We attributed this to the functional heterogeneity of T-cell subtypes across distinct cancer types, as we further found that CD8+ Tcms and CD4+ Tcms expressed higher levels of the exhaustion marker gene CTLA4 but lower levels of the integrin ITGA4 and the chemokine receptor CXCR5, indicating their exhausted and inactivated status,26 and therefore, their responsiveness to treatment was reduced. Here, CTLA4 is linked to cancer.