Characterization of acute lymphoblastic leukemia subtypes in Brazilian patients

Immunophenotype of acute lymphoblastic leukemia in minorities- analysis from the SEER database

Acute Lymphocytic Leukemia (ALL) is a malignancy that originates from immature lymphoid cells and is clinically established with flow cytometry through disease-specific markers. Variation between ethnic groups is an epidemiological aspect of ALL. Higher incidence rates have been observed in Latin American patients and ALL in Latinos carries a dismal prognosis. The cell of origin in ALL is derived from immature cells of either the B or T lineage. Most reported data among Latinos either exclusively looks at B cell precursor ALL or do not distinguish between subtypes. We used the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) database to delineate the differences in incidence rates of B-ALL and T-ALL across ethnic groups in the United States. Data from SEER-18 was used to compare incidence rates of T-ALL and B-ALL. Due to the utilization of cytogenetics and subsequent changes in ICD coding over the years examined the most recent data reported from 2002 to 2017. We compared rates in Non-Hispanic Whites (NHWs), Latinos, Blacks and Asian-Pacific Islanders (API). Age-adjusted incidence rates per 100,000 person-years were calculated. The incidence rate of B-ALL in the Latino population was consistently higher than other race/ethnicities throughout the years, ranging from 1.0 per 100,000 in 2002 to 2.5 per 100,000 in 2017. Blacks had the lowest age adjusted incidence rate (AAIR) of B-ALL overall, with rates approximately one third of those found in Latinos and the highest AAIR of T-ALL with an AAIR of 0.5 per 100,000.

Gamma-Delta T-Cell Acute Lymphoblastic Leukemia/Lymphoma: Immunophenotype of Three Adult Cases

Gamma-delta (γδ) T-cell acute lymphoblastic leukemia/lymphoma (T-ALL) is not commonly observed in adult patients. We report three adult cases and describe their immunophenotypes. Two of these cases were diagnosed as γδ T-ALL; one was diagnosed as a mixture of T-ALL and T-cell non-Hodgkin lymphoma (T-NHL). We also discussed the differential diagnoses.

The emerging story of acute lymphoblastic leukemia among the Latin American population - biological and clinical implications

Higher incidence rates and poor outcomes have been reported among Latin American patients (Latinos) with acute lymphoblastic leukemia (ALL). Distinct patterns in recent genomic studies allude to a predisposing genetic component. In this review, we critically examine the increasing amount of empirical information on the epidemiology, outcomes and genomics of Latinos with ALL. We discuss the immense diversity within the Latino community and varying definitions of what is considered Latino, which pose an epidemiological challenge. Environmental factors have been evaluated as possible predisposing factors in the development of ALL but studies have produced conflicting results. In this review we describe chromosomal abnormalities and the specific genomic landscape in Latinos with ALL and their association with unfavorable prognosis, focusing on the higher frequency of Philadelphia chromosome-Like ALL. Recent data suggest an association between polymorphisms that are commonly found in indigenous Americans and high rates of ALL. The review compares the distribution of ALL throughout the various countries in Latin America in an attempt to shed some epidemiological light on the genetic ancestry of ALL. We additionally identify areas where research is warranted in efforts toward the advent of novel targeted agents that are relevant in improving outcomes within the Latino community.

Immunophenotypic characterization of acute leukemia at a public oncology reference center in Maranhão, northeastern Brazil

CONTEXT AND OBJECTIVES

The incidence of acute leukemia (AL) subtypes varies according to geographical distribution. The aim here was to determine the incidence of morphological and immunophenotypic AL subtypes in the state of Maranhão, Brazil, and to correlate the expression of aberrant phenotypes in children with acute lymphoblastic leukemia (ALL) with prognostic factors.

DESIGN AND SETTING

Single prospective cohort study at a public oncology reference center in Maranhão.

METHODS

Seventy AL cases were diagnosed between September 2008 and January 2010. For the diagnosis, complete blood cell counts, myelograms (at diagnosis and at the end of the induction phase), cytochemical analysis and immunophenotyping were performed.

