Secondary Myelofibrosis Patients Research Articles

Atrial Fibrillation in Patients with Myelofibrosis

Background: Atrial fibrillation (AF) is the most common arrythmia (1-2% of the general population) and is associated with high risk of arterial thrombotic events. AF is not well characterized in the context of myeloproliferative neoplasms (MPN). Recent studies imply that thrombotic risk stratification among MPN AF patients may be suboptimal using the standard CHA2DS2VASC score, and true predictor of thrombotic risk may be presence of myelofibrosis instead. Clinical context in which AF occurs in myelofibrosis patients had not been investigated so far, but such analysis is needed to better understand why is the presence of myelofibrosis in particular the main predictor of thrombotic events among AF MPN patients. We aimed to evaluate prevalence and clinical associations of AF among patients with myelofibrosis. Methods: We retrospectively investigated a cohort of 154 patients with overt myelofibrosis treated in 6 Croatian hematology centers in period 2004-2022. Diagnoses were reassessed according to the 2016 WHO criteria for primary myelofibrosis (PMF) and the 2008 IWGMRT criteria for secondary myelofibrosis (SMF). Presence of AF documented in medical records and clinical correlations of AF status with main disease related characteristics were analyzed. Results: Among a total of 154 patients, 86 had PMF, 35 had post polycythemia vera (PV) and 33 had post essential thrombocythemia (ET) SMF. Median age was 69 years. There were 91 (59%) males, 111 (75%) patients were JAK2, 9 (7.3%) CALR and 4 (3.3%) MPL mutated. AF was present in 15 (9.7%) patients with myelofibrosis which was significantly more frequent than anticipated in the general population of similar age (P<0.001). There were no significant associations of AF with neither etiology of myelofibrosis, age, sex, mutational status, degree of bone marrow fibrosis, spleen size, history of thrombosis, estimated glomerular filtration rate, hemoglobin, WBC nor platelet count (P>0.05 for all analyses). DIPSS score did not differ between AF and non-AF PMF patients, but MYSEC-PM score was significantly higher among AF SMF patients (P=0.029). AF in comparison to non-AF patients more frequently had constitutional symptoms (87% vs 54%, P=0.015), positive bleeding history (27% vs 6%, P=0.004), heart failure (47% vs 12%, P<0.001), obesity (21% vs 4%, P=0.010), lower MCHC (313 vs 318 g/L, P=0.031), higher urea (median 8.5 vs 6.8 g/L, P=0.009) and higher CHA2DS2VASC score (4 vs 3 points, P=0.003). AF more frequently received anticoagulants and diuretics than non-AF patients (P<0.05), whereas similar rates of cytoreductive therapy and aspirin were utilized. Despite all myelofibrosis patients with AF patients having CHA2DS2VASC score ≥2 points, only 60% of them received anticoagulant therapy, 27% received aspirin and 73% received cytoreductive therapy. No significant difference in survival and thrombosis was observed between AF and non-AF myelofibrosis patients (P>0.05 for all analyses) although study may be underpowered for these analyses. Summary/Conclusion: AF is frequent in patients with myelofibrosis and might be associated with higher frequency of constitutional symptoms, particular cardiovascular comorbidities and consistently high predetermined CHAD2DS2VASC risk. Nevertheless, unexpectedly low proportion of patients receives anticoagulant therapy, possibly due to anticipated risk of bleeding and cytopenias common in myelofibrosis patients. It remains a question whether suboptimal treatment or presence myelofibrosis itself might be a risk factor for unfavorable outcomes among AF MPN patients.

Higher estimated plasma volume status is associated with increased thrombotic risk and impaired survival in patients with primary myelofibrosis

Blood plasma represents a large reservoir of cytokines and other mediators of inflammation. Higher estimated plasma volume status (ePVS) has been shown to correlate with increased thrombotic risk in polycythemia vera patients, but its clinical and prognostic associations in patients with myelofibrosis are unknown which we aim to evaluate in this study. We retrospectively analysed a multicentric cohort of 238 patients with primary (PMF) and secondary myelofibrosis (SMF). Estimated plasma volume status was calculated using the Strauss-derived Duarte formula. Overall survival (OS) and time to thrombosis (TTT) considering both arterial and venous thromboses were primary endpoints of interest. Median ePVS was 5.8 dL/g and it did not significantly differ between PMF and SMF patients. Patients with more advanced disease features, more pronounced inflammation and higher comorbidity burden had higher ePVS. Higher ePVS (> 5.6 dL/g) was associated with shorter OS in PMF (unadjusted hazard ratio, HR = 2.8, 95% confidence interval, CI (1.79-4.41), P < 0.001) and SMF (unadjusted HR = 2.55, 95% CI (1.1-5.71), P =0.025) and with shorter TTT in PMF (> 7 dL/g, unadjusted HR = 4.1, 95% CI (1.44-11.59), P = 0.009) patients. Associations with OS diminished in multivariate analyses after adjustments for the dynamic-international-prognostic-scoring-system (DIPSS) and myelofibrosis-secondary-to-PV-and ET-prognostic-model (MYSEC-PM), respectively. Association with TTT remained significant independently of JAK2 mutation, white blood cell count and chronic kidney disease. Myelofibrosis patients with more advanced disease features and more pronounced inflammation have higher ePVS, indicative of expanded plasma volume. Higher ePVS is associated with impaired survival in PMF and SMF and higher thrombotic risk in PMF patients.

Peripheral Blood Cytotoxic T Cells from Myelofibrosis Patients Show Early Exhausted Features Targetable By CTLA-4 Inhibition

