Screening for myeloid mutations in patients with myelodysplastic syndromes and AML with myelodysplasia-related changes

ABSTRACT Introduction: One of the most critical complications in myelodysplastic syndromes (MDS) is the progression to acute myeloid leukemia (AML). The dynamics of clonal evolution in MDS and how acquired mutations can be used as biomarkers to track disease progression remains under investigation. Objective and method: Herein, we investigated the frequency of common myeloid clonal mutations (FLT3, NPM1, JAK2, IDH1 and IDH2) in 88 patients with MDS and 35 AML patients with myelodysplasia-related changes, followed at a single reference center in northeastern Brazil. Results: Overall, 9/88 (10%) ofthe MDSpatients and 9/35 (26%) of the secondary AML patients had at least one mutation. While the JAK2 V617F mutation was the most frequent in the MDS patients, the FLT3, NPM1, IDH1 and IDH2 mutations were more frequently found in the secondary AML group. Furthermore, there was a higher frequency of FLT3, NPM1, IDH1 and IDH2 mutations in MDS patients classified as high-risk subtypes than in those of lower risk. Conclusion: Despite the limited sample size, our data suggest that mutations in FLT3, NPM1, IDH1 and IDH2 genes could be potential biomarkers to detect early disease progression in MDS.

Brain Tumor Heterogeneity

Tumor heterogeneity is the concept that different tumor cells provide distinct biomorphological lesions, gene expressions, proliferation, microenvironment and graduated capacity of metastatic lesions. Brain tumor heterogeneity has been recently discussed about the interesting interaction of chronic inflammation, microenvironment, epigenetics and glioma steam cells. Brain tumors remain a challenge with regards to medication and disease, due to the lack of treatment options and unsatisfactory results. These results might be the result of the brain tumor heterogeneity and its multiple resistance mechanisms to chemo and radiotherapy.

Clonal evolution and clinical significance of trisomy 8 in acquired bone marrow failure / 中华血液学杂志

Objective: To analyze clonal evolution and clinical significance of trisomy 8 in patients with acquired bone marrow failure. Methods: The clinical data of 63 patients with acquired bone marrow failure accompanied with isolated trisomy 8 (+8) from June 2011 to September 2018 were analyzed retrospectively, the clonal evolution patterns and relationship with immmunosuppressive therapy were summarized. Results: Totally 24 male and 39 female patients were enrolled, including 39 patients with aplastic anemia (AA) and 24 patients with relatively low-risk myelodysplastic syndrome (MDS) . Mean size of+8 clone in MDS patients[65% (15%-100%) ]was higher than that of AA patients[25% (4.8%-100%) , z=3.48, P=0.001]. The patients were was divided into three groups (<30%, 30%-<50%,and ≥50%) according to the proportion of+8 clone. There was significant difference among the three groups between AA[<30%:55.6% (20/36) ; 30-50%: 22.2% (8/36) ; ≥50%22.2% (8/36) ]and MDS patients[<30%:19.0% (4/21) ; 30%-<50%:19.0% (4/21) ; ≥50%61.9% (13/21) ] (P=0.007) . The proportion of AA patients with+8 clone <30% was significantly higher than that of MDS patients (P=0.002) ; and the proportion of AA patients with+8 clone ≥50%was significantly lower than that of MDS patients (P=0.002) . The median age of AA and MDS patients was respectively 28 (7-61) years old and 48.5 (16-72) years old. Moreover, there was no correlation between age and+8 clone size in AA or MDS (r(s)=0.109, P=0.125; r(s)=-0.022, P=0.924, respectively) . There was statistical difference in total iron binding capacity, transferrin and erythropoietin between high and low clone group of AA patients (P=0.016, P=0.046, P=0.012, respectively) , but no significant difference in MDS patients. The immunosuppressive therapy (IST) efficacy of AA and MDS patients was respectively 66.7% and 43.8% (P=0.125) . Comparing with initial clone size (27.3%) , the +8 clone size (45%) of AA patients was increased 1-2 year after IST, but no statistical difference (z=0.83, P=0.272) . Consistently, there was no significant change between initial clone size (72.5%) and 1-2 year clone size (70.5%) after IST in MDS patients. There was no significant difference in IST efficient rate between +8 clone size expansion and decline group of in AA patients at 0.5-<1, 1-2 and>2 years after IST. We found four dynamic evolution patterns of +8 clone, which were clone persistence (45%) , clone disappearance (30%) , clone emergence (10%) and clone recurrence (15%) . Conclusions: AA patients had a low clone burden, while MDS patients had a high burden of +8 clone. The +8 clone of AA patients didn't significantly expanded after IST, and the changes of +8 clone also had no effect on IST response.

