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Over the past decade NGS has expanded our understanding of the genomic landscape of hematological malignancies. New biomarkers discovered during NGS are now widely used in clinical practice to improve diagnosis, stratify patients into prognostic groups, and select targeted therapy for Ph-MPN patients.To assess possibilities of NGS in diagnosis and determination of prognostic features of disease course in Ph-MPN patients.The study included 36 patients from clinics in Moscow and St. Petersburg (17 men and 19 women), the median age was 55 (IQR 27-79) with diagnosed PV, ET, PMF, MDS, AML.A panel of 116 genes with an average reading depth of 200x or 1000x on MiSeq (Illumina) was used. NGS panel had a detection limit of 3% variant allele frequency. The clinical significance of mutations was determined using COSMIC and ClinVar.Genetic abnormalities were detected in all patients. On average, 10 mutations per one patient were revealed, including 4 somatic mutations in 92% (33/36) patients. In 70% (25/36), from 1 to 3 mutations with known clinical significance were found. In all patients without driver and somatic mutations (ASXL1, EZH2, etc.) and chromosomal aberrations, somatic mutations (both clinically significant and unknown clinical significance) were detected, that served as clonality confirmation. All patients were divided into two groups: 1) driver mutations, normal karyotype (16/36) (favorable prognosis) and 2) triple-negative mutational status (20/36) with additional patients having mutations in epigenetic regulators genes (4/36) (unfavorable prognosis). In the first group, NGS revealed additional mutations in 8/16 (50%) patients (ASXL1, EZH2, IDH1) and in 3/16 (19%) were noted mutations in TET2 gene. In an unfavorable group, additional mutations were also found in genes of epigenetic regulation (ASXL1, IDH1, SRSF2) and in signal transduction genes (RAS genes, PTPN11) and TET2.NGS data can confirm disease clonal nature, assess disease prognosis, and select target therapy for patients with Ph-negative myeloproliferative neoplasms. To get new information it is possible to expand the panel of sequenced genes, as well as study other genetic mechanisms underlying disease pathogenesis (e.g., changes in gene expression level, microRNAs, or transcription factors).

There is a subset of patients in the population who have undergone splenectomy for various reasons. Normally one of the spleen's functions is to eliminate defective blood cells and the impact of splenectomy on hematopoiesis is not clear yet.A patient born in 1993 with verified Minkowski-Chauffard's disease in 2005 is known to have a history of splenectomy at the age of 13 without any complications. The blood tests have been stable with minor deviations. In November 2016 patient consulted a hematologist due to complete blood count (CBC) which showed thrombocytosis (PLT -1101×10This patient with splenectomy in childhood developed clonal hemopoiesis though there were no diagnostic criteria of MPN.Splenectomy is frequently associated with thrombocytosis, its management and long-term outcomes in connection with diminished clonal hematopoiesis clearance are not yet well established.

