Mutations in the bZip region of the CEBPA gene: A novel prognostic factor in patients with acute myeloid leukemia.

BACKGROUND: Hematopoiesis, the process of blood cell formation involves on a complex network of transcription factors. Among them, the CCAAT-enhancer-binding protein alpha (CEBPA) plays a crucial role in maintaining the balance between myeloid proliferation and differentiation. Imbalances in this network can lead to disrupted differentiation and contribute to the development of malignant diseases. AIM: Understanding of disease development and explore potential therapeutic strategies for hematological disorders associated CEPBA gen. MATERIALS AND METHODS: The research involved a comprehensive analysis of CEBPA gene mutations in the context of acute myeloid leukemia (AML). This encompassed a thorough exploration of point mutations and double mutations in AML patients. RESULTS: In the context of acute myeloid leukemia (AML), mutations in the CEBPA gene, especially point mutations, are frequently observed. A significant number of AML patients present with double mutations in CEBPA, which have been linked to a more favorable prognosis in terms of overall survival and event-free survival. These patients also tend to exhibit enhanced responsiveness to treatment. DISCUSSION: Unraveling the intricate interplay of transcription factors, particularly CEBPA, holds significant implications for decoding the mechanisms governing hematopoiesis. This understanding offers a potential avenue for deciphering disease development and devising novel therapeutic strategies for hematological disorders. CONCLUSION: The findings underscore that CEBPA mutations correlate with enhanced overall survival and event-free survival, with relevance to those presenting within the bZip framework. This knowledge may contribute to advancing personalized treatments for hematological conditions.

Flow cytometry-detected changes in megaloblastic anemia secondary to cobalamin deficiency.

Introduction: Megaloblastic anemias secondary to Vitamin B12 deficiency are a group of pathologies produced by defective nuclear DNA synthesis. Objective: To describe the maturation alterations found in hematopoietic precursors of the bone marrow in a series of patients with megaloblastic anemia. Methods: Were included patients attended at the Regional Hospital of Concepción with bone marrow samples sent for the study of cytopenia by flow cytometry whose final diagnosis was megaloblastic anemia. The immunophenotype was performed with CD45, CD34, CD117, HLA-DR, markers of neutrophil (CD13, CD11b, CD10, CD16) and/or erythroblast (CD105, CD71, CD36) maturation. Results: From the flow cytometry laboratory database, 8 patients with megaloblastic anemia were identified, and myelodysplastic syndromes (n=9) and normal or reactive bone marrow (n=10) were used as controls. 44% were men, with a median age of 58 years. Megaloblastic anemia was associated with a higher proportion of size and complexity of erythroid and myeloid progenitors compared to lymphocytes compared to controls. The total percentage of erythroblasts and the proportion of CD34+ myeloid cells associated with erythroid lineage was higher in megaloblastic anemia, associated with a maturation arrest in the CD105+ precursor stage (69% vs 19% and 23%, p<0.001). The heterogeneity of CD36 and CD71 in megaloblastic anemia was similar to myelodysplastic syndromes. Conclusions: Megaloblastic anemia produces a heterogeneous involvement of hematopoiesis, characterized by a greater size and cellular complexity of precursors of the neutrophil and erythroid series and a maturation arrest of the erythroblasts.

Introducción: Anemias megaloblásticas secundarias a la deficiencia de vitamina B12 son patologías producidas por una síntesis defectuosa del ADN nuclear. Objetivo: Describir las alteraciones madurativas encontradas en precursores hematopoyéticos de la médula ósea de una serie de pacientes con anemia megaloblástica. Métodos: Se incluyeron pacientes atendidos en el Hospital Regional de Concepción con muestras de médula ósea enviadas para estudio de citopenias por citometría de flujo cuyo diagnóstico fue anemia megaloblástica. El inmunofenotipo se realizó con CD45, CD34, CD117, HLA-DR, marcadores de maduración de serie de neutrófilo (CD13, CD11b, CD10, CD16) y/o eritroblasto (CD105, CD71, CD36). Resultados: Se identificaron 8 pacientes con anemia megaloblástica y como controles se utilizaron síndromes mielodisplásicos (n=9) y médula ósea normal o reactiva (n=10). El 44% eran hombres, con una mediana de edad de 58 años. La anemia megaloblástica se asoció con una mayor proporción de tamaño y complejidad de progenitores eritroides y mieloides con respecto de los linfocitos en comparación a los controles. El porcentaje total de eritroblastos y la proporción de células mieloides CD34+ comprometidas con el linaje eritroide fue mayor en anemia megaloblástica, asociado a una parada madurativa en la etapa de precursor CD105+ (69% vs 19% y 23%, p <0.001). La heterogeneidad de CD36 y CD71 en anemia megaloblástica fue similar a los síndromes mielodisplásicos. Conclusiones: la anemia megaloblástica produce una afectación heterogénea de la hematopoyesis, caracterizada por un mayor tamaño y complejidad celulares de precursores de la serie neutrófilo y eritroide y una detención madurativa de los eritroblastos.