Clinical Significance of Additional Chromosomal 8 Clonal Evolution in CML Progression / 中国实验血液学杂志

OBJECTIVES@#To explore the clinical significance of clonal evolution of additional chromosomal 8 in CML progression.@*METHODS@#An unusual case with the clonal evolution from trisomy 8 to tetrasomy 8 accompanied by 2 time of CML blast crisis (BC) was reported.@*RESULTS@#This patient suffered from 2 time of CML blast crisis and the additional chromosome 8 aberrations were accompanied. Trisomy 8 and tetrasomy 8 were detected at first CML blast crisis and second CML blast crisis, respectively. After tetrasomy 8 was developed, the c-Myc was over-expressed and the central nervous system leukemia happened in this case. Only high dose Ara-C and MTX regimen could induce remission for a short period.@*CONCLUSION@#These findings suggested that additional chromosome 8 aberrations are important marker for poor prognosis of CML patients and contribute to a poor prognosis.

Granulocytic dysplasia: an indicator of clonal evolution in patients with chronic myeloid leukemia

No abstract available.

Clinical characteristics of clonal evolution after immunosuppressive therapy in children with severe/very severe aplastic anemia / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To evaluate the clinical characteristics and risk factors of clonal evolution after immunosuppressive therapy (IST) in children with severe/very severe aplastic anemia (SAA/VSAA).</p><p><b>METHODS</b>The clinical data of 231 children with newly-diagnosed SAA/VSAA who received IST were retrospectively studied. The incidence and risk factors of clonal evolution after IST were analyzed.</p><p><b>RESULTS</b>The 5-year overall survival rate of the 231 patients was 82.7%. Except for 18 cases of early deaths, 213 patients were evaluated for IST efficacy. Among the 231 patients, cytogenetic abnormalities for at least two chromosome metaphase were detectable in 14 (7.4%) patients, and PNH clones were detectable in either peripheral red blood cells or neutrophils for 95 patients. Among the 213 patients evaluated for IST efficacy, 15 patients experienced clonal evolution after IST. Five patients had PNH and trisomy 8 which were defined as favorable progressions, and ten patients experienced monosomy 7 and MDS/AML as unfavorable progressions. The 5-year accumulative incidence of favorable and unfavorable progression were (2.2±2.2)% and (4.8±3.3)%, respectively. Until the last follow-up, 100% (5/5) of patients with favorable progressions and 50% (5/10) of patients with unfavorable progressions survived. WBC>3.5×10/L, CD3T cell percentage>80%, dosage of antithymocyte globulin >3.0 mg/(kg·d) and no response to IST were related to unfavorable progressions by univariate analysis. Cox multivariate analysis revealed that an increased CD3T cell percentage (>80%) and no response to IST were independent risk factors for unfavorable progressions.</p><p><b>CONCLUSIONS</b>The children with SAA/VSAA who have an increased CD3T cell percentage at diagnosis or have no response to IST are in high risks of unfavorable progressions.</p>

Evaluation of prognostic factors in patients with relapsed AML: Clonal evolution versus residual disease

