Page 34 - IJSA, Vol. 4, No 2, 2021

International Journal of Science Annals, Vol. 5, No. 1-2, 2022
рrint ISSN: 2617-2682; online ISSN: 2707-3637; DOI:10.26697/ijsa

Introduction
Chronic Myeloid Leukemia (CML) is a Sensitive detection of aberrant haematopoietic
myeloproliferative neoplasm that is characterized by a populations is made possible by flow cytometry. Flow
balanced translocation between chromosome t (9;22) cytometry has been thought to be of limited use at this
(q34; q11), leading to the formation of the Philadelphia stage of the disease since CML-CP is characterised by
(Ph) chromosome (Narang et al., 2016). It mainly affects proliferation of mostly granulocytes and granulocytic
older persons and seldom happens in youngsters, but can precursors without immunophenotypic aberrancy or
occur at any age. There is an increased number of maturation arrest. However, there are reports of aberrant
granulocytes and their immature precursors, including lymphoblast populations being found when flow
occasional blast cells, seen in the peripheral blood cytometry has been used, and there is conflicting
smear. CML accounts about 20% of all adult leukemias information regarding the risk of the blast phase
(Pandey & Pal, 2021). developing as a result. mortality (Barge et al., 2022).
According to the latest updated fifth edition of the World The initial targeted treatments for CML were tyrosine
Health Organization (WHO), there are two different kinase inhibitors (TKIs). The first-generation TKIs were
phases of untreated CML: Chronic phase (CP), and Blast introduced as the primary therapy in 1998, and they
crisis (BC). Blast crisis of CML according to the WHO stopped the disease’s natural development. With the
is defined by: 1) presence of ≥ 20% myeloid blasts in the accomplishment of morphological, clinical, and
peripheral blood or bone marrow; 2) presence of molecular remission targets, this has allowed patients to
extramedullary blasts proliferation; or 3) presence of sustain chronic phase disease. The speed and depth of
increased number of lymphoblasts in bone marrow or molecular remission have improved after the advent of
peripheral blood. The significance of low-level B- second and third generation TKIs (Hodkinson et al.,
lymphoblasts or optimal cut-off for lymphoblasts 2022).
remain unclear (Khoury et al., 2022). The blasts in the The aim of the study. To assess the immunophenotyping
CML blast phase (CML-BP) can express myeloid, outcomes of flowcytometry performed on CML-BP
lymphoid, bi-phenotypic, monocytic, megakaryocytic, cases at a tertiary care facility in North India.
and very infrequently erythroid phenotypes (Khemka et
al., 2019; Rahnemoon, 2022). Materials and Methods
BC develops as a result of persistent BCR-ABL A five-year retrospective descriptive analysis was
activation, which causes genomic instability and an carried out in the Pathology Department at King
accumulation of further chromosomal abnormalities. George’s Medical University in Lucknow, North India
Acute leukemia symptoms could be seen in patients with (January 2017 – December 2021). A total of 43 cases of
blast transformation (e.g., bleeding diathesis, bone pain, CML with blast crisis were retrieved from January 2017
night sweats, weight loss, and fatigue). Complete blood to December 2021 and included in the final study. The
counts, an extensive metabolic panel, a bone marrow cases in which flowcytometry analysis and/or BCR-
aspiration, and a biopsy should be performed all during ABL translocation identification were not performed,
the initial assessment of BC patients. Flow cytometry, were excluded from the study. The patient’s peripheral
immunohistochemistry, and cytogenetics should be blood and bone marrow aspirate samples were analyzed.
requested for the latter. The immunophenotype of the Clinical, hematological findings and
blast population determines how CML-BP patients immunophenotypic data were retrieved from records.
respond to treatment; hence, flowcytometric For immunophenotyping of blasts, peripheral blood was
examination is required in every case of blast crisis used in 28 patients and bone marrow aspirate samples in
(Hehlmann et al., 2016). Almost all CML-CP patients 15 patients respectively. The flow cytometry samples
will develop BC in 3-5 years without treatment, were prepared by using the strict protocols and
although in the tyrosine kinase inhibitor (TKI) era, this standardized “lyse-stain-wash” method.
dreaded transition is now extremely uncommon. Most For immunophenotyping of the blasts the antibody panel
CML-BC cases are myeloid, but up to one-third of them was comprised of CD13, cCD13, CD14, CD15, CD33,
have the potential to become lymphoid BC. The B-cell cMPO, MPO, CD64, CD14, cCD79a, CD117, CD19,
lineage is more prevalent, and lymphoid blast crisis CD20, CD10, CD22, cCD22, CD2, CD4, CD5. CD7,
makes up about 30% of CML-BC. T-cell BC is a very CD8, CD3, sCD3, cCD3, CD34, CD38, CD25, TdT
infrequent presentation for patients (Yohannam & (terminal deoxynucleotidyl transferase), and HLA-DR.
George, 2022). In order to help with blast gating in all of the tubes,
Most individuals with CML will respond very well to CD45PerCP was utilized as an anchor marker. 2 ml of
TKI therapy when it is administered during the chronic samples (Peripheral blood or Bone marrow) were
phase (CML-CP), which is characterized by collected in Ethylene Diamine Tetraacetate (EDTA)
granulocytic proliferation. The prognosis is still bad for vacutainer and analyzed using a dual laser BD FACS-
those who advance to the blast phase, with less than 20% Canto II, and FACS Diva software.
of patients in the modern period surviving for five years. The single-cell basis of flow cytometry analysis makes
Response to TKI therapy is the most crucial indicator of it possible to examine multiple populations at once and
advancement. Age, spleen size, and basophil count are detect low-level aberrant populations, particularly when
other variables predicting likelihood of transformation a larger number of events are studied to boost sensitivity
or mortality. (Tembhare et al., 2020).

32