AAAS annual conference:RESEARCHERS HAVE developed a powerful new way to track down the presence of cancer cells even when no other imaging method can see them. The approach will also allow doctors to see whether a treatment is working or needs to be changed to eliminate the cancer.
The technique is so effective because it is based on using the patient’s own genetic code and means that doctors can personalise the treatments they give to a patient. “We believe that this is one of the first applications of new genome sequencing technologies that could be useful for cancer patients,” stated Prof Victor Velculescu of the cancer biology programme at the Johns Hopkins Kimmel Cancer Centre.
The new approach is based on finding “biomarkers” in a patient’s own tumour cells,using them as “red flags” that can show the presence of cancerous tissue, Prof Velculescu told a session at the American Association for the Advancement of Science’s annual meeting, which got under way in San Diego, California, yesterday morning.
Details of his work, co-authored by Dr Rebecca Leary at Johns Hopkins, will appear in the February 24th issue of the journal Science Translational Medicine but were released early at the AAAS meeting.
“There is currently no test for cancer patients that provides personalised biomarkers for clinical management of disease, and we feel this is an important step in bringing new genome sequencing technologies to personalised cancer care,” Prof Velculescu said.
One of the challenges in fighting cancer is knowing whether a treatment method has cleared away all of the cancer cells. Small numbers of residual cells can be left behind after chemotherapy, surgery or radiation and these can grow to re-establish a tumour.
The researchers took tumour tissue samples from four colorectal and two breast cancer patients and used a new DNA sequencing approach to look for telltale cancer biomarkers. Cancers typically have significant rearrangements in the normal DNA profile, like rearranging the chapters of a book, Prof Velculescu said. The team used these rearrangments as markers for the presence of residual cancer cells.
The patients underwent normal therapy, but armed with the personalised biomarkers the team was able to identify the presence of tumour cells that had survived treatment. They found that the method was highly sensitive and could spot the cells when no other method could have revealed them.
They developed a blood test unique to each patient that could look for the biomarkers as the patient received a variety of cancer therapies. This allowed them to see whether a given therapy was having an effect on the cancer cells, something that could provide a powerful new tool in the fight against cancer regrowth.
Although very sensitive, the approach is currently relatively expensive. A genome scan costs about $5,000 (€3,700), compared to $1,500 (€1,100) for a CT scan, but Prof Velculescu expects sequencing costs to continue to fall.
The new method should also prove more cost-effective, given that it will be able to spot the patients who need further treatment much quicker than when using a CT scan.