Although the sample size is small (n = 3 independent tumor-ROIs), the density of T cells, including CD39+ Tpex and CD39+ dTex cells, within the tumor area did not increase markedly (Fig. 8g), similar to the lack of increase in their frequency in PBMCs at PD (Fig. S6F) and consistent with previously reported findings in a study of MSI-high rectal cancer45. The gene discussed is ENTPD1; the disease is neoplasm.