Induced T cell dysfunction may be a potential mechanism of resistance to BiTE-mediated therapy as a preclinical study identified upregulation of the checkpoint inhibitor PD-1 in malignant cells exposed to blinatumomab, and in vivo upregulation of PD-1 and PD-L1 was observed in an ALL patient who had received blinatumomab [78]. This evidence concerns the gene PDCD1 and acute lymphoblastic leukemia.