When submitting an IND for a therapeutic biological molecule such as a humanized monoclonal antibody, the FDA recommends that a comprehensive Tissue Cross-Reactivity (TCR) evaluation be included as defined in the document "Points to Consider in the Manufacture and Testing of Monoclonal Antibody Products for Human Use". This document outlines a GLP protocol for the immunohistochemistry screening of the therapeutic molecule and its isotype control at two different dilutions across triplicate specimens of 33 frozen human tissue types. Because GLP studies require the disclosure of all results, the optimal assay conditions for each antibody should be determined under R&D conditions before proceeding. Our non-GLP TCR screening service is a timely, cost effective approach to gaining this valuable information.

We have the full complement of Human and Cynomolgus frozen normal tissues available for inclusion in these studies.

Phase I - Antibody Preparation and Characterization: Humanized antibodies and their corresponding control antibodies are labeled with FITC so that an anti-FITC secondary antibody conjugated with Alkaline Phosphatase or Horseradish Peroxidase can be used as the colorimetric detection system. The primary therapeutic antibody and an appropriate control antibody are then tested in IHC using frozen positive/negative control tissues as well as tissues known to exhibit non-specific background staining (human and/or Cyno). The results are analyzed by a LifeSpan pathologist and reported to the customer.

Phase II - Preliminary TCR Screen: Intended to identify potential cross-reactivity issues prior to conducting the full screen. This preliminary screen includes immunolabeling 1 specimen each of the 33 frozen normal tissue types with a single dilution of the therapeutic and control antibodies. The resulting slides are interpreted by a LifeSpan pathologist and the results are delivered to the customer in the form of an online tabular report.

The list of 33 tissues recommended by the FDA and screened as part of this study:

Phase III - Comprehensive TCR Screen: Both the test and IgG isotype control antibodies are then used at a high and a low concentration to immunolabel 3 individual specimens each of the 33 frozen normal tissue types recommended by the FDA. The resulting slides are interpreted by a LifeSpan pathologist and the results delivered in the form of duplicate bound reports. The report layout is based upon the FDA’s recommendations and includes a signature page, executive summary, methods, materials, and the scoring table results.