Myelofibrosis Grade Research Articles

Neuropilin2 in Mesenchymal Stromal Cells as a Potential Novel Therapeutic Target in Myelofibrosis.

Bone marrow fibrosis in myeloproliferative neoplasm (MPN), myelodysplastic syndromes (MDS), MPN/MDS overlap syndromes and acute myeloid leukemia (AML) is associated with poor prognosis and early treatment failure. Myelofibrosis (MF) is accompanied by reprogramming of multipotent bone marrow mesenchymal stromal cells (MSC) into osteoid and fiber-producing stromal cells. We demonstrate NRP2 and osteolineage marker NCAM1 (neural cell adhesion molecule 1) expression within the endosteal niche in normal bone marrow and aberrantly in MPN, MDS MPN/MDS overlap syndromes and AML (n = 99), as assessed by immunohistochemistry. Increased and diffuse expression in mesenchymal stromal cells and osteoblasts correlates with high MF grade in MPN (p < 0.05 for NRP2 and NCAM1). Single cell RNA sequencing (scRNAseq) re-analysis demonstrated NRP2 expression in endothelial cells and partial co-expression of NRP2 and NCAM1 in normal MSC and osteoblasts. Potential ligands included transforming growth factor β1 (TGFB1) from osteoblasts and megakaryocytes. Murine ThPO and JAK2V617F myelofibrosis models showed co-expression of Nrp2 and Ncam1 in osteolineage cells, while fibrosis-promoting MSC only express Nrp2. In vitro experiments with MC3T3-E1 pre-osteoblasts and analysis of Nrp2-/- mouse femurs suggest that Nrp2 is functionally involved in osteogenesis. In summary, NRP2 represents a potential novel druggable target in patients with myelofibrosis.

Impact of myelofibrosis on patients with myelodysplastic syndromes following allogeneic hematopoietic stem cell transplantation

BackgroundThe prognostic significance of myelofibrosis (MF) grade in patients with myelodysplastic syndrome (MDS) following an allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains elusive.MethodsWe retrospectively analyzed data from 153 patients with MDS who underwent allo-HSCT and divided the patients into the MF-0/1 (N = 119) and MF-2/3 (N = 34) cohorts to explore the impact of MF on outcomes of allo-HSCT.ResultsThe 2-year rates of relapse, non-relapse mortality (NRM), overall survival (OS), and progression-free survival (PFS) were 10.9% (95% confidence interval [CI] 5.9%–17.7%), 16.3% (95% CI 10.2%–23.6%), 76.6% (95% CI 69.0%–85.1%), and 72.8% (95% CI 65.0%–81.5%) in the MF-0/1 cohort, and 16.9% (95% CI 5.8%–32.9%), 14.7% (95% CI 5.3%–28.7%), 71.8% (95% CI 57.6%–89.6%), and 68.4% (95% CI 53.6%–87.2%) in the MF-2/3 cohort, respectively. No significant difference in the outcomes of allo-HSCT was observed between the two cohorts. Both univariate and multivariate analyses confirmed that MF-2/3 in patients with MDS had no effect on the prognosis of transplantation. In addition, major/bidirectional ABO blood type between donors and recipients was an independent risk factor for OS (hazard ratio [HR], 2.55; 95% CI 1.25–5.21; P = 0.010) and PFS (HR, 2.21; 95% CI 1.10–4.42; P = 0.025) in the multivariate analysis. In the subgroup of patients diagnosed with MDS with increased blasts (MDS-IB), it was consistently demonstrated that the clinical outcomes of the MF-2/3 cohort were comparable with those of the MF-0/1 cohort. The risk factors for OS and PFS in patients with MDS-IB were non-complete remission at transplantation and major/bidirectional ABO blood type.ConclusionsIn conclusion, MF grade had no significant effect on prognosis of allo-HSCT in patients diagnosed with MDS. Major/bidirectional ABO blood type should be carefully considered in the context of more than one available donor.

Application Value of 68 Ga-FAPI PET/CT in the Evaluation of Myelofibrotic Diseases.

Fibroblast activation protein is highly expressed in neoplastic lesions and various fibrotic tissues, making it an attractive target for disease evaluation. 68 Ga-labeled fibroblast activation protein inhibitor (FAPI), a new tumor interstitial imaging agent, holds promise for evaluating myelofibrosis. Therefore, this study aimed to use 68 Ga-FAPI PET/CT for the noninvasive visualization and quantification of the extent of myelofibrosis. This was a prospective clinical study involving 22 patients with myelofibrosis who underwent 68 Ga-FAPI PET/CT. The uptake of 68 Ga-FAPI was measured in their respective bone marrow and spleen, and the obtained imaging findings were compared with laboratory, cytogenetic, and histopathological data. 68 Ga-FAPI uptake in the bone marrow was significantly and positively correlated with the myelofibrosis grade ( r > 0.8, P < 0.001). 68 Ga-FAPI PET/CT showed visually negative results in patients with grades 0-1 myelofibrosis and positive in those with grades 2-3, but the level of involvement varied. 68 Ga-FAPI PET/CT provides a noninvasive means of visualizing the extent of systemic bone marrow involvement and differentiation between the early and advanced stages of fibrosis. 68 Ga-FAPI PET/CT shows promise as a method for visualizing and quantifying myelofibrosis, providing suitable sites for bone marrow biopsy. The extent of 68 Ga-FAPI uptake by bone marrow increases with the progression of myelofibrosis, thus it is a simple and noninvasive measurement that can be used to evaluate the progression of myelofibrosis. Nevertheless, although 68 Ga-FAPI PET/CT has demonstrated a potential value in prognostic assessment, further confirmation is needed.