BACKGROUND: It is widely known that the prognosis of acute myeloid leukemia (AML) depends on chromosomal abnormalities. The majority of AML patients relapse and experience a dismal disease course despite initial remission. METHODS: We reviewed the medical records and laboratory findings of 55 AML patients who had relapsed between 2004 and 2013 and who had been treated at the Division of Hematology of the Pusan National University Hospital. RESULTS: The event-free survival (EFS) was related to prognostic karyotype classification at the time of diagnosis and relapse (unfavorable vs. favorable or intermediate karyotypes at diagnosis, 8.2 vs. 11.9 mo, P=0.003; unfavorable vs. favorable or intermediate karyotypes at relapse, 8.2 vs. 11.9 mo, P=0.009). The overall survival (OS) was significantly correlated with karyotype classification only at diagnosis (unfavorable vs. favorable or intermediate vs. karyotypes at diagnosis, 8.5 vs. 21.8 mo, P=0.001; unfavorable vs. favorable or intermediate karyotypes at relapse, 8.5 vs. 21.2 mo, P=0.136). A change in karyotype between diagnosis and relapse, which is regarded as a factor of resistance against treatment, was not a significant prognostic factor for OS, EFS, and post-relapse survival (PRS). A Cox proportional hazards model showed that the combined use of fludarabine, cytosine arabinoside, and granulocyte colony-stimulating factor (FLAG) as a salvage regimen, was a significant prognostic factor for OS (hazard ratio=0.399, P=0.010) and the PRS (hazard ratio=0.447, P=0.031). CONCLUSION: The karyotype classification at diagnosis predicts survival including PRS in relapsed AML patients as well as in treatment-naïve patients. We suggest that presently, administration of salvage FLAG could be a better treatment option.

Analyses of the TCR repertoire of MHC class II-restricted innate CD4+ T cells

Analysis of the T-cell receptor (TCR) repertoire of innate CD4+ T cells selected by major histocompatibility complex (MHC) class II-dependent thymocyte-thymocyte (T-T) interaction (T-T CD4+ T cells) is essential for predicting the characteristics of the antigens that bind to these T cells and for distinguishing T-T CD4+ T cells from other types of innate T cells. Using the TCRmini Tg mouse model, we show that the repertoire of TCRalpha chains in T-T CD4+ T cells was extremely diverse, in contrast to the repertoires previously described for other types of innate T cells. The TCRalpha chain sequences significantly overlapped between T-T CD4+ T cells and conventional CD4+ T cells in the thymus and spleen. However, the diversity of the TCRalpha repertoire of T-T CD4+ T cells seemed to be restricted compared with that of conventional CD4+ T cells. Interestingly, the frequency of the parental OT-II TCRalpha chains was significantly reduced in the process of T-T interaction. This diverse and shifted repertoire in T-T CD4+ T cells has biological relevance in terms of defense against diverse pathogens and a possible regulatory role during peripheral T-T interaction.

Clonal evolution in leukemia / 中国实验血液学杂志

The theory of evolution of tumor cell population has been established for nearly 40 years. It was widely accepted for research and clinical anti-tumor treatment. Recently, it was suggested that cancer stem cells are the unit of evolution. Considering recent advances on genesis of tumor and leukemia with ecological and evolutionary views, this article reviews origin and evolution of leukemia stem cells. Over the last few years, clinical and experimental data suggest there are two paths for the origin of leukemia stem cells: from a transformed hematopoietic stem cell or progenitor. The mechanisms of leukemia stem cell formation and clonal evolution were elucidated. Sub-clonal mutations and clonal architectures in leukemia were studied and a mosaic evolution pattern is described. Random evolution or non-inherited mutations of leukemia cells would accelerate the progression of malignant disease. Finally, the mosaic or network mechanism for leukemogenesis is also discussed.

Molecular Mechanism and Malignant Clonal Evolution of Multiple Myeloma / 中国实验血液学杂志

Almost all patients with multiple myeloma (MM) have chromosomal translocation which can result in genetic variation. There are mainly five types of chromosomal translocations, involving the IGH gene translocation to 11q13 (CCND1), 4p16 (FGFR/MMSET), 16q23 (MAF), 6p21 (CCND3) and 20q11 (MAFB). It is possible that all IGH translocations converge on a common cell cycle signal pathway. Some MM develops through a multistep transformation from monoclonal gammopathy of undetermined significance (MGUS) to smoldering MM (SMM) and eventually to MM and plasma cell leukemia (PCL). Similarly to what Darwin proposed in the mid-19th century-random genetic variation and natural selection in the context of limited resources, MM clonal evolution follow branching and nonlinear mode. The failure of MM treatment is usually related with the minimal subclone which is hardly found at newlydiagnosed.

