Liquid Biopsy: A Paradigm Shift in Monitoring Cancer

Guest Author: Dr. Vijay Chandru
Chairman and Managing Director, Strand Life Sciences

Diagnosis, administration of chemo- or radiotherapy, a wait-and-watch approach for new clinical symptoms of cancer (6-12 months) and fresh rounds of chemo- and radiotherapy is the established pattern of cancer care. More often than not, the waiting period for the emergence of clinical symptoms is the hardest part where both doctors and patients are in limbo, without specific clues about how a cancer is going to ‘behave’- remain quiet or grow aggressively- after the last round of therapy. A method for monitoring cancer, that allows a sneak peek at the status of a cancer in this period, would be of immense value to the field.

This insight into the status of a cancer, before it shows up as new nodules of growth on a PET/CT scan or as other clinical symptoms, is precisely what a new technique- called Liquid Biopsy – is set to provide.

Liquid biopsy tests are a set of new blood tests that will enable scientists to extract and analyze DNA shed by cancer cells in a patient’s blood. In India, Strand Life Sciences has launched a portfolio of liquid biopsy tests that will help in identifying and tracking the genetic signature of a cancer, throughout the course of the disease, in every single patient. Cancers are dynamic diseases and the profile of genes that are mutated (changed) in these cells is likely to change naturally, as well as post treatment. So, monitoring how a patient’s cancer responds to treatment and whether it is likely to recur, are two important issues to be tackled.

Strand Life Sciences has developed and validated a set of genetic tests for monitoring cancer, on a per patient basis. Applicable to many cancer types, the identification of genetic changes from solid tumor tissue as well as liquid biopsy tests for tracking changes in the tumor are the essential components of these genetic tests.

Scientists at Strand are adept at extracting DNA shed by normal as well as cancerous cells from blood. Using highly sensitive and accurate genetic tests, a specific set of mutations can be identified from this DNA. The presence or absence and the concentration of characteristic mutations in the liquid biopsy provide an accurate snapshot of cancer.

As an added feature, the genetic analyses of tumor tissues are also likely to indicate very specific drugs that can be possibly used for treatment.

A patient was recently referred to Strand for identification of mutations in lung cancer. Genetic analysis of the patient’s tumor tissue showed that a specific mutation – a deletion in Exon 19 – in a gene called EGFR was present. This identification allows the patient to receive drugs like Erlotinib, Gefitinib, and Afatinib, that work in cancer cells but not in normal lung cells. The most significant advantage here is that side effects of the drugs are limited.

The same patient was referred for a follow-up screening using a liquid biopsy test to understand whether the patient was becoming resistant to the given therapy or not. Usually, lung cancer patients become resistant to Erlotinib, Afatinib, and Gefitinib when the EGFR gene develops another mutation – known as T790M. So, tracking the emergence of this new mutation is a good strategy to decide when a lung cancer patient should switch to new drugs that can target the T790M mutation.

In the first follow-up test using liquid biopsy, the tumor DNA did not show the presence of this resistant mutation. The patient is under surveillance and will be taking Strand’s LB Monitor test periodically to monitor the response of the cancer to therapy.

Strand’s scientists have developed and validated liquid biopsy-based genetic tests to a performance level that is ten-fold higher than that reported from other labs, while being 100% accurate. The average price of these tests is also significantly lower than that of tests provided by global genetic diagnostics companies. The launch of this portfolio of tests reflects Strand’s commitment to bring affordable excellence to healthcare delivery in India, at par with global standards of care.