Today’s big advances in medicine are built on a foundation of past discoveries, new technologies and forward thinking. At the Ludwig Center at Johns Hopkins, all the parts are coalescing into major gains for diagnosing and controlling cancer. The latest is a liquid biopsy, “a noninvasive way of monitoring a person’s cancer status,” typically by using the patient’s blood, explains Johns Hopkins neurosurgeon Chetan Bettegowda.

“Our research is focused on understanding the genetic makeup of a tumor. Once we know it, we can search for a particular DNA biomarker in a patient’s blood and use that signature to quantify the cancer, decide on the best treatment, and monitor the patient over time for drug resistance and other responses,” he says.

As a neurosurgeon, Bettegowda is focused on a unique aspect of a liquid biopsy for brain cancers. “Brain cancers do not shed much DNA into the blood, probably because of the natural blood-brain barrier,” he explains. The Ludwig Center researchers and worldwide collaborators are working to detect brain cancers in cerebrospinal fluid (CSF) instead, via a spinal tap.

Bettegowda wants to avoid surgical procedures whenever possible. He envisions, for example, using a CSF liquid biopsy for brain tumor patients who develop treatment side effects that mimic tumor progression. “We’d spare the patient going into surgery for a biopsy of the tumor itself.”

The researchers haven’t completely ruled out a blood-based liquid biopsy for analyzing brain tumors and responses to treatment. Blood- and CSF-based liquid biopsies are being researched in parallel. “We expect to develop new ways of detecting molecules of DNA from nervous system cancers that could show up in blood,” says Bettegowda. 

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