Low prevalence of MSI-High cancer in Japanese patients

According to materials published by Merck & Co., which manufactures and sells Pembrolizumab, In the classification of MSI-High cancers in various cancer types, MSI-High gastric cancer accounts for about 8.5% of all gastric cancers, and MSI-High esophageal gastric junction cancer accounts for about 4% of all esophageal cancers.

In cancer genomic medicine conducted at a national university in Japan during one year from April 2020 to March 2021, medical treatment was examined for 587 cases of all cancer types, and MSI-High cancer accounted for about 6.6% (39/587) of all cancer types. There was only one case of MSI-High gastric cancer. Currently, patients with MSI-High gastric cancer are being treated with Pembrolizumab. The antitumor effect of Pembrolizumab to this patients with MSI-High gastric cancer has not yet been clarified.

The incidence and characteristics of each cancer type in Japanese patients are different compared to other races. From clinical practice, the prevalence of MSI-High cancer is clearly lower in all Japanese cancer types than in other races.

Note: Cancers with high Microsatellite instability (MSI) express a large amount of neoantigen (cancer specific antigen). Therefore, it can be expected to have a therapeutic effect on MSI-H cancer by inhibiting immune checkpoints such as Pembro., Nivo., Atezo.

Doctor specializing in cancer treatment / Cancer genomic medicine / Emerging infectious diseases　　                                                               JAMA Oncology April 02, 2021. Published by Kyoto@Takuma H