Imaging just one week after starting treatment can predict melanoma response to immunotherapy

New Penn Medicine research shows that following a single dose of a particular immunotherapy drug, CT scans ‘lit up’ with metabolic changes in tumors that correlated with longer survival.

While the standard timing for imaging patients’ tumors after immunotherapy is three months, researchers found that imaging patients with melanoma after just one week of treatment illuminated metabolic changes in their tumors that corresponded with a response to the treatment and longer survival, according to new research from the Perelman School of Medicine.

An MRI machine.
Image: iStock/gorodenkoff

“Time is always valuable when treating cancer, and imaging tumors early can improve how clinicians develop personalized treatment plans for each patient,” says senior author Michael Farwell, an associate professor of radiology at Penn Medicine. “For example, if a patient’s scan shows a response, they could potentially de-escalate therapy or avoid surgery. On the other hand, if a patient isn’t showing a response, it tells their care team to try other treatment options which could better treat their cancer, and would reduce unnecessary side effects from an ineffective and costly treatment.”

Imaging patients with melanoma after just one week of immunotherapy illuminated metabolic changes in their tumors that corresponded with a response to the treatment and longer survival.

Immunotherapy activates the body’s own immune system to attack tumors. While it can be effective for many patients with cancer, not all patients respond to therapy, and the treatment can cause severe adverse events, like toxicity that affects the stomach and intestine, hormone, or skin.

In the study, published in Clinical Cancer Research, Farwell and his colleagues evaluated whether a 18-F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) scan could detect an increase in metabolic activity in patients shortly after their first dose of immunotherapy. FDG PET and CT is typically used to detect cancer in the body. It is FDG that causes tumors to “light up” in CT and PET scans.

Similarly, when a patient responds to immunotherapy, activated immune cells penetrate the tumor, which shows an increase in FDG activity on scans, which Farwell and his collaborators refer to as a “metabolic flare.” Then, as the tumor responds to therapy, the tumor cells die and pass back through a stable metabolism phase and ultimately show a decrease in FDG activity, which the researchers refer to as a state of “metabolic response.” In contrast, the tumors of nonresponding patients maintain stable metabolism.

Read more at Penn Medicine News.