MRI Reliably Captures Bone Marrow Metrics in Myelofibrosis

Purpose Biopsy remains the clinical standard for evaluating bone marrow of patients with myelofibrosis (MF). However, randomly sampling a small volume of bone marrow, typically from the ilium, fails to capture heterogeneity of disease across anatomic sites. The invasive, painful nature of the procedure limits patient acceptance of repeated biopsies to monitor disease status and response to therapy. Here, we present a non-invasive, MRI technique for evaluating bone marrow in MF. Participants and Methods We analyzed bone marrow of 66 study participants (45 with MF; 15 with essential thrombocytosis or polycythemia vera; and 6 healthy controls). We assessed participant bone marrow across three anatomic sites (vertebral bodies, ilium, and femoral heads), using three quantitative MRI sequences: proton density fat fraction (PDFF) for fat content; apparent diffusion coefficient (ADC) for cellular effect on water mobility; and magnetization transfer (MT) for macromolecular structure and fiber deposition. We correlated these MRI metrics with patient prognosis (dynamic international prognostic scoring system; DIPSS) and iliac biopsy data for cellularity and fibrosis (MF grade). Results Participants with MF had elevated MT ratio (MTR) and ADC and lower PDFF compared to healthy participants. Non-MF MPN participants demonstrated the same trend, though to a lesser extent. Individual MRI metrics correlated strongly across anatomic sites (r pearson from 0.57 to 0.89, p-value &amp;lt; 0.01), with notable heterogeneity both within and among different regions. DIPSS risk groups had limited correlation with MRI metrics. To understand to what extent quantitative MRI biomarkers identify fibrotic marrow, we developed a multivariate logistic regression model to stratify the 45 participants with MF by early fibrosis (MF grades 0-1) and overt fibrosis (MF grades 2-3). Of the seven total anatomy-MRI metric combinations, three had the greatest contributions toward grading marrow fibrosis: PDFF in the vertebral bodies and ilium along with ADC in the ilium. We developed the logistic regression model to predict early and overt fibrosis with these three parameters using a 70%/30% train/test split with 5-fold cross validation. Based on this model, quantitative MRI metrics are associated with the severity of fibrosis in the bone marrow (test set performance: accuracy = 84.6%, sensitivity to predict overt fibrosis = 88.9%, specificity = 75%, area under the receiver operator curve = 0.94). Conclusion Quantitative bone marrow MRI reliably captures relevant metrics of MF bone marrow, including cellularity and fat replacement by fibrosis, and may be useful in clinical drug trials and patient management for MF.

Zinpentraxin Alfa Reduces Myelofibrosis in a JAK2-V617F Mouse Model of Myeloproliferative Neoplasms

Background: Myeloproliferative neoplasms (MPNs) are clonal disorders of the hematopoietic stem cell (HSC), caused by somatic mutations in JAK2, MPL or CALR . Myelofibrosis, characterized by increased deposition of reticulin and/or collagen fibers, is found in advanced stages of MPN. Pentraxin-2 (PTX2, serum amyloid P component/SAP) belongs to the family of short pentraxins and acts as an inhibitor of fibrocyte differentiation and modulator of macrophage polarization. Zinpentraxin alfa (PRM-151, ZPN), a recombinant form of human PTX2, was reported to reduce myelofibrosis in a retroviral model of MPN driven by MPL-W515L (Verstovsek S et al, J Exp Med 2016). ZPN has also been investigated as monotherapy and in combination with ruxolitinib (RUX) in a phase 2 clinical study in patients with myelofibrosis (NCT01981850; Verstovsek S et al, Haematologica 2023). Evidence of clinical activity and tolerable safety as monotherapy and in combination with RUX was shown in that open-label, non-randomized trial. Here, we examined the effects of ZPN alone or in combination with RUX in a mouse model of MPN driven by Cre-inducible expression of human JAK2-V617F (Tiedt R et al, Blood 2008). Methods: To obtain sufficient numbers of mice for drug testing, bone marrow cells from JAK2-V617F mice were transplanted into lethally irradiated C57BL/6 recipients (Kubovcakova L et al., Blood 2013), and groups of 6 mice were sacrificed at 16, 20, and 24 weeks to determine the histological grade of reticulin fibrosis. 24 weeks post transplantation, grade 1-2 fibrosis was confirmed in these satellite mice and treatment was initiated. During treatment, weight and complete blood counts were monitored (n=8 mice per group). At terminal work-up, spleen weight and fibrosis grade were determined, along with flow cytometry of bone marrow and peripheral blood, single cell RNA sequencing of bulk bone marrow, and proteomics analysis by mass spectrometry of bone marrow and plasma. Additionally, we characterized the plasma pharmacokinetics (PK) in these mice following single IP (10 mg/kg) administration of ZPN. Results: Systemic exposure after IP administration was confirmed in each animal (T max at 4 h, C max 27.9 ug/mL,AUC 0-48 381 h*ug/mL). No weight loss or mortality were observed in ZPN monotherapy cohorts, and the slight weight loss observed in RUX treated animals was not potentiated by the addition of ZPN. A trend towards lower platelet, monocyte and total leukocyte counts was observed for ZPN treatment groups compared to vehicle controls (Figure 1A). RUX alone largely normalized hemoglobin values, while ZPN alone or in combination with RUX had less effect on hemoglobin. Terminal work-up showed grade 1-2 fibrosis in the vehicle group, whereas reticulin fibrosis decreased in the majority of mice with ZPN monotherapy or in combination with RUX (Figure 1B). ZPN monotherapy did not reduce spleen weight. Single cell RNA sequencing and proteomics analyses are currently being analyzed and data will be shown. Conclusion: ZPN treatment in a JAK2-V617F mouse model of MPN with myelofibrosis was well tolerated as monotherapy and in combination with RUX. A reduction in the grade of myelofibrosis was observed in all ZPN treatment groups. ZPN showed promising trends in reducing platelet and monocyte counts, while the decrease in hemoglobin by RUX was in part prevented in combination with ZPN.

Myelofibrosis at diagnosis is associated with the failure of treatment-free remission in CML patients.

The management of patients with chronic myeloid leukemia (CML) has been revolutionized by the introduction of tyrosine kinase inhibitors (TKIs), which induce deep molecular responses so that treatment can eventually be discontinued, leading to treatment-free remission (TFR) in a subset of patients. Unfortunately, leukemic stem cells (LSCs) often persist and a fraction of these can again expand in about half of patients that attempt TKI discontinuation. In this study, we show that presence of myelofibrosis (MF) at the time of diagnosis is a factor associating with TFR failure. Fibrotic transformation is governed by the action of several cytokines, and interestingly, some of them have also been described to support LSC persistence. At the cellular level, these could be produced by both malignant cells and by components of the bone marrow (BM) niche, including megakaryocytes (MKs) and mesenchymal stromal cells (MSCs). In our cohort of 57 patients, around 40% presented with MF at diagnosis and the number of blasts in the peripheral blood and BM was significantly elevated in patients with higher grade of MF. Employing a CML transgenic mouse model, we could observe higher levels of alpha-smooth muscle actin (α-SMA) in the BM when compared to control mice. Short-term treatment with the TKI nilotinib, efficiently reduced spleen weight and BCR::ABL1 mRNA levels, while α-SMA expression was only partially reduced. Interestingly, the number of MKs was increased in the spleen of CML mice and elevated in both BM and spleen upon nilotinib treatment. Analysis of human CML-vs healthy donor (HD)-derived MSCs showed an altered expression of gene signatures reflecting fibrosis as well as hematopoietic support, thus suggesting MSCs as a potential player in these two processes. Finally, in our cohort, 12 patients qualified for TKI discontinuation, and here we observed that all patients who failed TFR had BM fibrosis at diagnosis, whereas this was only the case in 25% of patients with achieved TFR, further supporting the link between fibrosis and LSC persistence.

