CD38 and acute myeloid leukemia: Mark Gurney et al. used CRISPR/Cas9 technology to disrupt the CD38 gene during expansion with a mean knockdown efficiency of 84% to achieve an affinity optimized CD38 CAR (87). The CD38 knockout NK cells expressing an affinity optimized CD38 CAR showed reduced NK cell fratricide and enhanced ability to target acute myeloid leukemia (AML) (87).