Personalized cancer medicine: present status and future perspectives

Most cancers have oncogenes and tumor suppressor genes. First successful drug targeting a oncogene is imatinib. It was very effective for chronic myelogenous leukemia as well as gastrointestinal stromal tumors. Many other targeted agents showed good response: trastuzumab for breast cancer, epidermal growth factor receptor tyrosine kinase inhibitors for non-small cell lung cancer, etc. Tests for EGFR and ALK gene mutation are routinely recommended for adenocarcinoma of lung cancer for selection of anticancer treatment. In addition, large-scale genomic data generation (next generation sequencing) is feasible in a clinical setting and gives us high hope for personalized cancer medicine. However, there are many hurdles to overcome. Driver genes must be distinguished from the passenger genes that are present in tumor DNA. In case of targeted cancer therapy, emergence of drug resistance due to tumor cell heterogeneity and clonal evolution is difficult to manage. Genetic testing for cancer risk showed some success in preventing familial breast or ovarian cancers, but it cannot be generalized in other tumors. Application of genetic information in cancer medicine showed promise but evidence-based approach is needed in clinical practice.

Clinical features of childhood refractory cytopenia / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the clinical features of patients with refractory cytopenia of childhood (RCC).</p><p><b>METHODS</b>The clinical data of 1 420 children (0-14 years old) with an initial diagnosis of non-severe aplastic anemia between January 1990 and June 2013 were retrospectively analyzed. Bone marrow cell morphology and histopathology were re-evaluated, and the patients were re-classified using the criteria proposed in the 2008 edition of the World Health Organization classification of RCC in hematopoietic and lymphoid tumor tissues. The clinical outcomes were followed up every 3-6 months.</p><p><b>RESULTS</b>Among all the 1 420 cases, 152 (10.7%) were reassessed as RCC. Patients with RCC had a lower level of hemoglobin and a higher percentage of fetal hemoglobin than those with non-severe aplastic anemia. Of the patients with RCC, 21.5% showed abnormal karyotypes at diagnosis. The median follow-up period for all patients was 36 months (ranging from 1 to 283 months). The rates of complete response, partial response, and no response to cyclosporine and androgen treatment in RCC patients were 19.0%, 26.7%, and 54.3%, respectively. The 5- and 10-year prospective overall survival rates of RCC patients were 87.9% and 72.4%, respectively. The 5- and 10-year prospective clonal evolution rates were 15.3% and 20.0%, respectively. The 2-year prospective incidence of newly diagnosed karyotype abnormality after the initial diagnosis was 3.6%. The 5- and 10-year prospective leukemia transformation rates were 10.0% and 20.0%, respectively.</p><p><b>CONCLUSIONS</b>RCC shows clinical features similar to adult myelodysplastic syndrome. Children with RCC have a poor prognosis, an increased risk of transformation to leukemia, and a low response rate to cyclosporine treatment.</p>

Outcome of children with severe acquired aplastic anemia treated with rabbit antithymocyte globulin and cyclosporine A, / Resultado de crianças com anemia aplástica grave adquirida tratadas com globulina antitimocítica de coelho e ciclosporina A,