Clinical characteristics and prognostic factors of patients with Philadelphia-negative myeloproliferative neoplasm accelerated/blast phase

Objective: To evaluate the clinical characteristics and prognostic factors of patients with Philadelphia-negative myeloproliferative neoplasm-accelerated phase/blast phase (MPN-AP/BP) . Methods: A total of 67 patients with MPN-AP/BP were enrolled from February 2014 to December 2021 at the Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences. Their clinical features and prognostic factors were analyzed retrospectively. Results: ① Sixty-seven patients with MPN-AP/BP with a median age of 60 (range, 33-75) years, including 31 males (46.3% ) and 36 females (53.7% ) , were analyzed. Forty-eight patients progressed from primary myelofibrosis (PMF) , and 19 progressed from other myeloproliferative neoplasms (MPNs) , which included polycythemia vera, essential thrombocythemia, and MPN unclassifiable. Patients who progressed from PMF had higher lactate dehydrogenase (LDH) levels than those who progressed from other MPNs (925.95 vs. 576.2 U/L, P=0.011) , and there were higher proportions of patients who progressed from PMF with splenomegaly (81.4% vs. 57.9% , P=0.05) , a myelofibrosis grade of ≥2 (93.6% vs. 63.2% , P=0.004) , and a shorter duration from diagnosis to the transformation to AP/BP (28.7 vs. 81 months, P=0.001) . ② JAK2V617F, CALR, and MPLW515 were detected in 41 (61.2% ) , 13 (19.4% ) , and 3 (4.5% ) patients, respectively, whereas 10 (14.9% ) patients did not have any driver mutations (triple-negative) . Other than driver mutations, the most frequently mutated genes were ASXL1 (42.2% , n=27) , SRSF2 (25% , n=16) , SETBP1 (22.6% , n=15) , TET2 (20.3% , n=13) , RUNX1 (20.3% , n=13) , and TP53 (17.2% , n=11) . The ASXL1 mutation was more enriched (51.1% vs. 21.1% , P=0.03) , and the median variant allele fraction (VAF) of the SRSF2 mutation (median VAF, 48.8% vs. 39.6% ; P=0.008) was higher in patients who progressed from PMF than those who progressed from other MPNs. ③ In the multivariate analysis, the complex karyotype (hazard ratio, 2.53; 95% confidence interval, 1.06-6.05; P=0.036) was independently associated with worse overall survival (OS) . Patients who received allogeneic stem cell transplantation (allo-HSCT) (median OS, 21.3 vs. 3 months; P=0.05) or acute myeloid leukemia-like (AML-like) therapy (median OS, 13 vs. 3 months; P=0.011) had significantly better OS than those who received supportive therapy. Conclusion: The proportions of patients with PMF-AP/BP with splenomegaly, myelofibrosis grade ≥2, a higher LDH level, and a shorter duration from diagnosis to the transformation to AP/BP were higher than those of patients with other Philadelphia-negative MPN-AP/BP. The complex karyotype was an independent prognostic factor for OS. Compared with supportive therapy, AML-like therapy and allo-HSCT could prolong the OS of patients with MPN-AP/BP.

Eltrombopag may induce bone marrow fibrosis in allogeneic hematopoietic stem cell transplant recipients with prolonged thrombocytopenia

Poor graft function (PGF) and secondary failure of platelet recovery (SFPR) are significant causes of transplant related morbidity and mortality. Although thrombopoietin receptor agonists (TPO-RA), particularly Eltrombopag (EPAG), have been reported to be efficacious in the treatment of prolonged thrombocytopenia, potential long term adverse effects remain to be elucidated. This retrospective study was performed to determine the efficacy and toxicity profile of TPO-RAs in allogeneic hematopoietic stem cell transplant (alloHCT) recipients. Medical records of 27 patients [median age: 55(21−73) years; male/female: 15/12] who received posttransplant EPAG for SFPR or PGF were analysed. Eltrombopag was started on day 110(33−670) after transplant. Median initial dose was 25(25−50) mg/day which was properly escalated to a maximum dose of 75(50−100) mg/day. Duration of the treatment was median 120(31−377) days. Overall response rate (ORR) was 59.3% in the study population. Time-to-treatment response was 42(3−170) days. Mild-to-moderate bone marrow fibrosis was detected in the posttreatment biopsies of 12/22 patients (54.5%), 9 of whom did not represent any grade of myelofibrosis in their inital biopsies. The grade of posttreatment fibrosis was significantly increased when time-to-treatment response was longer (p = 0.008). Long term use of TPO-RAs may be considered as a potential cause of myelofibrosis in alloHCT recipients.

Correlations Between the Expression of Stromal Cell Activation Related Biomarkers, L-NGFR, Phospho-ERK1-2 and CXCL12, and Primary Myelofibrosis Progression.

In myelofibrosis, pathologically enhanced extracellular matrix production due to aberrant cytokine signalling and clonal megakaryocyte functions result(s) in impaired hemopoiesis. Disease progression is still determined by detecting reticulin and collagen fibrosis with Gomori’s silver impregnation. Here, we tested whether the expression growth related biomarkers L-NGFR/CD271, phospho-ERK1-2 and CXCL12 can be linked to the functional activation of bone marrow stromal cells during primary myelofibrosis progression. Immunoscores for all tested biomarkers showed varying strength of positive statistical correlation with the silver impregnation based myelofibrosis grades. The intimate relationship between spindle shaped stromal cells positive for all three markers and aberrant megakaryocytes was likely to reflect their functional cooperation. L-NGFR reaction was restricted to bone marrow stromal cells and revealed the whole length of their processes. Also, L-NGFR positive cells showed the most intersections, the best statistical correlations with myelofibrosis grades and the strongest interrater agreements. CXCL12 reaction highlighted stromal cell bodies and a weak extracellular staining in line with its constitutive release. Phospho-ERK1-2 reaction showed a similar pattern to CXCL12 in stromal cells with an additional nuclear staining in agreement with its role as a transcription factor. Both p-ERK1-2 and CXCL12 were also expressed at a moderate level in sinus endothelial cells. Connexin 43 gap junction communication channels, known to be required for CXCL12 release to maintain stem cell niche, were also expressed progressively in the myelofibrotic stromal network as a support of compartmental functions. Our results suggest that, diverse growth related pathways are activated in the functionally coupled bone marrow stromal cells during myelofibrosis progression. L-NGFR expression can be a useful biological marker of stromal cell activation which deserves diagnostic consideration for complementing Gomori’s silver impregnation.