Introduction: Myelofibrosis (MF), either primary or secondary, belongs to Philadelphia-negative myeloproliferative neoplasms (MPN) and is characterized by bone marrow fibrosis, hematopoietic stem cell mobilization and extramedullary hematopoiesis. Compelling evidence are suggesting that persistent antigen stimulation in the tumor microenvironment can differentiate T effector cells into terminally exhausted T cells, a functional state characterized by decrease in proliferation, cytotoxicity, and cytokine production. Innovative therapies aim at reversing the exhausted state through immune checkpoint inhibition to recover the immune response against the tumor. Even in myeloid neoplasms such as MPNs, T cells are showing dysfunctional features; thus we investigated T cell exhaustion in MF to assess the possibility of immune checkpoint inhibition as a new effective therapy. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from 44 MF patients and 22 healthy donors (HD). CD3+CD8+ T cells were characterized by multicolor flowcytometry to assess surface expression of the following inhibitory receptors (IRs): PD-1, CD244, CD160, TIM-3, LAG-3, CTLA-4. Results were correlated with clinical features such as Dynamic International Prognostic Scoring System (DIPSS) classification, splenomegaly, high-molecular risk (HMR) mutation number and other negative prognostic factors. We performed intracellular flowcytometry staining to assess residual cytokine production in PBMCs stimulated overnight with anti-CD3, anti-CD28 and Brefeldin A. Total cellular RNA was isolated from granulocytes of 141 primary and secondary MF patients and 28 HDs, and we performed Gene expression profiling (GEPs) by microarray platform to evaluate IRs-ligands expression. To test the possible inhibitory effect of the neoplastic clone we cultured T cells either alone or in co-culture with the myeloid cells for 4 days in the presence of anti-CD3/CD28 stimulatory beads, SCF, TPO, FLT3l, IL6, IL7 and IL15 and then we tested the activation marker OX40 expression level. The co-culture system was also used to test the effect of CTLA-4 inhibition. Results: We observed increased expressions of PD-1, CD244, CTLA-4 and CD160 on cytotoxic T cells from MF patients together with the expansion of PD-1+CD57- cytotoxic T cell populations (Panel A), which also showed increased expression of all the IRs assessed, with CD160 and CTLA-4 being the more significantly upregulated. Higher levels of PD-1, CD244, CD160, CTLA-4, LAG-3 or TIM-3 on cytotoxic T cells correlate with detrimental features like splenomegaly, low hemoglobin levels, HMR mutation number and more severe DIPSS classification. Moreover, we observed decreased secretion of IFNɣ and TNFɑ by total CD3+CD8+ T cells and PD1+ subpopulation from MF patients (Panel B). A significant reduction of Granzyme B production was observed mainly in patients with expansion of PD1+CD57- exhausted T cells. GEPs analysis highlighted increased expression of IR-ligands like CD274, CEACAM1, CD48, CD80 on granulocytes from MF patients compared to HDs. While cytotoxic T cells from HDs were effectively activated either alone or in co-culture with myeloid cells, the activation of cytotoxic T cells from MF patients was damped in presence of myeloid cells and restored when T cells were cultured alone. Treatment with anti-CTLA-4 was able to partially restore the MF T cells activation potential in the presence of myeloid cells. Conclusions: Our data evidenced in MF patients the presence of an impaired population of peripheral blood cytotoxic T cells expressing multiple IRs and with reduced cytokine production after in vitro activation. Clinical correlations suggest a more severe disease in patients with higher IRs expression on cytotoxic T cells. Moreover, granulocytes from MF patients display higher level of IR-ligands transcripts suggesting an immunosuppressive interplay between the myeloid neoplastic clone and T cells. This was also suggested by reduced activation level of T cells in co-culture with myeloid cells that was restored by removing of myeloid cells or with anti-CTLA-4 treatment. Taken together this data highlights an exhausted state likely implicated in immune escape that could be targeted and potentially reverted by immune checkpoint inhibitions. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

MPN-541 Estimated Plasma Volume Status in Patients With Primary Myelofibrosis and Associated Thrombotic and Mortality Risks.

Blood plasma experiences substantial changes in both volume and composition in patients with chronic myeloproliferative neoplasms (MPN) and represents a large reservoir of cytokines and other mediators of inflammation. Higher estimated plasma volume status (ePVS) has recently been shown to correlate with increased thrombotic risk in polycythemia vera patients. To estimate clinical and prognostic associations of ePVS in patients with myelofibrosis. Retrospective cohort study. 6 hematology centers. 238 myelofibrosis patients, 168 with PMF, 34 with post-PV SMF and 36 with post-ET SMF. ePVS was calculated using the Strauss derived Duarte formula: (100-hematocrit (%)/hemoglobin (g/dL) and expressed as dl/g. Overall survival (OS) and time to thrombosis (TTT). Median ePVS was 5.8 dl/g and it did not significantly differ between PMF and SMF patients. Among other associations, higher ePVS was significantly associated with higher degree of bone-marrow fibrosis, absence of JAK2-mutation, lower white blood cells (WBC), platelets and hemoglobin, presence of circulatory blasts, higher C-reactive protein, higher lactate dehydrogenase, lower albumin and higher Charlson comorbidity index in an overall cohort, as well as with more pronounced splenomegaly and higher Dynamic International Prognostic Scoring System (DIPSS) risk in primary myelofibrosis (PMF) and higher Mysec-PM risk in secondary myelofibrosis (SMF) patients (P<0.05 for all analyses). Higher ePVS (>5.6 dl/g) was associated with shorter overall-survival (OS) in PMF (HR=2.8, P<0.001) and SMF (HR=2.55, P=0.025) and with shorter time-to-thrombosis in PMF (>7 dl/g, HR=4.1, P=0.009) patients. Associations with overall survival diminished in multivariate analyses after adjustments for DIPSS and Mysec-PM, respectively. Association with TTT remained significant independently of JAK2, WBC and chronic kidney disease. Myelofibrosis patients with more advanced disease features and more pronounced inflammation have higher ePVS, indicative of expanded plasma volume. Higher ePVS is associated with impaired survival in PMF and SMF and higher thrombotic risk in PMF patients.

P995: MYELOID NEOPLASMS-ASSOCIATED GENE VARIANTS IN 639 PATIENTS WITH POST-POLYCYTHEMIA VERA AND POST-ESSENTIAL THROMBOCYTHEMIA MYELOFIBROSIS: AN ANALYSIS OF THE MYSEC COHORT

