Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy is effective in patients with advanced B-cell acute lymphoblastic leukemia (B-ALL). However, efficacy data is sparse in subgroups of patients with high-risk features such as BCR-ABL+, TP53 mutation, extramedullary disease (including central nervous system leukemia) or posttransplant relapse. It is also uncertain whether there is an added benefit of transplantation after anti-CD19 CAR T-cell therapy. We conducted a phase 1/2 study of 115 enrolled patients with CD19+ B-ALL. A total of 110 patients were successfully infused with anti-CD19 CAR T cells. In all, 93% of patients achieved a morphologic complete remission, and 87% became negative for minimal residual disease. Efficacy was seen across all subgroups. One-year leukemia-free survival (LFS) was 58%, and 1-year overall survival (OS) was 64% for the 110 patients. Seventy-five nonrandomly selected patients (73.5%) subsequently received an allogeneic hematopoietic stem cell transplant (allo-HSCT). LFS (76.9% vs 11.6%; P < .0001; 95% confidence interval [CI], 11.6-108.4) and OS (79.1% vs 32.0%; P < .0001; 95% CI, 0.02-0.22) were significantly better among patients who subsequently received allo-HSCT compared with those receiving CAR T-cell therapy alone. This was confirmed in multivariable analyses (hazard ratio, 16.546; 95% CI, 5.499-49.786). Another variate that correlated with worse outcomes was TP53 mutation (hazard ratio, 0.235; 95% CI, 0.089-0.619). There were no differences in complete remission rate, OS, or LFS between groups of patients age 2 to 14 years or age older than 14 years. Most patients had only mild cytokine release syndrome and neurotoxicity. Our data indicate that anti-CD19 CAR T-cell therapy is safe and effective in all B-ALL subgroups that have high-risk features. The benefit of a subsequent allo-HSCT requires confirmation because of nonrandom allocation. This trial was registered at www.clinicaltrials.gov as #NCT03173417.

No abstract

Introduction CD19-targeting chimeric antigen receptor (CAR) T cell therapy has demonstrated high success; however, its therapeutic potential can still be further improved. In addition, the high cost and lengthy process of CAR-T production limit its broad application. We have developed a new platform termed FasT (F) CAR-T with shortened manufacturing time to one day (plus 7 days of additional testing for regulatory requirements). Here we report results from a pre-clinical study of FasT (F) CAR-T (GC007F) and a phase Ⅰ clinical trial to assess the safety and feasibility of treating patients with CD19+ relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). Methods In this study, a second generation of CD19-directed CAR-T was manufactured using the FasT CAR-T platform. Peripheral blood (PB) mononuclear cells were obtained by leukapheresis either from healthy donors for the pre-clinical study or from patients undergoing the clinical trial. T cells were separated and used for CAR-T generation. A xenograft mouse model was used to determine the efficacy of GC007F in vivo. Conventional (C) CAR-T derived from the same healthy donor were also made and tested in parallel for comparison. Between Feb. 2019 and July 2019, 10 adolescent and adult patients with CD19+ relapsed/refractory B-ALL were enrolled in a feasibility trial for CD19 FasT CAR-T (www.clinicaltrials.gov, NCT03825718). FasT CAR-T cells for all patients were successfully manufactured. All patients received a conditioning regimen of IV fludarabine (30mg/m2/d) and cyclophosphamide (250mg/m2/d) for 3 days followed by a single infusion of CAR-T cells. Six patients received a low-dose 6.5 (5.86-7.04) x104/kg of FasT CAR-T, 2 received a medium-dose 1 (1-1.16) x105/kg, and 1, a high-dose 1.56x105/kg. The primary end points of the study were to evaluate feasibility and toxicity, and the secondary end points included disease response and engraftment/persistence of infused FasT CAR-T cells. Results This preclinical study has demonstrated several significant improvements of CD19-directed F CAR-T over C CAR-T: 1) 5-30 fold superior expansion capability (p<0.01); 2) more abundant T central memory cells (Tcm) (73.47±2.85% vs 58.03±8.34%, p<0.05) and T memory stem cells (Tscm) (6.42±3.64% vs 0.39±0.13%, p<0.01); 3) less exhaustion with reduced levels of PD-1+ and LAG3+ (3.39±0.49% vs 12.66±1.87%, p<0.01); and 4) more effective in the elimination of B-ALL in a xenograft mouse model (p<0.01, Fig. 1). For the phase Ⅰ clinical trial, the median observation period was 86 days (37-166 days). The median percentage of pre-treatment bone marrow (BM) blasts was 9.05% (0.19-32.5%). On day 15 after CAR-T cell infusion, 10/10 (100%) cases achieved complete remission (CR) or CR with incomplete count recovery (CRi) and 9/10 (90%) had minimal residual disease (MRD)-negative CR. Four of ten patients had a good blood count recovery on day 15. The number further increased to 6/10 on day 30. Patient F15 had rapidly growing disease in that his PB blasts increased from 1% on enrollment to 7% immediately before CAR-T cells infusion, and increased to 77% on day 7 post infusion. Notwithstanding the rapid disease progression, the patient achieved MRD-positive CR on day 15 with residual 0.06% BM blasts. Five of ten patients were bridged into allogeneic hematopoietic stem cell transplantation (allo-HSCT). All 10 patients have remained in CR thus far. After CAR-T infusion, the level of infused CD19 FasT CAR-T cells in PB was analyzed by qPCR and flow cytometry. Superior in vivo proliferation and persistence were detected regardless of the infused CAR-T doses. The median peak level was reached on day 7 (7-10) with 2.1(0.22-5.2) x105 copy/µg PB genomic DNA (Fig. 2) and the median CAR-T expression ratio was 44.5 (13.6-69.5) %. The peaks of IL6, IFNγ, IL10, and CD25 were observed around day 7. Despite the achievement of a very high CR rate, 9/10 had grade 1 cytokine release syndrome (CRS) and only 1 patient experienced grade 3 CRS. None developed neurotoxicity. Conclusion This study has demonstrated that FasT CAR-T cells with superior expansion capability and younger/less exhausted phenotypes can be generated rapidly. This first-in-human clinical study showed that FasT CAR-T is safe and highly effective for treating patients with B-ALL. Disclosures No relevant conflicts of interest to declare.

