Spectrum and Immunophenotypic Profile of Acute Leukemia: A Tertiary Center Flow Cytometry Experience

Flow cytometry in acute myeloid leukemia and detection of minimal residual disease

Acute myeloid leukemia (AML) is a common type of acute leukemia (AL), belonging to malignant tumors of the hematopoietic system with the characteristics of rapid disease development, control with extreme difficulties, easy recurrence, poor prognosis, and incidence rate increasing with age. The traditionally diagnostic standard of French American British (FAB), being based on the morphological examination with high human subjectivity, can no longer meet the demand of clinical diagnosis and treatment of AML. Requirements of objective accuracy and low-dose sample, have become the indispensable method for AML diagnosis and monitoring prognosis. Flow cytometry is a modern technology that can quickly and accurately detect the series, antigen distribution, differentiation stage of AML cells, minimal residual lesions after AML therapy, so as to provide the great significance in guiding clinical diagnosis, hierarchical treatment, and prognosis judgement. This article will systematically elaborate on the application of flow cytometry in the diagnosis and classification of AML, and the detection of minimal residual lesions, thereby providing reference significance for dynamic monitoring and prognostic observation of AML with different immune subtypes of FAB.

Immunophenotypic Characteristics and Cytogenetic Analysis of Adolescent and Young Adult B-Cell Acute Lymphoblastic Leukemia: Correlations With Clinicopathological Parameters

Introduction Acute lymphoblastic leukemia (ALL) has suboptimal survival rates for adolescents and young adults (AYA) as compared to children. Very limited studies have been conducted on AYA patients in India. This study aimed to identify the cytogenetic and immunophenotype characteristics of B-cell ALL (B-ALL) in AYA patients and determine its correlation with clinicopathological parameters in the Southern India region. Method The study was a prospective study conducted for three years, from June 2019 to May 2022, in India. Newly diagnosed 90 patients with AYA (13-40 years) ALL were recruited. A B-ALL diagnosis was made based on morphology with cytochemical stains and immunophenotype by flow cytometry (FCM). Cytogenetic analysis was also performed using karyotyping and fluorescent in situ hybridization to identify chromosomal aberrations. The cytogenetics results were correlated with immunophenotyping and clinicopathological characteristics. Variables were analyzed using the Mann-Whitney U test and Chi-square test using IBM SPSS Statistics for Windows, Version 20.0 (Released 2011; IBM Corp., Armonk, NY, USA). Results The mean age was 22.68 ± 8.06 years. It was observed that the most common structural chromosomal abnormality for AYA was t(9;22) in 14 (15%) cases, followed by 6q deletions in seven (8%) cases, t(1;19) in four (4%) cases, and t(12;17) and t(6;14) in two (2%) cases each. In addition, t(3;12), t(2;11), t(12;21), t(1;9), t(2;12), and t(X;10) were found in one (1%) case each. The most common numerical abnormality was hyperdiploidy (15; 17%), followed by hypodiploidy (10; 11%). Further, myeloid antigen expression of CD33 was the most common aberrantly expressed marker found in 20 (28%) cases, followed by CD15 in three cases (5%), CD13 in three (4%) cases, and CD11b in two (3%) cases. It was also observed that in Ph+ve cases, CD33 and CD13 were most commonly expressed in three (33%) and two (17%) cases, respectively. In contrast, in Ph-ve patients, their expressions were lesser at 17 (27%) and one (2%) cases, respectively. In addition, leukemia-associated immunophenotype pattern (LAIP) markers CD44 6 (86%) and CD123 5 (55%) were also found to be significantly associated with Ph+ve, whereas their values in the Ph-ve group were lesser at 25 (42%) and 9 (17%), respectively. Our data also showed that older age wassignificantly associated with Ph+ve with a median age of 30 years (p = 0.012). In comparison, the median age of Ph-ve was only 21 years. Conclusion Our study established that the incidence of cytogenetic abnormalities for AYA was consistent with previously reported data. This study reaffirms that Ph+ve cases have significant associations with MyAg (CD13), LAIP (CD123 and CD44), and older age for the South Indian population.

CD146 Molecule Expression in B Cells Acute Lymphoblastic Leukemia (B-ALLs): A Flow-Cytometric Marker for an Accurate Diagnostic Workup

Background

B-lineage acute lymphoblastic leukemias (B-ALL) harboring the t(9;22)(q34;q11)/BCR::ABL1 rearrangement represent a category with previously dismal prognosis whose management and outcome dramatically changed thanks to the use of tyrosine kinase inhibitors (TKIs) usage and more recently full chemo-free approaches. The prompt identification of these cases represents an important clinical need.