Background: Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms evolving to post-PV (PPV-) and post-ET (PET-) myelofibrosis (MF), called secondary MF (SMF). In primary MF, knowledge on non-driver myeloid neoplasms-associated gene variants (M-GVs) influences clinical decision-making. In SMF, information on M-GVs is scant. Aims: The primary aim was to assess the pattern of distribution of M-GVs, their correlations with SMF subtype and with driver mutations, in a large cohort of SMF patients studied by next generation sequencing (NGS). Methods: The study involved SMF patients of the MYSEC (Myelofibrosis Secondary to PV and ET) project. In 97% of cases, NGS were performed within one-year pre/post-SMF diagnosis. Characteristics of study cohort were described by standard statistic. Associations were investigated by Chi-square or Fisher exact test. Results: The clinical features of the 639 NGS-annotated patients entering the analysis are reported in Table 1. Table 1. - Characteristics of 639 NGS-annotated SMF. SMF (639) PPV-MF (290) PET-MF (349) p Age at SMF (years), mean (SD) 62.2 (11.8) 63.2 (10.7) 61.4 (12.5) 0.17 Male gender, n (%) 323 (51) 151 (52) 172 (49) 0.48 JAK2 mutated, n (%) 477 (75) 290 (100) 187 (53) CALR mutated, n (%) 125 (19) 125 (36) MPL mutated, n (%) 24 (4) 24 (7) Triple negative, n (%) 13 (2) 13 (4) Hb (g/dl), mean (SD) 11.3 (2.1) 12.0 (2.1) 10.7 (1.9) <0.0001 WBC (x10^9/l), mean (SD) 13.7 (12.7) 15.8 (13.9) 11.9 (11.3) <0.0001 PLT (x10^9/l), mean (SD) 368.5 (248.4) 310.6 (211.6) 417.8 (266.4) <0.0001 Blasts (%), mean (SD) 0.7 (1.9) 0.7 (1.6) 0.7 (2.1) 0.59 Constitut. symptoms, n (%) 259 (41) 134 (46) 125 (36) 0.01 A total of 198 (31%) patients did not harbor any M-GV, with no imbalance as for SMF subtype. Among the 441 (69%) with M-GVs, 223 (51%) had one, 137 (31%) two, 52 (12%) three, 23 (5%) four and 6 (1%) five or more. PPV-MF subjects reported more frequently one M-GV, while those with PET-MF at least three (p=0.02). Mean number of M-GVs was 1.4 per patient (range, 0-7). In detail, it was 1.2 (range, 0-4) and 1.5 (range, 0-7) per patient in PPV- and in PET-MF, respectively (p=0.01). The most frequent (≥5% of dataset) M-GVs involved: ASXL1 (n=181, 41%), TET2 (n=145, 33%), DNMT3A (n=49, 11%), TP53 (n=43, 10%), EZH2 (n=39, 9%), SF3B1 (n=31, 7%), U2AF1 (n=29, ~7%), ZRSR2 (n=27, 6%), CBL and RUNX1 (n=21 each, 5%). In PET-MF there was a significantly higher frequency of M-GVs in ASXL1 (47% vs 34%, p=0.01), SRSF2 (5% vs 1%, p=0.01), U2AF1 (9% vs 4%, p=0.04) and CBL (7% vs 2%, p=0.01) compared to PPV-MF. The latter was significantly associated with ETV6 alterations (5% vs 1% in PET-MF, p=0.04). As regards driver mutations, we found an association between “triple negative” status (TN) and M-GVs in SETBP1 (38%, p=0.002), IDH2 (25%, p=0.02), EZH2 (25%, p=0.05), and SRSF2 (25%, p=0.01). Figure 1 shows the frequency of M-GVs found in the MYSEC cohort, distinguished by SMF subtype (a) and driver mutations (b). Image:Summary/Conclusion: Among 639 NGS-annotated SMF cases, 69% presented at least one M-GV with a mean of 1.4 per patient. Overall, the most frequent (≥10%) M-GVs were in ASXL1, TET2, DNMT3A and TP53 genes. Different pathways of progression among PPV- and PET-MF have been disclosed. PPV-MF showed an increased rate of ETV6 alterations, opening the question of possible predisposing genetic factors. TN cases clustered with specific M-GVs, potentially targetable (IDH2). This is the first study exploring the mutational landscape of a wide cohort of SMF patients, paving the way for further investigations on the topic.

Spleen Stiffness Measurement by Using Shear-Wave Elastography as a Predictor of Progression to Secondary Myelofibrosis.

Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic myeloproliferative diseases that can transform to secondary myelofibrosis (SMF). In this study, we evaluated spleen stiffness using shear-wave elastography (SWE) as a predictor of progression to SMF. Participants were grouped as healthy volunteers (HVs), PV/ET patients, and SMF patients. Participants' spleen sizes, spleen stiffness values, bone marrow fibrosis degrees, and the other parameters were evaluated. Spleen stiffness values and spleen sizes were compared between groups. Of the 121 participants included in this study, 52 patients were HVs, 52 patients were PV and/or ET patients, and 17 patients were SMF patients. In terms of age and sex, there was no difference between groups. Splenic parenchymal stiffness median values by using SWE were found to be 0.82 m/s in HVs, 1.41 m/s in PV/ET patients, and 2.32 m/s in SMF patients (P < 0.001). In terms of median length of the spleen, the difference between groups was significant (P < 0.001). In addition, we found a significant positive correlation between spleen stiffness and bone marrow fibrosis degree (P < 0.001, r = 0.757). However, in multivariate analysis, there was no strong independent risk factor for spleen stiffness. In this study, we showed that measurement of spleen stiffness using SWE can distinguish SMF from PV/ET patients and HVs. Therefore, we believe that SWE may be used as a noninvasive and easily accessible method to check the fibrotic progression of bone marrow in PV and ET patients to monitor the transformation to SMF, and enables to detect fibrosis in early phase.

Gene expression profile correlates with molecular and clinical features in patients with myelofibrosis

Myelofibrosis (MF) belongs to the family of classic Philadelphia-negative myeloproliferative neoplasms (MPNs). It can be primary myelofibrosis (PMF) or secondary myelofibrosis (SMF) evolving from polycythemia vera (PV) or essential thrombocythemia (ET). Despite the differences, PMF and SMF patients are currently managed in the same way, and prediction of survival is based on the same clinical and genetic features. In the last few years, interest has grown concerning the ability of gene expression profiles (GEPs) to provide valuable prognostic information. Here, we studied the GEPs of granulocytes from 114 patients with MF, using a microarray platform to identify correlations with patient characteristics and outcomes. Cox regression analysis led to the identification of 201 survival-related transcripts characterizing patients who are at high risk for death. High-risk patients identified by this gene signature displayed an inferior overall survival and leukemia-free survival, together with clinical and molecular detrimental features included in contemporary prognostic models, such as the presence of high molecular risk mutations. The high-risk group was enriched in post-PV and post-ET MF and JAK2V617F homozygous patients, whereas pre-PMF was more frequent in the low-risk group. These results demonstrate that GEPs in MF patients correlate with their molecular and clinical features, particularly their survival, and represent the proof of concept that GEPs might provide complementary prognostic information to be applied in clinical decision making.

