Unexpectedly, the exhausted CD4+ T cells [CD4-S5 (cluster 4) in BC; CD4-S9 (cluster 8) in CRC; CD4-S6 (cluster 5) in LC; CD4-S4 (cluster 3) in PDAC; and CD4-S4 (cluster 3) in SCC] were distinguished across five cancer types. The gene discussed is CD4; the disease is breast cancer.