Clinical and Laboratory Standards Institute document I/LA34-A—Design and Validation of Immunoassays for Assessment of Human Allergenicity of New Biotherapeutic Drugs; Approved Guideline provides a framework for the design and validation of a qualitative immunoassay that detects human immunoglobulin E (IgE) antibody to new drugs in various body fluids and tissue extracts. It addresses technical challenges that are uniquely associated with the development of an assay that detects drug-specific IgE antibody in human blood and tissue extracts. It provides an approach for validation of an assay in the absence of a positive drug-specific human IgE antibody serum, which involves a feasibility study phase and then development and validation, using a concomitantly established drug-specific human immunoglobulin G antibody assay as part of its quality control program. This guideline is intended for use by clinical and laboratory investigators who are involved in generating preclinical data and performing clinical trials involving new biotherapeutic drugs. It is also intended as a guideline for administrators of manufacturer safety programs, and government regulators who are required to critique IgE antibody assay methods and assess the validity of allergenicity data that have been submitted by innovator pharmaceutical investigators as part of a governmental licensing process for a new drug.

This guideline provides an overall strategy for the design and validation of assays to measure human immunoglobulin E (IgE) antibodies specific for new biotherapeutic drugs in the serum of subjects enrolled in clinical trials. This document builds on past drug-specific antibody–focused recommendations,1-4 incorporating new analytical technologies. Because IgE antibody responses are typically in the nanogram per milliliter range, human serum should be analyzed in IgE antibody assays minimally diluted. This guideline addresses the technical challenges associated with nonspecific binding (NSB) that can occur when specimens such as serum or tissue extracts are analyzed undiluted or concentrated. It also provides an approach for addressing potential assay interference that can result when nanogram per milliliter levels of IgE antibody attempt to bind to limited immobilized drug in the presence of microgram per milliliter quantities of drug-specific non-IgE antibody (eg, immunoglobulin G [IgG], and sometimes immunoglobulin A [IgA] and immunoglobulin M [IgM]). The guideline overviews supplemental serological analyses that can support the interpretation of human IgE antidrug assay results (eg, atopy screens, total IgE). It presents practical methods for the quality control (QC) of assay reagents. 

This document does not discuss the relationship between analytical measurement of IgE antibody quantity in blood or tissue and a subject’s clinical risk for type I hypersensitivity. It does not discuss assays used to assess adverse reactions to the active ingredients of vaccines. The I/LA34 document does not duplicate information in published recommendations for IgG antibody assays,1-4 except as needed for clarity. These published consensus strategies for defining the positive cut-point and validating IgG antidrug assays assume to be operative for IgE antibody assays as well, unless discussed in this document as not technically feasible due to the absence of a positive human IgE antidrug control. Assays that can be used to monitor cellular immune responses or the release of mediators and cytokines (eg, interleukin [IL]-4, IL-5, IL-6, transforming growth factor beta [TGFß]) from basophils and mast cells are also not discussed. 

The document is designed for use by academic and industrial laboratory scientists and clinicians, and drug manufacturers who are involved in generating preclinical data and performing clinical trials of new biotherapeutic drugs. Clinical laboratories involved in developing drug-specific IgE antibody assays for use in monitoring subjects involved in clinical trials or companies manufacturing IgE antibody assay kits for monitoring marketed drug effectiveness may need to meet applicable international, national, accreditation, local, and organizational requirements. Others reside in companies that are involved in developing IgE antibody assay kits for use in monitoring drugs following federal licensure. This guideline is also intended for use by administrators involved in establishing manufacturer safety programs and government regulators who are required to critique assay methods and assess the validity of allergenicity data that have been submitted by innovator pharmaceutical investigators as part of the licensing process for a new drug.