Establishment of Reproducible Xenotransplantation Model of T Cell Acute Lymphoblastic Leukemia in NOD/SCID Mice

T cell acute lymphoblastic leukemia(T-ALL) is an aggressive leukemia.However the poor prognosis and low morbidity restrict further analysis of the disease.Therefore there is an increasing demand to develop animal models for identifying novel therapeutic approaches.In this study,we inoculated the anti-mouse CD122 monoclonal antibody conditioned NOD/SCID mice with the leukemia cells from 9 T-ALL patients and 1 cell line via the tail vein.Four of the 9 patients and the cell line were successfully engrafted.Flow cytometry detected high percentage of human CD45 + cells in recipient mice.Immunohistochemistry showed infiltration of human CD45 + cells in different organs.Serial transplantation was also achieved.In vivo drug treatment showed that dexamethasone could extend survival,which was consistent with clinical observation.These results demonstrated that we successfully established 5 xenotransplantation models of T-ALL in anti-mCD122 mAb conditioned NOD/SCID mice,which recapitulated the characteristics of original disease.

γANDδCHAIN GENE REARRANGEMENT OF T CELL RECEPTOR IN ACUTE LYMPHOBLASTIC LEUKEMIA

The immunophenotype, rearrangements of T cell receptor(TCR) γ andδchain genes as well as the immunoglobulinheavy chain (IgH)gene were studied in 37 cases ofmorphologically defined acute lymphoblastic leukemia (ALL).According to the expression of differentiation antigens, 8 caseswere classified as T-ALL, 26 B lineage ALL, 2 acute un-differentiated leukemia (AUL) and myeloid phenotype. An or-der of TCR gene rearrangements was observed in T-ALL,with the rearrangement of δgene preceding that of γgene.Both genes were also found frequently rearranged and / or de-leted in high proportions of the ALL of B cell lineage. Howev-er, the patterns of gene rearrangements were somewhat differ-ent between the T and B lineage ALLs. In contrast, the lgHgene rearrangements were observed only in the B lineage ALL.The immunogenotype analysis of ALL proved to be a usefulmarker of the clonality and provided us with important informa-tion on early human lymphoid differentiation. We concludethat the determination of T

An analytical biomarker for treatment of patients with recurrent B-ALL after remission induced by infusion of anti-CD19 chimeric antigen receptor T(CAR-T) cells

Anti-CD19 chimeric antigen receptor-modified T(CAR-T-19) cells have emerged as a powerful targeted immunotherapy for B-cell lineage acute lymphoblastic leukemia with a remarkable clinical response in recent trials. Nonetheless, few data are available on the subsequent clinical monitoring and treatment of the patients, especially those with disease recurrence after CAR-T-19 cell infusion. Here, we analyzed three patients who survived after our phase I clinical trial and who were studied by means of biomarkers reflecting persistence of CAR-T-19 cells in vivo and predictive factors directing further treatment. One patient achieved 9-week sustained complete remission and subsequently received an allogeneic hematopoietic stem cell transplant. Another patient who showed relapse after 20 weeks without detectable leukemia in the cerebrospinal fluid after CAR-T-19 cell treatment was able to achieve a morphological remission under the influence of stand-alone low-dose chemotherapeutic agents. The third patient gradually developed extensive extramedullary involvement in tissues with scarce immune-cell infiltration during a long period of hematopoietic remission after CAR-T-19 cell therapy. Long-term and discontinuous increases in serum cytokines(mainly interleukin 6 and C-reactive protein) were identified in two patients(Nos. 1 and 6) even though only a low copy number of CAR molecules could be detected in their peripheral blood. This finding was suggestive of persistent functional activity of CAR-T-19 cells. Combined analyses of laboratory biomarkers with their clinical manifestations before and after salvage treatment showed that the persistent immunosurveillance mediated by CAR-T-19 cells would inevitably potentiate the leukemia-killing effectiveness of subsequent chemotherapy in patients who showed relapse after CAR-T-19-induced remission.