Objectives

We sought to identify an optimized cytofluorimetric diagnostic panel to predict the presence of Philadelphia chromosome (Ph) in B-ALL cases by the introduction of CD146 in our multiparametric flow cytometry (MFC) panels.

Methods

We prospectively evaluated a total of 245 cases of newly diagnosed B-ALLs with a CD146 positivity threshold >10% referred to the Division of Hematology of 'Sapienza' University of Rome. We compared the results of CD146 expression percentage and its mean fluorescence intensity (MFI) between Ph+ ALLs, Ph-like ALLs, and molecularly negative ALLs.

Results

Seventy-nine of the 245 B-ALL cases (32%) did not present mutations at molecular testing, with 144/245 (59%) resulting in Ph+ ALL and 19/245 (8%) Ph-like ALLs. Comparing the 3 groups, we found that Ph+ B-ALLs were characterized by higher expression percentage of myeloid markers such as CD13, CD33, and CD66c and low expression of CD38; Ph+ B-ALL showed a higher CD146 expression percentage and MFI when compared with both molecular negative B-ALL and Ph-like ALLs; neither the mean percentage of CD146 expression neither CD146 MFI were statically different between molecular negative B-ALL and Ph-like ALLs.

Conclusions

Our data demonstrate the association between CD146 expression and Ph+ ALLs. CD146, along with myeloid markers, may help to identify a distinctive immunophenotypic pattern, useful for rapid identification in the diagnostic routine of this subtype of B-ALLs that benefits from a specific therapeutic approach.

Spontaneous Remission of Blastic Plasmacytoid Dendritic Cell Neoplasm: A Case Report

Spontaneous remissions (SRs) in blastic plasmacytoid dendritic cell neoplasms (BPDCNs) are infrequent, poorly documented, and transient. We report a 40-year-old man presenting with bycitopenia and soft tissue infection. The bone marrow exhibited 3% abnormal cells. Immunophenotyping of these cells revealed the antigens CD45+ (dim), CD34+, CD117+, CD123+ (bright), HLA-DR+ (bimodal), CD56+ (bright), CD33+, CD13+, CD2+, and CD22+ (dim) and the partial expression of the CD10+, CD36+, and CD7+ antigens. All other myeloid, monocytic, and lymphoid antigens were negative. Genetic studies showed a complex karyotype and mutations in the TP53R337C and KRASG12D genes. On hospital admission, the patient showed a subcutaneous nodule on the right hand and left lower limb. Flow cytometry multiparameter (FCM) analysis showed the presence of 29% abnormal cells with the previously described immunophenotype. The patient was diagnosed with BPDCN. The patient was treated with broad-spectrum antibiotics for soft tissue infection, which delayed therapy for BPDCN. No steroids or chemotherapeutic or hypomethylating agents were administered. His blood cell counts improved and skin lesions disappeared, until the patient relapsed five months after achieving spontaneous remission. About 60% of abnormal cells were identified. No changes in immunophenotype or the results of genetic studies were observed. The patient underwent a HyperCVAD chemotherapy regimen for six cycles. Consolidation therapy was performed via allogeneic bone marrow transplantation with an HLA-unrelated donor. One year after the bone marrow transplant, the patient died due to the progression of his underlying disease, coinciding with a respiratory infection caused by SARS-CoV-2. In the available literature, SRs are often linked to infections or other stimulators of the immune system, suggesting that powerful immune activation could play a role in controlling the leukemic clone. Nevertheless, the underlying mechanism of this phenomenon is not clearly understood. We hypothesize that the immune system would force the leukemic stem cell (LSC) to undergo a state of quiescence. This loss of replication causes the LSC progeny to die off, resulting in the SR of BPDCN.

Frequency and Prognostic Impact of Aberrant Antigens Expression among Egyptian Adult Acute Leukemia

OBJECTIVE

Aberrant antigen expression was reported to be due to genetic and epigenetic dysregulation. This study aimed to address aberrant antigen expression and its link to poor prognostic genetic markers in acute leukemia patients.