Higher serum uric acid is associated with higher risks of thrombosis and death in patients with primary myelofibrosis

Serum uric acid (SUA) can promote inflammation and is associated with increased cardiovascular morbidity. Primary (PMF) and secondary myelofibrosis (SMF) are myeloproliferative neoplasms characterized by high cellular turnover and substantial risk of thrombosis and death. We have retrospectively investigated SUA in 173patients with myelofibrosis (125 PMF; 48SMF) and 30controls. The PMF patients had significantly higher SUA in comparison to SMF and controls. In both PMF and SMF higher SUA was significantly associated with arterial hypertension and decreased renal function. Among PMF patients, higher SUA was significantly associated with older age, larger spleen, higher white blood cell counts, higher lactate dehydrogenase, lower immunoglobulin G levels, allopurinol use and non-smoking. Among SMF patients, higher SUA was associated with male sex (P < 0.05 for all analyses). In PMF higher SUA was univariately associated with inferior survival (> 427 μmol/L hazard ratio (HR) = 2.22; P = 0.006) and shorter time to thrombosis (> 444 μmol/L HR = 5.05; P = 0.006), which could be shown separately for arterial (> 380 μmol/L; HR = 4.9; P = 0.013) and venous thromboses (> 530 μmol/L; HR = 17.9; P < 0.001). In multivariate analyses, SUA remained significantly associated with inferior survival independent of the Dynamic International Prognostic Staging System and with shorter time to thrombosis independent of age in PMF patients; however, the prognostic significance of SUA was diminished after including serum creatinine in the models. SUA was not prognostic in SMF patients. The PMF patients present with higher SUA levels, which are associated with features of more advanced disease and higher risks of arterial and venous thrombosis and death.

Overview of Primary and Secondary Myelofibrosis in Young Adults: Genomic Characteristics, Treatment Strategies and Outcomes

Introduction: Primary and secondary myelofibrosis (MF) [i.e. occurring after a prior diagnosis of polycythemia vera [PV] or essential thrombocythemia (ET)] are myeloid malignancies often diagnosed in the 6th and 7th decade of life. In the rare occurrence that younger patients receive this diagnosis, prognostic recommendations are poorly extrapolated and optimal treatment strategies are unclear. Prior studies assessing young MF patients have suggested a more indolent course for this cohort. Here we aim to analyze our experience with young MF patients in terms of genetic makeup, treatment history, and outcomes. Methods: We assessed a database of primary and secondary MF patients who presented to our center between 1/2000 and 6/2019. We identified patients who were 50 years or younger at the time of MF diagnosis. Clinical and genetic features along with treatment history and outcomes were analyzed. Kaplan-Meier method was used for survival analysis. Patients surviving at 240 months after diagnosis were censored at that time. Results: Among 599 MF patients, 63 (11%) were ≤50 at the time of diagnosis. Median age at diagnosis was 43.6 years (yr). Median time from diagnosis to first presentation to our institution was 4.2 months (mo) (range 0-35 yr). Thirty-eight (60%) and 44 (70%) were seen within 1 and 5 years of diagnosis, respectively. Females accounted for 62% (n = 39) of patients. Forty-five (71%) patients had primary MF, 4 (6%) had post-PV MF and 13 (21%) post-ET MF. Median follow-up for the cohort was 94.9 mo. Among 62 patients in whom IPSS at diagnosis could be calculated, 20 (32%) were low, 27 (44%) intermediate-1, 12 (19%) intermediate-2, and 3 (5%) high-risk. JAK2 mutation was detected in 22/60 (37%), CALR in 21/44 (48%), MPL in 0/49 (0%). One patient was triple-negative. Extended targeted gene sequencing was performed in 42/63 patients during their clinical course. Sequencing occurred at a median time of 2.6 yr after diagnosis (range 0-35 yr). Genes most commonly mutated were ASXL1 (12%), TET2 (12%), EZH2 (10%), and DNMT3A (10%). No mutations involving SRSF2, U2AF1, ZRSR2, or SF3B1 were seen. Thirteen patients did not receive active treatment during follow-up. Among those receiving treatment, median time to first treatment was 9.4 mo (range 0-331 mo). The most common initial treatments were erythropoiesis-stimulating agents (ESAs) (14%), hydroxyurea (28%), and ruxolitinib (22%). In total, 29 (46%) received ruxolitinib with median time to ruxolitinib treatment of 27.2 mo. Median duration of ruxolitinib treatment was 44.5 mo. Fourteen patients underwent allogeneic hematopoietic stem cell transplant (AHCT) at a median of 57.4 mo after diagnosis (range 6-123 mo). Transformation to acute myeloid leukemia (AML) occurred in 5 patients at a median time of 99 mo (range 51-178 mo) after diagnosis. Median overall survival (OS) was not reached. Five and 10-year OS estimated at 93% and 77%, respectively. No difference was seen in OS for patients with primary and secondary MF (p = 0.40). Conclusions: Primary and secondary MF are rarely diagnosed in patients ≤ 50 years old. In this cohort, patients are often CALR mutant, have lower-risk disease, and lack splicing mutations. Initial treatment strategies are varied, but favor cytoreductive approaches. The prognosis in these patients is favorable, but high-risk mutations can occur and progression to AML occurs in a minority of patients. AHCT remains a curative option; however, optimal timing for transplant is not clear. Figure Disclosures Kuykendall: Celgene: Honoraria; Janssen: Consultancy; Abbvie: Honoraria; Incyte: Honoraria, Speakers Bureau. Talati:Astellas: Honoraria, Speakers Bureau; Daiichi-Sankyo: Honoraria; Agios: Honoraria; Pfizer: Honoraria; Jazz Pharmaceuticals: Honoraria, Speakers Bureau; Celgene: Honoraria. Sweet:Abbvie: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Agios: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Celgene: Speakers Bureau; Jazz: Speakers Bureau; Incyte: Research Funding; Pfizer: Consultancy; Stemline: Consultancy. Sallman:Celyad: Membership on an entity's Board of Directors or advisory committees. List:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Lancet:Daiichi Sankyo: Consultancy, Other: fees for non-CME/CE services ; Agios, Biopath, Biosight, Boehringer Inglheim, Celator, Celgene, Janssen, Jazz Pharmaceuticals, Karyopharm, Novartis: Consultancy; Pfizer: Consultancy, Research Funding. Komrokji:JAZZ: Consultancy; Agios: Consultancy; celgene: Consultancy; pfizer: Consultancy; Incyte: Consultancy; Novartis: Speakers Bureau; DSI: Consultancy; JAZZ: Speakers Bureau.

Impact of Bone Marrow Fibrosis Grade in Post-Polycythemia Vera and Post-Essential Thrombocythemia Myelofibrosis. a Study of the Mysec Group

Impact of Bone Marrow Fibrosis Grade in Post-Polycythemia Vera and Post-Essential Thrombocythemia Myelofibrosis. a Study of the Mysec Group

Vitamin B6 deficiency is prevalent in primary and secondary myelofibrosis patients.

