Donor lymphocyte infusion induced molecular remission in relapse of acute myeloid leukaemia after allogeneic bone marrow transplantation.

Donor lymphocyte infusion (DLI) has been used successfully to induce remissions in relapse of acute myeloid leukaemia (AML) after bone marrow transplantation (BMT), but molecular eradication of leukaemia has rarely been documented. A patient with AML-M4Eo relapsed after HLA-identical sibling BMT in first complete remission (CR). Cytogenetic and molecular genetic investigations confirmed inv(16) and CBFbeta/MYH11 fusion characteristic of M4Eo. A second remission was obtained with chemotherapy. Full donor chimerism was demonstrated by fluorescence in situ hybridisation. However, molecular evidence of minimal residual disease still persisted, and donor lymphocyte infusion (DLI) was administered. This resulted in molecular eradication, and the patient remained in clinical and molecular remission 16 months from DLI. Our observations showed that, for AML relapse after BMT, molecular leukaemia eradication could be achieved by DLI so that, in cases where genetic markers are available, molecular monitoring should be performed to assess the efficacy of treatment.     

Human CD34+ cells expressing the inv(16) fusion protein exhibit a myelomonocytic phenotype with greatly enhanced proliferative ability

The t(16:16) and inv(16) are associated with FAB M4Eo myeloid leukemias and result in fusion of the CBFB gene to the MYH11 gene (encoding smooth muscle myosin heavy chain [SMMHC]). Knockout of CBFbeta causes embryonic lethality due to lack of definitive hematopoiesis. Although knock-in of CBFB-MYH11 is not sufficient to cause disease, expression increases the incidence of leukemia when combined with cooperating events. Although mouse models are valuable tools in the study of leukemogenesis, little is known about the contribution of CBFbeta-SMMHC to human hematopoietic stem and progenitor cell self-renewal. We introduced the CBFbeta-MYH11 cDNA into human CD34+ cells via retroviral transduction. Transduced cells displayed an initial repression of progenitor activity but eventually dominated the culture, resulting in the proliferation of clonal populations for up to 7 months. Long-term cultures displayed a myelomonocytic morphology while retaining multilineage progenitor activity and engraftment in NOD/SCID-B2M-/- mice. Progenitor cells from long-term cultures showed altered expression of genes defining inv(16) identified in microarray studies of human patient samples. This system will be useful in examining the effects of CBFbeta-SMMHC on gene expression in the human preleukemic cell, in characterizing the effect of this oncogene on human stem cell biology, and in defining its contribution to the development of leukemia.     

Childhood acute myeloid leukemia with CBFbeta-MYH11 rearrangement: study of incidence, morphology, cytogenetics, and clinical outcomes of Chinese in Hong Kong

We analyzed 43 consecutive cases of pediatric acute myeloid leukemia (AML) for the presence of the CBFbeta-MYH11 rearrangement using molecular techniques in a regional hospital in Hong Kong. Five cases (11.6%), 3 girls and 2 boys, ranging in age from 8 months to 14 years old, were found positive for the CBFbeta-MYH11 rearrangement. Morphologically, they were FAB M2 or M4 with or without eosinophilia (Eo). Typical M4Eo was observed in only one case. The molecular findings were in complete concordance with cytogenetic data, which revealed inv(16)(p13q22) in all and also gains of chromosome 4, 8, 22, and Y in one patient. Clinically, all 5 patients achieved complete remission after chemotherapy with favorable outcomes except for the patient with infantile AML, who relapsed 11 months after diagnosis, underwent cord blood transplantation, and was in second remission. This is the first clinicopathological study and documentation of the incidence of CBFbeta-MYH11 in childhood AML of Chinese in Hong Kong.     

