Combination of CD19 and CD70 Specific Chimeric Antigen Receptor T Cells Achieves Long-Term Disease-Free Survival in Relapsed and Refractory Primary Central Nervous System Diffuse Large B Cell Lymphoma
Authors: Tu Sanfang , Huang Rui , Zhou Xuan , He Yanjie , Liang Zhao , Wang Lei , Chang Lung-Ji , Li Yuhua 
Published: October 2019

Abstract
Background: Chimeric antigen receptor-modified T cells (CARTs) targeting CD19 has illustrated therapeutic efficacy in diffuse large B cell lymphoma (DLBCL). However, severe cytokine release syndrome (sCRS) reaction and CAR-T-cell-related encephalopathy syndrome (CRES) are the main adverse reactions of CART therapy. Because of the concern of severe CRES which is associated with potential mortality, patients with primary central nervous system Lymphoma(PCNSL) are excluded in most of CART clinical trials. CD70 is a promising therapeutic target due to the restricted expression pattern in normal tissues and overexpression in some lymphoma tissues, so CD70 specific CARTs maybe avoid CD19-negative relapse .Here we report a case with refractory and relapsed PCNSL who achieved long-term disease-free survival by combination therapy of CD19 and CD70 specific CARTs without inducing CRS or CRES.
Methods: CD3+ cells were selected from the apheresis PBMC and activated before lentiviral 4SCAR infection. The cells were transduced with a caspase 9-inducible, safety-engineered lentivector CAR containing anti-CD19 or -CD70 scFv fused with multiple intracellular signaling domains: CD28/CD27/CD3z-iCasp9 (4SCAR19 or 4SCAR70). The quality of apheresis cells, gene transfer and T cell proliferation efficiencies, and effective CAR T infusion dose were quantitatively scored and documented. Tumor sections were immunohistochemically stained with different antibodies including anti-CD19 and anti-CD70 antibodies to confirm antigen expression. The patient received cyclophosphamide and fludarabine conditioning regimen before the dual CARTs cell infusions.
Case presentation: A 67-year-old male who was diagnosed as PCNSL of DLBCL in 2011.The patient received 6 cycles of temozolomide and high does methotrexate, and achieved CR. In December 2016 he relapsed and was treated with right frontal lobe space-occupying resection and multi-course chemotherapy including 2 course of rituximab, high dose methotrexate and temozolomide ,and 6 courses of rituximab, high dose methotrexate and ibrutinib,and he achieved remission again.However, He relapsed again in August 2017, with the clinical symptoms of dizziness , fatigue, left corners of the mouth askew and occlusal difficulties.MRI presented a residual mass on the right side of the postoperative cavity of 26mm*35mm*30mm and stale hemorrhage in left basal ganglia. After confirmation for CD19 and CD70 expression in his tumor specimens, the pt enrolled in the clinicaltrail :"Combination CART cell therapy targeting hematological malignancies"(clinicaltrail.gov registry NCT03125577).He received 4SCAR19 and 4SCAR70 T cells targeting CD19 and CD70 following lymphodepletion chemotherapy with FC regimen conditioning (FLU 30mg/m2, d1-3; CTX 300mg/m2, d1-3) in October 2017. Brain MRI 1 month later showed complete remission and the pt had symptomatic improvement. To date, after more than 8 months of follow-up, the pt remains in CR (figure1) and CART cells still can be detected . There was no CRS or CRES during the treatment and in follow-up period.
Conclusions: The study results demonstrate that CARTs are able to pass through the blood-brain barrier without inducing CRS or CRES, suggesting that CNS tumor is not an absolute contraindication to 4sCART therapy. In addition, the combination of CD19 and CD70 specific 4sCARTs could effectively target PCNSL and achieves long-term disease-free survival without sCRS or CRES.

Disclosures
No relevant conflicts of interest to declare.