The impaired function and diminished persistence of CAR-T cells in vivo following infusion may also lead to relapse.74 Point mutations in CD19 exon 3 can affect the epitopes recognized by CD19 FMC63 CAR-T cells and induce CD19-positive relapse in patients with high-grade B-cell lymphoma.77 Most of the single-stranded variable fragments (scFv) in CAR are derived from mice and have high antigenicity, low persistence, and a high recurrence rate.78 Here, CD19 is linked to B-cell non-Hodgkin lymphoma.