Orasri Wittawatmongkol

Rapid and Massive Virus-Specific Plasmablast Responses during Acute Dengue Virus Infection in Humans

ABSTRACT Humoral immune responses are thought to play a major role in dengue virus-induced immunopathology; however, little is known about the plasmablasts producing these antibodies during an ongoing infection. Herein we present an analysis of plasmablast responses in patients with acute dengue virus infection. We found very potent plasmablast responses that often increased more than 1,000-fold over the baseline levels in healthy volunteers. In many patients, these responses made up as much 30% of the peripheral lymphocyte population. These responses were largely dengue virus specific and almost entirely made up of IgG-secreting cells, and plasmablasts reached very high numbers at a time after fever onset that generally coincided with the window where the most serious dengue virus-induced pathology is observed. The presence of these large, rapid, and virus-specific plasmablast responses raises the question as to whether these cells might have a role in dengue immunopathology during the ongoing infection. These findings clearly illustrate the need for a detailed understanding of the repertoire and specificity of the antibodies that these plasmablasts produce.

Pharmacokinetics and safety of a new paediatric fixed-dose combination of zidovudine/lamivudine/nevirapine in HIV-infected children.

BACKGROUND Alternatives to the available stavudine-containing paediatric fixed-dose combination (FDC) tablets are rapidly needed due to concerns regarding the cumulative toxicity of long-term stavudine exposure. We report the bioavailability and short-term safety of a novel paediatric FDC tablet of zidovudine (ZDV)/lamivudine (3TC)/nevirapine (NVP; 30/15/28 mg) in HIV-infected children. METHODS In this Phase I/II open-label pharmacokinetic study, 42 children weighing 6-30 kg treated with NVP-based HAART for ≥4 weeks were randomized to receive the FDC tablets (GPO-VIR Z30) or the liquid formulations. Dosing was weight-based. Intensive 12-h blood sampling was performed after 2 weeks; subjects then crossed-over to the alternate formulation at equal doses and sampling repeated 2 weeks later. Pharmacokinetic parameters were determined by non-compartmental analysis. Buccal-swab samples were collected for cytochrome P450 (CYP)2B6 polymorphism analysis. RESULTS With the FDC tablet, the geometric mean (90% CI) area under the curve (AUC) for ZDV, 3TC and NVP was 1.58 (1.49-1.68), 7.78 (7.38-8.19) and 68.88 (62.13-76.36) μg•h/ml, respectively. Rules for NVP therapeutic inadequacy were defined a priori, and despite lower NVP exposure with the tablet (P<0.001), the levels remained therapeutically adequate. ZDV AUC was similar between formulations. 3TC exposure was significantly higher with the tablet but comparable to historical data in adults and children taking branded tablets. While receiving the tablet, NVP AUC in children with CYP2B 516 GG (45%), GT (45%) and TT (10%) genotypes were 67.0, 74.5 and 106.4 μg•h/ml, respectively (P=0.04). CONCLUSIONS Disparities in drug exposure between formulations were observed; however, the FDC tablet delivered therapeutically adequate exposures of each drug and could well play an important role in simplifying antiretroviral treatment for children.

Thai national guidelines for the use of antiretroviral therapy in pediatric HIV infection in 2010

Abstract With better knowledge and availability of antiretroviral treatments, the Thai National HIV Guidelines Working Group has issued treatment guidelines for children in Thailand in March 2010. The most important aspects of these new guidelines are detailed below. ART should be initiated in infants less than 12 months of age at any CD4 level regardless of symptoms and in all children at CDC clinical stage B and C or WHO clinical stages 3 and 4. For children with no or mild symptoms consider CD4-guided thresholds of CD4 <25% (children aged one to five years) or CD4 <350 cells/mm3 (children 5 years or older). The preferred first-line regimen in children aged < 3 years is AZT+3TC+NVP. For children >3 years of age the preferred regimen is AZT+3TC+EFV. If an infant has previously been exposed to NVP perinatally, use AZT+3TC+LPV/r as empirical first regimen. In adolescents, consider TDF+3TC+EFV. The preferred ARV treatment in children who failed first line regimens of 2NRTI+NNRTI (Salvage treatment) comprises 2NRTI (guided by genotype) +LPV/r, and an alternative regimen is 2NRTI (guided by genotype) +ATV/ r (use in cases with dyslipidemia who are six years or older). In cases with extensive NRTI resistance with no effective NRTI option available, double boosted PI with LPV/r+SQV or LPV/r+IDV can be considered. Consultation with an expert is recommended. Laboratory monitoring is recommended for CD4 and every six months. Viral load at least at 6 and 12 months after initiation or change of regimen, then yearly thereafter. More frequent viral load monitoring is advised for cases with unsuccessful virologic response, infants, children with imperfect adherence, or those using of third line regimens. Toxicity monitoring depends on the drug received, at least every six months, and more often as clinically indicated. These include, but are not limited to, complete blood count, renal function tests, liver function tests, urinanalysis, and lipid profiles. Therapeutic drug monitoring is recommended in cases that have ARV-related toxicity, receiving non-standard dosing or regimens, using double boosted PI, and in those with renal or hepatic impairment.