MICM分型诊断在鉴别M2和M3型急性髓性白血病中的意义

目的：探讨形态学、免疫学、细胞遗传学和分子生物学(MICM)分型诊断在鉴别M2、M3型急性髓性白血病(AML)中的意义。方法：对10例按FAB方案难以区分M2、M3型的AML及2例在基层医院诊断为M3b，用全反式维甲酸(ATRA)治疗未获缓解的患者应用常规细胞遗传学(CC)进行核型分析；以筑巢式逆转录聚合酶链反应(nested—RT—PCR)技术检测PML／RARa及AML1／ETO融合基因转录本；以流式细胞术检测白血病细胞免疫表型。对2例在基层医院诊断为M3b而用ATRA治疗效果不好的病例用间期双色FISH技术检测AML1／ETO融和基因。结果：12例患者中，4例有t(8；21)．AML1／ETO融合基因转录本阳性，确诊为M2；2例有t(15；17)，PML／RARa融合基因转录本阳性，确诊为M3；其他6例患者为正常核型，其中，3例AML1／ETO阳性，确诊为M2；1例PML／RARa阳性，确诊为M3；2例PML／RARa及AML1／ETO均为阴性．1例免疫表型为CD13、CD33^ 、CD34^ 、CD19^ ，最后诊断为M2，另1例免疫表型为CD13^ 、CD33^ 、CD34^ 、CD19^ ．最后诊断为M3。2例行FISH检测的患者AML1／ETO融和基因均为阳性。结论：对形态学无法鉴别M2、M3的AML进一步进行细胞遗传学、分子生物学及免疫学检测，可提高确诊率，并为治疗提供可靠的依据。     

Clinical aspects of acute myeloid leukemias of the FAB types M3 and M4Eo

Summary Acute promyelocytic leukemia (AML FAB M3, APL) and acute myelomonocytic leukemia with abnormal eosinophils (AML M4Eo) are considered distinct entities with characteristic clinical, morphological, cytogenetic, and prognostic features. Promyelocytic leukemia is characterized by abnormal promyelocytes replacing normal hematopoiesis associated with a translocation between the long arms of chromosomes 15 and 17 t (15; 17), severe coagulopathy, and responsiveness to all-trans retinoic acid (tretinoin). Characteristic features of AML M4Eo are a myelomonocytic marrow infiltration, eosinophils with abnormal immature granules positive for chloroacetate esterase, an inversion or translocation of chromosome 16, and an increased risk of meningeal relapses. Prognosis of both types of AML has been reported to be better than prognosis of the other entities combined. Since most of the published data were collected from heterogeneous patient populations treated with various chemotherapeutic regimens, we have analyzed treatment outcome of AML M3 and M4Eo in the AMLCG-85 study for patients younger than 60 years. For the total population of 594 patients of this study, CR rate was 68.89%, early death rate 11.60%, and no or partial remission was achieved in 19.51% of the cases. Of 40 patients with AML M3 or M3v complete remission was attained in 62.5%. Nine patients died within 42 days after the start of antileukemic therapy (22.5%). Of these nine, four died because of infection, five because of bleeding. Relapse-free survival rate was 59% after 3 years, significantly better than the respective curve of the other FAB types combined (35% after 3 years). In AML M4Eo, 91.7% of the 24 patients reached complete remission. The early death rate was 8.3%. No case of nonresponse was seen. Relapse-free survival rate was 49% after 3 years compared with 35% for the other types combined.     

Additional chromosomal abnormality of inv(16)(p13q22) to del(7)(q32) in a patient with acute myelomonocytic leukemia

We report a 54-year-old man with acute myeloid leukemia (AML) carrying del(7)(q32) and inv(16)(p13q22). He was diagnosed as having AML M4Eo according to the FAB classification. RT-PCR for CBFβ/MYH11 gene was positive. Karyotype analysis revealed the primary chromosomal abnormality to be del(7)(q32) and inv(16)(p13q22) developed as a secondary abnormality. He achieved complete remission after one course of induction chemotherapy and remained in remission after several courses of consolidation therapy. del(7q) is classified into an intermediate risk group or an adverse risk group, while inv(16)/t(16;16) is classified into a favorable risk group. Some AML cases with inv(16)/t(16;16) exhibit del(7q) as an additional chromosomal abnormality. It was reported that such cases showed good prognosis despite the presence of del(7q). However, AML cases with del(7q) and inv(16)/t(16;16) as secondary chromosomal abnormalities are rare. Further study is needed to clarify the clinical manifestations of such cases.