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Abstract: The aim of our study was to analyze the potential survival benefit associated with hematopoietic stem cell transplantation (HSCT) according to clinicobiological scores, which incorporate mutation-enhanced international prognostic score system (MIPSS) to facilitate decision-making in this context. One transplant (n = 241) and 1 nontransplant cohort (n = 239) were used to test the hypothesis that patients with primary myelofibrosis with higher risk molecular score benefit from HSCT. A weighted propensity score was applied to balance confounding factors with the transplanted cohort as reference. Weighted Cox proportional hazard models and logistic regression analyses were performed. Overall, 105 patients who did not receive transplant could be matched to the 239 patients who did receive transplants. HSCT was associated with a higher 6-year overall survival rate in intermediate-2 (60.1% vs 41.5%) and high-risk DIPSS patients (44.4% vs 6.55%), high-risk MIPSS70 (46.5% vs 23.9%), high-risk (73.2% vs 39.7%) or very high-risk MIPSS70+V2 (51.8% vs 24%). Patients with intermediate MIPSS70 scores have an advantage of survival with HSCT only when their myelofibrosis transplant scoring system (MTSS) were low or intermediate. Patients who received transplant had an increased mortality risk the first year, but a significant benefit with HSCT after the 1-year landmark was observed in higher risk patients. This study confirms that, similar to DIPSS, MIPSS70 and MIPSS70+V2 risk score in addition to MTSS can be used to determine which patients with primary myelofibrosis have survival benefit from HSCT over non-HSCT strategies., (© 2025 American Society of Hematology. Published by Elsevier Inc. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Spleen volume reduction (SVR) is a key endpoint in inhibitors of Janus kinase (JAK) inhibitor studies. Retrospective analyses have demonstrated an association between SVR and improved overall survival (OS) among patients treated with ruxolitinib with a platelet count > 100 × 10 9 /L. Whether this association occurs in patients with thrombocytopenia is unclear. Pacritinib, a JAK2/IRAK1/ACVR1 inhibitor, demonstrated improved SVR versus best available therapy (BAT [best available therapy]; including ruxolitinib) in patients with myelofibrosis and platelet counts ≤ 100 × 10 9 /L in the PERSIST-2 study. Patients on study at the start of the 12-week SVR window on pacritinib 200 mg twice daily or BAT were included. OS was evaluated among SVR responders versus non-responders using different SVR thresholds (≥ 35%, ≥ 20%, ≥ 10%, and > 0%). Among patients on pacritinib (n = 89), SVR ≥ 10% demonstrated the greatest separation in OS curves between responders and non-responders (HR, 0.00; 95% CI, 0.00-0.14; p < 0.01), though SVR ≥ 0% and SVR ≥ 20% were also associated with improved OS. No SVR threshold conferred OS benefit on BAT (n = 84), including ruxolitinib (n = 39). In patients with myelofibrosis and platelets ≤ 100 × 10 9 /L, achieving SVR on pacritinib, but not BAT (including ruxolitinib), was associated with significant OS benefit, suggesting that pacritinib may offer a unique survival advantage in patients with myelofibrosis and thrombocytopenia who achieve any SVR. Trial Registration: ClinicalTrials.gov number: NCT02055781., (© 2024 The Author(s). European Journal of Haematology published by John Wiley & Sons Ltd.)

