CD19 CAR T-cell Escape in Large B-cell Lymphoma: Antigen Density Matters after All

In this issue of Blood Cancer Discovery, Corona, Gillmor, and colleagues show that quantitative CD19 density measured before chimeric antigen receptor (CAR) T-cell infusion stratifies progression-free survival in large B-cell lymphoma, yet low antigen density rarely reflects a genetic lesion at the CD19 locus itself, suggesting that other mechanisms of CD19 downregulation may promote CAR T-cell escape. Moreover, Newsam and colleagues offer one explanation-recurrent del(3p21.31)/RHOA loss that results in decreased CD19 in trans and impairs CAR T-cell efficacy. See related article by Corona, Gillmor, and colleagues, p. XX . See related article by Newsam and colleagues, p. XX .