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Introduction Multiple myeloma is a hematological malignancy that is prone to be companied by bone marrow destruction, renal impairment and extramedullary infiltration. Current treatments include proteasome inhibitor, immunomodulatory drug, hematopoietic stem cell transplantation, and monoclonal antibody targeted therapies. However, it is still clinically incurable. Chimeric antigen receptor (CAR) T-cell therapy is a new immune targeted therapeutic strategy. It is reported better clinical efficacy for relapsed/refractory multiple myeloma (r/r MM) treatment has been achieved by immunotherapies targeted B-cell maturation antigen (BCMA). Therefore, it is important to investigate the treatment of a novel human BCMA-specific CAR-T therapy for r/r MM. Objective The objective of this clinical study is to evaluate the safety and efficacy of the novel human BCMA-targeting CAR-T therapy in patients with r/r MM, especially patients who relapsed from prior CAR-T therapy. Method This work is a clinical study registered and investigated by our center. CD3+ T cells were negatively selected from patients' peripheral blood mononuclear cells, activated and modified by lentivirus to produce anti-BCMA CAR-T cells. The cells were administrated intravenously to patients after expanding for 7-13 days in vitro. 24 patients had enrolled in this study, with 13 males and 11 females. The median age was 53 years old (range,41-75), and patients with cytogenetically high risk factors accounting for 41.66% (10/24). 50% (12/24) was infiltrated with extramedullary lesions. 16.6% (4/24) of them had relapsed from other CAR-T therapies before this enrollment. 50% (12/24) had been previously conducted autologous hematopoietic stem cell transplantation (HSCT), whereas 4.16% (1/24) with allogeneic HSCT. Patients with the expression of BCMA in the plasma cells higher than 30%, accounted for 25% (6/24). 2-3 days after being administered the lymphodepleting chemotherapy regimen, CAR-T cells were infused intravenously. The indicators of patients' condition were detected, including inflammatory cytokine concentration, serum protein levels, CAR-T cell number copies, and the proportion of plasma cells by bone marrow biopsy. The improvement of patients, the occurrence of adverse reactions, the incidence and grade of cytokine release syndrome (CRS), was analyzed and evaluated. Result All patients received infusions of CAR-T positive cells at the average dose of 9.45×10 6/kg (5-17.5) and the median injection day is the 10th day (8th-13th day) after cell isolation. After infusion, 100% (24/24) of the patients had fever lasting for 48 hours, with 37.5% (9/24) of them showing low blood pressure and being treated with drug. Heart rate increase was found in 45.8% (11/24). Nausea, diarrhea and transient consciousness disorder occurred in 50% (12/24), 33.3% (8/24), and 12.5% (3/24) of them, respectively. 16.6% (4/24) was administrated with dexamethasone to relieve symptoms, with the total dose less than 20 mg, while nobody was treated with IL-6 receptor antagonist. CAR-T cells had expanded in all patients, reaching the peak at the 4th day after infusion (Figure). The levels of IL-6, IL-8 and IFN-γ in peripheral blood also increased significantly. The incidence of CRS is 100%, of which grade I, II and III is 62.5%, 33.3% and 4.2%, respectively. 2 patients showed grade I CRES, constituting 8.3% (2/24). All patients were assessed for the efficacy of CAR-T cells 2 weeks after infusion. ORR was 100%, with 4.2% (1/24) MR, 8.3% (2/24) PR, 62.5% (15/24) VGPR and 25% (6/24) CR. 18 patients were treated for more than 1 month, with 11.1% (2/18) PR, 44.4% (8/18) VGPR, 11.1% (2/18) CR, and 33.3% (6/18) sCR. 16 patients were infused before more than 2 months, with 25% (4/16) VGPR, 12.5% (2/16) CR, 50% (8/16) sCR, and 12.5% (2/16) PD. 6 patents were administrated more than 3 months ago, with 1 developing deep remission to sCR from VGPR. The others remain the same condition. Conclusion The novel human BCMA targeted CAR-T cell therapy of this study showed safety and efficacy in the treatment of r/r MM patients with extramedullary infiltration, high-risk cytogenetical factors as well as relapse with prior BCMA CAR exposures. Deep remission can be achieved. However, more observation need to be conducted. The CAR-T treatment of BCMA target still cannot prevent the disease progress of a small numbers of patients. The control after CAR-T therapy needs more investigation. