Genomic Marker Predicts Response to PD-1 Inhibitor | Cancer Discovery

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Genomic Marker Predicts Response to PD-1 Inhibitor | Cancer Discovery

CEA levels occurred quickly in the MMR-deficient group, usually within a few weeks of starting treatment. That's an indication that “the T cells were sitting there and that they were inhibited,” said Le. “They were waiting to be released.” In contrast, CEA levels increased in patients with MMR-proficient tumors.

Of note, MMR-deficient tumors had an average of 1,782 mutations; MMR-proficient tumors had just 73. Having a higher number of mutations was linked to a better response. However, some patients with MMR-deficient tumors didn't respond to pembrolizumab, which may mean that “those patients may not have a mutation that the immune system can recognize,” explained Le, adding that researchers plan to further assess the MMR-deficient non-responders.

Although MMR deficiency can occur in many cancer types, including those in the uterus, stomach, biliary tract, pancreas, ovaries, prostate, and small intestine, in addition to colorectal cancer, Le said it is too early to recommend that all patients with cancer be tested for it. Researchers first need to confirm their findings in a larger group of patients. “This was a small study,” she said.


http://cancerdiscovery.aacrjournals.org ... NB2015-079