In addition to high-molecular risk (HMR) mutations (ASXL1, EZH2, SRSF2, IDH, and U2AF1 Q157 ), lower JAK2V617F variant allele frequencies (VAF) have been demonstrated to be associated with poor prognosis of myelofibrosis (MF) patients. Nevertheless, the relationship between JAK2V617F VAF and HMR mutations remains inconclusive. To address this, we analyzed the mutation status of 54 myeloid neoplasm-relevant genes using targeted next-generation sequencing in 124 MF patients. Three cohorts from multiple international centers were analyzed for external validation. Among JAK2-mutated patients, the presence of HMR mutations drove poor prognosis in patients with lower JAK2V617F VAF but not in those with higher JAK2V617F VAF. Survival analyses showed consistent results across validation cohorts. In multivariable analysis, concurrent HMR and a lower JAK2V617F VAF was identified as an independent adverse prognostic factor for survival, irrespective of age, MIPSS70, MIPSS70 + v2, and GIPSS risk groups. Mutation co-occurrence tests revealed no shared mutational pattern over different cohorts, excluding potential confounding effect from other concurrent mutations. Importantly, the integration of HMR/JAK2V617F VAF (≤50%) status significantly enhanced existing prognostic models, as evidenced by higher c-indexes and time-dependent ROC analyses. Single-cell studies with sequential follow-ups are warranted to decipher the clonal evolution of MF and how it relates to JAK2V617F VAF dynamics., Competing Interests: Competing interests: The authors declare no competing interests. Ethics approval and consent to participate: This retrospective study was approved by the National Taiwan University Hospital Research Ethics Committee (reference number #201709072RINC) and institutional review boards of each participating hospital, with informed consent obtained from all patients in accordance with the Declaration of Helsinki. All methods were performed in accordance with the relevant guidelines and regulations., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Interferon alpha (IFN-α) is a fascinating molecule with many biological properties yet to be fully understood. Among these properties, several have demonstrated usefulness for targeting malignant cells, including hematopoietic cells from patients with myeloproliferative neoplasms. Indeed, IFN-α has been used for decades across all myeloproliferative neoplasms, but only recently a new form, ropegIFN-α2b, was approved to treat patients with polycythemia vera. Many phase 2 and more recently phase 3 studies have demonstrated IFN-α's promise in treating patients with essential thrombocythemia and early-stage myelofibrosis. In addition, although not approved in that situation, IFN-α is the only cytoreductive therapy that can be used during pregnancy. Today, IFN-α is a key medicine for polycythemia vera and essential thrombocythemia, while its place in the management of myelofibrosis must be better defined. The advantages of IFN therapy include a well-known safety profile, high rates of clinical and molecular responses, and a unique ability to deeply reduce the mutant allele burden of most of the driver mutations causing myeloproliferative neoplasms. Recent preliminary data from prospective studies suggest that molecular responses may be correlated with prolonged event-free survival, raising the hope that IFN therapy may ultimately alter the natural history of many diseases., (Copyright © 2024 by The American Society of Hematology.)

Despite the advances in the understanding and treatment of myeloproliferative neoplasm (MPN), the disease remains incurable with the risk of evolution to acute myeloid leukemia or myelofibrosis (MF). Unfortunately, the evolution of the disease to MF remains poorly understood, impeding preventive and therapeutic options. Recent studies in solid tumor microenvironment and organ fibrosis have shed instrumental insights on their respective pathogenesis and drug resistance, yet such precise data are lacking in MPN. In this study, through a patient sample-driven transcriptomic and epigenetic description of the MF microenvironment landscape and cell-based analyses, we identify homeobox B7 (HOXB7) overexpression and more precisely a potentially novel TGF-β/WNT/HOXB7 pathway as associated to a pro-fibrotic and pro-osteoblastic biased differentiation of mesenchymal stromal cells (MSCs). Using gene-based and chemical inhibition of this pathway, we reversed the abnormal phenotype of MSCs from patients with MF, providing the MPN field a potentially novel target to prevent and manage evolution to MF.

