Objective:Previous studies reported that 4-1BB-based CD19 chimeric antigen receptor(CAR)-T cells were more beneficial for the clinical outcomes than CD28-based CAR-T cells,especially the lower incidence rate of severe adverse events.However,the median progression-free survival(mPFS)of 4-1BB-based product Kymriah was shorter than that of CD28-based Yescarta(2.9 months vs.5.9 months),suggesting that Kymriah was limited in the long-term efficacy.Thus,a safe and durable 4-1BB-based CD19 CAR-T needs to be developed.Methods:We designed a CD19-targeted CAR-T(named as IM19)which consisted of an FMC63 scFv,4-1BB and CD3ζ intracellular domain and was manufactured into a memory T-enriched formulation.A phase Ⅰ/Ⅱ clinical trial was launched to evaluate the clinical outcomes of IM19 in relapsed or refractory(r/r)B cell non-Hodgkin lymphoma(B-NHL).Dose-escalation investigation(at a dose of 5×105/kg,1×106/kg and 3×106/kg)was performed in 22 r/r B-NHL patients.All patients received a single infusion of IM19 after 3-day conditional regimen.Results:At month 3,the overall response rate(ORR)was 59.1％,the complete response rate(CRR)was 50.0％.The mPFS was 6 months and the 1-year overall survival rate was 77.8％.Cytokine release syndrome(CRS)occurred in 13 patients(59.1％),with 54.5％of grade 1-2 CRS.Only one patient(4.5％)experienced grade 3 CRS and grade 3 neurotoxicity.Conclusions:These results demonstrated the safety and durable efficacy of a 4-1BB-based CD19 CAR-T,IM19,which is promising for further development and clinical investigation.