Liquid Biopsy Simpler Sampling

Liquid biopsy. Simpler sampling

Liquid biopsies are easier on patients, yield faster results and cost less than tissue biopsies, but these blood draws don’t yet replace traditional tests.

During winter 2013, Larry Gershon had a bad cold that he couldn’t shake. The then 65-year-old print broker took cold medicine and steroids to fight off the symptoms, but the illness persisted. When the wheezing and coughing got worse, he went to urgent care.

“The doctor thought it was best to take a chest X-ray to check for pneumonia. I didn’t have pneumonia, but it showed a spot in my right lung,” says Gershon, a resident of Palo Alto, California. After CT and PET scans revealed a mass in his upper right mediastinum, the chest area between the lungs, doctors surgically removed part of his lymph node for a tissue biopsy.

In late January, he learned he had adenocarcinoma of the lung, the most common type of non-small cell lung cancer (NSCLC). Initially, doctors thought it might be stage 3b because it had spread to his lymph nodes, but a subsequent MRI uncovered metastasis to the brain.

“I was told I had stage 4 lung cancer, and I was shocked — a deer in headlights,” says Gershon, now 72. “Because I was self-employed, one of my biggest concerns, when I was diagnosed, was if I would be able to continue to work.”

Gershon was first treated with chemotherapy in February 2013. A genomic test from his surgical biopsy revealed a mutation in the EGFR gene. In 2015, he moved on to Tarceva (erlotinib), an oral targeted therapy approved by the Food and Drug Administration (FDA) to treat patients whose cancer has spread to other parts of the body and have an EGFR mutation. After 20 months, Gershon’s disease progressed, so he switched to Tagrisso (osimertinib), another oral EGFR inhibitor, which he remains on.

About a year ago, he enrolled in a clinical trial to test a new diagnostic technology, known as liquid biopsy, in patients with previously diagnosed cancer. Instead of analyzing a piece of tissue, as a traditional biopsy does, a liquid biopsy looks for traces of cancer in the bloodstream, also known as circulating tumor DNA (ctDNA).

For the past two-and-a-half years, Gershon’s imaging scans have shown no signs of cancer. Every three months, he has blood drawn in hopes that a liquid biopsy will detect any recurrence as soon as it arises.

“When I progressed in 2016, I had bone metastases, and so they’re currently giving me bone density injections along with a blood draw to check my counts,” he says. “The liquid biopsy is a couple more vials of blood than I already do, so it’s a very simple test.”

Liquid Biopsy for Simpler Sampling

In 2016, the FDA approved the first liquid biopsy to detect EGFR mutations, which are present in 10% to 20% of all NSCLCs and more commonly found in women, Asians and individuals who never smoked tobacco. Today, liquid biopsy has become the standard of care in clinics, either alone or alongside a tissue biopsy.

Although tissue biopsy remains the gold standard, doctors praise liquid biopsy for its many advantages, such as ease of administration, faster turnaround time and lower cost. In addition, even patients with hard-to-reach or small tumors can have blood drawn.

“In lung cancer, we are often dealing with very small tissue biopsies, and sometimes not even a biopsy but an aspirate, which is just a collection of cells, because it is too difficult to get a real tissue biopsy,” says Dr. Fred Hirsch, executive director of the Center for Thoracic Oncology in The Tisch Cancer Institute at Mount Sinai. “With such limited tissue available, it is reasonable to do a liquid biopsy to test for molecular abnormalities like EGFR for the possibility of targeted therapy.”

Liquid biopsy research has focused on NSCLC, which represents 84% of all cases, because of its many molecular biomarkers that have been identified. This disease can exhibit changes not just in EGFR but also in the ALK, BRAF, NTRK and ROS1 genes. A patient with an identified biomarker may be able to be treated with a medication that targets the mutation, potentially working better than chemotherapy and causing fewer side effects.