Flow cytometry-detected changes in megaloblastic anemia secondary to cobalamin deficiency

Introduction: Megaloblastic anemias secondary to Vitamin B12 deficiency are a group of pathologies produced by defective nuclear DNA synthesis. Objective: To describe the maturation alterations found in hematopoietic precursors of the bone marrow in a series of patients with megaloblastic anemia. Methods: Were included patients attended at the Regional Hospital of Concepción with bone marrow samples sent for the study of cytopenia by flow cytometry whose final diagnosis was megaloblastic anemia. The immunophenotype was performed with CD45, CD34, CD117, HLA-DR, markers of neutrophil (CD13, CD11b, CD10, CD16) and/or erythroblast (CD105, CD71, CD36) maturation. Results: From the flow cytometry laboratory database, 8 patients with megaloblastic anemia were identified, and myelodysplastic syndromes (n=9) and normal or reactive bone marrow (n=10) were used as controls. 44% were men, with a median age of 58 years. Megaloblastic anemia was associated with a higher proportion of size and complexity of erythroid and myeloid progenitors compared to lymphocytes compared to controls. The total percentage of erythroblasts and the proportion of CD34+ myeloid cells associated with erythroid lineage was higher in megaloblastic anemia, associated with a maturation arrest in the CD105+ precursor stage (69% vs 19% and 23%, p<0.001). The heterogeneity of CD36 and CD71 in megaloblastic anemia was similar to myelodysplastic syndromes. Conclusions: Megaloblastic anemia produces a heterogeneous involvement of hematopoiesis, characterized by a greater size and cellular complexity of precursors of the neutrophil and erythroid series and a maturation arrest of the erythroblasts.

Introducción: Anemias megaloblásticas secundarias a la deficiencia de vitamina B12 son patologías producidas por una síntesis defectuosa del ADN nuclear. Objetivo: Describir las alteraciones madurativas encontradas en precursores hematopoyéticos de la médula ósea de una serie de pacientes con anemia megaloblástica. Métodos: Se incluyeron pacientes atendidos en el Hospital Regional de Concepción con muestras de médula ósea enviadas para estudio de citopenias por citometría de flujo cuyo diagnóstico fue anemia megaloblástica. El inmunofenotipo se realizó con CD45, CD34, CD117, HLA-DR, marcadores de maduración de serie de neutrófilo (CD13, CD11b, CD10, CD16) y/o eritroblasto (CD105, CD71, CD36). Resultados: Se identificaron 8 pacientes con anemia megaloblástica y como controles se utilizaron síndromes mielodisplásicos (n=9) y médula ósea normal o reactiva (n=10). El 44% eran hombres, con una mediana de edad de 58 años. La anemia megaloblástica se asoció con una mayor proporción de tamaño y complejidad de progenitores eritroides y mieloides con respecto de los linfocitos en comparación a los controles. El porcentaje total de eritroblastos y la proporción de células mieloides CD34+ comprometidas con el linaje eritroide fue mayor en anemia megaloblástica, asociado a una parada madurativa en la etapa de precursor CD105+ (69% vs 19% y 23%, p <0.001). La heterogeneidad de CD36 y CD71 en anemia megaloblástica fue similar a los síndromes mielodisplásicos. Conclusiones: la anemia megaloblástica produce una afectación heterogénea de la hematopoyesis, caracterizada por un mayor tamaño y complejidad celulares de precursores de la serie neutrófilo y eritroide y una detención madurativa de los eritroblastos.