Vitamin B6 (VB6) deficiency contributes to oncogenesis and tumor progression in certain cancers, and is prevalent in cancer patients in general. VB6 is also an essential element of heme synthesis, and deficiency can lead to anemia. Primary myelofibrosis (PMF) and secondary myelofibrosis (sMF) are myeloproliferative neoplasms often presenting with anemia along with other cytopenias. We performed a prospective study to determine whether PMF and sMF patients suffer from VB6 deficiency, and whether VB6-deficient patients show improvement of anemias with VB6 supplementation. Twelve PMF patients and 11 sMF patients were analyzed. A total of 16 of 23 patients (69.6%) were found to have VB6 deficiency, but VB6 supplementation with pyridoxal phosphate hydrate did not elevate hemoglobin levels in deficient patients. None of the patients presented with vitamin B12, iron, or copper deficiencies. Four patients showed serum folate levels below the lower limit of normal and eight patients showed serum zinc levels below the lower limit of normal; however, these deficiencies were marginal and unlikely to contribute to anemia. Compared to VB6-sufficient patients, VB6-deficient patients showed significantly lower serum folate levels and higher serum copper levels. Studies elucidating the relationship of VB6 deficiency and etiology of PMF/sMF are warranted.

PF655 PROGNOSTIC RELEVANCE OF THE GENE EXPRESSION SIGNATURE IN PRIMARY AND SECONDARY MYELOFIBROSIS

Background: Primary myelofibrosis (PMF) together with polycythemia vera (PV) and essential thrombocythemia (ET) belongs to the classic Philadelphia-negative myeloproliferative neoplasms (MPNs). PV and ET can evolve to secondary myelofibrosis (SMF) giving rise to post-PV (PPV) and post-ET (PET) myelofibrosis (MF). PMF and SMF patients are currently managed in the same way and prediction of survival is based on the same prognostic models, even if it has been demonstrated that they can’t accurately distinguish different risk categories in SMF. In the last few years interest grew concerning the ability of gene expression profiling (GEP) to provide valuable prognostic information for clinical decision making. Several studies demonstrated that GEP can improve risk classification in hematologic malignancies such as AML, MDS and lymphoma. Aims: As a preliminary result we performed GEP in PMF and SMF CD34+ cells and identified a gene signature that was able to distinguish patients with a better prognosis from that with a worse one. To confirm these results and to ease the possible clinical use of a molecular signature based on gene expression we decided to move to a more accessible cell population. Methods: Granulocytes were isolated from 114 MF patients (35 prefibrotic/early PMF, 37 overt PMF, 26 PET and 16 PPV) and total cellular RNA was extracted. Gene expression profiling (GEP) was performed using Affymetrix platform. In order to identify genes whose expression is related to survival in MF patients, we performed a Cox regression analysis by means of Partek GS Software. Results: Cox regression analysis led to the identification of a list of 650 transcripts which discriminate high-risk (HR) MF patients from low-risk (LR) ones. According to our results, the frequency of deceased patients was increased in the HR group and survival curves demonstrated that the median overall survival was lower in the HR group compared to the LR one (3.25 y vs 6.88 y, Log-rank p-value <0.01). Moreover, we observed that 11 out of 13 AML transformed patients clustered within the HR group. Interestingly, we found that HR group was enriched in patients carrying at least one high molecular risk mutation (EZH2, ASXL1, IDH1/2, SRSF2), while there was no significant difference between the two groups regarding the disease and the driver mutation. Concerning clinical variables, we observed that median age at diagnosis was higher in the HR group (65.6 y vs 62.1 y, p-value <0.05). WBC count was increased in the HR group (12.9 x109/L vs 9.3 x109/L, p-value <0.05), while platelet count was decreased in the same group compared to LR ones (218 x109/L vs 352 x109/L, p-value <0.01). Moreover, the percentage of patients with more than 1% circulating blasts is greater in the HR group. Finally, we studied the distribution of samples classified according to DIPSS prognostic model. Strikingly, our gene signature classifies as HR several patients belonging to the DIPSS low and intermediate-1 categories. These patients are deceased or leukemia transformed into a shorter time frame than the median survival reported for the reference prognostic class. Summary/Conclusion: Our results demonstrate that GEP of primary MF cells colud be a useful tool for risk prediction in PMF and SMF since it can improve the identification of patients’ subgroups characterized by a poor prognosis. These results should be validated in independent patient cohorts in order to confirm their predictive power.

Solid Tumors in Post-Polycythemia Vera and Post-Essential Thrombocythemia Myelofibrosis: A Study on 2220 Patients

Solid Tumors in Post-Polycythemia Vera and Post-Essential Thrombocythemia Myelofibrosis: A Study on 2220 Patients

Driver Mutation Profile By MLPA in Myelofibrosis Patients

Myelofibrosis is the rarest and most severe Ph- myeloproliferative neoplasm and can present de novo or post Polycythemia Vera or Essential Thrombocythemia. It is characterized by bone marrow fibrosis, extramedullary hematopoiesis and abnormal expression of inflammatory cytokines resulting in several atypical events and may progress to Acute Leukemia. The disease arises from clonal expansion of a single hematopoietic stem cell (HSC), driven by a somatic mutation of JAK2, CALR or MPL genes combined with dysregulation of hematopoietic microenvironment, additional mutations and cytogenetic abnormalities.The aims of this study are to assess driver mutations status in primary or secondary myelofibrosis patients and to correlate their mutational profile with clinical outcomes. The search for JAK2V617F, exon 12 JAK2, calreticulin exon 9 c.1092_1143del52 and c.1154_1155insTTGT, MPLW515K and MPLW515L mutations was performed in 31 subjects using MLPA technique, a method of DNA analysis that allows simultaneous appraisal of different mutations in multiple samples. 48.4% of patients present the JAK2V617F mutation,indel CALR mutations in 38.7% of patients (of these, 66.7% with del52 bp, 33.3% harbored insTTGTC),MPL W515L in 3.2% of patients and 9.7% of patients were triple-negative. From the mutational profile information obtained by MLPA,the clinical-molecular risk score was calculated for each of the individuals in the sample, according Rumi et al.. Being at 12,9% (4) as very low risk, 9.7% (3) as low risk,35.4% (11) as intermediary risk, 29.1% (9) and of high risk, and 12.9%(4) as very high risk. Patients with mutated JAK2 were older, with minor degree of anemia and more leukocytosis, whereas those with CALR mutations had less frequency of leukocytosis and thrombocytopenia. Triple-negative subjects displayed the lowest median age at diagnosis (49.3 years), and bone marrow failure phenotype, similar to Myelodysplastic Syndrome. Risk stratification provided by DIPSS was similar to other centers.Individuals with PMF present constitutional symptoms significantly more often than those with post-ET MF(p = 0.0365).Mortality rate was 29%, and mean survival after diagnosis was 68.3 months. CALR mutated individuals presented higher average survival and median survival according to DIPSS was higher than predicted by the prognostic model, possibly due to the higher frequency of CALR mutations reported.Median follow-up time was 32 months (ranging from 10 months to 13 years).Thromboembolic phenomena were recorded in 19.3% of patients, and evolution to AML in 6.4% of patients and it was verified that 75% of the individuals with Myelofibrosis Post-ET presented thrombotic events at some point in the disease. The association between the DIPSS clinical-laboratory parameters and the demand of transfusion at diagnosis, with the occurrence of Acute Leukemia was assessed using Fisher's exact test but have no significant difference in these parameters between patients who evolved or not for Acute Leukemia. The JAK2 V617F mutation is expected to be present in 60 to 65% of individuals with Myelofibrosis, but this mutation has been identified in only 48% of patients. In contrast, the observed frequency of indel of the CALR, of 38%, was higher than the classically described, from 25 to 30%. The rate of mutation type 2 (ins 5-bp) was also higher than expected, 33.6%.Regarding the mutation subtypes of CALR, mutation type 1 (52-bp deletion) is observed in up to 80% of MFP cases, but has a similar frequency as type 2 (5-bp insertion) in patients with ET. The grouping of patients with primary MF and post-ET may have contributed to the higher incidence of type 2 CALR mutation observed in this sample, although much higher than the 13% frequency described in the literature in a mixed population. The type 1 mutation was observed in 66% of our patients with post-ET and mutated CALR, but the small number of individuals in the study does not allow to estimate the impact of this mutation in the evolution of the disease. Our fraction of CALR-mutated patients is much higher than those described in Asian, European, North American and Argentinean populations. The complex genetic landscape involved in initiation and progression of Myelofibrosis, instigates the adoption of integrative prognostic stratification models. In this scenario, MLPA is a powerful tool for molecular study, and a promising ally for MPN molecular characterization. DisclosuresNo relevant conflicts of interest to declare.

