Novel approaches to prostate cancer detection, diagnosis and stratification

Lead Research Organisation: University of Manchester
Department Name: School of Medical Sciences

Abstract

Prostate cancer has received much press and public attention as an under researched cancer. It accounts for >47,000 new cases and 11,000 deaths pa in the UK. Despite improvements in terms of treatment over the last few decades, the increasing prevalence of prostatic malignancy due to an ageing population, and potentially over diagnosis, poses a significant challenge. Although prostate specific antigen (PSA) has been somewhat beneficial, its overall utility remains controversial. Following an era of PSA-based screening, it is fraught with problems of overdiagnosis and overtreatment. Thus, there is an unmet need to discover better reagents to 'improve' PSA and potentially novel biomarkers that are not only highly specific and sensitive for detecting prostate cancer earlier but that can also discriminate benign from malignant disease and, perhaps most importantly, distinguish indolent cancer from that which is aggressive. This need for improved reagents, sensitivity and specificity in detection and monitoring is for both patient benefit and health economic grounds.

The SISCAPA technique has been developed to combine optimal features of both mass spectrometry and immunoassay. SISCAPA is distinct to conventional immunoassays as enzymatically digested proteins are used to generate peptide analytes in the first instance and then the antibody specifically 'fishes' out the right peptides from the right protein with no interfering factors. Protein-specific proteotypic peptides are then measured using mass spectrometry.

We will develop an improvement(s) on this approach and compare it to more standard approaches using biotin labelled antibodies to proteotypic regions of PSA that has been manufactured for this purpose by Bioventix, our industrial partner. We will undertake the following:

- Establish PSA immunoassays using protein standards and standard ELISA protocols defining sensitivity and dynamic range
- Develop a PSA enrichment protocol using biotin labelled antibodies and determine the effect on sensitivity and dynamic range
- Develop an immunoprecipitation technique for PSA using the novel, Bioventix antibodies
- Analyse prostate cancer samples: plasma, plasma-spiked with PSA, immunoprecipitated PSA from plasma and plasma-spiked with PSA on a mass spectrometer in Selected Window Acquisition of Theoretical (SWATH) Mass Spectra mode and also in Selected Reaction Monitoring mode
- Determine the best assay for sensitivity and dynamic range
- Use the developed assay on a prostate cancer cohort available to us to detect PSA sensitivity and compare to Gleason score in prostate cancer patients

The successful student will receive extensive training in many transferable skills including antibody generation, immunoassays, processes for antibody characterisation, mass spectrometry, analytical biochemistry, prostate cancer pathology and patient stratification and PPI/E.

Publications

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