Primary plasma cell leukemia in Latin America: demographic, clinical, and prognostic characteristics. A study of GELAMM group.

Primary plasma cell leukemia (pPCL) is an infrequent and aggressive plasma cell disorder. The prognosis is still very poor, and the optimal treatment remains to be established. A retrospective, multicentric, international observational study was performed. Patients from 9 countries of Latin America (LATAM) with a diagnosis of pPCL between 2012 and 2020 were included. 72 patients were included. Treatment was based on thalidomide in 15%, proteasome inhibitors (PI)-based triplets in 38% and chemotherapy plus IMIDs and/or PI in 29%. The mortality rate at 3 months was 30%. The median overall survival (OS) was 18 months. In the multivariate analysis, frontline PI-based triplets, chemotherapy plus IMIDs and/or PI therapy, and maintenance were independent factors of better OS. In conclusion, the OS of pPCL is still poor in LATAM, with high early mortality. PI triplets, chemotherapy plus IMIDs, and/or PI and maintenance therapy were associated with improved survival.

[Flow cytometry increases the proportion of valuable samples in cerebrospinal fluid with normal cell count in malignant blood diseases]. / La citometría de flujo aumenta la proporción de muestras valorables en líquido cefalorraquídeo con recuento celular normal en hemopatías malignas.

BACKGROUND: The alteration of cerebrospinal fluid (CSF) in hematologic neoplasms is a poor prognostic marker. The characteristics of CSF are usually analyzed by flow cytometry or cytology. However, paucicellular CSF samples (≤5 cells/dL) can sometimes be considered unsuitable for analysis due to the low number of events. OBJECTIVE: To evaluate the proportion of samples reported as suitable for analysis obtained by cytometry (FCM) and cytology in paucicellular CSF samples. MATERIAL AND METHODS: 169 samples ofpaucicellular CSF corresponding to 115 patients with hematologic neoplasms were selected. The samples were obtained by lumbar puncture in tubes conditioned with EDTA and Transfix®. We characterized the immunophenotype ofCSF samples with an 8-color panel, and 55 samples (32%) were in a small sample tube (SST). In all cases, monocytes were identified by CD14 labeling and T lymphocytes by CD3 labeling. The acquisition was carried out in a FACSCantoII® cytometer, and the analysis was performed using Infinicyt® software. RESULTS: The proportion of samples suitable for analysis was higher in FCM compared to cytology (98% vs 61%, p < 0.000). We identified the presence of T lymphocytes and/or monocytes in most samples (98% and 90%, respectively). In the SST samples, the number of events recorded in low-volume samples (< 1 mL) was lower than in samples with higher volume (140 vs 556, p < 0.001), with a median of identification of 3 cell populations. CONCLUSION: FCM allows the analysis of a higher proportion ofpaucicellular CSF samples than cytology in hematologic neoplasms study.

Características y desenlace clínico de 30 pacientes con hemopatías malignas y COVID-19 en un hospital público regional / Features of COVID-19 infection among patients with hematological malignancies

BACKGROUND: COVID-19 infection can be especially severe in certain risk populations such as patients with hematologic malignancies. Aim: To describe the characteristics and clinical outcomes of a population of patients with hematologic malignancies and COVID-19. MATERIAL AND METHODS: Review of medical records of patients with COVID-19 and hematologic malignancies, treated in Hematology Service of a regional hospital in Chile, between April 1 and October 30, 2020. Demographic characteristics, chronic comorbidities and clinical characteristics related to the underlying disease and COVID-19 infection were recorded. Results: Thirty adults aged 17 to 73 years (67% men) with COVID-19 confirmed by RT-PCR, were evaluated. Forty percent had comorbidities, mainly hypertension (30%), obesity (27%) and diabetes (10%). Two thirds of cases came from a nosocomial outbreak and 77% were symptomatic. Half of the cases had mild disease and 20% required mechanical ventilation. Five patients (17%) died from COVID 19. Female sex, the presence of comorbidities and obesity were more common among deceased patients. Only 1 of 5 deceased patients were in complete remission. No differences were found in the mean survival according to requirement for intubation or the presence of complete remission. CONCLUSIONS: This population with hematologic malignancies and COVID-19 had special characteristics leading to a greater fatality rate which, in this series, does not increase with the use of mechanical ventilation.