Aim. To study the relationship of karyotype, JAK2, CALR, and MPL driver mutations and ASXL1 mutation status with the progression and prediction of primary myelofibrosis (PMF). Materials & Methods. The trial included 110 PMF patients (38 men and 72 women), median age was 59 years (range 18-82) with median follow-up after diagnosis of 2.6 years (range 0.1-23). The patients were examined for JAK2, CALR, MPL, and ASXL1 mutations. Restriction fragment length polymorphism technique was used for the analysis of V617F substitution in JAK2 and 515 codon mutation in MPL. CALR (exon 9) and ASXL1 (exon 12) mutation tests were performed using Sanger direct sequencing. In 48 (44 %) out of 110 patients bone marrow cell karyotype was determined. Clinical and hematological parameters and median overall survival (OS) of patients were analyzed with regard to detected genetic aberrations and combinations of them. Results. JAK2, CALR, MPL mutations were detected in 55 (50 %), 28 (25.5 %), and 7 (6.4 %) out of 110 patients, respectively. Triple negative (TN) status was identified in 20 (18.2 %) out of 110 examined patients. ASXL1 mutations were detected in 22 (20 %) out of 110 patients. Out of 48 patients in 32 (66.7 %) normal karyotype, in 3 (6.3 %) favorable karyotype, in 4 (8.3 %) intermediate-prognosis karyotype, and in 9 (18.7 %) unfavorable karyotype were detected. The comparison of clinical and hematological parameters showed a number of significant differences. JAK2-positive patients had a higher hemoglobin level (median 129 g/L; p = 0.021). TN was associated with a high IPSS risk (p = 0.011), low hemoglobin level (median 101 g/L; p = 0.006), drop in platelet count (median 266 x 109/L; p = 0.041), increased lymphocyte count (median 26.9 х 109/L; р = 0.001). The detection of terminating mutations in ASXL1 correlated with palpable enlarged spleen (р = 0.050), reduced platelet count (median 184 х 109/L; р = 0.016), leukocyte count > 25 х 109/L (р = 0.046), and blast count > 1 % (р < 0.001). Univariate regression analysis showed that terminating mutations in ASXL1 (hazard ratio [HR] 2.9; р = 0.018), unfavorable karyotype (HR 8.2; р < 0.001), and TN (ОР 8.1; р < 0.001) had prognostic value for OS. ASXL1 mutation was associated with significantly worse OS in TN patients. Median OS of ASXL1-negative patients without high-risk chromosomal aberrations was significantly longer than in patients with high-risk karyotype and/ or ASXL1 mutation. Conclusion. Several genetic defects in tumor cells are associated with phenotypic manifestations of PMF. Based on the results of cytogenetic analysis and mutation determination of JAK2, CALR, MPL, and ASXL1, patients can be classified in different “genetic” risk groups when PMF is diagnosed.

Aim. To analyze the effect on prognosis of mutations that are typical of acute myeloid leukemia (AML) patients. Materials & Methods. The study included 620 AML patients surveyed at Hematology Clinics of Saint Petersburg (Russia) and Charite Clinic (Berlin, Germany). G-banding of chromosomes was employed for cytogenetic testing. Aberration screening in DNMT3A, IDH1/2 genes was based on real-time polymerase chain reaction (PCR) with subsequent analysis of melting and sequencing profiles. Mutations in FLT3, NPM1 genes were revealed by PCR. Results. Mutations were identified in 343 (55.3 %) out of 620 patients. Significantly more often mutations were discovered in patients with normal karyotype (NK) (p = 0.001). FLT3-ITD mutation was associated with reduced medians of overall survival (OS) and disease-free (DFS) survival: 11.3 vs. 15.8 months with FLT3-ITD- (p = 0.005) and 10.0 vs. 13.3 months with FLT3-ITD+ (p = 0.009), respectively. The relation of FLT3-ITD allele burden to OS duration was also assessed. In the ITDlow/ITD- group the OS median was considerably longer than in the ITDhigh group (p = 0.028). In the group of patients with 1 mutation in NPM1 gene OS and DFS were much better in comparison with other patients (medians of 27.4 and 13.9 months, respectively, p = 0.040; 19.3 and 12.0 months, p = 0.049). Negative impact of mutations in DNM-T3A gene was noticed while assessing OS median: 12 (DN-MT3A+) and 15 months (DNMT3A-), respectively (p = 0.112). Mutations in IDH1 gene correlated with a better OS than in the group without mutations (p = 0.092). The rs11554137 polymorphism in IDH1 gene was associated with worse OS in the group of patients with NK (p = 0.186). In 144 patients various mutation combinations (from 2 to 5) were identified. It was demonstrated that mutations in FLT3 (FLT3-ITD), NPM1, DNMT3A, and IDH2 were identified significantly more often in combinations with other mutations (p = 0.001): NPM1+/ FLT3-ITD+ (20.8 %), NPM1+/FLT3-ITD+/DNMT3A+ (8.3 %), and FLT3-ITD+/DNMT3A+ (8.3 %). Patients with 1 mutation had a noticeably longer OS median compared with patients with 2 mutations (18.1 and 12.2 months; p = 0.003). In patients with NPM1+ according to their OS the most unfavorable additional mutation was FLT3-ITD (median 27.4 vs. 9.2 months; p = 0.019) and the combination of NPM1+/FLT3-ITD+/DNM-T3A+ (median 27.4 vs. 14.6 months; p = 0.141). OS of patients with DNMT3A+ showed a downward trend if FLT3-ITD additional mutation was identified (17.3 vs. 7.1 months; p = 0.074). Conclusion. Mutations in FLT3, DNMT3A, IDH1/2, NPM1 genes frequently occur in AML intermediate-risk patients, i.e. they determine the intermediate prognosis group in AML. The studied mutations considerably impact prognosis. It is important to take into consideration mutation type, its allele burden, and the presence of additional mutations. A patient with 2 mutations has a considerably worse OS compared with a patient with 1 mutation. The studied group of patients with the combination of NPM1+/FLT3-ITD+, NPM1+/ FLT3-ITD+/DNMT3A+, DNMT3A+/FLT3-ITD+ mutations has the poorest prognosis. Comprehensive analysis of genetic damages in AML patients allows to most accurately predict the course and prognosis of the disease and to plan targeted therapy.

Aim. To evaluate the clinical experience of bosutinib use for treatment of chronic myeloid leukemia (CML) patients with intolerance and resistance to other tyrosine kinase inhibitors (TKI), as well as to compare the obtained results with the data of clinical trials. Materials & Methods. The analysis was conducted on case history records of 51 CML patients (25 men and 26 women; median age was 56 years, range 28-86). By the beginning of bosutinib therapy 37 chronic phase, 8 acceleration phase, and 6 blast crisis patients were included in the study. Bosutinib was administered as second-line TKI treatment in 10 patients, as third-line treatment in 18 patients, and as fourth-line treatment in 23 patients. The causes for switching to bosutinib were poor tolerance of previous TKI therapy in 21 patients and resistance to previous TKI therapy in 30 patients. Results. The median duration of bosutinib treatment was 6 months (range 1-50). Bosutinib toxicity profile and its tolerance in common clinical practice corresponded to the data of clinical trials. Because of adverse events the therapy was discontinued only in 5 (10 %) patients. Complete hematological response was 88 % (persistent response was maintained in 76 % of patients); complete cytogenetic response (CCyR) was 39 %, (persistent response in 37 % of cases); major mo- lecular response (MMR) was 31 % (it was confirmed in 25 % of patients during the last follow-up visit). The efficacy of bosutinib in the real clinical setting was slightly higher compared to the results of clinical trials. This difference was associated with a disease phase, a reason for withdrawal of the previous TKI, line of treatment, BCR-ABL mutations, and the form of them. The therapy was continued in 22 (43 %) patients, most of them reached stable optimal response, both CCyR and MMR. Conclusion. Bosutinib appears to be an acceptable alternative to other TKIs having its specific mechanisms of action and adverse events. The efficacy and safety of bosutinib proved in routine clinical practice are sufficient to recommend it for use in national hematology.