Objective: To evaluate the outcome of children with severe acquired aplastic anemia treated with rabbit antithymocyte globulin and cyclosporine as first-line treatment at this institution. Methods: Retrospective analysis of 26 pediatric patients with aplastic anemia, treated between 1996 and 2011 with rabbit antithymocyte globulin plus cyclosporine. Results: The overall response rate at six months was 34.6% (9/26), and the cumulative incidence of relapse was 26.5% (95% confidence interval [CI]: 1.4%-66%) at 5 years. The cumulative incidence of clonal evolution after immunosuppressive therapy was 8.3% (95% CI: 0.001%-53.7%) at five years with both clonal evolutions in non-responders who acquired monosomy 7 karyotype. The overall survival at five years was 73.6% (95% CI: 49.2%-87.5%). Conclusions: The present results confirm the poor response rate with rabbit antithymocyte globulin as first therapy in pediatrics patients, similar to what has been reported for patients of all ages. This confirmation is problematic in Brazil, given the lack of horse antithymocyte globulin in many markets outside the United States. .

Objetivo: Avaliar o resultado de crianças com anemia aplástica grave adquirida tratadas com globulina antitimocítica de coelho e ciclosporina como tratamento inicial em nosso instituto. Métodos: Análise retrospectiva de 26 pacientes pediátricos com anemia aplástica tratados entre 1996 e 2011 com globulina antitimocítica de coelho e ciclosporina. Resultados: A taxa de resposta geral em seis meses foi de 34,6% (9/26), e a incidência acumulada de recorrência foi de 26,5% (intervalo de confiança [IC] de 95%,1,4%-66%) em cinco anos. A incidência acumulada de evolução clonal após a terapia imunossupressora foi de 8,3% (IC 95%, 0,001%-53,7%) em cinco anos, com ambas as evoluções clonais em pacientes sem resposta que adquiriram o cariótipo com monossomia 7. A sobrevida geral em cinco anos foi de 73,6% (IC 95%, 49,2%-87,5%). Conclusões: Nossos resultados confirmam a baixa taxa de resposta com globulina antitimocítica de coelho como terapia inicial em pacientes pediátricos, da mesma forma como relatado para pacientes de todas as idades. Essa confirmação é problemática em nosso país devido à falta de globulina antitimocítica de cavalo em muitos mercados fora dos Estados Unidos, incluindo o Brasil. .

Cancer stem cells - the current status of an old concept: literature review and clinical approaches

As regards their morphology and biology, tumours consist of heterogeneous cell populations. The cancer stem cell (CSC) hypothesis assumes that a tumour is hierarchically organized and not all of the cells are equally capable of generating descendants, similarly to normal tissue. The only cells being able to self-renew and produce a heterogeneous tumour cell population are cancer stem cells. CSCs probably derive from normal stem cells, although progenitor cells may be taken into consideration as the source of cancer stem cells. CSCs reside in the niche defined as the microenvironment formed by stromal cells, vasculature and extracellular matrix. The CSC assays include FACS sorting, xenotransplantation to immunodeficient mice (SCID), incubation with Hoechst 33342 dye, cell culture in non-adherent conditions, cell culture with bromodeoxyuridine. CSCs have certain properties that make them resistant to anticancer therapy, which suggests they may be the target for potential therapeutic strategies.

Evolución clonal en la leucemia mieloide crónica / Clonal evolution in chronic myeloid leukemia

Evolución clonal en la leucemia mieloide crónica se denomina a la presencia de alteraciones cromosómicas adicionales al cromosoma Filadelfia. Ocurre aproximadamente en el 30 por ciento de los pacientes en fase acelerada y en el 80 por ciento de los pacientes en crisis blástica. Es considerada un criterio de la fase acelerada de la enfermedad. Aunque se plantea que su presencia implica peor pronóstico, su significado es controversial y está en dependencia de la alteración citogenética específica, su frecuencia en el cariotipo, la asociación con otras alteraciones citogenéticas y clínicas de progresión, relación con el tiempo en que aparece en la evolución de la enfermedad y los tratamientos empleados

Clonal evolution in chronic myeloid leukemia is defined as the presence of a variety of additional, nonrandom chromosomal abnormalities besides the Philadelfia chromosome. It occurs in approximately 30 percent of patients in accelerated phase and 80 percent of patients in blastic phase. It is considered a criterion for accelerated phase. Although it is associated with a poor prognosis, its significance is controversial. It depends on the specific cytogenetic abnormality, its frequency in karyotype study, the association with other progression clinical and cytogenetic alterations, its relationship with the time of appearance during the course of the disease and the therapy used

