In early 2016, Matthew Tobin came down with a headache and persistent cough that lasted for months. When his doctor ordered an X-ray to test for pneumonia, it revealed a spot on his lung. After a tissue biopsy, doctors gave him the devastating diagnosis: lung cancer.
But to know the exact type of lung cancer — what its genetic characteristics were — Tobin’s oncology team at Dana-Farber Cancer Institute in Boston would have to wait a week or more to get results from the tissue sample. They suggested a relatively new option: a liquid biopsy, or blood sample, from which they might be able to quickly isolate the cancer’s genetic markers.
“We had results within a couple days of my giving the blood sample,” says Tobin, 50, a Massachusetts attorney in private practice. He tested positive for epidermal growth factor receptor (EGFR) gene mutation and also had metastatic disease, which made him a good candidate for a drug, Tarceva (erlotinib), that targets this receptor. “The day I got my results, I walked out of Dana-Farber with a targeted drug. Within days, I felt better. Within weeks, we had started to turn the tide.”
Not long ago, liquid biopsies were once the province of theory and hope. Now they are becoming part of the standard of care in lung cancer.
“We’ve been making a ton of headway on precision therapies and genomics,” explains Geoffrey Oxnard, M.D., Tobin’s oncologist at Dana-Farber and an assistant professor of medicine at Harvard Medical School. “But it’s not that easy to connect a patient to a drug. It’s not that easy to get tumor to test in all patients. With the convenience of liquid biopsy, there’s no excuse not to offer precision therapy and genomics to all your patients with lung cancer.”
In 2016, the Food and Drug Administration approved the first liquid biopsy test, to screen the blood plasma of patients with metastatic non-small cell lung cancer who may have particular mutations in the EGFR gene. But experts say this technique is being used in many different lung cancer scenarios. Specific genetic drivers, or suspected drivers, can be detected in more than half of lung cancers, studies show.
Second- and even third-line therapies have increased median progression-free survival rates two to three times longer than in patients receiving traditional chemotherapy. And liquid biopsies make it easier to test whether the cancer of a patient will react well to these new anti-tumor agents, experts say.
“Liquid biopsies are just another way of identifying molecular markers,” says Philip Mack, Ph.D., director of molecular pharmacology at the University of California, Davis. “But with a liquid biopsy, you can take a sample anytime. You can look to see how a tumor has evolved over time. You can test whether the tumor is developing resistance. It’s the next frontier of cancer research. We need to put a lot more energy into doing rigorous clinical trials that take advantage of liquid biopsies.”
Lung cancer is the leading cause of cancer deaths overall. Each year, more people die of lung cancer than of colon, breast and prostate cancers combined. Unfortunately, most cases of the disease are not diagnosed in early stages, when the disease typically causes no symptoms. And treatment options remain confusing for stage 3, locally advanced lung cancers. It’s unclear how to predict when and whether these patients will progress and whether it makes sense to use treatments designed for patients with metastatic disease.