Outcomes for Myelofibrosis Patients Following Myeloablative Allogeneic Stem Cell Transplantation Using the Orca-T Graft from HLA-Matched Related and Unrelated Donors

Background: Allogeneic stem cell transplantation (allo SCT) is the only potentially curative therapy for patients with intermediate-2 and high-risk myelofibrosis (MF). Allo SCT for MF has historically been challenging as many patients are transplanted with active or advanced disease and immune reconstitution in MF patients is often hindered by inflammation and bone marrow fibrosis. When compared to non-SCT therapies, MF patients who receive allo SCT achieve long-term survival benefits. However, it comes with an upfront cost of an increased risk of non-relapse mortality in the first year after allo SCT (Gowin K et al, Blood Av 2020). Therefore, there is an unmet need to improve on the early outcomes of transplantation for MF.Methods: We reviewed MF patients who underwent myeloablative allo SCT with Orca-T derived from HLA matched donors on NCT01660607 and NCT04013685. Orca-T is an investigational cellular product comprising stem and immune cells that leverages highly purified donor regulatory T cells to control alloreactive immune responses. Single agent GVHD prophylaxis was administered as tacrolimus or sirolimus.Results: We present outcomes for 7 MF patients with DIPSS risk of int-1 (n=1), int-2 or higher risk MF (n=6) treated with the Orca-T graft and compared this to 6 MF patients who underwent standard of care (SOC) allo SCT at Stanford, between 2017 - 2021 (Table 1). All patients were high or very high-risk based on MIPSS70 plus score v, 2.0. All patients had 10/10 HLA-matched donors, except 1 of 7 Orca-T patients who had 9/10 HLA-matched donor. All but 1 patient in both, Orca-T and SOC, recipients had prior Jakafi exposure.All Orca-T recipients had splenomegaly with spleen size of 16.3 - 23 cm. Engraftment occurred at median of D+13 (range 10-29) and 6 of 7 patients had 100% CD3 donor chimerism at D+100. 1 patient was 90% CD3 donor chimerism at D+100 but achieved 100% CD3 donor chimerism at D+180. All patients had significant marrow fibrosis, MF grade 2 or 3, before allo SCT. Regression of marrow fibrosis to MF grade 0 or 1 was noted by D+ 100 in 7 of 7 Orca-T recipients but only in 1 of 6 SOC patients. Orca-T recipients did not have grade 2-4 acute GVHD and 1 of 7 recipients had extensive chronic GVHD. Tacrolimus was tapered off in 3 of 7 patients at D+180. SOC recipients had 2 of 6 recipients with grade 2-4 acute GVHD, 3 of 6 recipients with extensive chronic GVHD and only 1 recipient was taken off tacrolimus at D+180. There were no deaths in Orca-T recipients and 2 deaths in SOC recipients before D+180, cause of death was acute GVHD and relapse. Finally, when compared to standard allo SCT, Orca-T recipients may have a reduced frequency and severity of infections without significant consequences while the SOC patients had severe and often multiple infections.Conclusion: Our data indicates that Orca-T graft was well tolerated and potentially efficacious in MF patients undergoing allo SCT. We observed early regression of marrow fibrosis at D+100 in all Orca-T recipients. This limited data suggests that Orca-T may afford an early resolution of an inflammatory microenvironment that allows for robust immune reconstitution and potentially lower incidence of serious infections. Orca-T is under continued investigation to reduce early non-relapse mortality for MF. [Display omitted] DisclosuresGandhi: CareDx Inc: Honoraria; Gamida Cell: Consultancy, Membership on an entity's Board of Directors or advisory committees. Muffly: Pfizer, Amgen, Jazz, Medexus, Pfizer: Consultancy; Astellas, Jasper, Adaptive, Baxalta: Research Funding; Adaptive: Honoraria, Other: fees for non-CME/CE services: , Research Funding. Shiraz: Kite Pharma-Gilead: Research Funding. Fernhoff: Orca Bio: Current Employment. McClellan: Orca Bio: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Gotlib: Allakos: Consultancy; Cogent Biosciences: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Chair for the Eligibility and Central Response Review Committee, Research Funding; PharmaEssentia: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kartos: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Deciphera: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Blueprint Medicines: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Meyer: Triursus Therapeutics: Current holder of stock options in a privately-held company; GigaImmune: Current holder of stock options in a privately-held company; Orca Biosystems: Research Funding; Indee, Jura: Consultancy.

A Phase 2 Study to Evaluate the Efficacy and Safety of Selinexor in Patients with Myelofibrosis Refractory or Intolerant to JAK Inhibitors

