April 24, 2017

A pinprick to detect cancer


 Drawing on genetics, Indian companies are offering blood tests to ferret out cancers
While the humble blood test has for long been the touchstone to catch diabetes, malaria and
HIV, companies are now drawing on knowledge from human genetics to make blood tests
smart enough to fish out several kinds of cancers.

Earlier this month, Strand Life Sciences, a Bengaluru-based company, began offering a test
called ‘STRAND LB’ that claims to be able to detect traces of a tumour “from a simple blood
draw”.

MedGenome, another company based in Bengaluru — also announced the launch of
“ONCOTRACK”, another ‘liquid biopsy’ test. “Management of cancer will undergo a
massive transformation in India with NGS (next-generation sequencing)-based liquid
biopsies… ONCOTRACK is one such offering,” says MedGenome chairman Sam Santhosh
in a press statement.

Liquid biopsies
NGS refers to techniques to scan genes and look for mutations that may cause cancer.
Traditionally, ferreting out cancer requires scooping out tissue from a suspected organ and
testing them for the disease. Depending on the location of the cancer, this frequently involves
invasive surgery.

Moreover, even after surgery or chemotherapy, several more biopsies are continually
required to check if the cancer has disappeared or worse, relapsed. Biopsies are also required
to check if the cancer is caused due to specific kinds of mutations that would render certain
kinds of treatment ineffective.

Liquid biopsies, as these tests are called, involve being able to catch free-floating pieces of a
tumour or particular pieces of tumour DNA in the blood. These are then analysed to see if the
DNA contains mutations that are known to be linked to particular kinds of cancer.

The trouble usually is that they are present in amounts too minuscule to be detected. To have
a shot at capture, any test has to be sharp enough to fish out about one molecule in 1,000.
“STRAND LB can detect tumour DNA traces in as many as 35% of patients with early-stage
cancer, going up to 70-90% in patients with locally advanced or metastatic cancer. These
figures are on a par with the best in the world,” says Dr. Vijay Chandru, chairman and
managing director, Strand Life Sciences. These numbers spanned a wide variety of cancer
types, including lung, colorectal, breast, and bladder cancer.

According to Dr. Chandru, liquid biopsy tests couldn’t yet be a replacement for traditional
biopsies but there were a variety of situations that made them useful — for instance, lung
cancer patients who couldn’t afford to part with enough tissue. These are important to
determine if their tumours carry mutations in genes such as EGFR, making them eligible for
specific treatments. It can also be used to monitor the very same patients for the emergence of
resistance to these treatments.

The cost barrier
Liquid biopsy tests approximately cost 15,000- 20,000, making them roughly three-four
times as costly as solid biopsies. However, proponents say the world over, liquid biopsies are
considered an emerging technology and it was quite likely that in the next five years there
would be blood tests powerful enough to find out if a seemingly healthy person has been
struck by cancer. “At least in the case of breast cancer, research shows that liquid biopsies are
extremely effective,” says Shantanu Chowdhury, a cancer researcher at the CSIR-Institute of
Genomic and Integrative Biology in Delhi.

India is likely to have over 1.73 million new cases of cancer and over 8,80,000 deaths due to
the disease by 2020. Around 70% of all cancer patients approach the doctor when the disease
has advanced and chances of a cure are very low.

Source: The Hindu

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