FIRST PHASE I TRIALS OF SLEEPING BEAUTY-MODIFIED CD19-SPECIFIC T CELLS

Background: T cells expressing antigen-specific chimeric antigen receptors (CARs) improve outcomes for CD19-expressing B-cell malignancies. We provide the first human application of T cells genetically modified using the Sleeping Beauty (SB) transposon/transposase system to express a CD19-specific CAR. Methods: T cells were genetically modified using DNA plasmids from the SB platform to stably express a second-generation CD19-specific CAR and selectively propagated ex vivo with activating and propagating cells (AaPC) and cytokines. Twenty-six patients with advanced NHL and ALL safely underwent hematopoietic stem-cell transplantation (HSCT) and infusion of CAR T cells as adjuvant therapy in the autologous (n=7) or allogeneic settings (n=19). Results: SB-mediated genetic transposition and stimulation resulted in 2,200-2,500-fold ex vivo genetically modified T-cell expansion, with 84% CAR expression, and without integration hotspots. The 30-month progression-free and overall survivals were 83% and 100%, respectively, following autologous HSCT, and the respective 12-month rates after allogeneic HSCT were 53% and 63%. No acute or late toxicities and no exacerbation of graft-versus-host-disease were observed. Despite a low antigen burden and unsupportive recipient cytokine environment, CAR T cells persisted for an average of 201 days for autologous and 51 days for allogeneic recipients. Conclusions: CD19-specific CAR T cells generated with SB and AaPC platforms were safe, and may provide additional cancer control as planned infusions after HSCT, supporting further clinical development of this non-viral gene therapy approach. Total RNA obtained from Unmanipulated quiescent CD3+ T cells and ex vivo expanded CD19CAR+ day 28 T cells