Abstract C3: Validation and fitness testing of a quantitative immunoassay for HIF1α in biopsy specimens.

Abstract

Abstract HIF1α is an important marker of hypoxia in human tumors that is altered in a number of cancers, but a reproducible method to determine changes in HIF1α protein expression in human tumor biopsy specimens has not been available. HIF1α is being used as a pharmacodynamic marker in a clinical trial of metronomic Topotecan (CTEP# 8610, 9534). However, an important limitation for studying the response of HIF1α to cancer therapeutic agents is the lability of the protein, in the presence of oxygen, upon collection of the sample. We have devised a method of specimen collection, handling and extraction that preserves and stabilizes HIF1α levels in tumor biopsies. Employing this specimen handling method allowed validation of a two-site immunoassay for HIF1α quantitation in solid tissue extracts, such as tumor biopsies. Intra-assay variability was less than 10% and inter-assay variability was less than 20%. Accuracy, assessed by spike recovery, was 100 +/− 10%. HIF1α readings declined linearly with decreasing sample load over a range of 1 to 10 μg protein per well. HIF1α is being used as a pharmacodynamic marker in a clinical trial of metronomic Topotecan, so fitness for purpose was demonstrated by quantifying a reduction in HIF1α protein levels following topotecan treatment of a xenograft model. HIF1α was also demonstrated to be upregulated under low oxygen tension culture conditions in DU145 human prostate cancer cells. The HIF1α immunoassay is currently being transferred to the NCI's National Clinical Target Validation Laboratory for use in support of NCI-sponsored early clinical trials. This Research has been funded with federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. HHSN261200800001E. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C3.