In an expanded, three–year clinical trial of 86 patients with colorectal and 11 other kinds of cancer that have so–called ‘mismatch repair’ genetic defects, scientists at Johns Hopkins Medicine and its Bloomberg~Kimmel Institute for Cancer Immunotherapy have found that half of the patients respond to an immunotherapy drug called pembrolizumab (Keytruda).

In a report on the findings, which led the U.S. Food and Drug Administration to approve expanded use of pembrolizumab for patients, the researchers also say they found evidence that the immune responses closely aligned with mutations found in their cancers.

The report was published online in the June 8 issue of the journal Science.

“Our study results may lead to a new standard–of–care that includes mismatch repair deficiency testing to help identify a wider group of patients who have failed other therapies but may benefit from immunotherapy drugs.” says Dung Le, MD, oncologist at the Johns Hopkins Bloomberg~Kimmel Institute, who led the clinical trial.