PB2039: CLINICAL FEATURES AND NEXT-GENERATION SEQUENCING LANDSCAPE OF ESSENTIAL THROM-BOCYTHEMIA，PREFIBROTIC PRIMARY MYELOFIBROSIS, AND OVERT FIBROTIC PRIMARY MYELOFIBROSIS: A CHINESE RETROSPECTIVE STUDY

Abstract

Background: Since prefibrotic primary myelofibrosis (pre-PMF) was recognized as a separate enti-ty in the 2016 revised classification of MPN differed from essential thrombocythemia (ET) or overt fibrotic primary myelofibrosis (overt PMF), it has been a subject of de-bate among experts due to its indefinite diagnosis. Aims: We conducted a retrospective study of patients with myeloproliferative neoplasms (MPNs) in China, including 56 ET pa-tients, 19 pre-PMF patients, and 43 overt PMF patients. Methods: We conducted a retrospective study of patients with BCR-ABL-negative MPN from October 2014 to May 2021 in the Fourth Affiliated Hospital of Zhejiang University School of Medicine. Patients who were diagnosed with ET, pre-PMF or overt PMF according to the 2016 WHO revised Classification of MPN were included. Patients with incomplete information from laboratory tests and medical records were excluded. This study was approved by the Ethics Committee of the Fourth Affiliated Hospital of Zhejiang University School of Medicine in line with the principles of the Declaration of Helsinki.Statistical analyses were performed using SPSS statistics 26.0 and GraphPad Prism 8.0 software. Results: Pre-PMF patients exhibited higher leukocyte counts[14.2(6.0-28.1)×109/L vs 9.6(4.0-55.0)×109/L, P=0.003], LDH values[307(233-479)U/L vs 241(129-1182)U/L, P<0.001], onset ages[67(32-76)years vs 50(16-79) years, P=0.006], a higher frequen-cy of splenomegaly(47.4% vs 16.7%, P=0.018) and hypertension(57.9% vs 23.2%, P=0.005) than ET patients. On the other hand, pre-PMF patients had higher platelet counts[960(500-2245)×109/L vs 633(102-1720)×109/L, P=0.017], haemoglobin levels[152(115-174)g/L vs 119(71-200)g/L, P=0.003], lower LDH val-ues[307(233-479)U/L vs 439(134-8100)U/L, P=0.007] and a lower frequency of splenomegaly(47.4% vs 75.6%, P=0.031) than overt PMF patients. Next-generation sequencing landscape was performed in 50 patients, revealed the frequency of EP300 mutations was significantly increased in pre-PMF patients compared with ET and overt PMF patients (60% vs 10% vs 15.79%, P=0.033), and WT1 was more often overexpressed (WT1/ABL1 copies≥1.0%) in patients with overt PMF than in those with ET or pre-PMF(54.55% vs 16.67% vs 17.65%, P=0.009). In terms of outcome, male sex, along with symptoms including MPN10, anaemia (haemoglobin<120g/L), thrombocytopenia (platelet count<100×109/L), leucocytosis (leukocyte counts>13×109/L), high LDH value (>350U/L), splenomegaly, WT1 overexpres-sion(WT1/ABL1 copies≥1.0%), KMT2A, ASXL1 and TP53 mutations, indicated a poor prognosis for PMF patients. The research was supported by the Key R&D Program of Zhejiang, No. 2022C03137; Public Technology Application Research Program of Zhejiang, China, No. LGF21H080003; the Key Project of Jinhua Science and Technology Plan, China, No. 2020-3-011; the 2019–2024 Academician Workstation of the Fourth Affiliated Hospi-tal of the Zhejiang University School of Medicine; the 2019–2022 Key Medical Dis-cipline (Hematology) Fund of Jinhua, China. *Correspondence to: Dr Jian Huang, Department of Hematology, The Fourth Affiliated Hospital of Zhejiang University School of Medicine. N1 Shangcheng Road. Yiwu, Zhejiang, Peoples R China. E-mail: [email protected] Image:Summary/Conclusion: In summary, the results of this study indicated that comprehensive evaluation of BM features, clinical phenotypes, haematologic parame-ters, and molecular profiles is needed for the accurate diagnosis and treatment of ET, pre-PMF, and overt PMF patients.