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Predictors of durable immune responses six months after the last vaccination in preventive HIV vaccine trials.

ABSTRACT: The evaluation of durable immune responses is important in HIV vaccine research and development. The efficiency of such evaluation could be increased by incorporating predictors of the responses in the statistical analysis. In this paper, we investigated whether and how baseline demographic variables and immune responses measured two weeks after vaccination predicted durable immune responses measured six months later.We included data from seven preventive HIV vaccine regimens evaluated in three clinical trials: a Phase 1 study of four DNA, NYVAC and/or AIDSVAX vaccine regimens (HVTN096), a Phase 2 study of two DNA and/or MVA vaccine regimens (HVTN205), and a Phase 3 study of a single ALVAC/AIDSVAX regimen (RV144). Regularized random forests and linear regression models were used to identify and evaluate predictors of the positivity and magnitude of durable immune responses.We analyzed 201 vaccine recipients with data from 10 to 127 immune response biomarkers, and 3-5 demographic variables. The best prediction of participants' durable response positivity based on two-week responses rendered up to close-to-perfect accuracy; the best prediction of participants' durable response magnitude rendered correlation coefficients between the observed and predicted responses ranging up to 0.91. Though prediction performances differed among biomarkers, durable immune responses were best predicted by the two-week response level of the same biomarker. Adding demographic information and two-week response levels of different biomarkers provided little or no improvement in the predictions.For some biomarkers and for the vaccines we studied, two-week post-vaccination responses can well predict durable responses six months later. Therefore, if immune response durability is only assessed in a sub-sample of vaccine recipients, statistical analyses of durable responses will have increased efficiency by incorporating two-week response data. Further research is needed to generalize the findings to other vaccine regimens and biomarkers. Clinicaltrials.gov identifiers: NCT01799954, NCT00820846, NCT00223080.

SUBMITTER: Huang Y

PROVIDER: S-EPMC5319823 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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Predictors of durable immune responses six months after the last vaccination in preventive HIV vaccine trials.

Huang Yunda Y Zhang Lily L Janes Holly H Frahm Nicole N Isaacs Abby A Kim Jerome H JH Montefiori David D McElrath M Julie MJ Tomaras Georgia D GD Gilbert Peter B PB

Vaccine 20170125 8

<h4>Background</h4>The evaluation of durable immune responses is important in HIV vaccine research and development. The efficiency of such evaluation could be increased by incorporating predictors of the responses in the statistical analysis. In this paper, we investigated whether and how baseline demographic variables and immune responses measured two weeks after vaccination predicted durable immune responses measured six months later.<h4>Methods</h4>We included data from seven preventive HIV v ...[more]

PMID: 28131393

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Project description:BackgroundVaccination against tuberculosis (TB) should provide long-term protective immunity against Mycobacterium tuberculosis (M.tb). The current TB vaccine, Bacille Calmette-Guerin (BCG), protects against disseminated childhood TB, but protection against lung TB in adolescents and adults is variable and mostly poor. One potential reason for the limited durability of protection may be waning of immunity through gradual attrition of BCG-induced T cells. We determined if a MVA85A viral-vector boost could enhance the durability of mycobacteria-specific T cell responses above those induced by BCG alone.MethodsWe describe a long-term follow-up study of persons previously vaccinated with MVA85A. We performed a medical history and clinical examination, a tuberculin skin test and measured vaccine-specific T cell responses in persons previously enrolled as adults, adolescents, children or infants into three different Phase II trials, between 2005 and 2011.ResultsOf 252 potential participants, 183 (72.6%) consented and completed the study visit. Vaccine-induced Ag85A-specific CD4+ T cell responses were remarkably persistent in healthy, HIV-uninfected adults, adolescents, children and infants, up to 6 years after MVA85A vaccination. Specific CD4+ T cells expressed surface markers consistent with either CD45RA-CCR7+ central memory or CD45RA-CCR7- effector memory T cells. Similarly durable Ag85A-specific CD4+ T cell responses were detected in HIV-infected persons who were on successful antiretroviral therapy when MVA85A was administered. By contrast, Ag85A-specific CD4+ T cell frequencies in untreated MVA85A-vaccinated HIV-infected persons were mostly undetectable 3-5 years after vaccination.ConclusionMVA85A induces remarkably durable T cell responses in immunocompetent persons. However, results from a recent phase IIb trial of MVA85A, conducted in infants from the same geographic area and study population, showed no vaccine efficacy, suggesting that these durable T cell responses do not enhance BCG-induced protection against TB in infants.

Project description:Response patterns may differ between patients with first-episode and multiepisode schizophrenia. This analysis explored trial duration with first-episode patients and asked whether early limited improvement predicts ultimate lack of treatment response with first-episode patients as it does with multiepisode patients.One hundred twelve subjects (mean age = 23.3 years, SD = 5.1 years) who presented between November 1998 and October 2004 with a first episode of psychosis and had a DSM-IV diagnosis of schizophrenia or schizophreniform or schizoaffective disorder were randomly assigned to treatment with olanzapine or risperidone for 16 weeks. Treatment response, the primary outcome measure, was defined as a rating of mild or better on all of the positive symptom items on the Schedule for Affective Disorders and Schizophrenia Change Version With Psychosis and Disorganization Items. Response rates were calculated for each study week. A logistic regression analysis examined the association between percentage reduction in symptom severity scores from baseline values at weeks 2, 4, or 8 and response by week 16. The study was conducted at The Zucker Hillside Hospital, Glen Oaks, New York and the Bronx-Lebanon Hospital Center, Bronx, New York.The estimated cumulative response rate was 39.59% (95% CI, 29.77%-49.41%) by week 8 and 65.19% (95% CI, 55.11%-75.27%) by week 16. The confidence intervals for estimated response at weeks 10, 12, 14, and 16 were not distinct. Response rates increased approximately 5 to 6 percentage points each 2-week interval between week 10 and 16. Percentage reduction in symptom severity score at week 4 (but not 2 or 8) was associated (?²? = 3.96; P < .05) with responder status at week 16 (odds ratio = 1.03; 95% CI, 1.00-1.05). However, receiver operating characteristic curves did not suggest any level of percentage symptom reduction that would be clinically useful as a predictor of response by week 16.Many first-episode patients respond between weeks 8 and 16 of treatment with a single antipsychotic medication. Limited early symptom improvement does not identify those first-episode patients who will not improve with a full 16-week trial with enough accuracy to be clinically useful.clinicaltrials.gov Identifier: NCT00000374.

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Predictors of durable immune responses six months after the last vaccination in preventive HIV vaccine trials.

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Predictors of durable immune responses six months after the last vaccination in preventive HIV vaccine trials.

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