Expression of CD7-specific CARs on T cells promotes fulminant fratricide of CD7⁺ T-cell subsets. Lu et al generated a CD7 CAR that sequesters the CD7 antigen away from external recognition, which leads to an expansion of fratricide-resistant CD7 CAR T cells. In a phase 1 clinical study, these naturally selected CD7 CAR T cells produced CRs in patients with refractory or relapsed T-cell malignancies.