METHODS

This study included 432 newly diagnosed acute leukemia patients (AML, B-ALL). For all included patients blast cells expression for line assignment CD33 CD13 on B-All and CD7 on cytogenetically normal-AML blasts was assessed by flow cytometry in parallel to FLT3 and Philadelphia and philadelphia like chromosome in B-ALL.

RESULTS

From the total 432 cases of acute leukemia, the most frequent aberrant antigen expressed in B acute lymphoid leukemia (ALL) was CD33 (23.3%) followed by CD13(16.7%); while the most frequent one in AML was CD7 (16.7%). Aberrant myeloid phenotype in B-ALL was associated with lower mean total leukocytes count (TLC), low platelets count, positive Philadelphia like chromosome, shorter overall survival compared to the B-ALL without. Aberrant lymphoid phenotype (CD7) in AML was associated with a higher platelets count, FLT3 mutation, shorter disease-free and overall survival compared to those patients without.

CONCLUSION

CD7 aberrant antigen expression is frequently detected in patients with CN-AML and frequently associated with FLT3 mutation. While in patients with B-ALL the most frequently detected ones are CD33 and CD13 which are frequently associated with Philadelphia like chromosome.

Hematological, clinical, immunophenotypic characterization, and treatment outcomes of prognostically significant genetic subtypes of B-lineage acute lymphoblastic leukemia: A report of 1021 patients from India

BACKGROUND

The published literature on hematological, clinical, flowcytometric-immunophenotyping, and minimal residual disease outcomes of the prognostically important genetic subtypes of acute lymphoblastic leukemia (ALL) is scarce from low-income countries. For newer classifications such as BCR::ABL1-like ALLs, the scarcity of patient-level data is even more pronounced.

METHODS

The authors performed comprehensive detection of recurrent gene fusions and BCR::ABL1-like ALL cases followed by immunophenotypic profiling and obtained clinical outcome parameters for a large cohort (n = 1021) of patients from India. This cohort included a significant number of patients with BCR::ABL1-like ALL subtype and other genetic subtypes of ALL.

RESULTS

Patients with BCR::ABL1-positive and BCR::ABL1-like ALL were significantly older, had male preponderance, and expressed a higher white blood cell count than BCR::ABL1-negative cases (p < .05). Logistic regression modeling of B-lineage-ALL (B-ALL) subtypes revealed that cluster of differentiation (CD)36 is a strong statistically significant predictive marker of BCR::ABL1-like ALL (p < .05). Furthermore, patients with BCR::ABL1-like ALLs show a significantly higher frequency of CD36 expression compared to BCR::ABL1-negative ALLs (p < .05). In terms of clinical symptoms, lymphadenopathy is a strong statistically significant predictive marker in BCR::ABL1-like ALLs compared to BCR::ABL1-negative ALL cases (p < .05). In terms of treatment outcomes, minimal residual disease (MRD) positivity in BCR::ABL1-positive ALL cases were statistically significant (p < .05), and BCR::ABL1-like ALL cases had high MRD-positivity as compared to BCR::ABL1-negative ALL cases but did not show statistical significance.

CONCLUSIONS

The findings evince the use of novel therapies and personalized treatment regimens to improve the overall survival of the newer incorporated entities in B-ALLs. This is the first report characterizing the hematological, clinical, flowcytometric-immunophenotyping, and minimal residual disease outcomes of the prognostically significant subtypes of ALLs in patients from India.

PLAIN LANGUAGE SUMMARY

Characterizing the hematological, clinical, flowcytometric-immunophenotyping, and minimal residual disease outcomes of the prognostically significant subtypes (n = 1021) of acute lymphoblastic leukemia (ALLs) in patients from India. We have made two independent logistic regression models of cluster of differentiation (CD) markers and clinical symptoms to differentiate prognostically significant subtypes of ALLs. Logistic regression analysis of CD markers revealed CD36 as a strong predictor in BCR::ABL1-like ALL cases compared to BCR::ABL1-negative ALL cases. Logistic regression analysis of clinical symptoms revealed lymphadenopathy significantly predicts BCR::ABL1-like ALLs (p < .05). In terms of treatment outcomes, BCR::ABL1-positive ALL had statistically significant minimal residual disease (MRD) (p < .05), and BCR::ABL1-like ALL cases had high MRD-positivity but did not show statistical significance as compared to BCR::ABL1-negative ALLs.