RESULTS

Among adult patients (n = 22), the incidence of AL types was: ALL (22.7%) and acute myeloid leukemia (AML) (77.3%). The subtype AML M0 occurred most frequently (29.4%). In children (n = 48), the types were: AML (18.7%), most frequently subtype AML M4 (33.4%); biphenotypic acute leukemia (BAL) (4.2%); and ALL (77.1%), including the subtypes B-ALL (72.9%) and T-ALL (27.1%). Among the children with ALL, there were no statistically significant differences between patients with and without aberrant phenotypes, in relation to hematological parameters and treatment response.

CONCLUSION

This work demonstrates that the frequencies of AML M0 cases among adults and T-ALL cases among children in Maranhão were high. This suggests that there may be differences in AML subtype incidence, as seen with ALL subtypes, in different regions of Brazil. No association was found between the expression of aberrant phenotypes and prognostic factors, in children with ALL.

Implications of infectious diseases and the adrenal hypothesis for the etiology of childhood acute lymphoblastic leukemia

Acute leukemia is the most frequent cancer in children. Recently, a new hypothesis was proposed for the pathogenesis of childhood acute lymphoblastic leukemia (ALL). The so-called 'adrenal hypothesis' emphasized the role of endogenous cortisol in the etiology of B-cell precursor ALL. The incidence peak of ALL in children between 3 to 5 years of age has been well documented and is consistent with this view. The adrenal hypothesis proposes that the risk of childhood B-cell precursor ALL is reduced when early childhood infections induce qualitative and quantitative changes in the hypothalamus-pituitary-adrenal axis. It suggests that the increased plasma cortisol levels would be sufficient to eliminate all clonal leukemic cells originating during fetal life. Because Brazil is a continental and tropical country, the exposure to infections is diversified with endemic viral and regionally non-viral infections, with some characteristics that support the recent adrenal hypothesis. Here we discuss this new hypothesis in terms of data from epidemiological studies and the possible implications of the diversity of infections occurring in Brazilian children.

The role of micro-ribonucleic acids in normal hematopoiesis and leukemic T-lymphogenesis

Micro-ribonucleic acids (microRNAs) are small molecules containing 20-23 nucleotides. Despite their small size, it is likely that almost every cellular process is regulated by them. Moreover, aberrant microRNA expression has been involved in the development of various diseases, including cancer. Although many data are available about the role of microRNAs in various lymphoproliferative disorders, their impact on the development of acute lymphoblastic leukemia of T-cell progenitors is largely unknown. In this review, we present recent information about how specific microRNAs are expressed and regulated during malignant T-lymphopoiesis and about their role during normal hematopoiesis.

Fatores prognósticos em crianças e adolescentes com Leucemia Linfóide Aguda

OBJETIVOS: descrever características clínico-laboratoriais, determinar taxas de resposta ao tratamento e identificar fatores de risco que influenciaram na sobrevida de pacientes pediátricos com leucemia linfóide aguda (LLA). MÉTODOS: estudo retrospectivo do tipo série de casos com 108 pacientes de idade até 18 anos, admitidos para tratamento de LLA na Fundação de Hematologia e Hemoterapia de Pernambuco (HEMOPE), Brasil, de janeiro de 1993 a dezembro de 2001. As variáveis analisadas foram: sexo, idade, principais sintomas e sinais, leucometria, imunofenótipo e grupo de risco ao diagnóstico, taxas de remissão e recaída, óbito e sobrevida global, local de recaída e fatores de risco para a sobrevida. Medidas descritivas foram usadas para a análise estatística. O tempo de sobrevida dos pacientes foi estimado através da função de sobrevida de Kaplan-Meier e Log-Rank. O efeito de fatores de risco no tempo de sobrevida foi avaliado através do Modelo de Regressão de Cox. RESULTADOS: foi encontrada a relação masculino:feminino de 1,7:1, mediana de idade ao diagnóstico de oito anos, freqüência de queixas músculo-esqueléticas (51%), infiltração do sistema nervoso central (8%), LLA-Precursor B (81%) e LLA-T (19%). A distribuição dos grupos correspondeu a Risco Básico Verdadeiro (12%), Risco Básico (21%) e Alto Risco (67%). As principais taxas foram: remissão (86%), óbitos na indução (5,5%), recaída (24%) e sobrevida global (62,5%). CONCLUSÕES: a variável de impacto na sobrevida foi a leucometria. A taxa de sobrevida global foi influenciada pela freqüência elevada de pacientes considerados de alto risco.