Rs2431697, a Polymorphism of Mir-146a, Is a Precozing Marker of Progression to Secondary Myelofibrosis: New Epigenetic Regulation of Jak/Stat3 Signaling

Introduction: Transformation to secondary myelofibrosis (MF) occurs as part of the natural history of polycythemia vera (PV) and essential thrombocythemia (ET), the two more indolent Ph-negative myeloproliferative neoplasms (MPN). Once transformed, survival is remarkably shorted. Chronic inflammation plays a critical role in the progression of MPN, driving clonal expansion toward end stage disease. Importantly, MPN are characterized by the production of inflammatory cytokines, by both malignant and non-malignant clone. Inflammation and cancer share a common pathway, i.e. NF-κB. Interestingly, miR-146a regulates TLR/NF-κB pathway through the inhibition of its targets, IRAK1 and TRAF6, decreasing the production of cytokines. Based on: i) miR-146a-/- mice develop an MF-like phenotype with aging; and ii) miR-146a polymorphism (miRSNPs) rs2431697, influences its expression levels (50% decrease in TT individuals); we hypothesized that lower miR-146a-5p levels associated to this miRSNPs may result in high risk to develop MF.Objective: To evaluate the association of rs2431697 with MF transformation and to study the molecular mechanisms beyond this association.Methods: We genotyped rs2431697 in 938 patients (312 MF, 299 PV, and 327 ET) recruited from 13 tertiary Spanish institutions belonging to GEMFIN and 600 controls. The levels of miR-146a and IRAK1 were evaluated by qRT-PCR in total blood RNA of homozygous patients (TT=30, CC=25) with PV or ET and in healthy subjects (TT=7, CC=7). In miR-146a-/- mice, 2 and 9 months old, we evaluated spleen size and cellularity: degree of fibrosis in bone marrow (H&E and silver staining); and STAT3 and pSTAT3 in granulocytic lysates by western blot.Results: Association analysis, taken controls as reference, showed that TT genotype (associated in the literature with low levels of mir-146a) is associated to MF with an OR of 1.36 (1.01-1.82, p=0.04). Among MF patients, the subgroup with the greatest differences was the one of secondary MF (OR = 1.47, CI: 0.98-2.20) (Table 1 a,b). Next, we compared the genetic frequencies of rs2431697 SNPs between the secondary MF patients and the population in risk. Confirming our hypothesis, we observed an enrichment of TT genotype in the post-PV/TE MF group (n=132) compared to the PV+TE group (n=626) (OR=1.51; p<0.05), Table 1c. In patients with PV or true-ET (WHO criteria) and known clinical follow-up (n=243), excluding pre-fibrotic MF, 8.6% were transformed. The median time to transformation was 27 years, being significantly shorter in patients with PV (vs. ET); homozygous for JAK2V617F; and in TT carriers (vs. TC+CC) (Figure 1A). The mayor differences were seen at early time points (Wilconxon test, p=0.001). In fact, 7 out of 10 TT patients who progress to MF, did so in the first 10 years after diagnosis (70%) as compared with 2 out of 11 CC/CT patients (18%).Both groups (TT and TC+CC) were similar in age, sex, cell counts, initial diagnosis (PV/ET), driver mutations and fibrosis grade 1. In the multivariate analysis, TT genotype remained statistically significative [OR 2.87; CI: 1.19-6.94; p=0.019], independently of phenotype (PV/ET) or V617F allele burden. Both in JAK2 mutated and wild type patients, the time to progression to secondary MF was significantly shorter among TT patients (p=0.027) (Figure 1B). Moreover, TT genotype helped to categorize the risk of progression to MF independently of the driver mutation (JAK2 or CALR) or JAK2 burden allele (p=0.06) (Figure 1C). Consistently, TT patients showed a trends towards a lower expression of miR-146a (p=0.08) and higher IRAK1 (p=0.07) with a significant correlation between both (p<0.01). Finally, we evaluated the association between the JAK-STAT3 and TLR/NF-κB pathways in mice miR-146a-/-. We observed higher total STAT3 and pSTAT3 expression levels in miR-146a-/- than in WT mice (Figure 1D). This increase correlated with aging, and were associated with the appearance of splenomegaly, extramedular hematopoyesis and bone marrow fibrosis at 9 months of age (Figure 1E).Conclusion: rs2431697-TT is an independent marker of early progression to secondary MF. The lower expression of miR-146a that this SNP confers is associated with an increase in JAK-STAT3 signaling. Our findings include, for the first time, miR-146a in the MPN signaling pathways. Thus, miR-146a, modulating the activation of NF-kB-IRAK1, could indirectly regulates JAK-STAT3 signalling.CINC424AES05T [Display omitted] DisclosuresFerrer Marin:Novartis: Consultancy, Research Funding; Incyte: Consultancy. Hernandez Boluda:Incyte: Consultancy; Novartis: Consultancy. García Gutiérrez:Incyte: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Research Funding, Speakers Bureau. Gómez-Casares:Bristol-Myers Squibb: Speakers Bureau; Incyte: Speakers Bureau; Novartis: Speakers Bureau. Besses:Novartis: Honoraria, Research Funding; Shire: Honoraria.