Control of acute myeloid leukemia by a trifunctional NKp46-CD16a-NK cell engager targeting CD123

CD123, the alpha chain of the IL-3 receptor, is an attractive target for acute myeloid leukemia (AML) treatment. However, cytotoxic antibodies or T cell engagers targeting CD123 had insufficient efficacy or safety in clinical trials. We show that expression of CD64, the high-affinity receptor for human IgG, on AML blasts confers resistance to anti-CD123 antibody-dependent cell cytotoxicity (ADCC) in vitro. We engineer a trifunctional natural killer cell engager (NKCE) that targets CD123 on AML blasts and NKp46 and CD16a on NK cells (CD123-NKCE). CD123-NKCE has potent antitumor activity against primary AML blasts regardless of CD64 expression and induces NK cell activation and cytokine secretion only in the presence of AML cells. Its antitumor activity in a mouse CD123+ tumor model exceeds that of the benchmark ADCC-enhanced antibody. In nonhuman primates, it had prolonged pharmacodynamic effects, depleting CD123+ cells for more than 10 days with no signs of toxicity and very low inflammatory cytokine induction over a large dose range. These results support clinical development of CD123-NKCE.

Immunophenotypic characterization of acute leukemias in Bahia, Brazil

OBJECTIVE

To characterize the immunophenotypic profile of acute leukemias in the population of the state of Bahia, Brazil.

METHODS

This is a descriptive, retrospective study. From 2014 to 2018, 796 new cases of acute leukemia were evaluated. The data were obtained from analysis of reports and records of tests performed by flow cytometry immunophenotyping. All individuals of all age groups diagnosed as acute lymphoblastic leukemia or acute myeloid leukemia were included in the study. Demographic variables and expression of leukemia antigens were evaluated.

RESULTS

Most cases were diagnosed as acute myeloid leukemia and 42.7% as acute lymphoblastic leukemia. Significant differences were found in expression of markers in acute leukemias when age groups were compared, as well as in demographic characteristics. B-cell acute lymphoblastic leukemia was more prevalent than cases of T-cell origin. Assessing the aberrant markers in acute myeloid leukemias, the non-acute promyelocytic leukemia group presented expression of CD7 and CD56 as the most frequent ones. In B-cell acute lymphoblastic leukemia, the most frequent aberrant markers were CD66c, CD13 and CD33.

CONCLUSION

Significant differences were found as to several antigens when comparing adults and children, and these findings may contribute to future studies correlating the phenotypic profile to genetic characteristics and therapeutic response, including specific antigen therapies, which may be better targeted.

The Frequency of Aberrant CD7 Antigen Expression in Acute Myeloid Leukaemia Patients

Background

Aberrant phenotype expression in acute myeloid leukemia (AML) may be due to genetic defects and is associated with a poor prognosis. CD7 is the first T-cell-associated antigen to be expressed during T-lymphocyte maturation. Aberrant expression of CD7 in AML influences clinical response, remission rate, and overall survival in these patients.

Objective

To determine the frequency of aberrant CD7 expression in patients with AML.

Materials and methods

This cross-sectional study was performed over a period of 12 months from July 2020 to June 2021 in the Hematology Department, Chughtai Lab, Lahore. This study included 120 patients who were newly diagnosed with AML. The following tests were performed for included patients: complete blood count (CBC), peripheral blood smear analysis, and flow cytometric analysis using a blood sample or bone marrow aspirate. Blast cells were analyzed for aberrant CD7 expression. Calculation of the sample size was performed by using the Select Statistics calculator. All statistical analyses were performed using SPSS ver. 23 software (IBM Corp., Armonk, NY). Data were expressed as frequencies, means ± standard deviation (SD), and percentages.

Results

Of 120 patients newly diagnosed with AML, the CD7 antigen was aberrantly expressed in 36 cases (30%). Of these patients, the AML2 subtype was the most common type of AML with aberrant CD7 expression, followed by AML M4, AML M1, M3, AML M5, and AML M0, respectively.

Conclusion

In our study, aberrant CD7 expression occurred at a high frequency in acute myeloid leukemia. Thus, this marker should be added to the current flow cytometry panels.

Immunophenotypic characteristics of T lineage acute lymphoblastic leukemia: absence of immaturity markers-TdT, CD34 and HLADR is not uncommon

INTRODUCTION

T ALL may show variable morphological features and immunophenotypic analysis for characterisation of immature nature of these cells is needed to establish a diagnosis and distinguish from reactive conditions and mature T cell leukemias. Sometimes immaturity markers-CD34, TdT and HLA DR may not be expressed by blasts. The aim of the present study was to analyse immunophenotype of T ALLs especially with respect to absence of immaturity markers.

