Mismatch repair deficiency assessment by immunohistochemistry: for Lynch syndrome screening and beyond.

Wong HL1,2, Christie M1,3, Gately L1,2,4, Tie J1,2,5,6, Lee B1,2,5,7, Semira C1,2, Lok SW1,2,5, Wong R1,2,8, Gibbs P1,2,6.

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Abstract

While mismatch repair (MMR) deficiency has been studied extensively, the assessment of MMR status in colorectal and other cancers remains highly relevant, particularly in light of recent data demonstrating that MMR deficiency is a strong predictor for treatment benefit with immune checkpoint inhibitors across multiple tumor types. In colorectal cancer, there is a growing consensus in support of routine MMR testing for Lynch syndrome screening, to inform prognosis and adjuvant chemotherapy use in early stage disease, and to predict response to immunotherapy in advanced disease. Here, we provide a review of the Ventana MMR Immunohistochemistry Panel, which was recently approved by the US FDA for use in Lynch syndrome screening.