SOHO Supplement 2016 Immunophenotypic Characterization of Cytogenetic Subgroups in Egyptian Pediatric Patients With B-Cell Acute Lymphoblastic Leukemia Shady Adnan Awad, 1 Mahmoud M. Kamel, 1 Mahmoud A. Ayoub, 1 Ahmed M. Kamel, 2 Essam H. Elnoshokaty, 1 Niveen El Hifnawi 1 Abstract ALL is the most common childhood malignancy and identification of prognostic factors is important for further improvement of the treatment outcome in this fatal disease. Cytogenetic changes and MRD are the most powerful prognostic factors in ALL. We identified significant correlations between some CD markers and cytogenetic subgroups which can be used in MRD monitoring and as potential therapy targets. Background: Identification of prognostic factors in acute lymphoblastic leukemia (ALL) patients is important for stratifying patients into risk groups and tailoring treatment accordingly. Molecular and cytogenetic abnormalities are the most important prognostic factors. Minimal residual disease (MRD) is also an important predictor of relapse in ALL. However, the correlation of both prognostic variables has not been thoroughly studied. Methods: We investigated the correlation between defined cytogenetic abnormalities and selected new MRD markers (CD79b, CD123, and CD200) in 56 newly diagnosed Egyptian pediatric B-cell ALL patients. Results: CD123 found to be expressed in 45% of patients, CD200 in 80.3%, and CD79b in 67.9%. MRD analysis during treatment showed stable expression patterns of CD200. There was significant association of CD123 expression with the hyperdiploid ALL group (P ¼ .017). Another association (P ¼ .029) was found between CD79b negativity and the t(12;21) group. CD200 was widely expressed in all groups. Conclusion: There is a significant correlation between some markers, and certain ALL recurrent cytogenetic subgroups (CD123 and hyperdiploidy, CD79b negativity, and ETV-RUNX1 group) have good prognostic value. CD200 can be used as MRD markers in ALL patients and can also can serve as therapy targets. Clinical Lymphoma, Myeloma & Leukemia, Vol. 16, No. S1, S19-24 ª 2016 Elsevier Inc. All rights reserved. Keywords: ALL, CD123, CD200, CD79b, Hyperdiploidy, MRD Introduction Acute leukemia accounts for about one third of all childhood malignancy, of which acute lymphoblastic leukemia (ALL) is the most common type, accounting for about 80% of pediatric leuke- mia. 1 In Egypt, the annual incidence of ALL is about 4 cases per 100,000 children, accounting for about 20% of pediatric malig- nancies. 2,3 In recent reports, the overall survival of pediatric ALL is close to 90%, and about 80% experience long event-free survival. 4,5 The cornerstone of improved survival is the careful risk stratification of patients according to defined prognostic variables, then tailoring the treatment accordingly. 6,7 Cytogenetic and molecular changes in ALL represent the most important, defined, and thoroughly studied prognostic variables; they are used in classification and risk stratification, though they do not entirely explain differences in treatment responses. 8-10 Also, currently, minimal residual disease (MRD) is the most powerful prognostic factor in ALL patients, even those with low-risk dis- ease. 11,12 Few publications have studied the correlation between specific CD markers and certain cytogenetic groups, which needs to be further explored. 13,14 The discovery of new cluster of differentiation (CD) markers of leukemia and its differential association with certain cytogenetic groups has many values, including increased resolution between leukemic and normal cells at diagnosis, characterization of different 1 Department of Clinical Pathology 2 Department of Pediatric Oncology, National Cancer Institute, Cairo University, Cairo, Egypt Submitted: Feb 9, 2016; Accepted: Feb 9, 2016 Address for correspondence: Shady Adnan Awad, MD, PhD, Vuolukiventie 1b D89, Helsinki 00710, Finland E-mail contact: Shady.awad@helsinki.fi 2152-2650/$ - see frontmatter ª 2016 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.clml.2016.02.032 Clinical Lymphoma, Myeloma & Leukemia August 2016 - S19