Determination of Anti-Adeno-Associated Viral Vector Neutralizing Antibodies in Patients With Heart Failure in the Cardiovascular Foundation of Colombia (ANVIAS): Study Protocol

Abstract

BackgroundRecent progress in the pathophysiology of heart failure (HF) has led to the development of new therapeutic options such as gene therapy and the use of adeno-associated viral (AAV) vectors. Despite the promising results in early clinical trials of gene therapy for HF, various obstacles have been faced, such as the presence of neutralizing antibodies (NAbs) against the capsid vectors. NAb activity limits vector transduction levels and therefore diminishes the final therapeutic response. Recent studies evaluating the prevalence of NAbs in various populations found considerable geographic variability for each AAV serotype. However, the levels of NAbs in Latin American populations are unknown, becoming a limiting factor to conducting AAV vector therapeutic trials in this population.ObjectiveThe goal of this study is to determine for the first time, the prevalence of anti-AAV NAbs for the serotypes 1, 2, and 9 in HF patients from the city of Bucaramanga, Colombia, using the in vitro transduction inhibition assay.MethodsWe will conduct a cross-sectional study with patients who periodically attend the HF clinic of the Cardiovascular Foundation of Colombia and healthy volunteers matched for age and sex. For all participants, we will evaluate the NAb levels against serotypes AAV1, AAV2, and AAV9. We will determine NAb levels using the in vitro transduction inhibition assay. In addition, participants will answer a survey to evaluate their epidemiological and socioeconomic variables. Participation in the study will be voluntary and all participants will sign an informed consent document before any intervention.ResultsThe project is in the first phase: elaboration of case report forms and the informed consent form, and design of the recruitment strategy. Patient recruitment is expected to begin in the spring of 2016. We expect to have preliminary results, including the titer of the viral vectors, multiplicity of infections that we will use for each serotype, and the general validation of the assay, at the end of 2016. The final results are expected mid-2017.ConclusionsThis project is the first effort to evaluate NAb levels against AAV1, AAV2, and AAV9 serotypes in patients with HF in Latin America. Our results will allow us to check the cross-reactivity response between the serotypes assessed, to describe the epidemiological characteristics of the participant population, and to set up a link with earlier reports of NAb prevalence in the literature.

Adeno-Associated Virus Neutralizing Antibodies in Large Animals and Their Impact on Brain Intraparenchymal Gene Transfer

“…The same issue exists when performing a pre-clinical toxicology study and/or gene-transfer efficiency study in large-animal species such as NHPs. Previous studies surveyed NAbs against several AAV serotypes in general human populations, 5 , 28 specific patient populations, 29 , 30 , 31 , 32 and several animal species. 33 , 34 Collectively, these studies provide a guidance for selecting AAV serotype vectors to maximize the serologically compatible study subjects.…”

Adenovirus‐associated antibodies in UK cohort of hemophilia patients: A seroprevalence study of the presence of adenovirus‐associated virus vector–serotypes AAV5 and AAV8 neutralizing activity and antibodies in patients with hemophilia A

“…Immunoassay is a capture‐based method to detect antibodies capable of binding to the AAV capsid. The AAV capsid or peptide is coated on a plate, plasma or serum added, and antibodies detected with a secondary reagent . In vitro cell‐based assays use a reporter AAV vector that is incubated with the test sample before transduction of a cell line.…”

“…The AAV capsid or peptide is coated on a plate, plasma or serum added, and antibodies detected with a secondary reagent. 17 In vitro cell-based assays use a reporter AAV vector that is incubated with the test sample before transduction of a cell line. These are amongst the most widely used methods of determining anti-AAV neutralizing factors and the transduction inhibition assay is considered a standard.…”

Cardiovascular Response Patterns to Sympathetic Stimulation by Central Hypovolemia

“…Traditionally, the first autonomic cardiovascular response to such a reduction in cardiac preload is believed to be represented by a fast and predominant increase in HR corresponding to vagal withdrawal as the first line of defense. Arterial blood pressure is maintained further by enhancement of sympathetic influence on both HR and TPR which occurs more slowly due to a longer time-constant (Lanfranchi and Somers, 2002 ; Shaffer et al, 2014 ). Recently, a more balanced model of sympatho-vagal control representing a continuous interplay between vagal and sympathetic modulation of HR has been proposed without clear on/off thresholds (White and Raven, 2014 ).…”