1.9 (P=0.050), respectively. Children with CD4+>15% (P=0.122), VL < or =30,000 (P < 0.001) copies/mL, and age >12 years (P=0.096) achieved an earlier control of VL during the follow-up. The children with virological failure or rebound of VL had higher baseline VL and lower CD4+ T-lymphocytes/mm3 and had taken a greater number of drugs previous to lopinavir/ritonavir. HIV-children with a new nucleoside reverse transcriptase inhibitor (NRTI), or protease inhibitor (PI) or PI plus non-nucleoside reverse transcriptase inhibitors (NNRTI) in the current regimen had a better virological response than children without these new drugs. Also, children with <6 protease mutations had an RP of 2.31 of achieving uVL. CONCLUSIONS: Highly active antiretroviral therapy (HAART) including lopinavir/ritonavir induces beneficial effects in terms of virological outcome responses, and it is an effective option for salvage therapy in PI-experienced HIV-1-infected children.