Abstract: With emerging new drugs in myelofibrosis (MF), a robust and harmonized framework for defining the severity of anemia and response to treatment will enhance clinical investigation and facilitate interstudy comparisons. Accordingly, the lead authors on the 2013 edition of the International Working Group-European LeukemiaNet (IWG-ELN) response criteria in MF were summoned to revise their document with the intent to (1) account for gender-specific differences in determining hemoglobin levels for eligibility criteria; (2) revise the definition of transfusion-dependent anemia (TDA) based on current restrictive transfusion practices; and (3) provide a structurally simple and easy to apply response criteria that are sensitive enough to detect efficacy signals (minor response) and also account for major responses. The initial draft of the 2024 IWG-ELN proposed criteria was subsequently circulated around a wider group of international experts and their feedback incorporated. The proposed articles include new definitions for TDA (≥3 units in the 12 weeks before study enrollment) and hemoglobin thresholds for eligibility criteria (<10 g/dL for women and <11 g/dL for men). The revised document also provides separate (TDA vs non-TDA) and graded (major vs minor response) response criteria while preserving the requirement for a 12-week period of screening and observation on treatment., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Background: Most patients with myelofibrosis develop ruxolitinib intolerance or disease that is relapsed or refractory, and survival rates after ruxolitinib discontinuation are poor. We aimed to evaluate the safety and efficacy of fedratinib versus best available therapy (BAT) in patients with myelofibrosis previously treated with ruxolitinib., Methods: FREEDOM2 was a multicentre, open-label, randomised, controlled, phase 3 trial in 86 clinics in 16 countries, in which patients aged at least 18 years with intermediate-2 or high-risk myelofibrosis that was relapsed or refractory or intolerant to ruxolitinib with Eastern Cooperative Oncology Group performance status 0-2 were stratified by spleen size by palpation, platelet count, and previous ruxolitinib treatment, and randomly assigned 2:1 by interactive response technology to receive fedratinib 400 mg per day (4 × 100 mg capsules orally once daily, open-label) or BAT. Patients received prophylactic antiemetics and thiamine supplementation, and symptomatic antidiarrhoeals as required. Primary endpoint was proportion of patients reaching spleen volume reduction (SVR) of at least 35% (SVR35) at end of cycle 6 in the intention-to-treat population. This manuscript reports the primary analysis of the trial; follow-up is ongoing. This trial is registered at clinicaltrials.gov, NCT03952039., Findings: Between Sept 9, 2019 and June 24, 2022, of 316 patients screened, 201 were randomly assigned and treated (134 to fedratinib, 67 to BAT [including 52 receiving ruxolitinib]); 46 patients from the BAT group crossed over to fedratinib. Approximately half of enrolled patients were male (fedratinib 75 [56%] of 134; BAT 30 [45%] of 67) and most were White (fedratinib 106 [79%] of 134; BAT 58 [87%] of 67). At data cutoff (Dec 27, 2022), median survival follow-up was 64·5 weeks (IQR 37·9-104·9). SVR35 at end of cycle 6 was seen in 48 (36%) of 134 patients receiving fedratinib versus four (6%) of 67 patients receiving BAT (30% difference; 95% CI 20-39; one-sided p-value <0·0001). During the first six cycles 53 (40%) of 134 patients in the fedratinib group and 8 (12%) of 67 patients in the BAT group had grade 3 or greater treatment-related adverse events, most frequently anaemia (fedratinib 12 [9%] of 134; BAT 6 [9%] of 67) and thrombocytopenia (fedratinib 16 [12%] of 134; BAT 2 [3%] of 67); one patient in the fedratinib group died from acute kidney injury suspected to be related to study drug (no treatment-related deaths in the BAT group). Gastrointestinal adverse events occurred more frequently in the fedratinib group compared with the BAT group, but were mostly grade 1-2 in severity and more frequent in early cycles, and were less frequent than in prior clinical trials. A total of 28 (21%) of 134 patients in the fedratinib group and 3 (4%) of 67 patients in the BAT group had thiamine levels below lower limit of normal per central laboratory assessment, with only one case of low thiamine in the fedratinib arm after the introduction of prophylactic thiamine supplementation., Interpretation: Findings from FREEDOM2 support fedratinib as a second-line Janus kinase inhibitor option to reduce spleen size after ruxolitinib failure or intolerance in patients with myelofibrosis, and shows effective strategies for management of gastrointestinal adverse events and low thiamine concentrations through prophylaxis, monitoring, and treatment., Funding: Bristol Myers Squibb., Competing