Abstract 2947: Towards advanced precision oncology assays - Selection of immunohistochemistry chromogen impacts microdissection and downstream molecular analysis of archival specimens

• Published in: Cancer research (Chicago, Ill.) Ill.), 2020-08, Vol.80 (16_Supplement), p.2947-2947
• Main Authors: Laun, Sarah, Roberge, Adam, Weigman, Robert, Lewis, Aubrey, Greisman, Valarie, Liu, Meeiyueh, Stephens, Owen, Peterson, Erich, Shin, Ikjae, Emmert-Buck, Michael, Tangrea, Michael, Johann, Donald J.
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2020-2947

Introduction: Precision medicine promises to improve patient treatment outcomes based on the application of molecular profiling methodologies to pathological specimens. This approach enables the development of rationally derived therapy assignments for each individual patient's tumor (versus categorical treatment assignments). Since tumors are composed of heterogeneous cells forming clusters of subtypes, dissimilar molecular profiles may emerge depending on which region is sampled and analyzed. Additionally, a manual slide scrape may result in a reduced or nearly absent molecular signal (i.e. key driver). Clearly, for cancer there is a need for an efficient, upfront enrichment method to specifically isolate specific tumor cell populations. Immuno-Laser Capture Microdissection (immuno-LCM) is a technology based on immunohistochemistry (IHC) that can isolate specific cell types from a heterogeneous cellular population. We sought to determine the impact of various IHC chromogens on the efficacy of microdissection and downstream molecular analysis from immuno-LCM samples. Methods: Histological tissue specimens (clinical colorectal and lung cancer PDX) were processed using traditional IHC methods with a variety of chromogens, including: Vector Black, Impact Vector Red, 3-amino-9-ethylcarbazole (AEC), and 3,3'-diaminobenzidine (DAB). These chromogens were evaluated for staining quality, microdissection efficiency, biomolecular extraction, and evaluation of specific molecular targets. Results: Interestingly, DAB, the most commonly used chromogen, demonstrated a negative impact on the retrieval of biomolecules from immuno-LCM samples. However, chromogens such as Vector Black and Impact Vector Red showed much improved biomolecule extraction compared to DAB even though the yield of microdissected material was comparable. While other chromogens, such as AEC, demonstrated a greater efficiency of biomolecule extraction but showed incomplete immuno-LCM of specific IHC-stained cells. Conclusions: The data indicate that traditional IHC chromogens should be carefully considered when using immuno-LCM to analyze biomolecules. Citation Format: Sarah Laun, Adam Roberge, Robert Weigman, Aubrey Lewis, Valarie Greisman, Meeiyueh Liu, Owen Stephens, Erich Peterson, Ikjae Shin, Michael Emmert-Buck, Michael Tangrea, Donald J. Johann. Towards advanced precision oncology assays - Selection of immunohistochemistry chromogen impacts microdissection and downstream molecular analysis of a