AAVS1KO/CD38-CAR NK cells avoid fratricide. (A) CD38 (PE) and CAR (APC) expression levels measured by flow cytometry for the CD38-CAR inserted into different loci. All CAR NK cells were generated with matched donors. (B) Fold expansion of WT and CD38-CAR NK cells over 12 days (n = 6; mean ± SD). P values were calculated using a 2-way ANOVA; ∗P < .05; ∗∗P < .01; ∗∗∗P = .001; ∗∗∗∗P < .0001. (C) Relative percentage of CD38-CAR expression (n = 6; mean ± SD). (D) Reverse-transcription qPCR was performed using CD38 primer probes to detect transcription of the CD38 gene in the WT and AAVS1KO/CD38-CAR NK cells. (E) CD38 expression measured by flow cytometry using a polyclonal anti-CD38 antibody.