Figure 1.
Oncogene vs. T cell driven immune checkpoint pathway upregulation. Tumor cells can induce PD-L1 expression in a cell autonomous manner via the oncogene EGFR. Alternatively, PD-1 pathway upregulation can be the consequence of CD8 T cell infiltration. These models generate different hypotheses to identify patients who will benefit from immune checkpoint blocking therapies. Future studies may resolve the contribution of each mechanism in various malignancies.