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Introduction: It has been made great clinical progresses in hematological malignancies by chimeric antigen receptor (CAR) T cell therapy which utilizes virus vector for manufacture. However, there're still issues unresolved, for instance, sophisticated virus production process, deadly Cytokine Release Syndrome (CRS) side-effect, and high recurrence rate, which probably limit the availability of CAR-T therapy. Non-viral Genome Targeting CAR-T (nvGT CAR-T) may provide a feasible solution to those unmet needs mentioned above. We used CRISPR-Cas9 and non-viral vector to insert anti-CD19 CAR DNA to a specific genome locus in human T cells, which in theory, produces more moderate CAR-T cells compared with conventional CAR-T cells. The efficacy of anti-CD19 nvGT CAR-T cells had been demonstrated in our previous pre-clinical studies, and in this Phase I clinical trial (ChiCTR2000031942), its safety and efficacy in relapsed/refractory B-Cell Acute Lymphoblastic Leukemia (r/r B-ALL) patients were explored. Objective: The primary objective of this Phase I trial is to assess safety, including evaluation of adverse events (AEs) and AEs of special interest, such as CRS and neurotoxicity. Secondary objective is to evaluate efficacy as measured by the ratio of complete remission (CR). Method: Peripheral blood mononuclear cells were collected from patients or allogeneic donors, then CD3+ T cells were selected and modified by nvGT vector to produce anti-CD19 CAR-T, then administrated to patients with r/r B-ALL. Up to July 2020, twelve patients with r/r B-ALL had been enrolled in this study and 8 patients completed their treatments and entered follow-up period. For 8 patients with follow-up data, the median age was 33 years (range, 13 to 61), and the median number of previous regimens was 5 (range, 2 to 11). The median baseline percentage of bone marrow (BM) blast is 72% (range, 24.5% to 99%). Among those subjects, 2 patients once have been conducted autologous or allogeneic hematopoietic stem cell transplantation (Auto-HSCT or Allo-HSCT), and 2 patients experienced serious infection before CAR-T infusion. No patient has been treated by any other CAR-T therapy before enrollment. Baseline characteristics refer to Table 1. Administering a lymphodepleting chemotherapy regimen of cyclophosphamide 450-750 mg/m2 intravenously and fludarabine 25-45 mg/m2 intravenously on the fifth, fourth, and third day before infusion of anti-CD19 nvGT CAR-T, all patients received an infusion at dose of 0.55-8.21×106/kg (Table 1). Result: Until day 30 post CAR-T cell infusion, 8/8 (100%) cases achieved CR and 7/8 (87.5%) had minimal residual disease (MRD)-negative CR (Table 1). Anti-bacterial and anti-fungal were performed in patients SC-3, SC-4 and SC-5 after CAR-T cell infusion, which seems no influence on efficacy. Patient SC-7 was diagnosed as T-cell Acute Lymphoblastic Leukemia before Allo-HSCT but with recent recurrence of B-ALL, which was MRD-negative CR on day 21 post nvGT CAR-T therapy. Up to July 2020, all cases remain CR status. CRS occurred in all patients (100%) receiving anti-CD19 nvGT CAR-T cell, including 1 patient (12.5%) with grade 3 (Lee grading system1) CRS, two (25%) with grade 2 CRS, and 5 (62.5%) with grade 1 CRS. There were no cases of grade 4 or higher CRS (Table 1). The median time to onset CRS was 9 days (range, 1 to 12 days) and the median duration of CRS was 6 days (range, 2 to 9 days). None developed neurotoxicity. No fatal or life-threatening reactions happened and no Tocilizumab and Corticosteroids administered following CAR-T treatment. Data including body temperature (Figure 1), CAR-positive T cell percentage (Figure 2), Interleukin-6 (IL-6) and Interleukin-8 (IL-8) (Figure 3 and 4), C-reactive Protein (CRP) (Figure 5), Lactate Dehydrogenase (LDH) (Figure 6), and Procalcitonin (PCT) (Figure 7), are in accordance with the trend of CRS. Conclusion: This Phase I clinical trial primarily validates the efficacy of this novel CAR-T therapy, however, it still needs time to prove its durability. Surprisingly, we find that nvGT CAR-T therapy is seemingly superior than viral CAR-T therapy in terms of safety. All subjects which are high-risk patients with high tumor burden had low grade CRS, even a few patients sent home for observation post infusion with limited time of in-patient care. Furthermore, patients could tolerate a higher dose without severe adverse events, which probably bring a better dose-related efficacy. Disclosures No relevant conflicts of interest to declare.