Prognostic implications of low transferrin saturation in patients with primary myelofibrosis

ObjectivesTransferrin saturation (TSAT) 20% or less is considered to represent functional iron deficiency in the context of malignant disease, phenomenon mediated through inflammatory changes of iron homeostasis. We aimed to investigate clinical and prognostic significance of low TSAT in patients with primary (PMF) and secondary myelofibrosis (SMF), malignant diseases characterized by strong inflammatory milieu. MethodsWe retrospectively analyzed 87 patients with myelofibrosis and compared TSAT with disease specific parameters. ResultsOne-third of patients had TSAT ≤20%. Lower TSAT was significantly associated with Janus-kinase-2 (JAK2) mutation (P = 0.007), transfusion independency (P = 0.003), higher platelets (P = 0.004), lower mean-corpuscular-volume (P < 0.001), lower ferritin (P < 0.001), higher absolute-neutrophil-count (P = 0.027), lower absolute-lymphocyte-count (P = 0.041) and lower albumin (P = 0.018). PMF patients presenting with low TSAT (≤20%) experienced significantly shorter overall-survival (OS) (HR = 2.43; P = 0.017), whereas TSAT did not affect OS of SMF patients (HR = 1.48; P = 0.623). Low TSAT remained significantly associated with inferior OS in PMF in a series of multivariate Cox regression models comparing its properties to anemia, transfusion dependency, ferritin and Dynamic-International-Prognostic-System (DIPSS). ConclusionsLow TSAT has detrimental effect on survival of PMF patients. This effect is independent of anemia and of ferritin levels that seem to be better at representing iron overload in PMF patients.

Increased mean platelet volume (MPV) is an independent predictor of inferior survival in patients with primary and secondary myelofibrosis.

Neoplastic megakaryopoiesis is a dominant feature of Philadelphia-chromosome-negative myeloproliferative neoplasms (Ph- MPNs), and elevated mean-platelet-volume (MPV) is a common finding in these diseases. The clinical and prognostic significances of MPV in patients with primary (PMF) and secondary myelofibrosis (SMF) have not been reported. We retrospectively analyzed 87 patients with myelofibrosis (66 with PMF, 21 with SMF) treated at our institution. MPV was recorded in addition to other hematological and clinical parameters. MPV was elevated in both PMF and SMF patients in comparison to controls, whereas there was no statistically significant difference between PMF and SMF. Elevated MPV was associated with lower platelets (P=0.016), higher white blood cells (P=0.015), higher percentage of circulatory blasts (P=0.009), higher lactate dehydrogenase (P=0.011), larger spleen size (P=0.014) and higher Dynamic International Prognostic score category (P=0.027), while there was no statistically significant association with driver mutations or degree of bone marrow fibrosis. Higher MPV was univariately associated with inferior overall survival in the whole cohort (HR=3.82, P=0.006), PMF (HR=4.35, P=0.007) and SMF patients (HR=7.22, P=0.034). These associations remained significant in multivariate analyses adjusted for DIPSS. Higher MPV is associated with more aggressive disease features and exhibits powerful independent prognostic properties in both PMF and SMF settings.

A clinical-molecular prognostic model to predict survival in patients with post polycythemia vera and post essential thrombocythemia myelofibrosis.

Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms with variable risk of evolution into post-PV and post-ET myelofibrosis, from now on referred to as secondary myelofibrosis (SMF). No specific tools have been defined for risk stratification in SMF. To develop a prognostic model for predicting survival, we studied 685 JAK2, CALR, and MPL annotated patients with SMF. Median survival of the whole cohort was 9.3 years (95% CI: 8-not reached-NR-). Through penalized Cox regressions we identified negative predictors of survival and according to beta risk coefficients we assigned 2 points to hemoglobin level <11 g/dl, to circulating blasts ⩾3%, and to CALR-unmutated genotype, 1 point to platelet count <150 × 109/l and to constitutional symptoms, and 0.15 points to any year of age. Myelofibrosis Secondary to PV and ET-Prognostic Model (MYSEC-PM) allocated SMF patients into four risk categories with different survival (P<0.0001): low (median survival NR; 133 patients), intermediate-1 (9.3 years, 95% CI: 8.1-NR; 245 patients), intermediate-2 (4.4 years, 95% CI: 3.2-7.9; 126 patients), and high risk (2 years, 95% CI: 1.7-3.9; 75 patients). Finally, we found that the MYSEC-PM represents the most appropriate tool for SMF decision-making to be used in clinical and trial settings.

Treatment-Related Infections and Risk Factors in Patients with Myeloproliferative Neoplasms Treated with Ruxolitinib

