Long-term follow-up of CD19 chimeric antigen receptor T-cell therapy for relapsed/refractory acute lymphoblastic leukemia after allogeneic hematopoietic stem cell transplantation.

BACKGROUND AIMS: The efficacy of CD19-targeted chimeric antigen receptor T (CAR T) cells for treatment of relapsed B-cell malignancies after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and the long-term outcomes of these patients remain inconclusive. METHODS: The authors focused on the survival of 35 patients with B-cell acute lymphoblastic leukemia who relapsed after allo-HSCT and received CAR T cells. RESULTS: Of the 34 eligible patients, 30 achieved minimal residual disease-negative complete remission (CR), with a total CR rate of 85.7% (79.8-91.6%). There were 14 patients who received various forms of additional therapy after achieving CR. After a median follow-up of 20.7 months, it was noted that 17 patients had relapsed at a median of 4.5 months (2-34 months). The cumulative recurrence rate (RR) at 18 months was 68.3% (57.6-79.0%). Additional treatment did not reduce the RR but seemed to delay the time to relapse (mean: 5.9 months vs 13.1 months; P = 0.046). Patients with a lower tumor burden (≤10%) had a lower RR (25.0% vs 78.6% at 12 months; P = 0.006). The overall survival (OS) rate for the CR patients was 30.0% (20.3-29.7%) at 18 months, with a median OS of 12.7 months. CONCLUSIONS: The authors' study indicated that for patients who relapsed after HSCT, although a high CR rate was achieved after CAR T therapy, the long-term efficacy was unsatisfactory. It is necessary to optimize additional treatment, including a second HSCT, to further improve long-term efficacy after CAR T infusion.

[Construct Mxi1 mutation gene expression vector from leukemia cell line KG1].

OBJECTIVE: To construct the eukaryotic expression vector for Max interacting protein 1 (Mxi1). METHODS: The full length cDNA of Mxi1 gene obtained from fetal lymphocyte and KG1 cells were inserted into plasmid pDs-red2-N1 respectively to generate pDs-red2-N1/Mri1 (wild/mutation type). Then the recombinant vector was transfected into Cos-7 cells via liposome. 48 hours post transfection, mRNA of Mri1 gene was detected by RT-PCR and Mxi1 protein expression was detected by flow cytometry and fluorescence microscope in the Cos-7 cells. RESULTS: The eukaryotic expression vector of Mxi1 was constructed and transfected into eukaryotic cells successfully. The expression of red fluorescence protein in the transfected Cos-7 cells was observed under fluorescence microscope which implied the expression of Mxi1. The transfect efficiency of both wild and mutation type were in a high level in 3 days after transfected, which lasted to 6 d. RT-PCR amplified the total RNA extracted from the transfected Cos-7 cells could find increased mRNA level of Mxi1 gene. CONCLUSION: We successfully constructed the eukaryote expression vector for Mri1 gene; Cos-7 cells transfected with the vector via liposome could express Mxi1 protein. These could be useful for the further study of the Myc gene modulation.

[Role of cytokines and gene expression characteristics in cultured lymphocytes ex vivo for adoptive immunotherapy].

Different cytokines are needed in the course of culturing cells to do adoptive immunotherapy. This study was aimed to investigate the differentiation directions of lymphocytes and related gene expression characteristics after combined stimulation of lymphocytes by different cytokines or EBV antigen peptide combined with cytokines. The experiment was divided into 4 groups. The levels of total T lymphocytes (CD3(+)), T helper lymphocytes (CD3(+)CD4(+)), cytotoxic T-lymphocyte (CD3(+)CD8(+)), memory T cells (CD3(+)CD8(+)CD45RO(+)), naive T cells (CD3(+)CD8(+)CD45RA(+)), Th2 cells (CD3(+)CD30(+)), B cells (CD19(+)), NK cells (CD56(+)), naive T regulatory cells (CD4(+)CD25(+)), precise T regulatory cells (CD4(+)CD25(+)FOXP3(+)) were detected by flow cytometry. The expression levels of house-keeping gene (mad1, pten), T helper cells transcriptional regulatory gene t-bet (Th1), gata3 (Th2), cytokine IFN-γ(Th1), IL-4(Th2) were detected by using RT-PCR. The results showed that CTL in EBV polypeptide group were dominant cells with certain clinical effects. Comparison of result of EBV polypeptide group with other 3 different cytokine stimulating groups demonstrated that EBV antigen peptide had much more effects on stimulating CTL generation. The expression of IFN-γ gene was significantly increased; the T helper differentiation-related gene t-bet, gata3 also increased evidently, while expression change of house-keeping gene mad1 and pten were not evident. Addition of different cytokines and antigen peptides in culture may be much more effective on stimulating CTL generation. It is concluded that specific CTL can be obtained by using the lymphocytes co-cultured with EBV and cytokines, and the different cytokines play different roles in cell differentiation.