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Introduction Methods Results Conclusion Leukemic stem cells (LSCs) are the transcriptionally low/silent cells which are resistant to the tyrosine kinase inhibitor. These have been found to play a pivotal role in disease relapse in chronic myeloid leukemia (CML) cases. The present study evaluated the correlation of absolute CML‐LSC count in the peripheral blood (PB) at diagnosis and achievement of major molecular response (MMR) at 12 months in patients of CML‐CP.This was a prospective, observational, non‐interventional single center study including newly diagnosed adult (>18 yrs) CML‐CP patients. Absolute CD26 + CML‐LSC quantification was done by multiparametric flow cytometry. Patients were treated with Imatinib treatment and subsequently monitored at 3‐month intervals for BCR::ABL transcript levels. MMR was defined as a BCR::ABL1 transcript level of less than 0.1% on international scale.A total of 89 patients were enrolled in the study out of which 40.5% achieved MMR at 12 months. There was a significant difference in the median absolute CML‐LSC count of the patients who achieved MMR at 12 months as compared to those who did not (58.5 vs 368.1 cells/μL; p value <0.001). Using a ROC analysis, a count of <165.69 CML LSC/μL was identified to have a sensitivity of 83.8% and specificity of 72.4%, in predicting the MMR at 12 months.Absolute CML‐LSC count at diagnosis in the PB predicts the MMR achievement at 12 months. An absolute count of less than 165 cells/μL is highly predictive of achieving MMR at 12 months. [ABSTRACT FROM AUTHOR]

Background: Recently, CD26 have been identified as one of the promising and specific marker for the identification of leukemic stem cells (LSCs) in chronic myeloid leukemia (CML). Methods: This was a prospective, observational validation study. Peripheral blood (PB) samples from suspected cases of CML and other hematolymphoid neoplasm were evaluated for the expression of CD26 on stem cells (SC) (CD45 dim/CD34+/CD38‐) fraction by flow cytometry (FCM) using a single tube four‐color antibodies cocktail: CD45‐V500 /CD26‐PE/CD34‐PerCPcy5.5/CD38‐APC‐H7. The diagnosis of CML was confirmed using cytogenetics and/or molecular studies. Additionally, 12 paired PB and bone marrow (BM) samples of CML cases were compared for the proportion of CD26+ LSCs. Results: Expression of CD26 on the SC fraction was invariably noted in all cases (116/116) of CML, irrespective of the disease phase and transcript type. None of other neoplasm (0/26), including the Ph + ALLs expressed CD26. Proportion of SCs expressing CD26 was variable with a median (range) proportion being 61.3% (7.6%–98.6%). Evaluation of paired PB and BM samples showed similar proportion of CD26 + LSCs (R2: 0.969). Conclusion: We confirmed that FCM evaluation of CD26 expression in the PB LSCs is a rapid and specific tool for CML diagnosis. Its utility as a marker for residual disease evaluation can also be explored in the future. [ABSTRACT FROM AUTHOR]

Myelodysplastic syndromes (MDSs) are characteristically defined by the presence of specific karyotypic abnormalities, based on which they have been prognosticated. Translocation t(9;22)(q34;q11.2) (Philadelphia positive [Ph +ve]) and corresponding BCR-ABL fusion transcript is the defining parameter of chronic myeloid leukemia. It is also seen in a fair proportion of adult acute lymphoblastic leukemia. Occurrence of a Ph +ve MDS is very uncommon, and that too is seen mostly on progression to higher stage/acute leukemia. Even rarer is the de novo presence of Ph positivity in an MDS. A literature search through PubMed has shown only about forty cases of Ph +ve MDS among which less than half had shown Ph positivity at the time of initial diagnosis. Due to its rarity, this entity has not yet found its space in current WHO 2008 classification and is still under "yet to be validated phase" in current practice of hematological malignancies. The benefit of using a tyrosine kinase inhibitor in such a situation is also debatable. We report here two such cases of de novo Ph +ve MDS, diagnosed in last 1½ year at our institute along with brief literature review. [ABSTRACT FROM AUTHOR]

Leukemoid reaction and myeloproliferative syndrome are close mimickers and frequently pose a diagnostic dilemma, particularly when the leukocyte count is very high. Leukocyte alkaline phosphatase score frequently aids in diagnosis but may or may not be contributory, especially in differentiating chronic neutrophilic leukemia. Herein, we document a case of leukemoid reaction with extensive hyperleukocytosis in a 46-year-old female with poorly differentiated carcinoma. The tumor itself as well as the associated leukocytosis portends a poor prognosis. [ABSTRACT FROM AUTHOR]