Background. The treatment of chronic myeloid leukemia (CML) with tyrosine kinase inhibitors (TKI) have diminished death probability and have changed the disease course. Achievement of complete cytogenetic response (CCyR) and major molecular response (MMR) are serve as warranties for freedom of progression and death from CML. There are many of CML patients are needed to change of initial TKI therapy with choice of the most efficient and safe drug for continuous life-long therapy to reach the optimal results of CML treatment. The newest of registered TKI drug in Russia is Bosutinib which has dual BCR-ABL and SRC kinase inhibitory activity and had showed good tolerability and efficacy in case of other TKIs resistance or intolerance. Aim. To analyze of own Bosutinib experience in patients with chronic myeloid leukemia with other TKIs resistance or intolerance and to make comparison with clinical trial results. Materials and methods. Clinical trials results from peer-reviewed journals. Outpatients charts of 51 patients (25 male and 26 females) with CML. Disease phase at the moment of Bosutinib therapy initiation was as follows: chronic - 37; acceleration - 8, blastic - 6. Bosutinib was used in the next lines of TKI therapy: second - 10; third - 18; fourth - 23. The indications for Bosutinib therapy were: intolerance to previous TKI - 21; resistance to previous TKI - 30. Results. Median of therapy duration was 6 months (1-50 months). The adverse events and tolerability of Bosutinib were similar with clinical trials data. The treatment was withdrawn by the adverse event only in 5 (10%) patients. The rates of the responses in the whole group of patients were as follows: CHR - 88%, stable in 76%; CCyR - 39%, stable in 37%, MMR - 31% and was 25% at the last follow-up. The Bosutinib efficacy in real life settings was slightly higher than clinical trials data. The factors influencing treatment responses were: disease phase, cause of switching to Bosutinib, line of therapy and presence and kind of BCR-ABL mutations, Therapy was continued in 22 (43%) patients, most them achieved stable optimal treatment response (CCyR and MMR). Conclusions. Bosutinib is a real alternative to other tyrosine kinase inhibitors and has its own mechanism of action and adverse events profile. The use of Bosutinib in real life clinical practice settings showed its efficacy and tolerability and could serve as base for recommendation to apply Bosutinib in hematology practice in Russia. Disclosures No relevant conflicts of interest to declare.

Background: Thrombosis in Primary Myelofibrosis (PMF) is one of the main but not fully covered problem. Thrombotic complications in PMF occur more frequently than in general population and could result to morbidity and lethality of patients. Several previous studies have demonstrated different thrombotic rates related to type molecular driver mutation (JAK2V617F, CALR, MPL) in myeloproliferative neoplasms, but this fact now is not fully understood. The standard clotting tests cover only initial stages of coagulation and could not evaluate anticoagulant system. Its results are not varied in PMF patients with different mutations. We have interested and initiated study of the coagulation system in PMF patients with integral hemostasis test - Calibrated Automated Thrombography (CAT). Here we present the results of pilot study group assessment. Aim: to investigate of the coagulation system in PMF patients with different molecular driver mutations (JAK2V617F, CALR, MPL) using thrombin generation test. Methods: The study included 13 MF patients (26 - 71 years, median = 40). There were 11 females and 2 males. Nine patients were JAK2V617F positive, 3 had CALR mutations and one patient was MPL-mutated. Thrombin generation was assessed by calibrated automated thrombinography (CAT) according to Hemker et al. Assessments were conducted in platelet poor plasma (PPP) with or without presence of thrombomodulin (PPP reagent +/- TM) as an activator of protein C system. The following parameters were evaluated: endogenous thrombin potential (ETP, nM*min), peak thrombin (Peak, nM), lag-time (Lag, min), and time to peak (TTP, min). Sensitivity ETP and Peak for TM were calculated as percent of decreasing of these parameters after adding to assay of TM (S ETP, % and S Peak, % respectively). STATISTICA 6.0 package was used in data analysis. Results were presented as median (Me) with 95% confidence intervals (CI). Results: ETP was highest in JAK2V617F patients (1213.57; min 781.60-max 1781.26 nM*min), intermediate in CALR (1058.47; min 933.14-max 1190.79 nM*min) and lowest in MPL group (972.49 nM*min). However, the Peak was higher in CALR (207.57; min 165.63-max 235.36 nM) than in JAK2V617F (160.9; (min 94.38-max 317.11 nM) and MPL (136.19 nM). We have observed disruption of protein C functioning in JAK2V617F (S-ETP 34%, min 8.65%-max 68.73%; S-Peak 20%, min 0.01%-max 44.64%) and MPL (S-ETP 46%; S-Peak 24%) groups compared to CALR patients (S-ETP 6.4%, min 2.5%-max 9.2%; S-Peak 1.8%, min 0.87%-max 1.8%). Conclusion: The results of thrombin production were differed in relation to driver mutation type. JAK2V617F-patients produced more thrombin and have protein C system dysfunction. It could be serve as an explanation of higher risk of thrombosis in MF patients with JAK2V617F mutation. The yielded results force us to continue research to confirm our findings on representative sample of PMF patients. Disclosures No relevant conflicts of interest to declare.

