The HOPE fixation technique - a promising alternative to common prostate cancer biobanking approaches

10 prostate cancer samples were each preserved with HOPE, formalin, and liquid nitrogen and studied with in-situ and molecular methods. Samples were H&E stained, and assessed by immunohistochemistry (i.e. PSA, GOLPH2, p63) and FISH (i.e. ERG rearrangement). We assessed DNA integrity by PCR, using control genes ranging from 100 to 600 bp amplicon size. RNA integrity was assessed through qRT-PCR on three housekeeping genes (TBP, GAPDH, β-actin). Protein expression was analysed by performing western blot analysis using GOLPH2 and PSA antibodies.Of the HOPE samples, morphologic quality of H&E sections, immunohistochemical staining, and the FISH assay was at least equal to FFPE tissue, and significantly better than the fresh-frozen specimens. DNA, RNA, and protein analysis of HOPE samples provided similar results as compared to fresh-frozen specimens. As expected, FFPE-samples were inferior for most of the molecular analyses.This is the first study, comparatively assessing the suitability of these fixation methods for diagnostic and research utilization. Overall, HOPE-fixed bio-specimens combine the benefits of FFPE- and fresh-frozen samples. Results of this study have the potential to expand on contemporary prostate tissue biobanking approaches and can serve as a model for other organs and tumors.The importance of prostate tissue bio-repositories is increasing as they are forming an invaluable resource of samples for profound translational research [1-4]. Long term and, preferably, native preservation is an essential requirement of stored samples. Due to the nature of prostate carcinomas which commonly develops multiple and independent tumor foci, they are difficult to identify macroscopically. For research purposes, it is recommended to fresh-freeze each second prostate slice in order to capture the tumour with all foci [2,5-7]. Thus, comprehensive prostate cancer biobanking requires significant amounts of resources, and large patient counts would eventually exhaust th