Blood Test Could Predict Treatment Response in Throat Cancer

A sensitive blood test shows promise for predicting whether patients with metastatic HPV-positive throat cancer will respond to treatment. The new test could signal whether treatment is working months earlier than standard imaging scans, allowing doctors to try alternatives sooner.

That’s according to a study, published in Oncotarget, validating the test in a small group of patients with metastatic human papillomavirus-related oropharyngeal squamous cell carcinoma — a type of head and neck cancer that develops in the back of the mouth and in the throat. The blood test is being developed by a team of researchers at the University of Michigan Rogel Cancer Center.

If the test can quickly determine that a treatment approach isn’t helping, it could allow doctors to seek out alternative therapies or clinical trials in a more timely manner. It could also potentially spare some patients months of toxic side effects from a treatment that isn’t working.

“Currently, the only way doctors know if a treatment is working is for the patient to get an imaging scan every few months to see whether their tumors are shrinking,” said oncologist Paul Swiecicki, MD, one of the study’s senior authors. “And this isn’t fully accurate since some cancers show what we call pseudoprogression, where a successful treatment actually makes the tumors bigger before it shrinks them. Our goal was to develop a test that could tell us whether a treatment is likely to work after a single cycle.”

The test is a form of “liquid biopsy” that looks for DNA shed by a patient’s cancer cells into their bloodstream using a method known as digital droplet PCR, which can amplify minute amounts of DNA for analysis. Development of the test was led by co-first authors Catherine Haring, MD, an otolaryngology resident, and Chandan Bhambhani, PhD, a postdoctoral research fellow in the lab of senior study author Muneesh Tewari, MD, PhD.

“We can actually identify DNA from a small tumor at the back of the throat circulating throughout the entire bloodstream,” Haring said.

"From a single tube of blood, this technology can isolate a single copy of tumor DNA,” Bhambhani added. “And quantifying the number of copies can tell us whether a patient’s cancer is responding to treatment.”