METHODS

Thirty-eight cases of T ALL diagnosed over a period of two and half years were analysed retrospectively with respect to clinical features, haematological features and flow cytometric immunophenotyping for T, B, Myeloid and immaturity markers. Student's T-test was used for comparing quantitative data and Chi-square test/Fishers exact T-test for qualitative variables. P value less than 0.05 was considered significant.

RESULTS

The most common T-lineage marker expressed was cCD3 and CD7 which were expressed in 100% cases followed by CD5 in 86.8% cases. The most common immaturity marker expressed was TdT (39.5% cases) followed by CD34 (34.2% cases). Thirteen cases (34.2%) were negative for all three of the immaturity markers i.e. TdT-/CD34-/HLADR. Absence of CD34 was associated with absence of expression of HLA DR (P<0.05) and aberrant expression of B lineage markers (P<0.05).

CONCLUSION

T-ALL is a rare and aggressive disease. Many cases lack immaturity markers viz, TdT, CD34 and HLADR. In such cases a comprehensive approach taking into account the clinical presentation, cytomorphology and immunophenotyping is diagnostic in experienced hands. Further, molecular studies may be needed to aid diagnosis.

Immunophenotypic challenges in diagnosis of CD79a negativity in a patient with B acute lymphoblastic leukemia harboring intrachromosomal amplification of chromosome 21: a case report

BACKGROUND

Being expressed in all stages of B-cell development and having a significant value on the European Group for the Immunological Characterization of Acute Leukemias scoring system, CD79a is considered as an excellent pan-marker for lineage assignment of B cells by flow cytometry. Therefore, any lack or decrease in CD79a expression makes the diagnosis of B acute lymphoblastic leukemia cases very challenging, especially in developing country laboratories where flow cytometry analyses are not always available and, when they are, they are limited in the number of markers used for lineage assignment. Since this case is potentially interesting, we report a B acute lymphoblastic leukemia case with a lack of expression CD79a associated with intrachromosomal amplification of chromosome 21 genetic abnormality. We further discuss the practical challenges in the diagnosis of this case.

CASE PRESENTATION

We present the case of an 8-year-old Caucasian boy from eastern Morocco who was initially hospitalized for a hemorrhagic syndrome. Peripheral blood smear examination showed a significant number of blasts suggesting acute leukemia. Bone marrow was studied for morphology, cytochemistry, immunophenotyping, and cytogenetics. Flow cytometry analyses showed expression of CD19, CD22, CD10, CD34, and HLA-DR markers by leukemic blasts. The expression of CD79a, which was checked with two different monoclonal antibodies, confirms that this marker was severely decreased in this case. Cytogenetic study performed by fluorescence in situ hybridization revealed the presence of intrachromosomal amplification of chromosome 21, a cytogenetic abnormality that is specific for B acute lymphoblastic leukemia.

CONCLUSION

CD79a is one of the critical markers in the assignment of B acute lymphoblastic leukemia. In our case, we were lucky enough to be assisted by a few other markers of the B lineage that were positive in this case. Also, we mention the importance of proceeding to cytogenetic study, which in our case helped us to confirm the diagnosis made by flow cytometry by highlighting a cytogenetic abnormality that is specific to B acute lymphoblastic leukemia.

Characterization of the immunophenotypic aberrancies with respect to common fusion transcripts in B-cell precursor acute lymphoblastic leukaemia - a report of 986 Indian patients

Objective:

Based on the immunophenotype, acute lymphoblastic leukemia (ALL) can be categorized into B-cell or T-cell lineages. B-cell precursor ALL (BCP-ALL) cases show various genetic/molecular abnormalities, and varying frequencies of chimeric fusion transcripts in BCP-ALL cases are reported from different parts of the world. We studied the immunophenotypic aberrancy profiles of a large number of BCP-ALL cases with respect to various common chimeric fusion transcripts.

Materials and Methods:

Flow cytometric immunophenotyping and multiplex reverse-transcription polymerase chain reaction assays were performed for 986 BCP-ALL cases.

