CTLA4 and gastric cancer: An association between a higher TMB and a treatment response to anti-PD-1 monotherapy has been demonstrated in dMMR/MSI-H colorectal, gastric cancer and other gastrointestinal malignancies.14,27,28 We did not observe any difference in the median TMB between responders and non-responders, which once again may relate to treatment with combined anti-PD-1/CTLA-4 checkpoint inhibition compared to anti-PD-1 monotherapy in the former trials.