Profiling and targetting cancer genes
CANCER, an increasingly common killer in today’s world, is driven by mutated genes that cause the body’s cells to grow in an uncontrolled way.
Our cells have many mechanisms to prevent mutations or damage in the DNA (deoxyribonucleic acid), but when such measures fail and rogue cells accumulate, this can lead to cancer.
“Errors happen in our DNA all the time, and there is a machinery that repairs it.
“It does a really good job most of the time, but in some cases, there are some that get through the net and these alterations can give rise to tumours,” says Roche Foundation Medicine international scientific lead Dr Nicolas Martin.
He was speaking at the Transforming Cancer Care Via Advances In Genomic Profiling workshop held in Kuala Lumpur recently.
The workshop was organised by Roche Malaysia as part of a series of educational workshops to inform and educate the public on developments in the pharmaceutical industry.
Conventionally, the approach to cancer care defined the disease and treatment by its location – for instance, cancer in the lung is lung cancer, cancer in the breast is breast cancer and so on, and will be treated as such.
Today, however, the spotlight is increasingly turning to precision oncology where treatment is guided by the genetic alterations that are driving the cancer.
The idea is that more information on the specific cancerous genetic mutations that are unique to the patient, can help create a more effective and personalised treatment for the patient.
Tests for molecular profiling of tumours range from simple to complex, from the detection of one mutation in one gene, to nextgeneration sequencing technologies that allow for multiple genes to be accessed at once.
“Nowadays, we look at the driver, or the mutation, of the cancer, rather than the site of the disease.
“Single-marker testing is a routine test we still do now – it’s very helpful, cheap, easy and fast.
“But we may miss some of the mutations,” says consultant clinical oncologist Dr John Low.
This is where comprehensive genomic profiling comes in.
Of late, there has been much interest in using genomic, or genetic, profiling to help identify targeted therapies for cancer patients.
Unlike conventional tests, which may miss critical information, genomic profiling enables detection of the different types of gene alterations, namely, DNA base substitutions, insertions and deletions, amplification and rearrangements.
“There are hundreds of genes that contribute to cancer development, but each patient’s cancer profile is unique.
“Genomic profiling is such a revolution as it allows physicians to test a small amount of tumour tissue for the many possible genomic alterations and then tailor a treatment plan,” says Dr Martin.
Dr Low agrees that by obtaining a complete picture of the patient’s unique genetic alterations, it will potentially enable the doctor to expand and optimise treatment plans that may be more effective and less toxic.
But revolutionary as it may be, the use of genetic profiling in precision oncology does come with its own set of challenges.
Firstly, genetic profiling can help with identifying cancer gene mutations, but there might not be drugs that have been developed to target all the mutations detected.
“Genomic profiling is an essential tool for the oncologist.
“But drug development has not caught up with the diagnostic part of genomic profiling.
“You will find in some cases, we don’t have the drug available to target the abnormality.
“Over time, we hope for better treatments to emerge, for new drugs to be developed to keep up with diagnostics,” says consultant clinical oncologist Dr Tho Lye Mun.
Another consideration is the price factor.
“Genomic profiling is expensive and not everyone can afford it.
“The turnaround time can also be long, especially if you have to send it abroad,” says Dr Low.
However, he adds, if all these constraints were taken away, genomic profiling could be a powerful tool in cancer care.
“Genomic profiling is still quite new, many trials are ongoing.
“But I believe it is the future for cancer diagnosis and treatment,” he concludes.