[Features of COVID-19 infection among patients with hematological malignancies]. / Características y desenlace clínico de 30 pacientes con hemopatías malignas y COVID-19 en un hospital público regional.

BACKGROUND: COVID-19 infection can be especially severe in certain risk populations such as patients with hematologic malignancies. AIM: To describe the characteristics and clinical outcomes of a population of patients with hematologic malignancies and COVID-19. MATERIAL AND METHODS: Review of medical records of patients with COVID-19 and hematologic malignancies, treated in Hematology Service of a regional hospital in Chile, between April 1 and October 30, 2020. Demographic characteristics, chronic comorbidities and clinical characteristics related to the underlying disease and COVID-19 infection were recorded. RESULTS: Thirty adults aged 17 to 73 years (67% men) with COVID-19 confirmed by RT-PCR, were evaluated. Forty percent had comorbidities, mainly hypertension (30%), obesity (27%) and diabetes (10%). Two thirds of cases came from a nosocomial outbreak and 77% were symptomatic. Half of the cases had mild disease and 20% required mechanical ventilation. Five patients (17%) died from COVID 19. Female sex, the presence of comorbidities and obesity were more common among deceased patients. Only 1 of 5 deceased patients were in complete remission. No differences were found in the mean survival according to requirement for intubation or the presence of complete remission. CONCLUSIONS: This population with hematologic malignancies and COVID-19 had special characteristics leading to a greater fatality rate which, in this series, does not increase with the use of mechanical ventilation.

Different outcomes for transplant-eligible newly diagnosed multiple myeloma patients in Latin America according to the public versus private management: a GELAMM study.

The aim of this study was to describe clinical and survival characteristics of transplant-eligible multiple myeloma (MM) patients in Latin America (LA), with a special focus on differences between public and private healthcare facilities. We included 1293 patients diagnosed between 2010 and 2018. A great disparity in outcomes and survival between both groups was observed. Late diagnosis and low access to adequate frontline therapy and ASCT in public institutions probably explain these differences. Patients treated with novel drug induction protocols, followed by autologous stem cell transplantation (ASCT) and maintenance, have similar overall survival compared to that published internationally.

Mieloma múltiple en Chile: Respuesta a tratamiento en pacientes con mieloma múltiple elegibles para trasplante autólogo de progenitores hematopoyéticos / Response rates to first-line treatment in eligible patients to autologous stem transplantation in Chile

Background The treatment of choice of newly diagnosed multiple myeloma (NDMM) is an induction with proteasome inhibitors followed autologous stem cell transplantation (HSCT). Since 2013, the treatment of these patients in the public system is based on CTD (cyclophosphamide, thalidomide, and dexamethasone). Aim To evaluate the response rates achieved with CTD, and the results of HSCT in patients with NDMM in the public setting. Material and Methods Data from patients considered as candidates for HSCT from different centers of the National Adult Antineoplastic Drug Program (PANDA, for its acronym in Spanish), diagnosed between 2013 and 2017, was analyzed. The response to treatment of first and second lines of treatment was evaluated, in addition to the results of HSCT. An optimal Response was defined as the sum of strict complete remission, complete remission and very good partial response (sCR, CR and VGPR). Results One hundred and seventy-seven patients were analyzed, 54% women, and 53% with IgG multiple myeloma. Information about the international staging system was retrieved in 127 patients (71%). Seventeen percent were ISS I, 22% in ISS II and 32% ISS III. CTD was used as first treatment in 106 patients (60%), and cyclophosphamide, bortezomib and dexamethasone (CyBorD) in 13 (7%). As first line, CTD had an overall response of 50.9%, and CyBorD of 76.9%. Thirty patients were treated with bortezomib as second line treatment. Forty patients (22%) underwent HSCT. The 5-year Overall Survival (OS) in transplanted patients and non-transplanted patients was 100 and 62% respectively (p < 0.01). Conclusions The response rate achieved by CTD in these patients is suboptimal. The response to CyBorD was better.