Thiopurine methyltransferase polymorphisms in a Brazilian population

Thiopurine methyltransferase (TPMT) catalyses the S-methylation of thiopurine drugs. Low-activity phenotypes are correlated with several mutations in the TPMT gene. Polymorphisms of TPMT have been reported for Caucasians, African-Americans and Asians. Since ethnic differences have been demonstrated worldwide, it remains to be elucidated in Brazil. The Brazilian population is the result of five centuries of interethnic crosses between peoples from almost all continents as well as autochthonous Amerindians, all forming the fifth largest and one of the most heterogeneous populations in the world. The frequency of six allelic variants of the TPMT gene, *2 (G238C) (2.2%), *3A (G460A and A719G) (1.5%), *3B (G460A) (0.2%), *3C (A719G) (1.0%), *5 (0%) and *6 (0%) were determined in Brazilian subjects using polymerase chain reaction (PCR)-RFLP and allele-specific PCR-based assays. This study provides the first analysis of TPMT mutant allele frequency in a sample of the Brazilian population.

Direct association of socio-economic status with T-cell acute lymphoblastic leukaemia in children

Lymphoblasts from 186 consecutive untreated children <18 years were analysed by flow cytometry in Brazil. Socio-economic status was defined by family income; undernourishment by height and weight for age standardised z scores below -1.28. The observed frequencies were precursor-B (pre-B) CD10 positive acute lymphoblastic leukaemia (ALL) (CD10+) 65%, pre-B CD10 negative (CD10-) 13%, and T-ALL 18%. The typical incidence peak at age 2-5 years was observed among the CD10 positive cases. Nutritional variables were not associated with immunophenotypes. Low monthly per capita income was associated with T-immunophenotype (P=0.024). In conclusion, a direct association between unfavourable socio-economic status and the T-phenotype indicates a potential role of socio-economic factors on the genesis of ALL in children, thus confirming indirect data of the international literature.

The Brazilian Pediatric Myelodysplastic Cooperative Group strategies: are they relevant to improve educational approach and correct diagnosis?

Brazil is a wide country with huge contrasts. Its peculiarities can highlight environmental factors that could influence the frequencies of different cancers. The standard treatment and results achieved from several different areas of the country may not be found in others. The establishment of a national cooperative group has the potential to improve outcomes. The The Brazilian Cooperative Group on Pediatric Patients with Myelodysplastic Syndrome (BCG-MDS-PED) was first organized in January 1997 as a working group of hematologists, pediatric oncologists, pediatric-hematologists, molecular biologists and other professionals in order to study pediatric (age <18 years) MDS. Six distinct subcommittees constituted with members from several universities: cytology, histopathology, clinical, cytogenetics, molecular biology and epidemiology. The goals of the BCG-MDS-PED were: (i) to offer support for diagnosis and orientation for treatment; (ii) educational support for the colleagues all over the country and (iii) research on pathogenesis and new approaches for pediatric MDS patients. There are socio-economical differences among the five regions of the country. The BCG-MDS-PED believes that it is absolutely necessary to study the clinical, cellular, molecular and epidemiological aspects of MDS, taking in account these peculiar differences among populations and regions. Since 1997, 114 pediatric cases were referred to the BCG-MDS-PED from 21 centres. Seven Brazilian states have sent cases to the group, 31 patients were referred from universities, 73 patients from pediatric oncology units (foundations ) and 10 patients came from private clinics. Some of these patients have been followed up and/or treated by the physician who referred them to the BCG-MDS-PED for confirmation of the initial diagnosis. The majority of these physicians have required orientation on diagnostic and treatment issues, as well as to complete cytogenetic and molecular studies. From these 114 patients, 64 patients were confirmed as MDS. We believe that, the more numerous the MDS-studied cases, the more experienced will be the referee group on clinical and laboratory features on childhood MDS in Brazil.

