Abstract 6294: Absolute, quantitative and high throughput measurement of tissue biomarkers in FFPE specimens using QDB method

Abstract

Abstract Absolute quantitation of tissue biomarkers in FFPE samples to aid drug discovery efforts. Tissue protein biomarkers play irreplaceable role in clinical diagnosis, prognosis and prediction. It is also heavily used in drug discovery to evaluate the effectiveness of a drug candidate, or to monitor its potential side effects at both preclinical stage and during clinical trials. In recent years, several tissue protein biomarkers are used as companion diagnostics to identify right patients for the right treatment. However, while the consistency and objectivity are the prerequisites for any assays to be used in scientific studies, the current prevailing method for tissue biomarker assessment, immunohistochemistry (IHC), is known to be associated with inconsistency and subjectivity. For example, there were studies demonstrating as much as 20% inaccuracy in Her2 assessment for breast cancer patients using IHC method. Conceivably, this practice leads to significantly increased cost and efforts in drug discovery. In this study, we demonstrated the usage of Quantitative Dot Blot (QDB) method to achieve absolute and quantitative measurements of tissue biomarkers in Formalin Fixed Paraffin Embedded (FFPE) samples in high throughput format. We were able to develop multiple QDB-based immunoassays using clinically validated antibodies for IHC in several types of cancers including breast cancer, lung cancer and prostate cancer. In the case of Her2, when the quantitatively measured results were converted into dichotomous variables using Receiver Operative Characteristics, we were able to achieve concordance with IHC at 94.8% (n=748), and 94.2% with Fluorescence in situ hybridization (FISH) (n=141). QDB-based assays also require minimum amount of total protein lysates, ranging from 0.1 to 0.5 μg per sample. Total protein lysates extracted from 2X5μm is sufficient to measure at least 5 to 10 protein biomarkers in triplicate. The introduction of QDB method in drug discovery promises significantly increased objectivity and consistency of the results. The high throughput aspect of QDB method also suits well the daily activity in drug development. We believe the adoption of this method should significantly speed up the drug discovery process while reduce the related costs and efforts. Citation Format: Jiandi Zhang. Absolute, quantitative and high throughput measurement of tissue biomarkers in FFPE specimens using QDB method [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6294.