Backgrounds As CAR T-cell therapy is a highly personalized therapy, process of generating autologous CAR-T cells for each patient is complex and can still be problematic, particularly for heavily pre-treated patients and patients with significant leukemia burden. Here, we analyzed the feasibility and efficacy in 37 patients with refractory/relapsed (R/R) B-ALL who received CAR T-cells derived from related donors. Patients and Methods From April 2017 to May 2020, 37 R/R B-ALL patients with a median age of 19 years (3-61 years), were treated with second-generation CD19 CAR-T cells derived from donors. The data was aggregated from three clinical trials (www.clinicaltrials.gov NCT03173417; NCT02546739; and www.chictr.org.cn ChiCTR-ONC-17012829). Of the 37 patients, 28 were relapsed following allogenic hematopoietic stem cell transplant (allo-HSCT) and whose lymphocytes were collected from their transplant donors (3 HLA matched sibling and 25 haploidentical). For the remaining 9 patients without prior transplant, the lymphocytes were collected from HLA identical sibling donors (n=5) or haploidentical donors (n=4) because CAR-T cells manufacture from patient samples either failed (n=5) or blasts in peripheral blood were too high (>40%) to collect quality T-cells. The median CAR-T cell dose infused was 3×105/kg (1-30×105/kg). Results For the 28 patients who relapsed after prior allo-HSCT, 27 (96.4%) achieved CR within 30 days post CAR T-cell infusion, of which 25 (89.3%) were minimal residual disease (MRD) negative. Within one month following CAR T-cell therapy, graft-versus-host disease (GVHD) occurred in 3 patients including 1 with rash and 2 with diarrhea. A total of 19 of the 28 (67.9%) patients had cytokine release syndrome (CRS), including two patients (7.1%) with Grade 3-4 CRS. Four patients had CAR T-cell related neurotoxicity including 3 with Grade 3-4 events. With a medium follow up of 103 days (1-669days), the median overall survival (OS) was 169 days (1-668 days), and the median leukemia-free survival (LFS) was 158 days (1-438 days). After CAR T-cell therapy, 15 patients bridged into a second allo-HSCT and one of 15 patients (6.7%) relapsed following transplant, and two died from infection. There were 11 patients that did not receive a second transplantation, of which three patients (27.3%) relapsed, and four parents died (one due to relapse, one from arrhythmia and two from GVHD/infection). Two patients were lost to follow-up. The remaining nine patients had no prior transplantation. At the time of T-cell collection, the median bone marrow blasts were 90% (range: 18.5%-98.5%), and the median peripheral blood blasts were 10% (range: 0-70%). CR rate within 30 days post CAR-T was 44.4% (4/9 cases). Six patients developed CRS, including four with Grade 3 CRS. Only one patient had Grade 3 neurotoxicity. No GVHD occurred following CAR T-cell therapy. Among the nine patients, five were treated with CAR T-cells derived from HLA-identical sibling donors and three of those five patients achieved CR. One patient who achieved a CR died from disseminated intravascular coagulation (DIC) on day 16. Two patients who achieved a CR bridged into allo-HSCT, including one patient who relapsed and died. One of two patients who did not response to CAR T-cell therapy died from leukemia. Four of the nine patients were treated with CAR T-cells derived from haploidentical related donors. One of the four cases achieved a CR but died from infection on day 90. The other three patients who had no response to CAR T-cell therapy died from disease progression within 3 months (7-90 days). Altogether, seven of the nine patients died with a median time of 19 days (7-505 days). Conclusions We find that manufacturing CD19+ CAR-T cells derived from donors is feasible. For patients who relapse following allo-HSCT, the transplant donor derived CAR-T cells are safe and effective with a CR rate as high as 96.4%. If a patient did not have GVHD prior to CAR T-cell therapy, the incidence of GVHD following CAR T-cell was low. Among patients without a history of transplantation, an inability to collect autologous lymphocytes signaled that the patient's condition had already reached a very advanced stage. However, CAR T-cells derived from HLA identical siblings can still be considered in our experience, no GVHD occurred in these patients. But the efficacy of CAR T-cells from haploidentical donors was very poor. Disclosures No relevant conflicts of interest to declare.

Aim: To assess the efficacy of dendritic cells-cytokine induced killer (DC-CIK) and natural killer (NK) cell-based immunotherapy in treating the low- and intermediate-risk acute myeloid leukemia. Patients & methods: DC-CIK or NK cells were infused once every 3 months for 2–4 cycles to 85 patients. Results & conclusion: The 5-year overall survival (OS) and relapse-free survival (RFS) rates were 90.5 and 65.2%, respectively. The OS of the very favorable, the favorable and the intermediate-risk groups was 94.4, 86.3 and 93.3% (p = 0.88), and the RFS 83.3, 81.8 and 62.2% (p = 0.14), respectively. The OS and RFS of the 60 patients treated with DC-CIK alternating with NK cells were better than the 25 patients treated with DC-CIK or NK alone (96.5 vs 71.2%; p = 0.003. 79.5 vs 28.9%; p < 0.001).