Gastric stem cells and gastric cancer stem cells / 대한해부학회지

The gastric epithelium is continuously regenerated by gastric stem cells, which give rise to various kinds of daughter cells, including parietal cells, chief cells, surface mucous cells, mucous neck cells, and enteroendocrine cells. The self-renewal and differentiation of gastric stem cells need delicate regulation to maintain the normal physiology of the stomach. Recently, it was hypothesized that cancer stem cells drive the cancer growth and metastasis. In contrast to conventional clonal evolution hypothesis, only cancer stem cells can initiate tumor formation, self-renew, and differentiate into various kinds of daughter cells. Because gastric cancer can originate from gastric stem cells and their self-renewal mechanism can be used by gastric cancer stem cells, we review here how critical signaling pathways, including hedgehog, Wnt, Notch, epidermal growth factor, and bone morphogenetic protein signaling, may regulate the self-renewal and differentiation of gastric stem cells and gastric cancer stem cells. In addition, the precancerous change of the gastric epithelium and the status of isolating gastric cancer stem cells from patients are reviewed.

Serial Determination of FLT3-ITD and NPM1 Mutations and Its Clinical Significance in Patients with MDS at Diagnosis and After Progression to AML with Myelodysplasia-related Changes

BACKGROUND: Accumulation of genetic aberrations in MDS is closely associated with progression to AML. FLT3-ITD is commonly found in AML and less frequently in MDS. FLT3-ITD in MDS is associated with a high risk of transformation to AML. Recently, significant interaction of NPM1 and FLT3-ITD was described in AML. This study was conducted to investigate the incidence and prognostic role of FLT3-ITD and NPM1 mutations (NPM1mt) on paired samples at diagnosis of MDS and AML. METHODS: Patients who were diagnosed as MDS transforming to AML were included. FLT3-ITD was detected by PCR, and NPM1mt was confirmed by direct sequencing after screening for NPM by immunohistochemistry. RESULTS: AML developed in 12.0% (43/357) of MDS patients. FLT3-ITD was detected in none of MDS and 14.7% (5/34) of AML. NPM1mt was detected in 2.4% (1/41) of MDS and 11.6% (5/43) of AML. One patient with type B NPM1mt at MDS transformed to type A NPM1mt at AML. FLT3-ITD positive AML showed a tendency of shorter survival and a significantly longer time to achieve complete remission than FLT3-ITD negative AML (P=0.007). Normal karyotype AML with FLT3-ITD showed shorter overall survival than that group of AML without FLT3-ITD (P=0.017). CONCLUSIONS: MDS patients acquired FLT3-ITD during AML transformation, and FLT3-ITD positive AML, especially that with normal karyotype, predicted a poor outcome. NPM1mt was identified in both MDS and AML. NPM1mt was rarely found in MDS patients, and mostly was acquired after AML transformation. Clonal evolution of NPM1mt subtype was found in one patient during acute transformation.

Coexisting with Clonal Evolution and BCR-ABL Mutant in CML Patients Treated with Second-generation Tyrosine Kinase Inhibitors Predict the Discrepancy of in vitro Drug Sensitivity / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Second-generation tyrosine kinase inhibitors (second TKIs) such as nilotinib and dasatinib control the activity of most ABL kinase domain mutations observed in patients with imatinib resistance. Although in vitro data show that both agents can inhibit all mutations except T315I, some discrepancies have been observed in a small subset of mutation clones. Cytogenetic clonal evolution is the important resistance mechanism of chronic myeloid leukemia (CML). Accordingly, we observed the clinical significance of coexisting with clonal evolution and BCR-ABL mutant in CML patients treated with second TKIs. MATERIALS AND METHODS: We monitored BCR-ABL transcript kinetics, interrelationship of clones expressing non-mutated and mutant transcripts and clonal aberrations within Philadelphia (Ph) positive and negative clones, respectively, in eight patients with CML receiving dasatinib or nilotinib for 3~41 months. RESULTS: Clinical responses were correlated with in vitro sensitivity of the BCR-ABL mutants to the second TKIs in four patients. Four patients showed resistance to the second TKIs as compared to in vitro observations; three of them developed chromosomal abnormalities in the Ph chromosome positive or negative metaphases. Another patient lost the original mutation but acquired a more resistant new mutation and became resistant to the second TKI. CONCLUSION: Cytogenetic clonal evolution is an independent poor prognostic factor in CML, which could explain the onset of mechanisms for second TKIs resistance to ABL kinase domain mutations. The results indicate that an additional evaluation of chromosomal abnormalities is warranted when BCR-ABL mutants are more resistant than indicated by in vitro data.