Interests: Declaration of interests CNH reports research funding from Bristol Myers Squibb, Constellation–Morphosys, and Novartis; consulting fees from Galecto, Geron, and GlaxoSmithKline; honoraria from AbbVie, AOP Health, Bristol Myers Squibb–Celgene, CTI BioPharma, Galacteo, Geron, Gilead, IMAGO, Janssen, Keros, Novartis, Promedior, Roche, Shire, and Sierra; participation on a data safety monitoring board or advisory board with Galacteo and Keros; and leadership at the European Hematology Association. RM reports honoraria from AbbVie, Blueprint, Bristol Myers Squibb, CTI BioPharma, Genentech, Geron, GlaxoSmithKline, Incyte, Morphosys, Novartis, Sierra Oncology, and Telios. MT reports research funding from Bristol Myers Squibb; travel support from Sumitomo; participation on a data safety monitoring board or advisory board with Bristol Myers Squibb, Novartis, and Sumitomo; and leadership in the Society of Hematologic Oncology. HKA-A reports research funding from Bristol Myers Squibb, Incyte, and Novartis; travel support from AbbVie and Bristol Myers Squibb; and participation on a data safety monitoring board or advisory board with AbbVie, AOP Health, Blueprint, Bristol Myers Squibb, Novartis, and SGK. FPas reports research funding from Bristol Myers Squibb–Celgene; consulting fees from AbbVie, AOP Health, Bristol Myers Squibb–Celgene, Kartos, Karyopharma, Kyowa Kirin–MEI, Novartis, Roche, Sierra Oncology, and Sumitomo; and honoraria from AbbVie, AOP Health, Bristol Myers Squibb–Celgene, Novartis, and Roche. FPal reports research funding from Bristol Myers Squibb; honoraria from AbbVie, Amgen, AOP Health, Bristol Myers Squibb, CTI BioPharma, GlaxoSmithKline, Kartos, Novartis, and Telios; travel support from AbbVie and Novartis; and participation on a data safety monitoring board or advisory board with AbbVie, AOP Health, Bristol Myers Squibb, CTI BioPharma, GlaxoSmithKline, and Novartis. GB reports honoraria and participation on a data safety monitoring board or advisory board with Bristol Myers Squibb, Janssen, and Novartis. AMV reports honoraria from AbbVie, Bristol Myers Squibb, Geron, GlaxoSmithKline, Incyte, and Novartis; and participation on a data safety monitoring board or advisory board with Bristol Myers Squibb, Geron, Incyte, and Novartis. CM reports research funding from AbbVie and Bristol Myers Squibb; and honoraria from AbbVie, Bristol Myers Squibb, and Novartis. AI reports honoraria from Bristol Myers Squibb, GlaxoSmithKline, Incyte, Novartis, and Pfizer; and participation on a data safety monitoring board or advisory board with AOP Health, Bristol Myers Squibb, Incyte, Novartis, and Pfizer. PB reports employment and stock or stock options with Bristol Myers Squibb. CH reports employment with Bristol Myers Squibb. SR reports employment and stock or stock options with Bristol Myers Squibb. JW reports employment with Bristol Myers Squibb. J-JK reports consulting fees from AbbVie and GlaxoSmithKline; honoraria from AOP Health and Novartis; and participation on a data safety monitoring board or advisory board with Bristol Myers Squibb and Incyte. BX and IK report no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)

Abstract: The ACE-536-MF-001 trial enrolled patients with myelofibrosis (n = 95) into 4 cohorts: patients in cohorts 1 and 3A were non-transfusion dependent (NTD) and had anemia; patients in cohorts 2 and 3B were transfusion dependent (TD); and patients in cohort 3A/3B had stable ruxolitinib treatment before and during the study. All patients received luspatercept (1.0-1.75 mg/kg, 21-day cycles). Treatment was extended if clinical benefit was observed at day 169. The primary end point was anemia response rate (NTD, ≥1.5 g/dL hemoglobin increase from baseline; TD, transfusion-independence) over any 12-week period during the primary treatment period (weeks 1-24). Overall, 14% of patients in cohorts 1 and 3A, 10% in cohort 2, and 26% in cohort 3B met the primary end point. In cohorts 1 and 3A (NTD), 27% and 50% of patients, respectively, had mean hemoglobin increase of ≥1.5 g/dL from baseline. Among TD patients, ∼50% had ≥50% reduction in transfusion burden. Reduction in total symptom score was observed in all cohorts, with the greatest response rate seen in cohort 3A. Overall, 94% of patients had ≥1 adverse event (AE); 47% had ≥1 treatment-related AE (TRAE; 11% grade ≥3), most frequently hypertension (18%), managed with medical intervention. One patient had a serious TRAE leading to luspatercept discontinuation. Nine patients died on treatment (unrelated to study drug). In most patients, ruxolitinib dose and spleen size remained stable. In patients with myelofibrosis, luspatercept improved anemia and transfusion burden across cohorts; the safety profile was consistent with previous studies. This trial was registered at www.ClinicalTrials.gov as #NCT03194542., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

