A fully validated flow cytometry method to quantitatively analyze active rATG in human serum and its application in pharmacokinetic study for therapeutic drug monitoring.

Rabbit anti-thymocyte globulin (rATG) has been widely used to prevent graft-versus-host disease (GvHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The therapeutic window of rATG is narrow, and it may increase the risk of relapse, viral reactivation, delayed immune reconstitution and GvHD when overexposed or underexposed. Therefore, a reliable method for detecting the rATG concentration in human serum by flow cytometry was established and fully validated for therapeutic drug monitoring. In this method, Jurkat T cells were used to capture active rATG in human serum, and PE-labeled donkey anti-rabbit IgG was used as a secondary antibody. The method showed good specificity, selectivity and excellent linearity at concentration of 0.00300-20.0 AU/mL. The intra- and interday precision values were all within 20% at four concentration levels for the analyte. The stock solutions of rATG showed no significant degradation after storage at ambient temperature for 8 h and at - 80 °C for 481 days. No significant degradation of rATG in serum was observed at ambient temperature for 6 h, during six freezethaw cycles and at - 80 °C for at least 373 days. This method was fully validated and successfully applied to monitor active rATG concentration in serum of patients with haploid-identical hematopoietic stem cell transplantation.

CD7-directed CAR T-cell therapy: a potential immunotherapy strategy for relapsed/refractory acute myeloid leukemia.

Relapsed/refractory acute myeloid leukemia (AML) patients generally have a dismal prognosis and the treatment remains challenging. Due to the expression of CD7 on 30% AML and not on normal myeloid and erythroid cells, CD7 is an attractive target for immunotherapy of AML. CD7-targeted CAR T-cells had demonstrated encouraging efficacy in xenograft models of AML. We report here on the use of autologous CD7 CAR T-cells in the treatment of a relapsed/refractory AML patient with complex karyotype, TP53 deletion, FLT3-ITD mutation, and SKAP2-RUNX1 fusion gene. Before the CAR T-cell therapy, the patient achieved partial remission with IA regimen and attained complete remission after reinduction therapy (decitabine and venentoclax). Relapse occurred after consolidation (CLAG regimen). Then she failed CLIA regimen combined with venetoclax and exhibited resistance to FLT3 inhibitors. Bone marrow showed 20% blasts (CD7+ 95.6%). A total dose of 5 × 106/kg CD7 CAR T-cells was administered after the decitabine +FC regimen. Seventeen days after CAR T-cells infusion, she achieved morphologic leukemia-free state. The patient developed grade 3 cytokine release syndrome. No severe organ toxicity or immune effector cell-associated neurotoxicity syndrome was observed. In summary, the autologous CD7 CAR T-cell therapy could be considered a potential approach for AML with CD7 expression (NCT04762485).Trial registration Clinical Trials.gov, NCT04762485. Registered on February 21, 2021, prospectively registered.