{
  "abstract": "Background Specificity profiling is a requirement for monoclonal antibodies (MAbs) and antibody-based biotherapeutics such as CAR-T prior to initiating human trials. Traditional approaches to assess MAb specificity, primarily tissue cross-reactivity (TCR) studies, have been unreliable and have resulted in undetected off-target binding. Cell-based protein arrays represent an alternative and improved assessment tool for MAb specificity that have been recommended in recent FDA guidance.Methods We developed a cell-based protein array, the Membrane Proteome Array (MPA), to assess binding across the full human membrane proteome. The MPA encompasses ~6,000 membrane proteins, each individually expressed in their native structural configuration within live or unfixed cells. The MPA enables quantitative and high sensitivity detection using flow cytometry. Here, we used the MPA to assess the prevalence of off-target binding by candidate antibody therapeutics. We conducted a retrospective analysis of 250 customer preclinical antibodies screened on the MPA. We also produced and screened 83 biosimilars of FDA-approved and clinical-stage therapeutic antibodies.Results Retrospective analysis of customer antibodies that were screened using the MPA indicates a surprisingly high off-target rate, with 33% of lead candidates displaying off-target binding. Moreover, about 20% of therapeutic MAbs in clinical development and currently on the market displayed off-target binding. To directly compare cell-based protein arrays to TCR studies, we compared our own MPA data for therapeutic MAbs to publicly available TCR data and in several cases identified discrepancies in off-target binding results.Conclusions Overall, the presented case studies and off-target rates at the different phases of drug approval suggest that off-target binding is a major cause of adverse events and drug attrition that could be ameliorated with better specificity screening.",
  "authors": [
    {
      "affiliations": [
        "Integral Molecular, Philadelphia, PA, USA"
      ],
      "name": "Diana Norden"
    },
    {
      "affiliations": [
        "Integral Molecular, Philadelphia, PA, USA"
      ],
      "name": "Carmen Navia"
    },
    {
      "affiliations": [
        "Integral Molecular, Philadelphia, PA, USA"
      ],
      "name": "Tabb Sullivan"
    },
    {
      "affiliations": [
        "Integral Molecular, Philadelphia, PA, USA"
      ],
      "name": "Jonathan H Richards"
    },
    {
      "affiliations": [
        "Integral Molecular, Philadelphia, PA, USA"
      ],
      "name": "Rachel Fong"
    },
    {
      "affiliations": [
        "Integral Molecular, Philadelphia, PA, USA"
      ],
      "name": "Benjamin Doranz"
    }
  ],
  "title": "991 Up to one-third of antibody drugs are nonspecific: a systematic evaluation of drugs throughout clinical and preclinical development",
  "uid": "e8b69408-70aa-5dcc-8af8-b2d801fbc8d3"
}