PB2201 PROGRESS AND SURVIVAL IN TRIPLE NEGATIVE PRIMARY MYELOFIBROSIS PATIENTS

Background: Primary myelofibrosis (PMF) is a Philadelphia negative myeloproliferativ neoplasm characterized by a clonal myeloid expansion which determines progressive bone marrow fibrosis resulting in inefficient hematopoiesis. Diagnosis is based both on bone marrow morphology but also clinical aspects. There were described several mutations such as those in JAK 2 V617F, MPL exon 10 and CALR exon 9 indel genes in aproximately 90% of the patients while the rest of 10% were so‐called triple negative. Aims: To evaluate survival and prognosis in triple negative PMF patients. Methods: In this retrospective study, 58 patients diagnosed with PMF were enrolled from January 2014 to December 2018. Data were analyzed with SPSS 24. Results: The median age was 58 years. The male to female ratio was 3:1. Of the total 58 patients studied, 30 (51,72%) carried JAK 2 (V617F), 14 (24,14%) showed positivity for CALR exon 9 indel, 4 (6,9%) had MPL (exon 10) mutation and 10 (17,24%) were so‐called triple negative PMF. Median overall survival was 3,8 years in CALR mutant patients, 2,1 years in those presenting mutation in JAK 2 gene, 2,3 years in MPL mutant patients and 1,6 years in triple negative patients. An analysis of the frequency of blast transformation at 1 year, revealed that it was identifyied in 71% of triple negative patients, 22% of JAK 2 mutant patients and in 3% of both CALR and MPL mutant patients. Summary/Conclusion: This study reveals the importance of genetic analysis not only for diagnosing PMF but also for risk stratifying, prognos estimation and furthermore treatment choice. Triple negative PMF patients had a higher incidence of blast transformation compared with those presenting mutations.