The phase 3b FREEDOM trial (ClinicalTrials.gov: NCT03755518) evaluates efficacy/safety of fedratinib in intermediate- or high-risk myelofibrosis patients with platelet count ≥50 × 10 9 /L, previously treated with ruxolitinib. The trial design included protocol specified strategies to mitigate the risk for gastrointestinal (GI) adverse events (AEs), thiamine supplementation, and encephalopathy surveillance. Due to COVID-19, accrual was cut short with 38 patients enrolled. In the efficacy evaluable population ( n  = 35), nine (25.7%; 95% confidence interval 12.5-43.3) patients achieved primary endpoint of ≥35% spleen volume reduction (SVR) at end of cycle (EOC) 6; and 22 (62.9%) patients showed best overall response of ≥35% SVR up to end of treatment. Sixteen (44.4%) patients showed ≥50% reduction in total symptom score at EOC6 ( n  = 36). Compared to previously reported JAKARTA-2 trial, rates of GI AEs were lower, and no patient developed encephalopathy. Overall, FREEDOM study showed clinically relevant spleen and symptom responses with fedratinib, and effective mitigation of GI AEs.

The current standard-of-care for treatment of myelofibrosis (MF) comprises inhibitors of the Janus kinase (JAK)/signal transducers and activators (STAT) pathway; however, despite their ability to alleviate symptoms, they do not appear to modify underlying disease and have not demonstrated substantial survival benefit. Allogeneic-hematopoietic stem cell transplantation remains the only curative option for patients with MF but is limited to a subset of high-risk and fit patients. Early disease modification could positively affect disease trajectory for lower risk patients with MF as well as those with conditions that can precede MF, such as polycythemia vera and essential thrombocythemia. Here, the authors discuss critical unmet needs in the MF treatment paradigm, including: the need for safe, impactful therapies for lower risk patients, thus allowing intervention when success is most likely; better development of first-line therapies (likely highly novel or combination strategies) for intermediate-risk/higher risk patients; and approved drugs to manage cytopenia. Finally, a consensus definition of disease modification is needed that informs trial design, allowing the development of clinical end points that enable understanding of therapies and responses and that facilitate the development of therapies that work according to this definition. Through close collaboration between clinicians, patients, and the pharmaceutical industry, better efforts to define benefit and identify patients most likely to benefit from a particular combination or treatment strategy should enable the development of more effective and safe treatments to extend and improve quality of life for patients with MF., (© 2024 The Authors. Cancer published by Wiley Periodicals LLC on behalf of American Cancer Society.)

Objectives: Patients with myelofibrosis develop symptoms due to bone marrow fibrosis, systemic inflammation, and/or organomegaly. Alleviating symptoms improves overall quality of life. Clinical trials have historically defined symptom response as a reduction of at least 50% in Total Symptom Score at week 24 compared with baseline. Whether 50% constitutes a meaningful benefit has not been established. This study determined the meaningful change threshold (MCT) for 2 momelotinib phase III trials, SIMPLIFY-1 and SIMPLIFY-2., Methods: The absolute and percentage MCT was determined using anchor-based methods applied to the modified Myeloproliferative Neoplasm Symptom Assessment Form v2.0 and Patient Global Impression of Change. MCTs were applied retrospectively to determine responder rates. Generalized estimating equations estimated the treatment-related difference in likelihood of improvement., Results: In SIMPLIFY-1, a Janus kinase inhibitor-naive population, the MCT was 8 points. In SIMPLIFY-2, a previously Janus kinase inhibitor-treated population, the MCT was 6 points. A 32% MCT was determined in both studies, showing that the historic 50% reduction threshold may be a conservative choice. In SIMPLIFY-1, a similar proportion of patients achieved responder status with 24 weeks of momelotinib or ruxolitinib therapy based on the absolute MCT (39% vs 41%, respectively). In SIMPLIFY-2, a significantly greater proportion of patients treated with momelotinib achieved responder states compared with best available therapy based on absolute and percent change MCTs., Conclusions: This study demonstrates that momelotinib provided clinically meaningful symptom benefit for patients with myelofibrosis and provides insight into the appropriateness of the symptom change threshold used in historical studies., Competing Interests: Author Disclosures Author disclosure forms can be accessed in the Supplemental Material section., (Copyright © 2024. Published by Elsevier Inc.)

