Dr. Shiller Discusses Molecular Testing in Gastrointestinal Cancers

Shirley Michelle Shiller, DO, member of the Precision Medicine Institute's Advisory Committee, Baylor University Medical Center, discusses molecular testing in gastrointestinal cancers.

Molecular markers have increasingly driven selection for therapies in the gastrointestinal space, says Shiller. Some of the most impactful agents have been PD-L1 inhibitors for gastric cancer, but it is important to note that the interpretations of the tests are different than the ones used in the lung, Shiller explains.

Mismatch repair deficient (dMMR) and microsatellite instability-high (MSI-H) tumors are also important to identify, as there are specific agents that have shown efficacy in patients who harbor those alterations. For example, pembrolizumab (Keytruda) is currently approved for the treatment of adult and pediatric patients with unresectable or metastatic, MSI-H or dMMR solid tumors, as well as for patients with MSI-H or dMMR colorectal cancer following progression on a fluoropyrimidine, oxaliplatin, and irinotecan. When looking at this space, Shiller says that it is important to utilize markers that screen for hereditary predisposition to gastrointestinal cancers. Several sites of origin—apart from the colon—have been seen in patients with hereditary syndromes.