Abstracts Clinical Lymphoma, Myeloma & Leukemia September 2023 S256 in the different preclinical models. Keywords: MPAL, ETP-ALL, lineage-ambiguous leukemia, venetoclax, gilteritinib ALL-596 Primary Philadelphia Chromosome‑Negative Acute Lymphoblastic Leukemia Among Adolescents and Young Adults Between 2017‑2022 in Armenia Iveta Mosesyan MD1, Hayk Grigoryan MD1,2, Miranush Saaryan MD2 1Yerevan State Medical University, Yerevan, Armenia. 2Hematology Center after Prof. R. Yeolyan, Yerevan, Armenia Background: Acute lymphoblastic leukemia (ALL) is characterized by the involvement of B-cell or T-cell lineages and is classified into subtypes based on the immunophenotype of the cells, which is determined by the presence of specific antigens on the cells. The presence of the Philadelphia (Ph) chromosome is significant for the choice of treatment strategy and in the prognosis of the disease. Objective: To determine the frequency of Ph-negative ALL among adolescents and young adults (AYAs) aged 15-39 years. Setting: Hematology center after prof. R. Yeolyan, Yerevan, Armenia. Materials and Methods: Retrospective ALL cases were observed and diagnosed within 2017-2022 years. Within this time period, 15 cases were associated with AYAs and were identified as primary Ph-negative ALL. The average age of the patients was 24 years. The sex ratio was 9 males to 6 females. Results: Among them, 10 primary cases were associated with B-cell lineage and 5 primary cases with T-cell lineage ALL. Based on flow cytometry, the 15 cases were classified immunophenotypically: 3 cases of early precursor B-cell (early pre-B-cell) (20%), 7 cases of pre-B-cell (46.6%), 2 cases of early T-cell precursor (ETP) (13.3%), 1 case of early immature T-cell (6.6%) and 2 cases of cortical/thymic T-cell (13.3%) ALL. Conclusion: Among youth, as the age increases, the incidence of the disease decreases. B-cell lineage ALL is more common and is often represented by the pre-B-cell subtype. Keywords: acute lymphoblastic leukemia, Philadelphia chromosome-negative ALL, adolescents and young adults ALL-606 A Comprehensive Retrospective Analysis of Cases from 2020‑2022 in Children With Relapsed Acute Leukemia: Temporal Trends and Clinical Characteristics Clodet Stepanians MD1,2,3, Narek Dzoyan MD3, Medea Anastasiadi MD1,2,3, Elya Minasyan MD1,2,3, Gevorg Tamamyan MD MSc PhD DSc1,2,3,4 1Hematology Center after professor R. Yeolyan, Yerevan, Armenia. 2Pediatric Cancer and Blood Disorders Center of Armenia, Yerevan, Armenia. 3Yerevan State Medical Univeristy, Yerevan, Armenia. 4Immune Oncology Research Institute, Yerevan, Armenia Context: Despite advancements in childhood leukemia treatment, relapses remain challenging, particularly in resource-limited settings. Understanding and managing pediatric patients is vital for optimizing their care. Objective: We aimed to enhance our understanding by examining three years of data, providing valuable insights to improve care. Design: We analyzed the data of newly diagnosed relapses (both ALL and AML) over a three-year (2020-2022) period. Comprehensive review of medical records was conducted to identify patients and extract information. Setting: A single-institution study in Armenia provides a detailed analysis among pediatric patients with relapses, applicable to similar healthcare settings. Patients or Other Participants: Generally, 11 pediatric patients were diagnosed with new relapses. Among them, 3 children had AML (M2, M3, M5 subtypes), while 8 patients had ALL (10 B-cell, 2 T-cell). The study included cases identified in 2022 (3 patients), 2021 (7 patients), and 2020 (1 patient), meeting the eligibility criteria of pediatric patients with relapsed disease during the specified timeframe. Results: Collectively 11 patients were identified, ranging in age (1-18), who experienced relapsed acute leukemia (median age at relapse was 9 years). Relapse was categorized into three groups: “very early” (VER), “early” (ER), and “late” (LR). We found that five patients (45.45%) were diagnosed with VER, five patients (45.45%) with ER, and one patient (9.09%) with LR. The male-to-female ratio was approximately 2.67 to 1. The median time from diagnosis to relapse was 19 months. Most frequent site of relapse was bone marrow (54.54%), followed by combined extramedullary plus bone marrow relapse (27.27%) while isolated extramedullary site relapse was the least common (18.18%). Patients with ALL received first-line treatment according to ALL IC-BFM 2002, ALL IC-BFM 2009, and EsPhALL2010 protocols. Patients with AML were treated with PETHEMA/HOVON,AML-BFM-2004, and AML-MRD-2018 protocol (depending on the diagnosis year and treatment protocol in Armenia). Conclusions: This study provides insight into the relapse patterns of acute childhood leukemia, demonstrating a higher incidence in the ‘very-early’ and ‘early’ stages. Timely identification, implementation of appropriate treatment, and vigilant symptom monitoring are imperative for optimizing outcomes. Further research is necessary to validate and assess survival. Keywords: relapsed acute leukemia, pediatric hematology-oncology ALL-616 Analysis of PEG‑Asparaginase Associated Adverse Events in the Treatment of Pediatric Acute Lymphoblastic Leukemia Elya Minasyan MD1,2, Clodet Stepanians MD1,2, Gevorg Tamamyan MD, MSc, PhD, DSc1,2,3, Lala Vagharshakyan MD1,2 1Pediatric Cancer and Blood Disorders Center of Armenia, Hematology Center after Prof. R.H. Yeolyan, Yerevan, Armenia. 2Yerevan State Medical University, Yerevan, Armenia. 3Immune Oncology Research Institute, Yerevan, Armenia Background: Peg-Asparagninase (Peg-Asp) is an essential part of the treatment for pediatric acute lymphoblastic leukemia (ALL). PegAsp administration is associated with serious complications, including
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