Efficacy, safety and pharmacokinetics of tenofovir disoproxil fumarate in virologic-suppressed HIV-infected children using weight-band dosing.

Background: Tenofovir disoproxil fumarate (TDF) is approved for children but concerns remain about long-term renal and bone toxicity. We evaluated the efficacy, safety and pharmacokinetics of TDF in treatment-experienced children during 96 weeks. Methods: This was a prospective, open-label study in HIV-infected children 3–18 years of age (≥15 kg), with viral suppression on their first-line regimen without tenofovir. Children were given TDF/lamivudine/efavirenz once daily at entry; TDF was prescribed according to weight bands. Age-, gender- and CD4-matched controls receiving TDF-sparing regimens were concomitantly enrolled. Tenofovir pharmacokinetic assessment was performed at week 4. CD4 counts, HIV-1 RNA viral load and safety assessments were determined at baseline, 24, 48 and 96 weeks. Results: Eighty children were enrolled (40 per group); 35 (44%) were male. Median age was 12.2 (range 3.1–17.7) years. The median administered dose was 214 mg/m2. Tenofovir geometric mean AUC0–24 hours, Cmax and C24 hours were 2.66 [90% confidence interval (CI) 2.49–2.84] &mgr;g hours/mL, 0.26 (0.24–0.29) &mgr;g/mL and 0.057 (0.052–0.062) &mgr;g/mL, respectively. Estimated glomerular filtration rate did not significantly change overtime. The fractional excretion of calcium slightly increased but fractional excretion of phosphate was unchanged among children in TDF group. The bone mineral density Z score decreased in the first 24 weeks of TDF treatment and was stable afterward. The TDF group had lower cholesterol levels (P = 0.001). Thirty-nine of 40 children remained virologically suppressed. No serious adverse event related to tenofovir. Conclusion: TDF substitution in children and adolescents who were otherwise stable while receiving a first-line nonnucleoside reverse transcriptase inhibitor–based regimen achieved adequate exposure without clinically significant renal or bone adverse events over 96 weeks. While reassuring, these preliminary safety findings may not exclude delayed effects on renal function and bone density.

Immunogenicity and safety of monovalent influenza A (H1N1) 2009 in HIV-infected Thai children.

To evaluate the immunogenicity and safety of the monovalent pandemic influenza A (H1N1) 2009 (pH1N1) vaccine in HIV-infected Thai children, 2 doses, 28days apart, of non-adjuvant monovalent pH1N1 vaccine (Panenza(®) by Sanofi Pasteur, 15μg/dose) provided by the National Health Promotion Program of the Thai Ministry of Public Health were given to HIV-infected children. Immunogenicity was measured by hemagglutination inhibition test (HAI) using two antigens, pH1N1 (A/Thailand/104/09) and seasonal influenza A H1N1 (A/Brisbane/59/07-like), at baseline, and 28days after each dose. Serologic response was defined as four-fold rising of HAI titer or HAI titer ≥1:40 for those with baseline titer ≤1:10. Adverse events were recorded for 7days after each vaccination. Of the 119 HIV-infected children enrolled, 60 (50.4%) were female with a median (IQR) age of 10.4 (7.2-13.7)years. All but 2 (98.3%) children were receiving antiretroviral therapy. At baseline, the median CD4 cell count was 782 (570-1149)cells/mm(3), 91 (80.5%) children had HIV RNA level <40copies/ml. The baseline HAI titer ≥1:40 for pH1N1 and seasonal H1N1 were 45.4%, and 39.5%, respectively. At 28 days after doses 1 and 2, the serologic response rates for pH1N1 were 54.2% and 67.8% with the geometric mean titer of 109.9 and 141.8; and serologic response rate when tested with seasonal H1N1 were 2.5% and 3.5%, respectively. The presence of baseline HAI titer for pH1N1 or seasonal H1N1 was found to be associated with serologic response. The vaccine was well tolerated. The results suggested that monovalent pH1N1 vaccine was immunogenic and safe in well controlled HIV-infected children with low level of cross reacting antibody to seasonal H1N1.

A comparative study of the serological response to Japanese encephalitis vaccine in HIV-infected and uninfected Thai children.

