Schneider Amy K, Vainshtein Inna, Roskos Lorin K, Chavez Carlos, Sun Bo, Liang Meina
Clinical Pharmacology & DMPK, Medimmune, LLC, 319 North Bernardo Avenue, Mountain View, CA 94043, USA.
Clinical Pharmacology & DMPK, Medimmune, LLC, 319 North Bernardo Avenue, Mountain View, CA 94043, USA.
J Immunol Methods. 2016 Aug;435:68-76. doi: 10.1016/j.jim.2016.05.007. Epub 2016 May 21.
Immunogenicity can impact PK, PD, efficacy and safety of biopharmaceuticals, and is often evaluated as a secondary objective in clinical studies. Methods to detect anti-drug antibodies (ADA) and neutralizing ADA (NAb) are semi-quantitative and utilize cut points to determine positive or negative samples. Assay cut points are established by the statistical analysis of treatment-naïve subject specimens that are assumed ADA and NAb-negative. Pre-existing antibodies to various biopharmaceuticals have been observed in treatment-naïve subjects and may artificially elevate the cut point, resulting in compromised assay sensitivities, inaccuracy in immunogenicity reporting and ultimately misleading assessment of the impact of immunogenicity on clinical outcomes. Although several approaches such as removal of pre-existing antibody samples or increasing the sample dilution could be used for cut point establishment to mitigate impact of pre-existing antibodies, they each have limitations, especially when a high prevalence of pre-existing antibodies is observed. Here we describe an innovative approach used to establish cut points for ADA and NAb assays of moxetumomab pasudotox (moxetumomab), a recombinant anti-CD22 immunotoxin, to which a high prevalence of pre-existing antibodies was observed. In order to overcome the challenges associated with this high prevalence and prevent establishment of an artificially elevated cut point, we developed an immunoinhibition approach that allowed generation of pseudo ADA and NAb-negative populations for cut point determination. Immunoinhibition was performed by adding excess moxetumomab (for ADA) or a non-CD22 binding PE38-containing immunotoxin, CAT-5001 (for NAb), to treatment-naive samples prior to evaluating samples for cut point establishment. This approach successfully eliminated pre-existing antibody activity in treatment-naive samples, enabling establishment of more accurate ADA and NAb assay cut points. A comparative analysis of the clinical immunogenicity results using cut points derived with immunoinhibition and without immunoinhibition (conventional method) demonstrated that the immunoinhibition approach markedly improved detection sensitivity and accuracy of immunogenicity characterization in patient samples. This innovative approach provides an alternative, practical solution for immunogenicity assay cut point establishment when biopharmaceuticals have a high prevalence of pre-existing antibodies.
免疫原性会影响生物制药的药代动力学、药效学、疗效和安全性，并且在临床研究中通常作为次要目标进行评估。检测抗药抗体（ADA）和中和性ADA（NAb）的方法是半定量的，并利用截断值来确定样本的阳性或阴性。检测截断值是通过对未经治疗的受试者样本进行统计分析来确定的，这些样本被假定为ADA和NAb阴性。在未经治疗的受试者中已经观察到对各种生物制药的预先存在的抗体，这可能会人为地提高截断值，导致检测灵敏度受损、免疫原性报告不准确，并最终对免疫原性对临床结果的影响产生误导性评估。虽然可以使用几种方法，如去除预先存在抗体的样本或增加样本稀释度来确定截断值，以减轻预先存在抗体的影响，但它们各自都有局限性，特别是当观察到预先存在抗体的高流行率时。在此，我们描述了一种创新方法，用于确定重组抗CD22免疫毒素莫昔妥单抗（moxetumomab）的ADA和NAb检测的截断值，在该毒素中观察到预先存在抗体的高流行率。为了克服与这种高流行率相关的挑战，并防止建立人为提高的截断值，我们开发了一种免疫抑制方法，该方法允许生成用于确定截断值的假ADA和NAb阴性群体。在评估用于确定截断值的样本之前，通过向未经治疗的样本中添加过量的莫昔妥单抗（用于ADA）或不含CD22结合的含PE38免疫毒素CAT - 5001（用于NAb）来进行免疫抑制。这种方法成功地消除了未经治疗样本中预先存在的抗体活性，从而能够建立更准确的ADA和NAb检测截断值。使用通过免疫抑制和不使用免疫抑制（传统方法）得出的截断值对临床免疫原性结果进行的比较分析表明，免疫抑制方法显著提高了患者样本中免疫原性特征的检测灵敏度和准确性。当生物制药存在预先存在抗体的高流行率时，这种创新方法为免疫原性检测截断值的确定提供了一种替代的、实用的解决方案。