Introduction. A generic drug is a pharmaceutical drug considered to be equivalent to a brand-name product. A generic drug has to contain the same active ingredients as those of the original formulation. Regulatory agencies used to require that generics be identical to their brand-name counterparts with regards to pharmacokinetic properties. In most cases, generic products are available after the patent protection given to a drug's original developer expires. In Russia, a patent protection lasts for a 10-year period from registration of the original drug. To this day, twelve Imatinib generics have been registered in Russia. Aim. To assess the safety and efficacy of Imatinib generics for treatment of newly diagnosed Chronic myelogenous leukemia patients that have been in our center since August 2012. Materials and methods. 30 newly diagnosed CML patients were started on generics. The drugs: 1) GenericPh 100 mg, in capsules (Ph-Syntez, Russia); 2) GenericG 100 mg, in tablets (Laboratorio TUTEUR S.A.C.I.F.I.A., Argentina); 3) GenericIm 100 mg, in tablets (Sandoz d.d. (Slovenia). Switching from one generic to another was done due to intolerance. We analyzed the range and frequencies of adverse events (AE), cumulative incidences of complete hematologic (CHR), major cytogenetic (MCyR), complete cytogenetic (CCyR), and early molecular responses (BCR-ABL Results. Duration of the treatment with generics was 7-45 months, with a median of 13 months (GenericPh (27) + GenericG (2) + GenericIm (1)). No unexpected adverse events were observed during the Imatinib generics treatment. The generics tolerance did not differ from that of the original brand-name drug. Six patients were switched to second-generation tyrosine kinase inhibitors (TKI2) due to Imatinib intolerance. One patient progressed to blastic phase at 3 months after diagnosis. Three deaths were registered (1 - due to CML and 2 due to concomitant diseases). Overall survival rate was 90% and CML-related mortality - 3%. CHR at 3 months of the treatment was achieved in 93% of the patients. Cumulative response rates for cytogenetic and molecular responses are presented in Table 1. MR4.0 was registered in 23% of patients during overall treatment. Seven patients were switched to TKI2 due to insufficient efficacy of Imatinib. At the time of analysis 13 patients remained on Imatinib generics treatment: 12 patients with CCyR and 1 with PCyR, including 10 patients with MMR. Conclusion. Use of generics demands evaluation of its equivalency and control during its adoption into clinical practice. In terms of efficacy or tolerance no significant differences between the Imatinib generics studied and the original brand-name drug in newly diagnosed CML patients were found. Disclosures Shuvaev: Pfizer: Honoraria; BMS: Honoraria; Novartis pharma: Honoraria. Fominykh:BMS: Honoraria; Novartis Pharma: Honoraria.