▪Background:Selinexor is an oral, small molecule, selective inhibitor of nuclear export (SINE) compound that specifically blocks the karyopherin protein exportin 1 (XPO1, CRM1). In an shRNA library screen, we discovered that the survival of JAK2V167F mutant HEL cells is dependent on XPO1-mediated nuclear-cytoplasmic transport. Selinexor selectively suppressed primary myelofibrosis (MF) cells as compared with normal progenitor cells and induced hematologic responses in an MPN mouse model.Methods:An open label, prospective, investigator-initiated single center study is ongoing in adults with primary or secondary MF with resistance or intolerance to JAK inhibitor (JAKi) therapy with platelets > 30 K/μL and neutrophils > 500/μL. Selinexor was given orally once a week. Spleen volume was assessed by MRI at week 12 and week 24. The study was amended to include additional MRIs every 12 weeks in the year 1 and 24 weeks in the year 2. Primary end point is spleen response, defined as ≥ 35% spleen volume reduction (SVR) by MRI or CT, where applicable) at week 24. Bone marrow was evaluated at baseline and at week 24. The projected sample size of 24 will provide 83% power to reject a response rate of 15% and allow for up to a 25% dropout rate. We provide an interim report after completing 50% enrollment.Results:Between May 2019 and February 2021, 12 patients (pts) were enrolled. JAK2, CALR and MPL mutations were present in 7 (58.3%), 4 (33.3%) and 1 (8.3%) pts respectively. Eight pts (66.6%) had at least one high molecular risk mutation at baseline (Table 1). Median duration of prior JAKi therapy was 22 months (0.5 to 96 months) and 11 out of 12 were refractory to ruxolitinib at study enrollment. Median baseline spleen volume was 1454 cm 3(range 835 to 5792). Selinexor starting dose was 80 mg weekly in the first 6 pts and 60 mg for subsequent pts. At data cutoff, median duration of selinexor therapy was 36 weeks (range 11-114 weeks). One pt was not response evaluable and died due to liver abscess at week 12 (unrelated). One pt discontinued selinexor at week 18 due to grade 3 fatigue and was not evaluable for the primary end point. Of the 11 pts who had week 12 MRI or CT, 6 showed ≥ 10% SVR, 3 showed ≥ 25% SVR and 1 pt had early progression (Figure 1). At week 24, 5/9 (56%) pts had ≥ 25% SVR and 2/9 (22%) had ≥ 35% SVR (Figure 1). In 9 pts who had ≥24 weeks of selinexor, SVR ≥ 25% and ≥ 35% occurred at any point during study treatment in 4 (44%) and 3 (33%) pts, respectively. Two pts were red cell transfusion dependent at baseline; 1 became transfusion independent after 36 weeks of treatment, has not required transfusion for 49 weeks and remains on study treatment to date (114 weeks). Six pts (50%) discontinued selinexor. Reasons for treatment discontinuation are death in 1 pt, progressive disease in 1 pt, alternative treatment in 2 pts, and toxicity in 2 pts. Ten pts required dose reduction due to fatigue (1pt), anemia (1 pt), thrombocytopenia (2 pts), abdominal pain (1pt) and weight loss (5 pts). The most common treatment related adverse event was weight loss (grade 2 in 4 pts and grade 3 in 1 pt). This was manageable with treatment interruption and dose reduction, except in one pt who discontinued selinexor. As yet no changes in reticulin fibrosis MF grade were observed among 9 patients who received at least 24 weeks of treatment.Conclusions:Once weekly, oral selinexor showed single agent activity with sustained spleen responses in pts with JAKi refractory MF. Long-term administration of selinexor was well tolerated over time in MF pts. Correlatives studies including circulating inflammatory cytokine levels and mutant allele burden, as well as clonality studies by X-chromosome inactivation studies in woman, are underway and will be presented. [Display omitted] DisclosuresTantravahi: BMS: Research Funding; Novartis: Research Funding; CTI BioPharma: Research Funding; Abbvie Inc.: Research Funding; Karyopharm Therapeutics Inc.: Consultancy, Honoraria, Research Funding. Patel: Stemline: Research Funding; Genentech: Research Funding; Roche: Research Funding. Chamoun: Karyopharm Therapeutics Inc.: Current Employment, Current equity holder in publicly-traded company. Shah: Karyopharm: Current Employment. George: Celgene: Consultancy; Bristol Meyers Squibb: Consultancy; Incyte Corporation: Consultancy; Blueprint Medicines: Consultancy. Deininger: Fusion Pharma, Medscape, DisperSol: Consultancy; SPARC, DisperSol, Leukemia & Lymphoma Society: Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Part of a Study Management Committee, Research Funding; Blueprint Medicines Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Part of a Study Management Committee, Research Funding; Novartis: Consultancy, Research Funding; Sangamo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Honoraria, Research Funding.

Quantitative analysis of myelofibrosis and its prognostic significance in patients with myelodysplastic syndrome

Objective: To quantitatively analyze the reticulin fiber intensity density (RFD) in patients with myelodysplastic syndrome (MDS) by using the computer-aided grid point method, and preliminarily explore its correlation with the prognosis of MDS patients. Methods: Bone marrow (BM) slices from 32 primary MDS patients treated in Tongren Hospital Shanghai Jiao Tong University School of Medicine from February 2017 to December 2019 were observed. Images were taken by the optical microscope imaging system after the Gomori staining. The computer grid marking software was developed according to the principle of the mesh micrometer to assess RFD, meanwhile, the artificial semi-quantitative were used to assess the fibrosis of bone marrow. The co-relation between the above two methods was evaluated, and the relationship between RFD and prognosis of MDS patients were further investigated with Cox regression analysis. Results: Of the patients, there were 17 males and 15 females with a median age of 69 years (32-91 years). The RFD quantitatively analyzed by the computer-based method was positively correlated with the myelofibrosis grade by the artificial semi-quantitative analysis (r=0.497, P=0.004). The RFD in patients diagnosed with MDS complicated with excess blasts (MDS-EB) was significantly higher than that in the non-MDS-EB group((9.55%±0.75%) vs (1.71%±0.23%), P<0.001). Cox regression model analysis showed that the RFD of MDS patients had better prognostic value when compared with the artificial semi-quantitative analysis, which was also a poor prognostic factor (RR=1.337, 95%CI: 1.085-1.648, P=0.006). The overall survival (OS) of patients with RFD>5.54% was significantly shorter than that with RFD≤5.54% (P=0.001). The OS of MDS-EB patients with RFD>9.81% was significantly shorter than that in patients with RFD≤9.81% (P=0.003). Conclusion: Abnormal proliferative fibrosis of bone marrow is a potential high-risk factor for poor prognosis of MDS patients.