We report a prospective study of mouse brain derived inactivated Japanese encephalitis (JE) vaccine, given in 3-dose EPI program to human immune deficiency virus (HIV)-exposed Thai infants. 18 HIV-infected receiving antiretroviral therapy with median baseline CD4 of 33.1%, and 92 HIV-uninfected children were studied. All but one HIV-infected child seroconverted after the second dose. The geometric mean titers (GMTs) 3 months after the second and third doses in HIV-infected vs HIV-uninfected children were 247 vs 938 (p=0.022), and 2273 vs 24069 (p=0.009), respectively. Urticaria or angioedema found in 4% and 6% in HIV-infected and -uninfected children, respectively (p=1.0). The vaccine was safe and immunogenic but antibody response in HIV-infected children was not as high as in uninfected children.

Lipodystrophy and reversal of facial lipoatrophy in perinatally HIV-infected children and adolescents after discontinuation of stavudine

Lipodystrophy (LD) was evaluated in 205 children receiving antiretroviral therapy by a single investigator: 51 (24.9%) had LD; 46 peripheral lipoatrophy, three central lipohypertrophy and two combined type. All cases of peripheral and combined LD also had facial lipoatrophy. Serial photographs were provided by the families to confirm the severity of facial lipoatrophy. Forty-six (95.8%) children with peripheral or combined LD, and 75 (48.7%) without LD were exposed to stavudine (d4T) for a median duration of 45.9 versus 26.4 months (P = 0.005). In multivariate analysis, exposure to d4T for more than three months was the only factor associated with peripheral or combined LD (P < 0.001). Noticeable improvement of facial lipoatrophy was found in 11/48 (22.9%) children after a mean duration of 45.6 months following d4T discontinuation, mostly occurring during early adolescence.

Risk of first-line antiretroviral therapy failure in HIV-infected Thai children and adolescents.

Background: Adolescence may affect adherence and response to highly active antiretroviral therapy (HAART). Limited data are available regarding the long-term treatment outcomes of perinatal HIV-infected adolescents. Methods: Data from perinatally acquired HIV-infected Thai children who started first-line nonnucleoside analog-based HAART before 18 years of age and treated for ≥24 weeks were analyzed. Children were categorized by age at HAART initiation; age <3 years, 3–9 years, early adolescence (10–13 years) and middle adolescence (14–16 years). CD4 and HIV-RNA were monitored every 6–12 months. Virologic failure (VF) was defined as HIV-RNA ≥ 1000 copies/mL after ≥24 weeks of HAART. Results: Of 840 children, 68% were in pre-adolescence. Median baseline CD4% was 7.9%. Use of nevirapine versus efavirenz was 77:23%. Median duration of nonnucleoside reverse transcriptase inhibitor-based HAART was 5.6 years. No differences between groups were observed for rate of HIV-RNA < 50 copies/mL (68%, P = 0.18) and rate of VF (28%, P = 0.82), median time to VF (22 months, P = 0.13). Incidence of VF per 100 child-year in children age <3 years, 3–9 years, early adolescence and middle adolescence were 7.9, 4.7, 7.4 and 10.8, respectively (P = 0.012). Median adherence by pill count was 97.3% (P = 0.23). By multivariate analysis, predictors for VF were age at HAART initiation of <3 years (HR: 1.73, 95% CI: 1.18–2.55), age 10–16 years (HR: 1.47, 95% CI: 1.09–1.97), and nevirapine use (HR: 1.63, 95% CI: 1.14–2.32). Conclusions: VF rates were observed in one-third of long-term treated Thai children on first-line HAART. Age 3–9 years at HAART initiation was associated with less VF compared with those younger or older, whereas children who used nevirapine had higher VF.

Echocardiography and carotid intima-media thickness among asymptomatic HIV-infected adolescents in Thailand.

