Immunophenotypic markers for the evaluation of minimal/measurable residual disease in acute megakaryoblastic leukemia.

Acute megakaryoblastic leukemia is characterized by heterogeneous biology and clinical behavior. Immunophenotypic characteristics include the expression of megakaryocytic differentiation markers (e.g. CD41, CD42a, CD42b, CD61) associated with immaturity markers (CD34, CD117, HLA-DR) and myeloid markers (e.g. CD13, CD33) and even with lymphoid cross-lineage markers (e.g. CD7, CD56). Although the diagnostic immunophenotype has already been well described, given the rarity of the disease, its immunophenotypic heterogeneity and post-therapeutic instability, there is no consensus on the combination of monoclonal markers to detect minimal/measurable residual disease (MRD). Currently, MRD is an important tool for assessing treatment efficacy and prognostic risk. In this study, we evaluated the immunophenotypic profile of MRD in a retrospective cohort of patients diagnosed with acute megakaryoblastic leukemia, to identify which markers, positive or negative, were more stable after treatment and which could be useful for MRD evaluation. The expression profile of each marker was evaluated in sequential MRD samples. In conclusion, the markers evaluated in this study can be combined in an MRD immunophenotypic panel to investigate for megakaryoblastic leukemia. Although this study is retrospective and some data are missing, the information obtained may contribute to prospective studies to validate more specific strategies in the detection of MRD in acute megakaryoblastic leukemia.

Minimal residual disease assessment in acute lymphoblastic leukemia by 4-color flow cytometry: Recommendations from the MRD Working Group of the Brazilian Society of Bone Marrow Transplantation.

INTRODUCTION: The minimal residual disease (MRD) status plays a crucial role in the treatment of acute lymphoblastic leukemia (ALL) and is currently used in most therapeutic protocols to guide the appropriate therapeutic decision. Therefore, it is imperative that laboratories offer accurate and reliable results through well standardized technical processes by establishing rigorous operating procedures. METHOD: Our goal is to propose a monoclonal antibody (MoAb) panel for MRD detection in ALL and provide recommendations intended for flow cytometry laboratories that work on 4-color flow cytometry platforms. RESULTS AND CONCLUSION: The document includes pre-analytical and analytical procedures, quality control assurance, technical procedures, as well as the information that needs to be included in the reports for clinicians.

Updating recommendations of the Brazilian Group of Flow Cytometry (GBCFLUX) for diagnosis of acute leukemias using four-color flow cytometry panels.

INTRODUCTION: Flow cytometry has become an increasingly important tool in the clinical laboratory for the diagnosis and monitoring of many hematopoietic neoplasms. This method is ideal for immunophenotypic identification of cellular subpopulations in complex samples, such as bone marrow and peripheral blood. In general, 4-color panels appear to be adequate, depending on the assay. In acute leukemias (ALs), it is necessary identify and characterize the population of abnormal cells in order to recognize the compromised lineage and classify leukemia according to the WHO criteria. Although the use of eight- to ten-color immunophenotyping panels is wellestablished, many laboratories do not have access to this technology. OBJECTIVE AND METHOD: In 2015, the Brazilian Group of Flow Cytometry (Grupo Brasileiro de Citometria de Fluxo, GBCFLUX) proposed antibody panels designed to allow the precise diagnosis and characterization of AL within available resources. As many Brazilian flow cytometry laboratories use four-color immunophenotyping, the GBCFLUX has updated that document, according to current leukemia knowledge and after a forum of discussion and validation of antibody panels. RESULTS: Recommendations for morphological analysis of bone marrow smears and performing screening panel for lineage (s) identification of AL were maintained from the previous publication. The lineage-oriented proposed panels for B and T cell acute lymphoblastic leukemia (ALL) and for acute myeloid leukemia (AML) were constructed for an appropriate leukemia classification. CONCLUSION: Three levels of recommendations (i.e., mandatory, recommended, and optional) were established to enable an accurate diagnosis with some flexibility, considering local laboratory resources and patient-specific needs.

Minimal residual disease assessment in acute lymphoblastic leukemia by 4-color flow cytometry: Recommendations from the MRD Working Group of the Brazilian Society of Bone Marrow Transplantation

Abstract Introduction: The minimal residual disease (MRD) status plays a crucial role in the treatment of acute lymphoblastic leukemia (ALL) and is currently used in most therapeutic protocols to guide the appropriate therapeutic decision. Therefore, it is imperative that laboratories offer accurate and reliable results through well standardized technical processes by establishing rigorous operating procedures. Method: Our goal is to propose a monoclonal antibody (MoAb) panel for MRD detection in ALL and provide recommendations intended for flow cytometry laboratories that work on 4-color flow cytometry platforms. Results and conclusion: The document includes pre-analytical and analytical procedures, quality control assurance, technical procedures, as well as the information that needs to be included in the reports for clinicians.

Updating recommendations of the Brazilian Group of Flow Cytometry (GBCFLUX) for diagnosis of acute leukemias using four-color flow cytometry panels

ABSTRACT Introduction: Flow cytometry has become an increasingly important tool in the clinical laboratory for the diagnosis and monitoring of many hematopoietic neoplasms. This method is ideal for immunophenotypic identification of cellular subpopulations in complex samples, such as bone marrow and peripheral blood. In general, 4-color panels appear to be adequate, depending on the assay. In acute leukemias (ALs), it is necessary identify and characterize the population of abnormal cells in order to recognize the compromised lineage and classify leukemia according to the WHO criteria. Although the use of eightto ten-color immunophenotyping panels is wellestablished, many laboratories do not have access to this technology. Objective and Method: In 2015, the Brazilian Group of Flow Cytometry (Grupo Brasileiro de Citometria de Fluxo, GBCFLUX) proposed antibody panels designed to allow the precise diagnosis and characterization of AL within available resources. As many Brazilian flow cytometry laboratories use four-color immunophenotyping, the GBCFLUX has updated that document, according to current leukemia knowledge and after a forum of discussion and validation of antibody panels. Results: Recommendations for morphological analysis of bone marrow smears and performing screening panel for lineage (s) identification of AL were maintained from the previous publication. The lineage-oriented proposed panels for B and T cell acute lymphoblastic leukemia (ALL) and for acute myeloid leukemia (AML) were constructed for an appropriate leukemia classification. Conclusion: Three levels of recommendations (i.e., mandatory, recommended, and optional) were established to enable an accurate diagnosis with some flexibility, considering local laboratory resources and patient-specific needs.