Immunophenotype of normal and leukemic bone marrow B-precursors in a Brazilian population. A comparative analysis by quantitative fluorescence cytometry

The distinction between normal and leukemic bone marrow (BM) B-precursors is essential for the diagnosis and treatment monitoring of acute lymphoblastic leukemia (ALL). In order to evaluate the potential use of quantitative fluorescence cytometry (QFC) for this distinction, we studied 21 normal individuals and 40 patients with CD10+ ALL. We characterized the age-related changes of the CD10, CD19, TdT, CD34 and CD79a densities in normal and leukemic BM. Compared to normal adults, the B-precursors from normal children expressed significantly lower values of CD34-specific antibody binding capacity (SABC) (median value of 86.6 vs 160.2 arbitrary units (a.u.) in children and adults, respectively). No significant age-related difference was observed in the expression of the other markers in the normal BM, or in any of the markers in the leukemic BM. Based on the literature, we set the cut-off value for the normal CD10 expression at 45 x 10(3) a.u. for both age groups. For the remaining markers we established the cut-off values based on the minimum-maximum values in the normal BM in each age group. The expression of CD10 was higher than the cut-off in 30 ALL cases and in 18 of them there was a concomitant aberrant expression of other markers. In 9 of the 10 CD10+ ALL with normal CD10 SABC values, the expression of at least one other marker was aberrant. In conclusion, the distinction between normal and leukemic cells by QFC was possible in 38/40 CD10+ ALL cases.

Applications of flow cytometry to hematopoietic stem cell transplantation

Applications of flow cytometry to clinical and experimental hematopoietic stem cell transplantation (HSCT) are discussed in this review covering the following topics: diagnosis and classification of lymphohematologic disorders, quantitation of hematopoietic progenitors in the graft, lymphohematopoietic reconstitution following HSCT and animal models of human HSCT. At the end, the utilization of flow cytometry in clinical HSCT by Brazilian transplant centers is briefly reviewed.

CD10 and CD19 fluorescence intensity of B-cell precursors in normal and leukemic bone marrow. Clinical characterization of CD10(+strong) and CD10(+weak) common acute lymphoblastic leukemia

In order to assess the age-related changes in CD10 and CD19 fluorescence intensity (FI) the present study analyzed by flow cytometry 56 sternal biopsies from 'normal' infants, children and adults undergoing cardiac surgery. The CD10(+weak) subset was predominant in all age groups, representing approximately 50% of the bone marrow (BM) lymphoid cells in children younger than 4 years. Both CD10+ subsets significantly decreased with age but their ratio did not differ significantly. Moreover, the intensity of CD10 and CD19 fluorescence in the strong and weak subsets did not vary with age. The CD19 intensity was significantly higher in CD10(+weak) than in CD10(+strong) cells. In addition, we classified as CD10(+weak) or CD10(+strong) the leukemic cells from BM aspirates of 117 patients with common acute lymphoblastic leukemia (cALL) (78 children and 39 adults). A higher frequency of cases expressing the CD19+ CD10(+strong) phenotype was observed both in children and adults. Children of the CD10(+weak) group tended to be older than those of the CD10(+strong) group (median = 7 vs. 4 years, P = 0.07), and presented a significantly higher frequency of splenomegaly (93.7 vs. 55%, P = 0.04), which was massive in about 60% of these cases. Among adults, a significantly higher frequency of cases expressing the CD10(+weak) phenotype was observed in females. No other clinical or biological difference was detected between the two groups either for children or adults. Concerning the treatment outcome, we did not observe significant differences in complete remission rate (CRR) or in disease free survival (DFS) among the 32 children and 28 adults analyzed. Finally, we compared the CD10 and CD19 intensity in normal and leukemic BM. Overexpression of either or both antigens in leukemic cells was observed in 42.4% of the cALL cases. In these cases, using cut off values of 110 afu for the CD10 FI and of 100 afu for the CD19 FI, the detection of leukemic cells was possible at levels of 0.2% based on CD10 analysis, of 0.6% based on CD19, and 0.02% when both antigens were overexpressed. In conclusion, we demonstrated that the heterogeneity of CD10 and CD19 fluorescence intensity is of no clinical relevance in cALL, although its study may be helpful for the diagnosis and the detection of minimal residual disease.