ROR1 and neoplasm: To investigate if the combination of anti-ROR1-CAR-NK cells and C021 has advantages over anti-ROR1-CAR-NK cells alone or C021 alone in limiting NB tumor growth and improving mice survival, we xenografted luciferase-expressing CHLA-255 cells subcutaneously into NSG mice and treated the animals with PBS or 1 × 104 PFU C134 or C021 intratumorally (once) followed by intraperitoneal injection of PBS or 5 × 106 mock NK or ROR1-CAR-NK cells (twice: 2 and 9 days after viral injection) (Figures 3B and S5).