Introduction. The substitution of brand-name drugs with cheaper generics is a modern tendency in health-care to decrease the burden on government budget and improve access to efficient treatment. Worldwide, generics have to be identical to the original drug in terms of pharmaceutical (active ingredients) and biological (pharmacokinetic) properties. Unfortunately, in Russia, as in most countries, there are no government regulations of equivalency to a brand-name product regarding dosage, strength, route of administration, quality, performance, and intended use. In Russia, since August 2012 the original Imatinib has almost fully been substituted with generics for the treatment of chronic myelogenous leukemia (CML). Aim. To assess tolerance and efficacy of Imatinib generics in terms of response durability by comparing it with that achieved previously in CML patients, who had received treatment with original Imatinib before switching to the generics. Materials and methods. Seventy-nine CML patients treated initially with original Imatinib (Novartis AG) with median treatment duration of 6.5 years (range, 0.5-11 years) were switched to generic drugs. The drugs: 1) GenericPh 100 mg, in capsules (Ph-Syntez, Russia) - 54 patients (44 with complete cytogenetic response (CCyR), including 32 with major molecular response (MMR); 2) GenericG 100 mg, in tablets (Laboratorio TUTEUR S.A.C.I.F.I.A., Argentina) - 25 patients (22 with CCyR, including 19 with MMR). In case of loss of response, besides non-compliance, we changed treatment to second-generation tyrosine kinase inhibitors (TKI2). Switching from one generic to another was made due to intolerance. We analyzed the range and frequency of adverse events (AE) and durability of responses achieved previously (hematologic, cytogenetic and molecular). IRIS data1 was used as a comparator for AE frequency during long-term Imatinib treatment. Statistical analysis included the Fisher exact test. Results. Tolerance of Imatinib generics was good with few exceptions. One patient in the GenericPh group suffered severe edema and was switched to Nilotinib with AE resolution. In the GenericG group 4/25 (16%) patients had severe gastroenterological toxicity (nausea, vomiting, abdominal distension, diarrhea) and were successfully switched to GenericPh. This might have been caused by the tablet filler (lactose) and related to concomitant lactose insufficiency in these patients. One patient had frequent infectious complications. Having stable deep molecular response, she entered the treatment free remission phase and had successful molecular response for more than two years. The frequency of other AEs is presented in Table 1. No significant differences were revealed between the generics and the original Imatinib in comparison with IRIS results. However, only 25% (20) of patients were free of any AE. No progression to AP/BC during the generics treatment was observed. Three deaths were registered (CML-related 1, blastic phase on Dasatinib treatment, the patient had only partial cytogenetic response to Imatinib and was switched to Dasatinib, with progression after 2 years on Dasatinib; cancer -1, cardiovascular disease -1). The patients who had inadequate responses to Imatinib before and after switching on generics were subsequently switched to TKI2: GenericPh - 11 patients (Nilotinib - 9 (CCyR - 8, MMR-7), Dasatinib - 2 (no CCyR with progression - 1, complete hematologic response -1)); GenericG - 3 patients (Nilotinib - 2, both with CCyR and MMR, Dasatinib - 1 -hematologic response with non-compliance). Durability of previousresponses was as follows: 4 patients lost their MMR: 3/54 (5.6%) while taking GenericPh and 1/25 (4%) - GenericG; 3 patients lost their CCyR: 2/54 (3.7%) while taking GenericPh and 1/25 (4%) - GenericG. All those patients were subsequently switched to TKI2 (3 re-achieving previous MMR and 1 demonstrating non-compliance). At the time of analysis there were still 58 (73%) patients on the generics treatment. 57 patients had CCyR and MMR, and one was not cytogenetically evaluated due to non-compliance (BCR-ABL 0.102%). Conclusion. No significant differences between the generics studied and the original Imatinib were observed in terms of their efficacy or tolerability in CML patients who were previously treated with a brand-name drug and subsequently switched to generics. Disclosures Shuvaev: Novartis pharma: Honoraria; Pfizer: Honoraria; BMS: Honoraria. Fominykh:Novartis Pharma: Honoraria; BMS: Honoraria.

