PDCD1 and neoplasm: Beane et al. (79) demonstrate a significant decrease in the number of tumors after treatment with ZFN-PD-1 KO TILs as well as an improved in vitro effector function through TNF-α, GM-CSF and IFN-γ secretion after co-culture with tumor cells, with a predominant effector memory-like phenotype in engineered TILs, and no detectable proliferative defects or tumor formation in NSG mice (79).