[Response rates to first-line treatment in eligible patients to autologous stem transplantation in Chile]. / Mieloma múltiple en Chile: Respuesta a tratamiento en pacientes con mieloma múltiple elegibles para trasplante autólogo de progenitores hematopoyéticos.

Background The treatment of choice of newly diagnosed multiple myeloma (NDMM) is an induction with proteasome inhibitors followed autologous stem cell transplantation (HSCT). Since 2013, the treatment of these patients in the public system is based on CTD (cyclophosphamide, thalidomide, and dexamethasone). Aim To evaluate the response rates achieved with CTD, and the results of HSCT in patients with NDMM in the public setting. Material and Methods Data from patients considered as candidates for HSCT from different centers of the National Adult Antineoplastic Drug Program (PANDA, for its acronym in Spanish), diagnosed between 2013 and 2017, was analyzed. The response to treatment of first and second lines of treatment was evaluated, in addition to the results of HSCT. An optimal Response was defined as the sum of strict complete remission, complete remission and very good partial response (sCR, CR and VGPR). Results One hundred and seventy-seven patients were analyzed, 54% women, and 53% with IgG multiple myeloma. Information about the international staging system was retrieved in 127 patients (71%). Seventeen percent were ISS I, 22% in ISS II and 32% ISS III. CTD was used as first treatment in 106 patients (60%), and cyclophosphamide, bortezomib and dexamethasone (CyBorD) in 13 (7%). As first line, CTD had an overall response of 50.9%, and CyBorD of 76.9%. Thirty patients were treated with bortezomib as second line treatment. Forty patients (22%) underwent HSCT. The 5-year Overall Survival (OS) in transplanted patients and non-transplanted patients was 100 and 62% respectively (p < 0.01). Conclusions The response rate achieved by CTD in these patients is suboptimal. The response to CyBorD was better.

Efectividad de Rituximab en el tratamiento de citopenias autoinmunes refractarias en adultos / Effectiveness of Rituximab in the treatment of cytopenias refractory autoimmune in adults

The term autoimmune cytopenias is referred to a heterogeneous group of diseases characterized by a reduced peripheral blood cell counts in one or more cellular series, because an immunological disorder. The first line therapy is steroids, followed by splenectomy or immunesupressant therapy in non-responders. Rituximab is an anti CD20 monoclonal antibody used as a third line in refractory patients or as an alternative to splenectomy. We present a retrospective study of nine patients with autoimmune cytopenias treated in a public hospital setting with rituximab. Five patients with the diagnosis of inmune thrombocytopenic purpura received it, all of them achieved hematological response (4 complete and one partial). The median time to the best response was 6 weeks, staying in this category after 6 months of follow up. Four patients with autoimmune hemolytic anemia received rituximab, three of them achieving partial response and one was lost from follow up. No severe adverse effects related to rituximab were registered.

[Blastic plasmacytoid dendritic cell neoplasm with complete clinical remission with chemotherapy and central nervous system relapse: Report of one case]. / Neoplasia de células dendríticas plasmocitoides blásticas con respuesta inicial a quimioterapia y recaída en sistema nervioso central: Caso clínico.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, clinically aggressive hematologic malignancy that most commonly manifests as cutaneous lesions with or without bone marrow involvement and leukemic dissemination. The demonstration of tumor cells with the characteristic immunophenotype with expression of CD56, generally CD4 and dendritic cell antigens (CD123, cyTCL-1, HLA-DR), in the absence of myeloid or lymphoid lineage markers is required for the diagnosis. Responses to chemotherapy are initially satisfactory, with frequent systemic and central nervous system relapses. We report a 24 year-old male with BPDCN, initially diagnosed and treated as non-Hodgkin CD4+ T-cell lymphoma, with initial complete remission who evolved with early central nervous system relapse. A second attempt of chemotherapy failed and the patient died two months later.

