Long-term benefit of immunotherapy in a patient with mismatch repair deficient/microsatellite instability-high/high tumor mutational burden lung cancer: case report and literature review

Genetic mutations that cause defective mismatch repair, may result in microsatellite instability, which is common in colorectal carcinoma and gastric cancers as well as Lynch syndrome. Mismatch repair deficiency/microsatellite instability-high(dMMR/MSI-H) predicts the tumor response to immune checkpoint inhibitors. However, few studies have evaluated the effects of immune checkpoint inhibitors on dMMR/MSI-H non-small cell lung cancer (NSCLC). We report here a squamous lung cancer patient with dMMR/MSI-H and high tumor mutational burden(TMB-H) who obtained the long-term benefit from immunotherapy. We consider that NSCLC patient with dMMR/MSI-H can benefit from immune checkpoint inhibitors.