Summary
Early T‐cell precursor acute lymphoblastic leukaemia (ETP‐ALL) is a recently identified subtype of T‐ALL with distinctive gene expression and cell marker profiles, poor response to chemotherapy and a very high risk of relapse. We determined the reliability of restricted panel of cell markers to identify EPT‐ALL using a previously classified cohort. Then, we applied the cell marker profile that best discriminated ETP‐ALL to a cohort of 91 patients with T‐ALL enrolled in the Tokyo Children’s Cancer Study Group L99‐15 study, which included allogeneic stem cell transplantation (allo‐SCT) for patients with poor prednisone response. Five of the 91 patients (5·5%) met the ETP‐ALL criteria. There were no significant differences in presenting clinical features between these and the remaining 86 patients. Response to early remission induction therapy was inferior in ETP‐ALL as compared with T‐ALL. The ETP‐ALL subgroup showed a significantly poorer event‐free survival (4‐year rate; 40%) than the T‐ALL subgroup (70%, P = 0·014). Of note, three of four relapsed ETP‐ALL patients survived after allo‐SCT, indicating that allo‐SCT can be effective for this drug‐resistant subtype of T‐ALL.
I@Sllnlnlagy CD38 is a transmembrane glycoprotein expressed in many cell types, including lymphoid progenitors and activated lymphocytes. High levels of CD38 expression on immature lymphoid cells suggest its role in the regulation of cell growth and differentiation, but there is no evidence demonstrating a functional activity of CD38 on these cells. We used stroma-supported cultures of B cell progenitors and anti-CD38 monodonal antibodies (T16 and IB4) to study CD38 function. In cultures of normal bone marrow CD19 + cells (n = 5), addition of anti-CD38 markedly reduced the number of cells recovered after 7 d. Cell loss was greatest among CD19 § slg-B cell progenitors (mean cell recovery +_ SD = 7.2 _ 11.7% of recovery in control cultures) and extended to CD19~CD34 + B cells (the most immature subset; 7.6 • 2.2%). In contrast, CD38 ligation did not substantially affect cell numbers in cultures of normal peripheral blood or tonsiUar B cells. In stroma-supported cultures of 22 B-lineage acute lymphoblastic leukemia cases, anti-CD38 suppressed recovery of CD19 + slg-leukemic calls. CD38 ligation also suppressed the growth of immature lymphoid cell lines cultured on stroma and, in some cases, in the presence of stroma-derived cytokines (interleukin [IL] 7, II-3, and/or stem cell factor), but did not inhibit growth in stroma-or cytokine-free cultures. DNA content and DNA fragmentation studies showed that CD38 ligation of stroma-supported cells resulted in both inhibition of DNA synthesis and induction of apoptosis. It is known that CD38 catalyzes nicotinamide adenine dinudeotide (NAD+) hydrolysis into cyclic ADP-ribose (cADPR) and ADPR. However, no changes in NAD+ hydrolysis or cADPR and ADPR production after CD38 ligation were found by high-performance liquid chromatography; addition of NAD+, ADPIL, or cADPK to cultures of lymphoid progenitors did not offset the inhibitory effects of anti-CD38. Thus, anti-CD38 does not suppress B lymphopoiesis by altering the enzymatic function of the molecule. In conclusion, these data show that CD38 ligation inhibits the growth of immature B lymphoid cells in the bone marrow microenvironment, and suggest that CD38 interaction with a putative ligand represents a novel regulatory mechanism of B lymphopoiesis.
We developed a stroma cell culture system that suppresses apoptosis of malignant cells from cases of B-lineage acute lymphoblastic leukemia. By multiparameter flow cytometric measurements of cell recovery after culture on stromal layers, we assessed the growth potential of 70 cases of newly diagnosed B-lineage acute lymphoblastic leukemia and related the findings to treatment outcome in a single program of chemotherapy. The numbers of leukemic cells recovered after 7 d of culture ranged from Ͻ 1 to 292% (median, 91%). The basis of poor cell recoveries from stromal layers appeared to be a propensity of the lymphoblasts to undergo apoptosis. The probability of event-free survival at 4 yr of follow-up was 50 Ϯ 9% (SE) among patients with higher cell recoveries ( Ͼ 91%), and 94 Ϯ 6% among those with reduced cell recoveries ( Յ 91%; P ϭ 0.0003). The prognostic value of leukemic cell recovery after culture exceeded estimates for all other recognized high-risk features and remained the most significant after adjustment with all competing covariates. Thus, the survival ability of leukemic cells on bone marrow-derived stromal layers reflects aggressiveness of the disease and is a powerful, independent predictor of treatment outcome in children with B-lineage acute lymphoblastic leukemia. ( J. Clin. Invest. 1996. 97:755-760.)
Generally, the outcome results of conventional chemotherapy for high-risk PTCL are poor in adult patients. However, the excellent results in our study suggest that PTCL of childhood is quite different from that of adulthood. Although this study is first report about PTCL of Asian children, the number of patients was small in this study. Larger studies are needed to confirm these findings.
DEXA administered at 8 mg/m2 during induction and 6 mg/m2 during intensification showed no advantage over PRED administered at 60 mg/m2 during induction and 40 mg/m2 during intensification in both the SR and IR groups.
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