Dr. Nixon on the Role of IHC and Multiplex PCR in Detecting MSI-H 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 detect​s 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 look​s 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.