Introduction. The characteristics of pathological clone cells in the Primary Myelofibrosis (PMF) strongly influence on the variability of the clinical course and prognosis. The main of them are type of driver mutation in JAK2, MPL or CALR genes ("clonal markers" (CM)), cytogenetic and epigenetic alterations. It is very important to provide the physicians necessary and sufficient information about the molecular profile of the disease to select the appropriate therapy for the patient. The aim of our study was to investigate mutational diversity in PMF patients from the North-West region of the Russian Federation and to estimate overall survival (OS) depending on the type of CM, cytogenetic and epigenetic features. Materials and methods. We examined 115 patients with PMF (45 male, 70 female). Median age was 59 years (range 19-82). The detection of V617F mutation of JAK2 was carried out for all the patients. JAK2(-) samples were tested for MPL gene 515 codon mutations and 9th exon mutations in the CALR gene. All patients underwent the analysis of mutations in EZH2, ASXL1 and IDH1 genes. Karyotype research was done for 47 patients with suitable bone marrow samples. Differences of mutation/karyotype occurrence in groups were assessed using the χ2 test. Survival curves were estimated by the method of Kaplan-Meier. Differences were considered as statistically significant with p-value Results. CM were detected in 87 patients: JAK2(+) 47% (54/115), CALR(+) 23% (26/115), MPL(+) 6% (7/115) cases. No CM were found in 24% (28/115) patients, who considered as triple-negative (TN). The median survival of TN patients was significantly shorter than in the group of patients with any CM: 4 years vs 14.5 years, p=0.005. Five-year OS in TN patients was 30.6%, JAK2(+) - 83.8% and CALR(+) - 93.5% (p=0.046) (Figure 1). Median survival in JAK2(+) patients was 14.7 years, CALR(+) - 9.8 years. In MPL(+) patients with follow-up of 4 years median survival has not been reached. Patients were divided into 2 groups based on the results of cytogenetic analysis: low-risk group (LR) included 27 patients with normal karyotype (NK) and 5 patients - with del(13)(q22), del(20)(q12), add(6)(p25), del(6)(q15) single features; high risk group (HR) consisted of 15 patients with complex abnormalities and unfavorable aberrations (+8, -7/7q-, i(17q), inv(3), -5/5q-, 12p-). Median survival in the LR group was 7.5 years, in the HR group - less than 1.5 years (p=0.025). Unfavorable karyotype frequency was distinct in groups with different CM: CALR(+) - 9.1% (1/11), JAK2(+) - 35% (7/20), TN - 54% (7/14), MPL(+) - 0% (0/2) cases but these differences were not significant (p=0.107). We detected 28 mutations of the ASXL1 gene in 26/115 patients (22.6%): 24 patients had single mutation and two patients harbored two ASXL1 mutations at once. Mutation frequency was 13% (7/54) in JAK2(+) patients, 27% (7/26) in CALR(+), 32% in TN, 29% in MPL(+) (2/7). Differences in OS depending on the ASXL1-status were statistically significant in the TN group: median survival of the ASXL1(-) patients was 3.5 years, ASXL1(+) - 1.5 years (p=0.013). Two mutations in the EZH2 gene (1.7%) were observed - each one in TN and ASXL1(+) patients. Both cases were characterized by rapid disease progression. The first patient (a 61-year-old male, complex karyotype) progressed rapidly to the blast phase from diagnosis and died after 8 months. The second patient (a 75-year-old male, NK) had severe thrombocytopenia and died from a hemorrhagic stroke 5 months from diagnosis. We also detected 8 (7%) mutations in the IDH1 gene: 5 in CALR(+), 2 in TN, 1 in JAK2(+) patients. In seven cases it was a synonymous substitution G105 and in one case it was missense mutation R132C. The patient with the R132C mutation (a 74-year-old female, CALR(+), NK) had an unfavorable disease course: progression to blast phase was observed after 9 months from diagnosis. The patient died 13 months after disease progression. Conclusion. CM and epigenetic mutations frequencies in our PMF patients is consistent with international data. Type of CM, cytogenetic aberrations and epigenetic changes can be correlated with different prognosis of PMF. The absence of any CM, unfavorable karyotype and ASXL1-status in TN patient are associated with reduced OS. The impact of ASXL1-status in patients with CM as well as EZH2 and IDH1-status on the prognosis in PMF patients requires further studies. Figure OS in different groups of PMF patients. Figure. OS in different groups of PMF patients. Disclosures Shuvaev: Novartis pharma: Honoraria; BMS: Honoraria; Pfizer: Honoraria. Fominykh:BMS: Honoraria; Novartis Pharma: Honoraria.