<h4>Rationale</h4>Chimeric antigen receptor (CAR)-engineered natural killer (NK) cells represent a promising modality for cancer immunotherapy, yet their efficacy in solid tumors is limited by immunosuppressive cues from the tumor microenvironment (TME), particularly, transforming growth factor β (TGFβ).<h4>Methods</h4>Primary human NK cells were cytokine-activated (IL-12/15/18) and engineered via a one-step electroporation that delivered Cas9 ribonucleoprotein and a dsDNA donor (1 kb homology arms, SFFV promoter, poly(A), GRE element) to knock out TGFBR2 and knock in a mesothelin CAR. Here, TGFB1 is linked to neoplasm.