Objectives:To evaluate the carotid intima–media thickness (cIMT) in perinatally HIV-infected adolescents and factors associated with cardiovascular abnormalities. Designs:A cross-sectional study was conducted in perinatally HIV-infected adolescents who had no known cardiovascular condition and healthy controls. Methods:Transthoracic echocardiogram and cIMT measurements were taken by pediatric cardiologists. Serum lipid profiles, high-sensitivity C-reactive protein and N-terminal pro-brain natriuretic peptide were measured. Results:Hundred HIV-infected and 50 healthy adolescents were enrolled. Echocardiograms revealed overall normal systolic function (median left-ventricular ejection fraction 66 vs. 66%; P = 0.825). The mean overall cIMTs of common carotid arteries and internal carotid arteries were not different between the groups (0.373 vs. 0.371; P = 0.744). Among the HIV-infected adolescents, those who had been receiving protease inhibitor-containing regimens had an increased cIMT (0.364 vs. 0.381 mm; P = 0.009). Hypertriglyceridemia was found in 52% of those who had received protease inhibitors for more than 6 months, but only in 21% of those who had never received protease inhibitors (odds ratio 4.0, 95% confidence interval 1.6–9.7, P = 0.002). Current HIV-RNA, CD4+, BMI, sex, cholesterol and low-density lipoprotein-cholesterol were not associated with increased cIMT. Serum high-sensitivity C-reactive protein and N-terminal pro-brain natriuretic peptide were not different between the groups and not associated with cardiac abnormalities. Conclusions:Perinatally HIV-infected adolescents had comparable myocardial function and similar cIMT measurements to healthy adolescents. However, hypertriglyceridemia and increased cIMT were found in HIV-infected adolescents receiving protease inhibitor-based regimens. Longer-term follow-up is needed to evaluate HIV-associated cardiovascular disease risk in this population.

A genetically inactivated two-component acellular pertussis vaccine, alone or combined with tetanus and reduced-dose diphtheria vaccines, in adolescents: a phase 2/3, randomised controlled non-inferiority trial

BACKGROUND Increasing evidence shows that protection induced by acellular pertussis vaccines is short-lived, requiring repeated booster vaccination to control pertussis disease. We aimed to assess the safety and immunogenicity of a recombinant acellular pertussis vaccine containing genetically inactivated pertussis toxin and filamentous haemagglutinin, as either a monovalent vaccine (aP[PTgen/FHA]) or in combination with tetanus and reduced-dose diphtheria vaccines (TdaP[PTgen/FHA]), versus a licensed tetanus and reduced-dose diphtheria and acellular pertussis combination vaccine (Tdap). METHODS We did this phase 2/3, randomised controlled non-inferiority trial at two sites in Bangkok, Thailand. Healthy adolescents (aged 12-17 years) were randomly assigned (1:1:1), via a computer-generated randomisation list with block sizes of three, to receive one dose (0·5 mL) of aP(PTgen/FHA), TdaP(PTgen/FHA), or Tdap (comparator). Clinical research staff responsible for participant randomisation, vaccine preparation and administration, and accountability were aware of group allocation. However, allocation was concealed from all other site study staff, data management personnel, statisticians, laboratory staff, and study participants. The primary outcome was non-inferior immunogenicity of TdaP(PTgen/FHA) to Tdap based on seroconversion rates (a four-fold increase or more) for pertussis toxin and filamentous haemagglutinin IgG antibodies 28 days after vaccination, with a predefined 10% margin of equivalence. We did analysis by per protocol. This study is registered with the Thai Clinical Trial Registry, number TCTR20150703002. FINDINGS Between July 6 and Aug 20, 2015, we allocated 450 participants to receive one dose of TdaP(PTgen/FHA) (n=150), aP(PTgen/FHA) (n=150), or comparator Tdap (n=150). 28 days after vaccination, seroconversion rates for anti-pertussis toxin IgG were 96·6% (95% CI 93·8-99·5; n=144) in the TdaP(PTgen/FHA) group and 55·0% (47·1-63·0; n=82) in the comparator Tdap group (difference 41·6%, 95% CI 33·1-50·1; p<0·0001). Seroconversion rates for anti-filamentous haemagglutinin were 82·6% (95% CI 76·5-88·6; n=123) in the TdaP(PTgen/FHA) group and 54·4% (46·4-62·4; n=81) in the comparator group (difference 28·2%, 95% CI 18·1-38·2 p<0·0001). 28 days after vaccination, seroconversion rates in the aP(PTgen/FHA) group were 96·0% (95% CI 92·8-99·1; n=142) for anti-pertussis toxin IgG and 93·2% (89·2-97·3; n=138) for anti-filamentous haemagglutinin IgG. These findings support the non-inferior immunogenicity of TdaP(PTgen/FHA) over comparator Tdap. Reactogenicity and incidence of adverse events were similar between groups. INTERPRETATION The new TdaP(PTgen/FHA) vaccine is safe and induces higher pertussis responses 28 days after vaccination than does the available licensed Tdap booster vaccine. Results of our trial led to the licensure of new acellular pertussis vaccines containing genetically inactivated pertussis toxin in Thailand. The availability of recombinant monovalent pertussis vaccines that induce high antibody responses provides the medical community and consumers with the opportunity to vaccinate against pertussis when immunisation against diphtheria and tetanus is not required or not desired. Studies are underway to pave the way for licensure studies of this acellular pertussis vaccine in other countries. FUNDING BioNet-Asia.