Neoplasia de células dendríticas plasmocitoides blásticas con respuesta inicial a quimioterapia y recaída en sistema nervioso central: caso clínico / Blastic plasmacytoid dendritic cell neoplasm with complete clinical remission with chemotherapy and central nervous system relapse: report of one case

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, clinically aggressive hematologic malignancy that most commonly manifests as cutaneous lesions with or without bone marrow involvement and leukemic dissemination. The demonstration of tumor cells with the characteristic immunophenotype with expression of CD56, generally CD4 and dendritic cell antigens (CD123, cyTCL-1, HLA-DR), in the absence of myeloid or lymphoid lineage markers is required for the diagnosis. Responses to chemotherapy are initially satisfactory, with frequent systemic and central nervous system relapses. We report a 24 year-old male with BPDCN, initially diagnosed and treated as non-Hodgkin CD4+ T-cell lymphoma, with initial complete remission who evolved with early central nervous system relapse. A second attempt of chemotherapy failed and the patient died two months later.

Minimal residual disease evaluation by flow cytometry is a complementary tool to cytogenetics for treatment decisions in acute myeloid leukaemia.

The clinical utility of minimal residual disease (MRD) analysis in acute myeloid leukaemia (AML) is not yet defined. We analysed the prognostic impact of MRD level at complete remision after induction therapy using multiparameter flow cytometry in 306 non-APL AML patients. First, we validated the prognostic value of MRD-thresholds we have previously proposed (≥ 0.1%; ≥ 0.01-0.1%; and <0.01), with a 5-year RFS of 38%, 50% and 71%, respectively (p=0.002). Cytogenetics is the most relevant prognosis factor in AML, however intermediate risk cytogenetics represent a grey zone that require other biomarkers for risk stratification, and we show that MRD evaluation discriminate three prognostic subgroups (p=0.03). Also, MRD assessments yielded relevant information on favourable and adverse cytogenetics, since patients with favourable cytogenetics and high MRD levels have poor prognosis and patients with adverse cytogenetics but undetectable MRD overcomes the adverse prognosis. Interestingly, in patients with intermediate or high MRD levels, intensification with transplant improved the outcome as compared with chemotherapy, while the type of intensification therapy did not influenced the outcome of patients with low MRD levels. Multivariate analysis revealed age, MRD and cytogenetics as independent variables. Moreover, a scoring system, easy in clinical practice, was generated based on MRD level and cytogenetics.

[Bone marrow microenvironment in chronic myeloid leukemia: implications for disease physiopathology and response to treatment]. / Microambiente medular en la leucemia mieloide crónica: su relación con la enfermedad y la respuesta al tratamiento.

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm related to the presence of the BCR-ABL1 fusion gene, linked to t (9;22) (q34;q11). It is originated from an abnormal hematopoietic stem cell, which is characterized as its normal counterparts by long-term self-renewal and multi-lineage differentiation. Both leukemic and quiescent normal hematopoietic stem cells preferentially reside in the osteoblastic niche. Mesenchymal stromal cells (MSC) are located near them, playing a critical role in their regulation. Currently, with tyrosine kinase inhibitor (TKI) therapy, long term clinical responses are achieved in most CML cases. However, late treatment failures may be observed related to the persistence of leukemic stem cells. The interactions between the leukemic stem cell and the microenvironment may be responsible in part for these events. We review the interactions between the leukemic stem cell and BM stroma and its potential clinical and therapeutic implications.

[Sustained hematologic response in chronic eosinophilic leukemia with low dose imatinib. Report of one case]. / Leucemia eosinofílica crónica con respuesta hematológica sostenida tras tratamiento con bajas dosis de imatinib.

We report a 58 year-old-man without comorbid conditions, with a history of two months of weight loss, malaise and headache. His initial laboratory analysis showed leukocytosis of 16,100/mL with 65% eosinophils and an absolute eosinophil count of 10,465/mL. Both bone marrow biopsy and aspirate showed infiltration by mature appearing eosinophils. Treatment was started with hydroxyurea, associated with prednisone without satisfactory decrease in the eosinophil count. Polymerase chain reaction showed the presence of the gene fusion product FIP1L1/PDGFRA. Imatinib therapy was initiated, resulting in a rapid and progressive reduction in the absolute eosinophil count, with normalization at the second week of treatment. The incidence of the myeloproliferative variant causing hypereosinophilic syndrome is rare. However, the dramatic response to imatinib emphasizes the need to study the presence of the fusion product FIP1L1/PDGFRA in all patients with eosinophilia of unknown etiology.

