Team including UCSD bioengineer develops blood test to catch cancer years sooner

Colon cancer cells with DNA stained red. Colon cancer is one of five types of cancer detected by the PanSeer blood test.
Human colon cancer cells with DNA stained red. Colon cancer is one of five types of cancer detected by the PanSeer blood test, according to researchers.

Researchers from Shanghai and San Diego have developed a blood test that catches certain cancers up to four years before patients show symptoms, which could help doctors remove or treat tumors before they become deadly, according to a UC San Diego news release.

The blood test, called PanSeer, detects stomach, esophageal, colon, lung and liver cancer. The international research team published its results July 21 in the journal Nature Communications.

“The ultimate goal would be performing blood tests like this routinely during annual health checkups,” UCSD bioengineer Kun Zhang, one of the study’s authors, said in a statement. “But the immediate focus is to test people at higher risk, based on family history, age or other known risk factors.”

The blood test measures bits of DNA from tumor cells. Tumor DNA often has little chemical changes that turn certain genes on and others off; PanSeer looks for those modifications.

To test how well the test works, researchers used blood samples from people who were symptom-free as well as those who had already been diagnosed with cancer. The samples are part of a decade-long health study in China that monitored more than 100,000 people between 2007 and 2017.

Some people who were initially symptom-free were diagnosed with cancer years later. PanSeer detected nine of every 10 such cases. The test performed about equally well in detecting cancer in patients who had already been diagnosed.

In 2014, Zhang co-founded Singlera Genomics, a San Diego company working to fine-tune PanSeer and other early-stage cancer tests. In 2018, Singlera announced that it had raised $60 million in venture capital.

Zhang said PanSeer probably needs two to four more years to be ready for use. That’s about how long he thinks it will take to run clinical trials testing PanSeer’s usefulness and accuracy.

Several other biotech companies, including San Diego’s Biocept, also are working on cancer blood tests. Medical oncologist Ivor Royston, who sits on Biocept’s board, said Zhang’s findings are early-stage but could one day be useful in catching cancer earlier.

“If you’re positive on the test, it would certainly make some sense, if I were the oncologist, to monitor that patient more closely and more regularly but not scare the patient,” said Royston, who co-founded San Diego’s first biotech, Hybritech.

Royston cited a couple of issues for the authors to sort out. One is that about 5 percent of study patients who tested positive on the blood test didn’t develop cancer. If the researchers could reduce that error rate, he said, they would avoid scaring patients with false alarms.

And he said the test would be more useful if it identified exactly what type of cancer a patient might develop rather than lumping the five types together. ◆