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Chimeric antigen receptor (CAR) T-cell therapy has shown excellent clinical efficacy in patients with hematologic malignancies. However, severe bleeding after this treatment is a life-threatening complication for most patients. This study evaluated the risk factors associated with bleeding in CAR T treatment and developed a predictive model for this complication. Analysis performed in the First Affiliated Hospital of Suzhou University and external validation launched in Suzhou Hongci Hematology Hospital (Jiangsu, China). We conducted a real-world study incorporating data from 400 patients with hematologic malignancies treated with CAR T between 1 November 2015 and 1 September 2019. Also, 39 patients from another hospital were selected for external validation. Patients with severe bleeding (hazard ratio [HR] 13.04, 95% confidence interval 5.82-29.18; p < 0.001) had a higher risk of death after CAR T. Stage III and IV cytokine release syndrome (CRS) (odds ratio [OR] 6.07, 95% CI 2.35-16.76; p < 0.001) and higher tumor necrosis factor-α (TNF-α) levels (OR 4.00, 95% CI 1.53-11.35; p < 0.001) were independent factors of bleeding in patients after CAR-T treatment. The predictive model developed by Lasso regression, which selected factors such as CRS period, transfusion volume, platelet percentage, platelet count, thrombinogen time, interleukin 6, and TNF-α levels, and showed Nomogram, yielded excellent agreement (C-statistics = 0.905) with the calibration curve, which improved clinical benefit with respect to established bleeding scores such as outpatient bleeding risk index (MOBRI). External validation was performed using 39 patients from another hospital with an AUC of 0.700. Patients with severe bleeding after Car-T therapy had increased the risk of death. A cross-validated bleeding risk score based on CRS stages and TNF-α level show significant prognostic value in patients undergoing CAR-T treatment.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment for acute myeloid leukemia (AML). However, most patients experience relapse after allo-HSCT, with a poor prognosis, and treatment options are limited. The lack of an ideal targetable antigen is a major obstacle for treating patients with relapsed AML. CD38 is known to be expressed on most AML and myeloma cells, and its lack of expression on hematopoietic stem cells (HSCs) renders it a potential therapeutic target for relapsed AML. To investigate the clinical therapeutic efficacy and safety of CD38-targeted chimeric antigen receptor T (CAR-T-38) cells, we enrolled 6 AML patients who experienced relapse post-allo-HSCT (clinicaltrials.gov: {"type":"clinical-trial","attrs":{"text":"NCT04351022","term_id":"NCT04351022"}}NCT04351022). Prior to CAR-T-38 treatment, the blasts in the bone marrow of these patients exhibited a median of 95% (92–99%) CD38 positivity. Four weeks after the initial infusion of CAR-T-38 cells, four of six (66.7%) patients achieved complete remission (CR) or CR with incomplete count recovery (CRi); the median CR or CRi time was 191 (range 117–261) days. The cumulative relapse rate at 6 months was 50%. The median overall survival (OS) and leukemia-free survival (LFS) times were 7.9 and 6.4 months, respectively. One case relapsed 117 days after the first CAR-T-38 cell infusion, with remission achieved after the second CAR-T-38 cell infusion. All six patients experienced clinically manageable side effects. In addition, multiparameter flow cytometry (FCM) revealed that CAR-T-38 cells eliminated CD38 positive blasts without off-target effects on monocytes and lymphocytes. Although this prospective study has a limited number of cases and a relatively short follow-up time, our preliminary data highlight the clinical utility and safety of CAR-T-38 cell therapy in treating relapsed AML post-allo-HSCT.

Severe bleeding is a major cause of death in acute leukemia (AL) patients with graft-versus-host disease (GVHD) after allogene hematopoietic stem-cell transplantation (allo-HSCT). However, the prognostic value and prediction of HSCT-associated severe bleeding in GVHD patients have not been reported in cohort studies. We did a retrospective analysis of 200 AL patients with GVHD after allo-HSCT from Feb 1, 2014, to Dec 1, 2015. Multivariate analysis showed that the severe bleeding class was associated with the risk of death (HR 2.26, 95% CI 1.31-3.92, p

Abstract 3550 Background and Objectives Relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is still a major cause for the failure in treatment. It has been shown that there was a closely relationship between the level of minimal residual disease (MRD) and relapse in acute leukemia (AL) patients; However, the application of multiparameter flow cytometry (MFC) for MRD assessment in high risk patients with AL who undergoing allo-HSCT is little concerned. We retrospectively analysed the serial results of MRD of 52 high risk patients with AL to evaluates the prognostic value of MRD pre and post transplantation. Methods 52 patients with a median age of 29 (13–55) years have been enrolled on this study in our hospital from January 2003 to September 2008.Diagnoses included AML (n=27) and ALL (n=25). The patients had been analyzed retrospectively the level of MRD pre-(day-30)and post-HSCT(day+30 and +100)using three color FCM with CD45/SSC gating and a comprehensive panel of monoclonal antibodies, at least one leukemia associated aberrant immunophenotype (LAIP) at diagnosis. According to the cutoff value 0.1%, two groups were defined based on the level of patient's MRD level< (low level group) or >= (high level group) 0.1%. Results The median follow up were 23 (range 1–60) months. 1.MRD level declines significantly (P=0.03) post transplant. 2. There were significantly difference between low level and high level group at day -30 before transplant with 3 years event free survival(EFS) and relapse free survival (RFS)(77.4% and 88.4% vs. 22.3% and 25.7%, p=0.007and p=0.001 respectively). 3. Concerning about MRD at day +100 after transplant, outcome was significantly better among patients with low level MRD group versus high group including 3 years OS,EFS and RFS(84.2%, 79.5% and 89.5% versus 22.9%, 9.5% and 11.2%).4. The median time from high level MRD detected first time to clinical relapse was 2.5 (range from 1 to 33) months in relapsed patients. 5. The patients with cGVHD had better 3 years OS and EFS than that without cGVHD(86.3% vs 12.1%, p Conclusions MRD monitoring pre- and post-transplant is an important tool to predict the outcome of transplantation for patients with high risk AL. The MRD check point at day +100 should be considered crucial for subsequent therapeutic decisions after allogeneic transplantation. Disclosures: No relevant conflicts of interest to declare.