Despite clinical benefit with the use of CAR T-cells, the need to manufacture patient-specific products severely limits the clinical utility of this therapy. To overcome this barrier, we developed an allogeneic, "off-the-shelf" CAR T-cell product using Epstein-Barr virus (EBV)-specific T cells (EBV-VSTs) genetically modified with a CD19-specific CAR (19-28z). Patients with relapsed/refractory (R/R) B-cell malignancies (n=16) were stratified into 3 treatment cohorts: cohort 1 (n=8; disease recurrence after allogeneic or autologous hematopoietic cell transplant (HCT)), cohort 2 (n=6; consolidative therapy after autologous HCT), or cohort 3 (n=2; consolidative therapy after allogeneic HCT) (NCT01430390). The primary objective of this trial was to determine safety of multiple CAR EBV-VST infusions. Most patients (n=12/16; 75%) received multiple doses (overall median 2.5; range 1-3) with 3x106 T-cells/kg determined to be the optimal dose enabling multiple treatments per manufactured cell line. Severe cytokine release syndrome or neurotoxicity did not occur post-infusion, and no dose limiting toxicity was observed in the trial. Median follow-up was 48 months (range 4-135 months) with 4 deaths due to disease progression. Overall survival of all patients was 81% (95% confidence interval: 64-100%) at 12 months and 75% (57-100%) at 36 months. Post-infusion expansion and persistence were limited, and CAR EBV-VSTs demonstrated a unique T-cell phenotype as compared to autologous 19-28z CAR T-cells. Our study demonstrates the feasibility and safety of an allogeneic, "off-the-shelf" CAR EBV-VST product with favorable outcomes for patients with R/R B-cell malignancies when targeting the CD19 antigen.
Read full abstract