Bionomics files for new breast cancer test patents

Adelaide biotech Bionomics (ASX:BNO) has filed a provisional patent on a new method of determining the prognosis for women with early-stage breast cancer.

The test is based on the BNO64 candidate tumour-suppressor gene. The gene's reduced activity appears to increase a patient's risk of developing correlated with a higher risk of the patient developing breast cancer.

Tumour-suppressor genes prevent cancer by triggering apoptosis, or programmed cell death, in pre-cancerous cells. The loss of both alleles of a tumour-suppressor gene is commonly a key event in a cell's progression to cancerous growth. The P53 tumour-suppressor gene, for example, is mutant in some 50 per cent of common cancers.

But Bionomics CEO Dr Deborah Rathjen said that, with BNO64, the inactivation mechanism was not mutation, but methylation -- the gene is normal, but undergoes hypermethylation, greatly reducing its normal expression.

Prof Grant Sutherland's research group at the Women's and Children's Hospital in Adelaide has identified a number of putative tumour-suppressor genes involved in breast cancer. BNO64 showed promise as a good diagnostic marker, but was expressed at such low levels in early-stage breast cancer that it was a problem to measure its activity.

A Bionomics research group led by Dr Gabriel Kremmidiotis has solved the technical problems involved in measuring the gene's expression.

Rathjen described methylation of tumour-suppressor genes as a "hot field" in cancer research. Analysing the level of expression of these genes to predict the risk of breast cancer could provide an alternative to existing DNA tests that identify high-risk variants of the tumour-suppressor genes BRCA1 and BRCA2.

The BRCA1 and BRCA2 gene tests rely on genetic markers in non-coding DNA, and are thus covered by the controversial international patents on non-coding DNA owned by Melbourne biotechnology company Genetic Technologies.

Rathjen said Bionomics' method of analysing methylation-induced down-regulation of cancer-associated genes could ultimately help specialists and patients make informed decisions about treatment options for cancer.

Breast cancer is the world's third most common cancer, accounting for 34 per cent of all new cancers in women.