Dominant-negative PD1-armored CART cells induce remission in refractory diffuse large B-cell lymphoma (DLBCL) patients.

Abstract

e19028 Background: The chimeric antigen receptor (CAR) T cell treatment has been demonstrated as an effective therapy to relapse/refractory B cell malignancy. However, tumor microenvironment influences and affects CAR T treatment. For example, programmed death ligand 1/2 (PDL1/2) may inhibit the CAR T cells via interaction with up-regulated Programmed cell death protein 1 (PD1) during T cells activation, suppressing the tumor-killing capability of the CAR T cells. Thus, blockade of the PD1-PDL1/2 interaction may enhance the anti-tumor efficacy of CAR T therapy. Methods: We generated CAR T cells including an anti-CD19 second generation (2G) CAR molecule and a dominant negative PD1 molecule (Figure A). Compared with conventional CART cells, these “armored” CART cells show the enhanced capability of tumor killing after multiple-round tumor challenging and more “memory-like” phenotypes (Figure B). These results suggest dominant negative PD1 molecules may protect CART cells from exhaustion in the tumor microenvironment. Results: We report clinical trials of three refractory diffuse large B cell lymphomas (DLBCLs) patients that were successfully treated using the armored CAR T cells described above. All of these three patients failed to achieve response after multiple rounds of chemotherapy and radiotherapy. However, after infused with autologous CART cells at 5.23×10^6/kg and 1.97×10^6/kg, respectively, they showed significant tumor mass decrease and SUV max declines in PET/CT results and ongoing responses (e.g., from 34.48 to 3.89 at day 27, from 25.02 to 2.38 at day 31, respectively, see Figure C). Conclusions: These three clinical trials revealed the significant anti-bulky lymphoma response with respect to these armored CAR T cells and limited and tolerated cytokine release syndrome and central nervous system toxicity. Also, dominant negative PD1 molecules may augment CAR T cells persistence in patients after activation by lymphoma cells, thus enhancing the efficacy of CAR T cells in the treatment of hematomas. Finally, the techniques described herein are a platform technology and may be applied to other adoptive cellular immunotherapies such as TCR-T or TIL in the treatment of solid tumors. We are continuing to recruit more patients for the clinical trials. Clinical trial information: ChiCTR1900021295.