▪Ruxolitinib is an orally available JAK1/2 inhibitor FDA approved for the treatment of myelofibrosis and polycythemia vera. Evidence suggest the effect of ruxolitinib on IL-1, IL-6, and TNF-α, among other immune mediators, may predispose patients to both opportunistic and non-opportunistic infections. Identification of patients at risk for infection while on a JAK inhibitor may impact clinical management. Authors sought to determine the cumulative incidence of ruxolitinib-related infections in the clinical practice setting and evaluated patient factors in order to characterize the types, onset, and severity of infections.This IRB approved, single-center, retrospective study at Memorial Sloan Kettering Cancer Center included myeloproliferative neoplasm (MPN) patients treated with ruxolitinib who were ≥18 years of age between 12/1/11 and 12/31/15. Patients on ruxolitinib for less than seven days, receiving ruxolitinib therapy for a non-MPN diagnosis, or had a manifestation of acute leukemia were excluded. Patients who met inclusion criteria were censored at time of splenectomy and hematopoietic stem cell transplant. Patients were identified through electronic medical records and an internal pharmacy database. Cumulative incidence of treatment-related infection was estimated and association with factors was assessed using competing risk regression analysis. Death without an infection was considered a competing risk event.A total of 44 patients were included in this analysis. The median age of this cohort was 66.5 years, with a slightly predominant male population (57%). There were 19 (43%) primary and 19 (43%) secondary myelofibrosis patients, 4 (9%) with polycythemia vera, and 2 (5%) patients with an unclassifiable MPN. For myelofibrosis patients, according to the Dynamic International Prognostic Scoring System (DIPSS), 2 (5%) were low risk, 3 (7%) were intermediate-1, 16 (36%) were intermediate-2, and 7 (16%) were high; remaining patients did not have available DIPSS scores at the time of evaluation. The median number of prior lines of therapy was 1.5 (range 0-4); median total daily dose of ruxolitinib was 10 mg. A majority of patients (70%) were not on concomitant immunosuppressive therapy during ruxolitinib treatment or strong CYP3A4 inhibitors (95%) that may have increased exposure to ruxolitinib.A total of 20 documented infections were identified throughout the evaluation period; median follow-up among survivors was 16 months (range 3-51). Cumulative incidences of treatment related infection were 33% by year 1 and 56% by year 2 of ruxolitinib treatment. Of these infections, four were CTCAEv4.0 grade 1 (one asymptomatic upper respiratory tract infection (URI) occurred after discontinuation was censored), seven were grade 2, and eight were grade 3. One grade 5 infection, septic shock of unknown origin occurred. Only one opportunistic pulmonary tuberculosis infection occurred 13 months post ruxolitinib treatment. The remainder of infections varied, including URIs(n=9), pneumonia, diverticulitis, osteomyelitis, clostridium difficile, proctitis, catheter-associated UTI, dental abscess, herpes zoster activation of the skin, and oral herpes simplex reactivation (all n=1)). One patient required viral prophylaxis for recurrent herpes simplex infections.With the limited number of events, no factors were found to be significantly associated with increased risk of infection but a trend toward increased risk of ruxolitinib-related infection was observed with baseline renal impairment. (Table 1).Conclusion: This data suggests a higher incidence of ruxolitinib associated infections observed in clinical practice compared to rates described in trials of ruxolitinib therapy. This may be attributable to differences between populations in the COMFORT and RESPONSE trials and patients in the clinical practice setting. Generally, infections were non-life threatening and managed with appropriate supportive care. Plasma values of ruxolitinib metabolites increase as renal function declines, correlation of infection risk via increased metabolites exposure warrants further exploration. Routine antimicrobial prophylaxis for all patients receiving ruxolitinib therapy is likely not warranted. However larger studies are needed to confirm these observations. [Display omitted] [Display omitted] DisclosuresMauro:Pfizer: Consultancy; Ariad: Consultancy; BMS: Consultancy; Novartis: Consultancy.

A New International Multicenter-Based Model to Predict Survival in Myelofibrosis Secondary to Polycythemia and Thrombocythemia: The Mysec Prognostic Model (MYSEC-PM)

Background. Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic myeloproliferative neoplasms that can progress to secondary myelofibrosis (MF), named post-PV (PPV) MF and post-ET (PET) MF. While outcome of primary myelofibrosis is defined on the basis of the IPSS models, information on outcome of secondary myelofibrosis (SMF) is scant. The objective of this study is to develop a prognostic model to predict survival of SMF.Patients and Methods.A total of 718 patients from 16 international Centers were included in this study. Diagnosis of PPV-MF and PET-MF was according to the IWGMRT criteria. Since survival varied among centers, statistical analyses took into account this cluster effect. Survival was calculated utilizing Kaplan-Meier estimates for univariate categorical risk factors and Cox proportional hazard regression, when performing multivariate analysis. The log-rank test was applied to compare Kaplan-Meier curves. Survival was censored at date of stem cell transplant, splenectomy or trial enrollment.Results. Among 718 SMF, 364 (51%) were PET-MF and 354 (49%) PPV-MF. The median follow-up was 2.4 years (range, 0.6-20.1). Median age was 64 years (range, 25-96), 370 were males (52%). Median time from PV/ET diagnosis to SMF diagnosis was 10.6 years (range, 2.5-41). Median values of hemoglobin, white blood cell count and platelet count were 11.2 g/dL (range, 5-17), 10.2 x10(9)/L (range, 1.1-98.4) and 343 x10(9)/L (range, 16-1908), respectively. Splenomegaly was present in 606 patients (87%) and constitutional symptoms in 329 (47%). Cytogenetic profile (N= 338) was normal in 222 (66%), unfavorable in 40 (12%), abnormal but favorable in 76 (22%), and the JAK2 (V617F) mutation (N=679) in 73%. Anemia, leukocytosis, thrombocytopenia, advanced age, circulating blasts, JAK2(V617F), constitutional symptoms, time to SMF, history of thrombosis negatively affected survival in univariate analysis (maximum P values, 0.043), while type of diagnosis (PPV, PET), splenomegaly, spleen size, cytogenetics, and cardiovascular risk did not. Since survival did not differ between PPV and PET, multivariable analysis was carried out on a subset of 493 SMF patients randomly selected and stratified by diagnosis from the original cohort of 718 patients to generate the MYSEC-PM. The remaining 225 were used as validation cohort. By multivariable analysis, age over 65 years (Hazard Ratio –HR- 2.6, 95%CI: 1.5-4.4; p<0.0001), time from PV/ET to SMF exceeding 15 years (HR 1.7, 95%CI: 1.3-2.2, p<0.0001), history of thrombosis (HR 2.1, 95%CI: 1.2-3.6, p=0.01), presence of constitutional symptoms (HR 1.8, 95%CI: 1.3-2.6; p=0.001), hemoglobin level less than 10 g/dl (HR 1.5, 95%CI: 1.1-2.0, p=0.004) and circulating blast cells equal to or higher than 1% (HR 2.1, 95% CI: 1.5-2.8, p< 0.0001) retained their significant impact of survival. To develop the prognostic model, we assigned each factor an integer weight closest to the corresponding HR in 421 patients with all available data: age >65 years (3 points), time to SMF >15 years (2 points), history of thrombosis (2 points), constitutional symptoms (2 points), hemoglobin <10 g/dL (1 point) and circulating blast >= 1% (2 points). To facilitate the use in clinical practice, the MYSEC-PM was recoded into three broader categories: low-risk (score, 0 to 2), intermediate-risk (score, 3 to 6), high-risk (score >6). Survival was significantly different among the risk groups (Figure 1, p< 0.0001): median survival and its 95% CI was not reached in low-risk, 7.9 years (95% CI: 6.7-9.3) in intermediate and 3.8 (95% CI: 2.2-5) in high-risk. The predictive value of MYSEC-PM was confirmed in the validation cohort (N=190) with the maximum p value in pairwise comparisons of 0.01. In the validation cohort, by Akaike information criterion, MYSEC-PM model better predicted survival than the IPSS/DIPSS models (N=190, AIC, 330.5 vs. 336.5 vs. 334.3, respectively) and also compared to the DIPSS-plus (N=91, 103.8 vs. 106.5, respectively): lower score implies better prediction.Conclusions. The MYSEC prognostic model, based on age >65 years, time to SMF >15 years, previous thrombosis, constitutional symptoms, hemoglobin <10 g/dL and circulating blast equal or >1%, clearly distinguishes outcome of patients with SMF and outperforms PMF risk models among those patients. This model can be considered for tailoring treatment according to disease risk in SMF. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.