Objective: To observe the changes of PD-1 expression, mRNA level and cytotoxic activity of CD19 CAR-T cells during the culture process of CAR-T cells. Methods: The peripheral blood T cells of 6 lymphoma patients with high expression of PD-1 and 6 healthy volunteers were the source of CAR-T cells. The expression of PD-1 was analyzed by flow cytometry. The mRNA level of PD-1 was analyzed by PCR. The cell proliferation was analyzed by CCK-8 assay. The cytotoxicity was analyzed by LDH assay. Results: ①The transfection efficiency of high PD-1 expression T cells and healthy volunteer T cells were as the same (P>0.05) . ②The cell proliferation capacity of CD19 CAR-T cells from high PD-1 expression T cells or healthy volunteer T cells, with or without PD-1 inhibitor were as the same (P>0.05) . ③The cytotoxicity to lymphoma cells of high PD-1 expression T cells and CAR-T cells were lower than that of these two T cells combined with PD-1 inhibitor and the CAR-T cells from healthy volunteer T cells (P<0.001) . There was no difference of the cytotoxicity between the CAR-T cells from high PD-1 expression T cells combined with PD-1 inhibitor and the CAR-T cells from healthy volunteer (P>0.05) . ④There was no difference of the expression of PD-1 in all CAR-T cell groups during the culture process (P>0.05) . There was no difference of mRNA level of PD-1 in all groups during the culture process (P>0.05) . ⑤The PD-1 expression of CAR-T cells increased by the time of culture after contacting with lymphoma cells (P<0.001) . The PD-1 inhibitors could antagonize this effect. There was no difference of mRNA level of PD-1 in all groups after contacting with lymphoma cells (P>0.05) . Conclusion The PD-1 expression of CAR-T cells from high PD-1 expression T cells increased by the time of culture after contacting with lymphoma cells. However, the mRNA level of PD-1 of all groups did not change, even if PD-1 inhibitor was applied.

Objective:This study aimed to evaluate the maintenance therapy following an anti-CD19-CAR T-cell therapy for a B-cell acute lymphoblastic leukemia (ALL) patient who relapsed after allogeneic hematopoietic cell transplantation (allo-HSCT) and investigate the effect of donor stem cells and donor T lymphocyte infusion on the amplification of CD19 CAR-T cells.Methods:One refractory B-ALL patient relapsed after murine CD19 CAR-T cell therapy followed by a sibling allo-HSCT. He underwent a humanized CD19 CAR-T cell therapy followed by donor stem cell and donor T lymphocytes infusions as maintenance therapy in our hospital. The level of cytokines, the proportion of CD19 CAR-T cell, the level of CAR19 DNA expression in the peripheral blood, and the proportion of leukemia cells and donor chimerism in the bone marrow were detected. Correspondingly, T lymphocytes from the C57 spleen were separated to modify the CD19 CAR lentivirus and refused into C57 mice, and after 14 days, the B lymphocytes from C57 mice were separated and refused into the same C57 mice. The CD19 CAR T cells, B cells, and CD19 CAR gene counts in the peripheral blood were evaluated at different time points.Results:①The patient achieved a complete response (CR) 14 days after a humanized CD19 CAR-T therapy with grade 1 cytokine release syndrome (CRS) and restored a donor chimerism to 99.76%. ② Following the remission from humanized CD19 CAR-T therapy, the patient received a maintenance therapy of donor stem cell infusion. Mild graft-versus-host disease (GVHD) manifested 24 days after infusion with an increased proportion of CD19 CAR-T cells and an increased level of CAR19 DNA expression in the peripheral blood. It fell with the remission of GVHD. The patient maintained CR and 99.69% donor chimerism during this period. ③ Throughout the subsequent donor T lymphocytes maintenance therapy, mild GVHD surfaced12 days after infusion without an increased proportion of CD19 CAR-T cells and an increased level of CAR19 DNA expression in the peripheral blood. The patient maintained CR and 99.87% donor chimerism during this period. ④ In vivo experiments on C57 mice confirmed that the proportion of CD19 CAR-T cells and the level of CAR19 DNA expression were upregulated in mice following CAR-T cell infusion, accompanied by depletion of CD19 + B lymphocyte. After infusion of CD19 + B lymphocyte cells, an increased proportion of CD19 CAR-T cells and an increased level of CAR19 DNA expression in the peripheral blood were observed again. Conclusions:The infusion of donor stem cells and donor T lymphocytes could be used as a maintenance treatment after CD19 CAR-T cell therapy for B-ALL patients who relapsed after allo-HSCT. Infusion of donor stem cells induced an increased proportion of CD19 CAR-T cells and an increased level of CAR19 DNA expression with the occurrence of GVHD. It might lead to further elimination of minimal residual disease.

Objective:To observe the local reactions and efficacy of CD19 CAR-T therapy in recurrence/refractory B-cell non-Hodgkin's lymphoma (R/R NHL) patients with >7.5 cm lesions.Methods:32 R/R NHL patients with >7.5 cm lesions were enrolled and injected with CD19 CAR-T cells. Flow cytometry was used to detect and observe the amplification of CD19 CAR-T cells in vivo. Enzyme-linked immunosorbent assay (ELISA) was used to detect cytokines in peripheral blood of patients. The side effects of CD19 CAR-T cell therapy included systemic side effects and local reactions of tumor. The local side effects were observed by Ultrasound, Computed tomography and Magnetic resonance imaging. Treatment options included glucocorticoid, interleukin-6 antibody and drainage of exudate. Overall response rate (ORR) and overall survival rate (OS) were observed.Results:①Among the 32 patients, CR (40.63%) , PR (31.25%) and ORR (71.88%) were 13, 10 and 23, respectively. ②In all 23 patients received ORR, 13 patients had grade 1-2 CRS, while 10 patients had grade 3-4 CRS. All the 9 patients in the SD+PD group had grade 1-2 CRS ( P=0.030) . ③A total of 15 patients with tumor local reactions, included 9 patients with CR, 5 patients with PR and 1 patient with SD. The local reactions of the tumor included that the diameter of the superficial lesions increased with redness, swelling and heat pain. The deep lesions presented abdominal pain, abdominal distension, suffocation and local pain, and burning of the tumor. The deep lesions were enlarged or accompanied by local edema. The local exudative lesions were found in the abdominal cavity and pleural cavity. ④ Peak proportion of CD19 CAR-T cells in ORR group was higher than that of in SD+PD group[16.8% (5.3%-48.2%) vs 2.9% (1.5%-5.7%) , z=-4.297, P<0.001]. The peak proportion of CD19 CAR-T cells in ORR group with local reactions was higher than that of in patients without local reactions [22.2% (10.5%-48.2%) vs 12.6% (5.3%-21.6%) , z=-3.213, P=0.001]. The peak proportion of CD19 CAR-T cells in multiple lesion group was higher than that of in single lesion group [35.8% (1.5%-48.2%) vs 16.8% (10.5%-18.5%) , z=-2.023, P=0.040]. ⑤Occurrence of local reactions and tumor shrinkage time were both delayed compared with systemic side effects. ⑥In the ORR group, the OS of patients with tumor local reactions was longer than that of patients without tumor local reactions, but there was no difference in the two groups (75% vs 34.6%, P=0.169) . Conclusions:CD19 CAR-T cell therapy in R/R NHL patients with >7.5 cm lesions might cause tumor local reactions later than systemic side effects.Clinicaltrial::ChiCTR1800018059