Tumor cells from α-PD-L1 mAb treated mice retained low expression levels of PD-L1, compared to tumor cells from untreated mice, whether or not additional α-PD-L1 mAb was administered (Figure 2D) and CD8+ TILs isolated from PD-L1 mAb resistant tumors continued to exhibit decreased expression of PD-1 but elevated expression of CTLA-4, while LAG3 expression remained unchanged (Figure 2E-G). Here, CTLA4 is linked to neoplasm.