Genetic biomarker may predict cancer patients’ response to immunotherapy drug

In a report of a proof-of-principle study of patients with colon and other cancers for whom standard therapies failed, researchers at the Johns Hopkins Kimmel Cancer Center say that mistakes in so-called mismatch repair genes, first identified by Johns Hopkins and other scientists two decades ago, may accurately predict who will respond to certain immunotherapy drugs known as PD-1 inhibitors. Such drugs aim to disarm systems developed by cancer cells to evade detection and destruction by immune system cells.

“This study gives us a solid clue about how immunotherapy may work in cancer and how to guide immunotherapy treatment decisions based on the genetic signatures of a cancer rather than class of cells or organ of origin,” says Luis Diaz Jr., M.D., an oncologist at the Johns Hopkins Kimmel Cancer Center.

“Defects in mismatch repair genes are found in a small percentage of many cancer types, and this type of biomarker for immunotherapy response could apply to tumours containing errors in other DNA repair genes, as well,” says Dung Le, M.D., an oncologist at the Johns Hopkins Kimmel Cancer Center. “Using a predictive biomarker can help us direct the use of immunotherapy drugs to patients who are more likely to respond, avoiding giving people expensive and time-consuming treatments that are not likely to work or delaying the use of other treatments.” John Hopkins Medicine