MO802DOES ETELCALCETIDE REVERSE MYELOFIBROTIC BONE CHANGES DUE TO HYPERPARATHYROIDISM? A CASE REPORT

Abstract Background and Aims A 21 year old boy with a diagnosis of Autosomal Recessive Polycystic Kidney Disease and Caroli disease reached a final stage of chronic kidney disease (CKD) and started haemodialysis. Method After 3 years in haemodialysis he underwent a kidney transplant from a cadaveric donor. His transplanted kidney worked fairly well until the patients was 31 year old when he developed graft dysfunction (serum creatinine from 2.7 to 5 mg/dL in a very short period). There was a concomitant increase in serum phosphate levels (8.3 mg/dl) and iPTH that progressively increased to 1032 pg/ml despite a traditional therapy. Results At age 32, the patient returned to haemodialysis treatment thrice weekly with a concomitant a progressive worsening of hyperparathyroidism with bone pain . Cinacalcet at a dosage of 30 mg daily treatment was initiated, then it was increased to 120 mg daily without any benefit. Two years later, being the clinical situation without any improvement and being the patient scarcely compliant to the therapy and because a further enlargement of parathyroid glands was observed, a Parathyroidectomy (PTX) was advised. Nevertheless, PTX was not performed because of patient’s refusal. Furthermore, despite Erythropoietic Stimulating Agent (ESA) therapy, he developed severe anemia that required regular and frequent blood transfusions. iPTH increased to 4500 pg/ml [Fig.1] with a parallel rise in alkaline phosphatase &amp;gt;600 UI/L [Fig.2]. A Computed Tomography scan showed multiple bone-thickening lesions. He thus initiated Etelcalcetide 5 mg e.v. 3 times a week, after the HD session but without any benefit. The dosage was then increased to 7.5 mg but the patient gradually became frail and developed pancytopenia and low-grade fever. Hematological evaluation with bone marrow biopsy was performed in December 2019. Bone marrow histology showed severe fibrosis [Myelofibrosis (MF) grade 3] with normal bone marrow cytogenetics. Blood samples for mutations in JAK-2, CALR, and MPL and BCR-ABL rearrangement were negative. There was no evidence for a myeloproliferative neoplasm (MPN) or metastatic lesions. During the following months, while on a 7,5 mg dose of etalcalcetide, there was a gradual reduction in iPTH [Fig.1] and serum alkaline phosphatase [Fig.2], up to 500 pg/dl and 200 IU/L respectively. The patient developed asymptomatic, often severe, hypocalcemia which was managed with therapy. The patient’s clinical conditions gradually improved, anemia responded to lower doses of ESAs. A bone marrow biopsy was repeated after one year (December 2020) and it showed a reduction in fibrosis (MF grade varying from 1-2). Then etelcalcetide dosage was reduced while serum calcium and phosphate levels were in the normal limit. Conclusion Myelofibrosis secondary to renal osteodystrophy is an uncommon complication. It has been rarely reported and usually is associated with primary hyperparathyroidism. Marrow fibrosis and pancytopenia is related to the excessive iPTH that upregulates production of cytokines and paracrine factors in the bone marrow (IL-1a, IL-6, FNF-a, TGF–b, and platelet-derived growth factor) and it has an important stimulatory effect on fibroblast proliferation. It is known that surgical parathyroidectomy is associated with a reduction of bone marrow fibrosis in primary hyperparathyroidism. To our knowledge, this is probably the first case of tertiary hyperparathyroidism in which the effect of etelcalcetide is comparable to parathyroidectomy as far as on calcium-phosphate balance, and a significant improvement in bone marrow fibrosis and hemoglobin. In conclusion, etelcalcetide at least in this patient seems as effective as PTX on bone balance, bone marrow and anemia.

Fibrosis-driving cells in patients with primary myelofibrosis and myelodysplastic syndromes with myelofibrosis

目的比较原发性骨髓纤维化（PMF）和骨髓增生异常综合征伴骨髓纤维化（MDS-MF）患者纤维驱动细胞的差异。方法随机选取MF-0/1、MF-2和MF-3级的初诊PMF和MDS患者各10例，骨髓活检组织切片利用特异性免疫荧光抗体标记Gli1、LeptinR、平滑肌肌动蛋白（α-SMA）、CD45和ProcollagenⅠ，共聚焦显微镜成像后利用Fiji-ImageJ软件计数Gli1+、LeptinR+细胞及α-SMA+、α-SMA+/Gli1+、α-SMA+/LeptinR+和ProcollagenⅠ+/CD45+等纤维驱动细胞。结果MF-2/3级PMF和MDS患者LeptinR+、α-SMA+、α-SMA+/Gli1+和ProcollagenⅠ+/CD45+等细胞计数均显著高于MF-0/1级患者（P<0.05）。但MF-2/3级PMF患者Gli1+、α-SMA+/LeptinR+细胞计数显著高于MF-0/1级PMF患者（P值分别为0.001、0.006），而MDS患者中两组患者两群细胞计数差异无统计学意义（P值分别为0.169、0.067）。MF-0/1级患者中，PMF与MDS患者所有纤维驱动细胞计数相比差异均无统计学意义（P>0.05）。但MF-2/3级患者中，PMF患者ProcollagenⅠ+/CD45+计数显著高于MDS患者（P＝0.007），其他纤维驱动细胞计数相比较差异均无统计学意义（P>0.05）。MF分级及纤维驱动细胞计数与PMF和MDS患者总生存时间无相关性。结论PMF患者α-SMA+细胞来源于Gli1+和LeptinR+细胞，而MDS-MF患者α-SMA+细胞仅来源于Gli1+细胞；PMF患者ProcollagenⅠ+/CD45+细胞计数显著高于MDS-MF患者。

Analysis of clinical features, gene mutation, and prognostic characteristics in de novo acute myeloid leukemia patients with myelofibrosis

目的探讨初诊急性髓系白血病（AML）合并骨髓纤维化（MF）患者的基因突变、临床及预后特征。方法2016年1月1日至2020年2月1日河南省人民医院收治的初诊并同时行骨髓活组织检查的103例AML患者纳入研究，根据WHO（2016）骨髓纤维化分级标准将患者分为AML伴MF组（MF-1～3）与AML不伴MF组（MF-0），并对两组患者的临床特征、基因突变、疗效和预后进行回顾性比较。结果①103例患者中AML伴MF组46例（44.7％），其中MF-1 39例（84.8％），MF-2/3 7例（15.2％）；AML不伴MF组57例（55.3％）。和AML不伴MF组相比，AML伴MF组中位WBC显著增高［11.205（0.69～191.82）×109/L对4.64（0.18～95.10）×109/L，P＝0.024］；外周血出现有核红细胞的比例明显增高（43.5％对24.6％，χ2＝4.119，P＝0.042）；FAB分型：4例AML-M0患者均在AML伴MF组，而AML不伴MF组AML-M2所占比例更高（P＝0.014）。②AML伴MF组患者FLT3-ITD及NPM1基因突变率更高（15.2％对1.8％，P＝0.021；26.1％对10.5％，P＝0.039），而CEBPA基因突变率明显低于AML不伴MF组（2.2％对17.5％，P＝0.029）。③AML伴MF组完全缓解（CR）率显著低于AML不伴MF组（69.7％对93.2％，χ2＝7.412，P＝0.006）。多因素分析显示MF，尤其是纤维化程度是影响初诊AML患者CR的独立危险因素。④AML伴MF组3年总生存（OS）率明显低于AML不伴MF组（20.5％对72.2％，χ2＝4.032，P＝0.045）；亚组分析显示MF-1和MF-2/3两组患者的OS率、无进展生存（PFS）率显著低于AML不伴MF组（P＝0.001）。Cox多因素分析显示MF，尤其是MF-2/3是影响初诊AML患者OS和PFS的独立危险因素（P值分别为0.021和0.044）。结论AML合并MF患者具有较为独特的实验室及临床特征；MF是影响AML患者CR、OS和PFS的独立预后不良指标，MF的评估对初诊AML的疗效和预后判断具有重要意义。

Myelofibrosis in Patients of Chronic Myeloid Leukemia in Chronic Phase at Presentation.

