Whole genome testing used to guide breast cancer treatment

Whole genome testing has been used to guide tailored treatment against advanced breast cancer in a group of 43 patients. The scientists behind the study say their research is a step on the path towards 'personalised medicine' where individual genetic makeup informs treatment choice.

'For the first time, we have shown that scanning the whole genome can identify both frequent and rare genomic alterations and can be done in clinical practice with large numbers of women', said study leader Dr Fabrice André from the Institut Gustave Roussy in France. 'Until now, genetic testing has only analysed a limited number of genes to select which targeted drugs are suitable for individual patients and many treatment opportunities may be missed'.

In the study researchers first pinpointed individual genetic abnormalities in tumour samples from patients with breast cancer which had spread to other parts of the body. This analysis was then used to then classify patients for appropriate early clinical trials on new medicines, thus hopefully increasing the chances of successfully combating their disease.

The scientists obtained biopsy samples from 407 patients and 297 of these qualified for genomic testing. Of these, 195 patients had changes in their genes which were identified as potentially responsive to tailored medicines. However only 43 were treated accordingly, mainly because of limited availability of the matched therapy. Finally, 13 patients were treated successfully: in four cases a measurable response of the tumour was recorded, and in nine the disease remained stable with no progression for over 16 weeks.

For their analysis the team used high-throughput DNA testing methods like comparative genomic hybridisation (CGH) array to detect abnormal numbers of gene copies in the tumour tissue, and DNA sequencing to find mutations in cancer gene 'hotspots'.

However, the results also revealed that 117 of the 297 women who received genomic testing had very rare alterations that occur in less than 5 percent of general population. For most of these cases no treatment, either licenced or in clinical trials, are currently available.

Professor Charles Swanton from the Cancer Research UK London Research Institute wrote an editorial in the Lancet Oncology to accompany the study. He says: 'In view of the challenges highlighted by SAFIR01 [the study], efforts to accelerate genomic analyses for personalised medicine must continue to be embedded within the context of clinical trials, and integrated with scientific and clinical collaborative structures to deliver measurable benefits to patients'.

If you want to hear more about the possibility of personalised prevention and treatment of breast cancer, and about other aspects of breast cancer come to the Progress Educational Trust's free public Relative Risk: Breast Cancer and Genetics in central London on the evening of Thursday 3 April 2014. Find out more here.