The technology consists of markers whose expression discriminates between patients with prostate cancer and patients without at a rate of 95% correct diagnosis, and between localised and metastatic prostate cancer with a correct diagnosis of 85%.

The test is based on quantitative RT-PCR measuring mRNA extracted from circulating prostate cancer cells in patient blood samples.

Prostate cancer is increasingly recognised as a major health problem, being the second most common cause of cancer related deaths in men in the US, behind lung cancer.  219 000 new cases will be diagnosed in the US this year, but while 1 man in 6 will get prostate cancer during his lifetime, only 1 in 34 will die of the disease. 

40million PSA tests, the current gold standard diagnostic, are carried out annually in the US, with sales of $450 million.  Serum PSA levels demonstrate large areas of overlap, resulting in sensitivity of around 30%. Generally, the next stage of diagnosis is biopsy, which is painful and invasive, and accuracy depends on sampling of correct area and accurate histological examination.  These figures demonstrate the urgent need for new accurate tests to identify and characterise prostate cancer.

The group at St George’s have measured mRNA expression levels of 25 biomarkers in over 400 patient and control blood samples. This information is backed up by a comprehensive database of clinical details providing known patient diagnosis and stage of disease development.  Statistical methods were employed to identify the most discriminatory combinations of biomarkers.  

There is a highly significant improvement in disease diagnosis and monitoring using selected combinations of these biomarkers over PSA measurement.  Results indicate that a combination of four markers gives 95% correct diagnosis of cancer/non-cancer from a population of patients referred on the basis of positive PSA results.  A combination of just two of these markers gives 82% correct diagnosis.   

Differential regulation at different stages of disease has enabled markers to be identified that accurately diagnose early stage disease development, late stage transition form localized to metastatic disease and response to therapy. Not only could this information reduce the cost associated with biopsy, but it could enable case management decisions to minimise intervention where it is not necessary.   

The data generated here could form the basis of a number of tests for various scenarios, as follows.   

1. To replace the PSA test in first-line screening for cancer/non-cancer 

2. To provide a further screening step to filter positive PSA results to identify those patients who are really appropriate for biopsy.    

3. To further stage disease in addition to histological examination. 

4. To monitor response to therapy

Early Stage

PCT filed November 2005 (PCT/GB2005/004494) claiming priority from:

UK 0425873.7 filed 24/11/04

UK 0521524.9 filed 21/11/05

Industrial partner to collaborate or licence the technology