To determine the frequency and grading of myelofibrosis in patients of chronic myeloid leukaemia in chronic phase, and the association of cytopenias/cytosis with the degree of fibrosis. Descriptive study. King Edward Medical University, Lahore, from March 2015 to April 2017. Patients of both genders and all age groups with Philadelphia chromosome/BCR-ABL positivity were included in the study. Detailed medical history and examination findings were recorded. Sample for CBC was taken in EDTA and run on automated haematology analyser. Bone marrow aspirate and trephine biopsy was done from posterior iliac crest. Bone marrow aspirate slides were stained with Giemsa stain. The trephine biopsy was processed and stained with haematoxilyn and eosin. Silver (reticulin) and trichrome staining was done on trephine biopsy to assess the degree of fibrosis. Grading of fibrosis was done according to WHO revised classification 2016. Among the 82 cases, 65% (n=53) were having WHO Grade MF 1 myelofibrosis, 27% (n=22) WHO Grade MF 2 myelofibrosis; whereas, 08% (n=07) WHO Grade MF 3 myelofibrosis. CBC counts were analysed to see any association between anemia, thrombocytocytosis and leucocytosis with advanced fibrosis (p=0.148, 0.413 and 0.174, respectively). Some degree of bone marrow fibrosis was present in all patients of chronic myeloid leukemia, while advance fibrosis (WHO Grade MF 2 and 3) is also common. Peripheral blood counts are not predictor of increased fibrosis. Therefore, bone marrow biopsy with special staining should be done in all cases of chronic phase of CML.

Platelet-derived growth factor receptor β activation and regulation in murine myelofibrosis.

There is prevailing evidence to suggest a decisive role for platelet-derived growth factors (PDGF) and their receptors in primary myelofibrosis. While PDGF receptor β (PDGFRβ) expression is increased in bone marrow stromal cells of patients correlating with the grade of myelofibrosis, knowledge on the precise role of PDGFRβ signaling in myelofibrosis is sparse. Using the Gata-1low mouse model for myelofibrosis, we applied RNA sequencing, protein expression analyses, multispectral imaging and, as a novel approach in bone marrow tissue, an in situ proximity ligation assay to provide a detailed characterization of PDGFRβ signaling and regulation during development of myelofibrosis. We observed an increase in PDGFRβ and PDGF-B protein expression in overt fibrotic bone marrow, along with an increase in PDGFRβ–PDGF-B interaction, analyzed by proximity ligation assay. However, PDGFRβ tyrosine phosphorylation levels were not increased. We therefore focused on regulation of PDGFRβ by protein tyrosine phosphatases as endogenous PDGFRβ antagonists. Gene expression analyses showed distinct expression dynamics among PDGFRβ-targeting phosphatases. In particular, we observed enhanced T-cell protein tyrosine phosphatase protein expression and PDGFRβ–T-cell protein tyrosine phosphatase interaction in early and overt fibrotic bone marrow of Gata-1low mice. In vitro, T-cell protein tyrosine phosphatase (Ptpn2) knockdown increased PDGFRβ phosphorylation at Y751 and Y1021, leading to enhanced downstream signaling in fibroblasts. Furthermore, Ptpn2 knockdown cells showed increased growth rates when exposed to low-serum growth medium. Taken together, PDGF signaling is differentially regulated during myelofibrosis. Protein tyrosine phosphatases, which have so far not been examined during disease progression, are novel and hitherto unrecognized components in myelofibrosis.

Progressive Diagnosis of Chronic Myeloproliferative Neoplasms: A Case Study

Chronic myeloproliferative neoplasms are hematologic diseases characterized by the clonal proliferation of peripheral blood components. A series of laboratory tests are required for diagnosis. This patient is a 74-year-old male incidentally noted to have a leukocytosis, monocytosis, and rare blasts in his peripheral blood. He presented with a CBC showing 6.6 g/dL Hgb, 114fL MCV, 15.3x10(9)/L, WBC, 304.10(9)/L Platelet. WBC differential consisting of 21% neutrophils, 21% lymphocytes, 45% monocytes, 6% eosinophils, 4% basophils and 3% blasts. The peripheral blood smear showed hypochromic microcytic red cells with marked macrocytosis and slight polychromasia. In addition, atypical hypogranular neutrophils, and hypogranular platelets were revealed. A pathology consultation reported a bone marrow aspirate of 22% neutrophils, 6% metamyelocytes, 11% myelocytes, 1% promyelocytes, 12% eosinophils, 8% blasts, 18% normoblasts, 15% monocytes, and 7% lymphocytes. The M:E ratio was increased, 4:1, with 90% hypercellularity. There was a decreased quantity of erythroid precursors and an increased quantity of myeloid precursors. Blasts contained intermediate-sized nuclei, reticulated chromatin and variably granulated cytoplasm and megakaryocytes were markedly increased. Ancillary tests included both iron and reticulin staining of the bone marrow. Storage iron was decreased and reticulin fibers increased with a myelofibrosis grade 1 of 3. Flow cytometry immunophenotyping of the bone marrow revealed mildly increased myeloid blasts, increased mature monocytes, increased monoblasts/promonocytes with other abnormal findings consistent with a myeloid neoplasm with high grade features. In summary, the pertinent and unusual findings were the rare blasts, increased monocytes and basophils, and dysplastic neutrophils, and leukocytosis seen in the peripheral blood along with slightly increased blasts in the marrow. Along with additional cytogenetic and molecular testing results, the above laboratory finds were essential to the diagnosis of an unusual myelodysplastic/myeloproliferative neoplasm, Chronic Myelomonocytic Leukemia (CMML). The sequence of testing lead to the proper diagnosis and will aid in treatment options.

