Andrew B. Nixon, PhD, MBA, discusses the role of immunohistochemistry and multiplex polymerase chain reactions tests in detecting microsatellite instability–high tumors.
Andrew B. Nixon, PhD, MBA, director, Phase 1 Biomarker Laboratory, associate professor of medicine, Duke University School of Medicine, discusses the role of immunohistochemistry (ICH) and multiplex polymerase chain reactions (PCRs) tests in detecting microsatellite instability–high (MSI-H) tumors.
Historically, IHC has been the gold standard to measure MSI status in patients with cancer, says Nixon.
Notably, this technique is practical and readily available in many laboratories.
Moreover, IHC detects the 4 genes that regulate the mismatch repair mechanism: MLH1, MSH2, MSH6, and PMS2, Nixon explains. When one of these genes are lacking, the tumor is deemed MSI-H.
Multiplex PCR, which looks for differences in tandem repeats found at the end of each chromosome, could be considered a second gold standard in identifying MSI status, Nixon says. When differences are found in multiplex PCR testing, the tumor is understood to be MSI-H.
Although IHC and multiplex PCR have historically been the 2 main techniques that have been utilized, next-generation sequencing may play a role in the future of MSI testing as more patients are molecularly profiled, Nixon concludes.