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.
jacob.koshy@thehindu.co.in