PB2227 COMPASSIONATE USE OF ROPEGINTERFERON TO TREAT MYELOPROLIFERATIVE NEOPLASMS IN TAIWAN

Background:There is a high unmet medical need for therapeutic options for patients suffering from myeloproliferative neoplasms (MPN), who have failed or are not eligible to available treatment options. Ropeginterferon‐alfa‐2b (P1101) is a novel, third generation pegylated interferon‐alfa, recently approved by EMA to treat polycythemia vera (PV). Ropeginterferon‐alfa‐2b is also in the late stages of development in several countries for treatment of PV and other MPNs.Aims:Ropeginterferon‐alfa‐2b is a new and attractive treatment option for patients suffering from MPN who have exhausted all therapeutic options and require treatment. The Compassionate Use Program (CUP) was approved and initiated in Taiwan with the purpose of granting access to P1101 to patients with MPN disease with no therapeutic options who are not eligible to enroll in existing clinical trials for their disease.Methods:Patients were identified that had the potential to benefited from P1101 therapy and were eligible according to the protocol. Patients were treated at a starting dose of 250 ug with subsequent dose escalation every 2 weeks over a 6‐week period to 350 ug, 450 ug and 500 ug. Dose adjustments were permitted based on tolerability and efficacy.Results:The CUP currently contains 15 patients from two academic hospitals: 9 with PV, 2 with post‐PV myelofibrosis (MF), two with pre‐fibrotic MF, one with primary MF, and one essential thrombocythemia patient. The driver mutation was JAK2 in 13 patients, CALR in one, and another one was triple negative. Pre‐treatment with hydroxyurea and/or anagrelide was reported in 13 patients. P1101 was given for &gt; 12 weeks to 14 patients (range 4 ‐ 64 weeks). The highest administered dose of P1101 was: 500 ug in 11 patients (time to highest dose – 6 weeks in 9 patients, 10 weeks – in 1 and 20 weeks in another patient); 250 ug, 350 ug and 450 ug in three other patients. The need to decrease or temporarily interrupt P1101 therapy occurred in 4 patients, all due to transaminase(s) elevation. Notably, these events did not require permanent discontinuation of therapy and could be alleviated by appropriate dose modifications. The majority of observed adverse events were of grade 1 and included fatigue, arthralgia, myalgia, chills and dizziness. Grade 2 events included elevation of transaminases (in 3 patients), dizziness, pruritus and lower limbs pain (in 1 patient each). One patient developed elevation of transaminases of grade 3. Normalization of blood parameters within complete hematologic response range was observed in 3 PV and 2 post‐PV MF patients. Two PV patients fulfilled the partial response criteria. In other patients, decrease of platelet count (even in previously treatment‐resistant thrombocytosis) and symptomatic improvement were also observed. No major cardiovascular events were recorded. One pre‐PMF patient transformed into MF (grade 5). No patients progressed to acute myelogenous leukemia (AML) during the observation.Summary/Conclusion:In this cohort of MPN patients, not amenable for established treatment options, P1101 demonstrated good tolerability and substantial efficacy. The dose administration schema with a starting dose of 250 ug and escalation to the highest dose of 500 ug within the first 6‐8 weeks was feasible, tolerated and allowed rapid control of blood parameters. The observed efficacy demonstrate P1101 as a promising treatment option for patients with MPNs with limited or no alternate therapeutic option. These results mandate access to P1101 at earlier stages of disease as recommended by international MPN treatment guidelines.

Impact of Myelofibrosis at Presentation on Outcomes in Chronic Myeloid Leukemia in Chronic Phase

Background:Presence of myelofibrosis on bone marrow examination is considered as poor prognostic factor in patients with chronic myelogenous leukemia (CML). Scant data is available on myelofibrosis, especially in the era of tyrosine kinase therapy. The present study was designed to analyze impact of myelofibrosis on outcomes in newly diagnosed patients with chronic myeloid leukemia in chronic phase (CML-CP).Aims and objectives:The primary objective of this analysis was to study event free survival (EFS) and major molecular response rates (MMR) at one year in patients with CML-CP with myelofibrosis.Secondary objectives were to study the parameters impacting outcomes in patients with CML-CP with myelofibrosisMaterials and methods:Study period: 2010 to 2016Type of study: retrospective analysis.The diagnosis of CML-CP was done by demonstration of BCR-ABL translocation by polymerase chain reaction or fluorescence in situ hybridization. Event free survival was defined as the time from start of therapy to death, transformation to accelerated or blast phase, hematologic resistance or toxicity intolerance. Statistical analysis was done using SPSS software, version 25. Overall survival curves were plotted using the Kaplan-Meier method. Grade of myelofibrosis, EUTOS risk, age and compliance were analyzed on multivariate analyses.Results:Data of 147 patients with CML-CP with myelofibrosis at presentation was retrospectively collected, of which 79(53.7%) were males and 68(46.3%) were females. The baseline characters were tabulated in Table 1. Abdominal fullness (60.5%) was the most common symptom at presentation followed by fatigue (48.9%), weight loss (36.7%), fever (25.1%) and bleeding manifestations (12.9%). EUTOS risk was low in 94(64%) patients and high in 53 (36%) patients. Myelofibrosis grade 1, 2, 3 and 4 were seen in 20(13.6%), 36(24.5%), 38(25.9%) and 27(18.3%) patients respectively. Grade of myelofibrosis was not available in 26(17.7%) patients.Of 147 patients, outcome parameters were available in 92 patients. Of 92 patients, 34(37%) attained MMR at 1 year. At a median follow up of 46 months, event free survival was 60.9%. Of 92 patients, MMR at one year differed significantly in patients with grade 1 and 2 myelofibrosis (48.8%) compared to patients with grade 3 and 4 myelofibrosis (26.5%) (p=0.02). Event free survival was higher in patients with grade 1 and 2 myelofibrosis (76.7%) compared to patients with grade 3 and 4 myelofibrosis (46.9%) (p=0.005). Drug induced myelosuppression was seen in 27(29.3%) patients, of which 7(26%) patients received dose reduction. Phase transformation was seen in 6 patients, of which 1(16.7%) and 5(83.3%) patients were transformed to accelerated phase and blastic phase respectively. On multivariate analysis, only grade of myelofibrosis had significant impact on event free survival(p=0.013).Conclusion:In patients with newly diagnosed CML-CP, major molecular response was significantly lower for those with higher grade of myelofibrosis. Grade of myelofibrosis at presentation had significant impact on outcomes in CML-CP. Hence, bone marrow examination for presence and grade of myelofibrosis helps in prognosticating CML-CP patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.