Although our anti-CD138 CAR construct improved the anti-tumor function with 49% CAR+ pNK cells in vivo, we also observed a marked decline in CAR expression during ex vivo expansion, with expression dropping from 51% on TD + 5 to 15% on TD + 12, leading to the limited use of CAR-pNK cells within short expansion time (Figure 2I). This evidence concerns the gene SDC1 and neoplasm.