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TP53 mutation is rare in primary myelofibrosis

Abstract 5241 Introduction TP53 is the most frequently mutated tumor suppressor gene in human cancers and is usually associated with an aggressive disease course. TP53 mutation has been described in a variety of hematopoietic neoplasms, and has been suggested to play a role in leukemic transformation of myeloproliferative neoplasms (MPN). However, the incidence as well as the clinical and pathogenetic implications of TP53 mutation in each sub-category of MPN, including primary myelofibrosis, have not been described. In this study, we investigated the presence and potential clinical significance of TP53 mutations in a large series of primary myelofibrosis cases. Patients and Methods We retrieved archival bone marrow DNA from 51 consecutive patients diagnosed with primary myelofibrosis at The University of Texas MD Anderson Cancer Center between the years 2005 and 2007. Diagnosis was based on morphologic, immunophenotypic, cytogenetic and molecular evaluation of bone marrow in conjunction with clinical data. Only 2 patients had blast counts >10% (11 and 14%). Twenty nine of 50 (58%) patients showed JAK2 p.V617F mutation and all patients were negative for BCR-ABL1 translocation on routine clinical testing. DNA samples were assessed for sequence variation in exons 4 through 9 of TP53 by both high resolution melting curve (HRM) analysis using LightCycler® 480 System (Roche, Indiana IN) and bidirectional Sanger sequencing using 3730XL DNA Analyzer (Life technologies, Carlsbad CA). Results The mean overall survival was 5.7 years. Five patients developed acute leukemia, all of whom died of disease. By Sanger sequencing, only one (1.9%) case showed an amino acid-altering mutation in TP53: c.707A>G (TAC to TGC) in codon 236 (p.Y236C) of exon 7. In addition, 8 cases showed silent mutations/single nucleotide polymorphisms of unknown significance - c.36G>A (CCG to CCA) in exon 4 (n=3) and c.213A>G (CGA to CGG) in exon 6 (n=6). The p.R72P polymorphism in exon 4 which has been described in other hematopoietic neoplasms was present in 1 patient. All cases with a mutant sequence by Sanger sequencing also showed a variant melting curve pattern by HRM analysis. The patient with TP53 mutation died 2 years after presentation from progressive myelofibrosis without developing acute leukemia. Conclusion TP53 mutation is very rare in primary myelofibrosis. Disclosures: No relevant conflicts of interest to declare.