Results:

Among 986 BCP-ALL cases, the incidence of various fusion transcripts was 38.36% in adult cases and 20.68% in pediatric cases. Adult BCP-ALL patients with t(9;22)(BCR-ABL1) fusion transcripts and expression of aberrant myeloid markers were significantly older at presentation (p=0.0218) with male preponderance (p=0.0246) compared to those without aberrant myeloid expression. In pediatric patients with the t(12;21)(ETV6-RUNX1) chimeric fusion transcript, aberrant expression of CD13 was observed in 39.13%, CD33 in 36.95%, and CD117 in 8.69% of patients, respectively. Pediatric BCP-ALL patients with the ETV6-RUNX1 fusion transcript and expression of aberrant myeloid markers were not significantly different compared to those without with respect to demographic and clinical/hematological characteristics (p=0.5955). Aberrant myeloid markers were rarely or never expressed in pediatric and adult BCP-ALL patients with the t(4;11)(KTM2A-AF4) and t(1;19)(TCF3-PBX1) fusion transcripts.

Conclusion:

Aberrant myeloid markers were frequently expressed among BCP-ALL patients with the t(9;22)(BCR-ABL1) and t(12;21)(ETV6-RUNX1) fusion transcripts. However, BCP-ALL patients with the t(4;11)(KTM2A-AF4) and t(1;19)(TCF3-PBX1) fusion transcripts rarely or never expressed aberrant myeloid markers. Aberrant myeloid CD markers can be used in predicting chimeric fusion transcripts at baseline so as to plan appropriate tyrosine kinase inhibitor therapy in cases of BCP-ALL with specific chimeric fusion transcripts. This study has delineated the relationship of chimeric fusion transcripts with the aberrant expression of myeloid markers in a large cohort of BCP-ALL cases.

CD34 is not Expressed by Blasts in a Third of B-ALL Patients and its Negativity is associated with Aberrant Marker Expression: A Retrospective Analysis

BACKGROUND

CD34 antigen is expressed by early hematopoietic progenitor cells and acute leukemia cells. Its expression is associated with good prognosis in acute myeloid leukemia. Literature is sparse on its prognostic significance in B- acute lymphoblastic leukemia (B-ALL) especially from India. Hence the present study was undertaken to analyse the frequency of CD34 expression in B-ALL in Indian patients and determine its prognostic significance by associating with other prognostic markers and aberrant antigen expression.

METHODS

Seventy-five B-ALL patients diagnosed by flow cytometry over a period of 3½ year were studied. Correlation of CD34 expression was studied with gender, age, total leucocyte count (TLC), French-American-British (FAB) morphological type, immuno-phenotypic markers, cytogenetics and minimal residual disease. Differences between groups were evaluated using Student's T-test for quantitative data and Chi-square test/Fishers exact T-test for qualitative variables. P value.

Distribution of subtypes and immunophenotypic characterization of 1379 cases of paediatric acute leukaemia

Objectives:

Acute leukaemia is the most common and highly curable childhood malignancy; subtyping and identification of antigens via immunophenotyping helps in treatment plan as well as minimal residual disease monitoring.

Methods:

This retrospective study was conducted at the Haematology section of the clinical laboratories of Ziauddin University Hospital and The Indus Hospital, Karachi conducted at January 1st, 2012 to December 31^st, 2017. The study included 1379 cases of de novo acute leukemia from 2012 to 2017. Among these, 80% were diagnosed by using four color flowcytometry (FACS Calibur), 9% and 11% via immunohistochemistry on bone marrow trephine biopsy samples and morphological examination respectively.

Results:

The mean age of patients was 7.4 ± 4.3 years while male to female ratio was 1.75:1. Lymphoblastic leukaemia accounted for 77.2% and myeloid leukaemia 21.2%. Amongst lymphoblastic lineage, B-ALL was 80.4% while T-ALL was 19.6%. Among the phenotypic expression of B-ALL, CD79a (99.8%) had the highest positivity. In B-ALL, CD13 (29.8%) was the most common aberrant myeloid marker. Aberrant expression of CD79a observed in 11.1% of T-ALL cases. In non APL AML, aberrant expression of CD79a and CD19 was observed in 6.6% and 5.5% of cases respectively.

Conclusion:

Overall immunophenotypic profile, expression of aberrant phenotypes and subtype distribution in our patients was similar to international literature except for a relatively high frequency of T-ALL which was discordant from the western data.