Multiparameter flow cytometry for staging of solitary bone plasmacytoma: new criteria for risk of progression to myeloma.

Solitary plasmacytoma represents a heterogeneous group of patients; approximately half develop multiple myeloma (MM) in 2 or 3 years, whereas others remain disease-free at 10 years. By definition, these patients do not have morphologic bone marrow (BM) plasma cell (PC) infiltration. Here, we investigated whether sensitive BM evaluation of patients with solitary bone plasmacytoma (SBP; n = 35) and extramedullary plasmacytoma (EMP; n = 29) through multiparameter flow cytometry (MFC) would unravel the presence of clonal PCs in otherwise disease-free BM, and whether BM clonality predicted higher risk of progression. BM clonal PCs were detected in 17 of 35 SBP (49%) and 11 of 29 EMP (38%) patients. Seventy-one percent of flow-positive vs only 8% of flow-negative SBP patients evolved to MM (median time to progression of 26 months vs not reached; hazard ratio, 17.4; P < .001). No significant differences were observed among EMP cases. Our results highlight the importance of MFC for sensitive BM evaluation of SBP patients, to predict risk of developing treatment-requiring MM and to plan disease monitoring.

Microambiente medular en la leucemia mieloide crónica: su relación con la enfermedad y la respuesta al tratamiento / Bone marrow microenvironment in chronic myeloid leukemia: Implications for disease physiopathology and response to treatment

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm related to the presence of the BCR-ABL1 fusion gene, linked to t (9;22) (q34;q11). It is originated from an abnormal hematopoietic stem cell, which is characterized as its normal counterparts by long-term self-renewal and multi-lineage differentiation. Both leukemic and quiescent normal hematopoietic stem cells preferentially reside in the osteoblastic niche. Mesenchymal stromal cells (MSC) are located near them, playing a critical role in their regulation. Currently, with tyrosine kinase inhibitor (TKI) therapy, long term clinical responses are achieved in most CML cases. However, late treatment failures may be observed related to the persistence of leukemic stem cells. The interactions between the leukemic stem cell and the microenvironment may be responsible in part for these events. We review the interactions between the leukemic stem cell and BM stroma and its potential clinical and therapeutic implications.

Involvement of primary mesenchymal precursors and hematopoietic bone marrow cells from chronic myeloid leukemia patients by BCR-ABL1 fusion gene.

For decades now, it is well established that chronic myeloid leukemia (CML) is a hematopoietic stem cell(HPC) disorder. However, it remains to be determined whether BCR-ABL1 gene rearrangement occurs in a HPC or at an earlier stem cell and whether the degree of involvement of hematopoiesis by the BCR-ABL1 fusion gene relates to the response to therapy. Here, we have investigated by interphase fluorescence in situ hybridization (iFISH) the distribution of BCR-ABL1 fusion gene in FACS-sorted bone marrow (BM) populations of mesenchymal precursor cells (MPC) and other hematopoietic cell populations from 18 newly diagnosed CML patients. Overall, our results showed systematic involvement at relatively high percentages of BM maturing neutrophils (97%615%), basophils (95%612%), eosinophils (90%68%), CD341 precursors cells (90%67%),monocytes (84%630%), nucleated red blood cells (87%624%), and mast cells (77%633%). By contrast, MPC(30%634%), B-cells (15%627%), T-lymphocytes (50%626%), and NK-cells (35%634%) were involved at lower percentages. In 8/18 CML patients, 2 tumor BCR-ABL11 subclones were detected by iFISH. Of note, all tumor cell subclones were systematically detected in CD341 cells, whereas MPC were only involved by the ancestral tumor cell subclone. In summary, here we confirm the presence at diagnosis of the BCR-ABL1 fusion gene inMPC, CD341 precursors, and other different BM hematopoietic myeloid cell lineages from CML patients,including also in a significant fraction of cases, a smaller percentage of T, B, and NK lymphocytes.Interestingly, involvement of MPC was restricted to the ancestral BCR-ABL11 subclone.