Study on clonal evolution of monosomy 7 in patients with aplastic anemia by interphase- fluorescence in situ hybridization / 中华血液学杂志

<p><b>OBJECTIVE</b>To explore the clonal evolution of monosomy 7 in patients with aplastic anemia (AA).</p><p><b>METHODS</b>Monosomy 7 (-7) in 81 AA patients with normal karyotype at diagnosis and 46 AA treated with immunosuppressive therapy (IST) and more than 6 months of recombinant human granulocyte colony-stimulating factor (rhuG-CSF) were detected by interphase- fluorescence in situ hybridization (FISH) retrospectively.</p><p><b>RESULTS</b>There were 5.4% - 7.6% of -7 cells in 11 (13.6%) of 81 patients at diagnosis, the survival and response rate to IST in -7 positive patients did not differ significantly from that in -7 negative patients (P = 0.481, 0.865); -7 cells disappeared after IST in all of the 11 patients including 5 received long-term rhuG-CSF therapy, and none of them evolved to myelodysplastic syndromes/acute myeloid leukemia (MDS/AML) at a median follow-up of 44 months. Serial assessments of -7 clones were performed in 46 patients, none of whom detected -7 clones 3-6 months after IST, but -7 recurrence in 5 patients 12 - 15 months after IST. At a median follow-up of 48 months, FISH identified 6 patients with -7 clones while the conventional cytogenetic analysis (CCA) recognized in 5. Moreover, the first demonstration of -7 by FISH was 3 - 18 months earlier than that by CCA. All of the 6 patients with FISH detected -7 evolved to MDS/AML with -7 and four of them were retrospectively analysed for in samples at -7 diagnosis of AA, but none of them was positive.</p><p><b>CONCLUSIONS</b>Monosomy 7 exists in a part of AA patients, but the preexisting -7 cells seems neither associated with fatality nor evolvation to MDS/AML. rhuG-CSF might facilitate the expansion of -7 clones; It is necessary to monitor -7 in AA, especially when received long-term rhuG-CSF therapy.</p>

Aplastic anemia / 소아과

Aplastic anemia is a rare disease, which is characterized by pancytopenia and hypocellular bone marrow without infiltration of abnormal cells or fibrosis. The incidence in Asia is higher than in the West and new cases are diagnosed at a rate of 5.1 per million pediatric populations per year in Korea. The pathophysiology is understood roughly by defective hematopoiesis, impaired bone marrow microenvironment and immune mechanism. Treatments are performed on basis of pathogenesis and selected depending on the severity. Immunosuppressive therapy with antilymphocyte or antithymocyte globulin and cyclosporine is effective in the majority of patients but has some problems including relapse or clonal evolution. Recently, there have been clinical trials of immunosuppression with hematopoietic growth factors or other drugs. Allogeneic hematopoietic stem cell transplantation (HSCT) is curative in children with severe aplastic anemia. The overall survival in HSCT from HLA-identical sibling is higher than alternative donor, including HLA matched unrelated donor or cord blood. We have to consider quality of life after HSCT because of high survival rate. However, chronic graft versus host disease and graft failure are important factors that affect the quality of life and overall survival. We need further investigation to make new regimens aimed at overcoming these risk factors and perform clinical trials.