Systematic Review of the Burden and Treatment Patterns of Adult and Adolescent Acute Lymphoblastic Leukemia in India: Comprehending the Challenges in an Emerging Economy

BACKGROUND

In the present systematic literature review, we sought to describe the burden and treatment practices of adult acute lymphoblastic leukemia (ALL) in India, which reflect the realities and outcomes in a middle-income country.

MATERIALS AND METHODS

We conducted a search for reported studies using terms such as "adult ALL," "epidemiology," and "treatment" in the Medline, Embase, Cochrane, and other database sources. We obtained 249 articles and 18 conference abstracts reported until December 2019. A total of 40 studies were selected to qualitatively summarize the data.

RESULTS

The proportion of ALL among adult patients diagnosed with acute leukemia at reporting institutions from 16 Indian studies ranged from 7.3% to 57.8%. Most studies were performed in Northern India (n = 12), had a male preponderance (range, 57%-80%), and had a predominance of B-ALL (range, 65.2%-75.9%). The treatment protocols used for ALL included MCP-841, BFM (Berlin-Frankfurt-Münster)-90, chemotherapy plus a tyrosine kinase inhibitor, GMALL (German Multicenter Study Group for Adult Acute Lymphoblastic Leukemia), and hyper-CVAD (cyclophosphamide, vincristine, doxorubicin, dexamethasone). The complete remission rates and median overall survival for these protocols ranged from 46.7% to 91.4% and 7 to 46 months, respectively. The overall relapse rates were 24.3% to 57.1% within median time of 9 to 24 months, with bone marrow the most frequent relapse site. After relapse, most patients had chosen palliative therapy (range, 78.7%-96.0%). The major treatment-related toxicities included neutropenia, myelosuppression, and infection.

CONCLUSIONS

The results from Indian studies on adult ALL are heterogeneous, reporting a diverse incidence and poor overall outcomes using varied non-contemporaneous treatment protocols adapted from the developed world. A comprehensive countrywide approach to diagnosis, treatment, and follow-up and the potential incorporation of novel therapies could improve the prognosis and outcomes of adult ALL in India.

Transposon-Based CAR T Cells in Acute Leukemias: Where are We Going?

Chimeric Antigen Receptor (CAR) T-cell therapy has become a new therapeutic reality for refractory and relapsed leukemia patients and is also emerging as a potential therapeutic option in solid tumors. Viral vector-based CAR T-cells initially drove these successful efforts; however, high costs and cumbersome manufacturing processes have limited the widespread clinical implementation of CAR T-cell therapy. Here we will discuss the state of the art of the transposon-based gene transfer and its application in CAR T immunotherapy, specifically focusing on the Sleeping Beauty (SB) transposon system, as a valid cost-effective and safe option as compared to the viral vector-based systems. A general overview of SB transposon system applications will be provided, with an update of major developments, current clinical trials achievements and future perspectives exploiting SB for CAR T-cell engineering. After the first clinical successes achieved in the context of B-cell neoplasms, we are now facing a new era and it is paramount to advance gene transfer technology to fully exploit the potential of CAR T-cells towards next-generation immunotherapy.

CD33 expression on natural killer cells is a potential confounder for residual disease detection in acute myeloid leukemia by flow cytometry

Detection of minimal/measurable residual disease (MRD) in acute myeloid leukemia (AML) is important for guiding patient-specific clinical management. Natural killer (NK) cells can express various markers not typically associated with NK lineage, potentially confounding the detection of MRD by flow cytometry. We have observed CD33 expression on NK cells when evaluating for AML MRD in routine clinical practice in multiple patient samples. To characterize CD33 expression on NK cells, 40 peripheral blood or bone marrow samples with NK cells present at >5% of lymphocytes were selected for further assessment of NK cell phenotype and CD33 expression. Seven of the 40 samples (17.5%) were found to have CD33 expression on at least 5% of the NK cells. The CD33-positive NK cell population accounted for an average of 11.4% of NK cells (median 11.9%, range 8.0-15.3%) and 2.2% of total white cells (median 1.1%, range 0.1-10.1%). This NK cell subset expressed bright CD2, bright CD56, and dim CD16. On average, CD33 expression on NK cells was dimmer than on monocytes (mean median fluorescence intensity ratio 0.4; range 0.1-1.0). This study characterizes expression of CD33 on NK cells. Recognition of this pattern of antigen expression is critical in evaluating samples for MRD in patients with myeloid neoplasms, particularly AML.