Purpose: Standard therapy for myelofibrosis comprises Janus kinase inhibitors (JAKis), yet spleen response rates of 30%-40%, high discontinuation rates, and a lack of disease modification highlight an unmet need. Pelabresib (CPI-0610) is an investigational, selective oral bromodomain and extraterminal domain inhibitor (BETi)., Methods: MANIFEST (ClinicalTrails.gov identifier: NCT02158858), a global, open-label, nonrandomized, multicohort, phase II study, includes a cohort of JAKi-naïve patients with myelofibrosis treated with pelabresib and ruxolitinib. The primary end point is a spleen volume reduction of ≥ 35% (SVR35) at 24 weeks., Results: Eighty-four patients received ≥ 1 dose of pelabresib and ruxolitinib. The median age was 68 (range, 37-85) years; 24% of patients were intermediate-1 risk, 61% were intermediate-2 risk, and 16% were high risk as per the Dynamic International Prognostic Scoring System; 66% (55 of 84) of patients had a hemoglobin level of < 10 g/dL at baseline. At 24 weeks, 68% (57 of 84) achieved SVR35, and 56% (46 of 82) achieved a total symptom score reduction of ≥ 50% (TSS50). Additional benefits at week 24 included 36% (29 of 84) of patients with improved hemoglobin levels (mean, 1.3 g/dL; median, 0.8 g/dL), 28% (16 of 57) with ≥ 1 grade improvement in fibrosis, and 29.5% (13 of 44) with > 25% reduction in JAK2 V617F-mutant allele fraction, which was associated with SVR35 response ( P = .018, Fisher's exact test). At 48 weeks, 60% (47 of 79) of patients had SVR35 response. Grade 3 or 4 toxicities seen in ≥ 10% patients were thrombocytopenia (12%) and anemia (35%), leading to treatment discontinuation in three patients. 95% (80 of 84) of the study participants continued combination therapy beyond 24 weeks., Conclusion: The rational combination of the BETi pelabresib and ruxolitinib in JAKi-naïve patients with myelofibrosis was well tolerated and showed durable improvements in spleen and symptom burden, with associated biomarker findings of potential disease-modifying activity.

In patients with cytopenic myelofibrosis, treatment with the JAK2/IRAK1 inhibitor pacritinib was associated with anemia benefit in the phase 3 PERSIST-2 study. The impact of pacritinib on transfusion independence (TI) has not been previously described, nor has the mechanism by which pacritinib improves anemia been elucidated. Because it has been previously postulated that inhibition of activin A receptor, type 1 (ACVR1)/activin receptor-like kinase-2 improves anemia in patients with myelofibrosis via suppression of hepcidin production, we assessed the relative inhibitory potency of pacritinib compared with other JAK2 inhibitors against ACVR1. Pacritinib inhibited ACVR1 with greater potency (half-maximal inhibitory concentration [IC50] = 16.7 nM; Cmax:IC50 = 12.7) than momelotinib (IC50 = 52.5 nM; Cmax:IC50 = 3.2), fedratinib (IC50 = 273 nM; Cmax:IC50 = 1.0), or ruxolitinib (IC50 > 1000; Cmax:IC50 < 0.01). Pacritinib's inhibitory activity against ACVR1 was corroborated via inhibition of downstream SMAD signaling in conjunction with marked suppression of hepcidin production. Among patients on PERSIST-2 who were not transfusion independent at baseline based on Gale criteria, a significantly greater proportion achieved TI on pacritinib compared with those treated on best available therapy (37% vs 7%, P = .001), and significantly more had a ≥50% reduction in transfusion burden (49% vs 9%, P < .0001). These data indicate that the anemia benefit of the JAK2/IRAK1 inhibitor pacritinib may be a function of potent ACVR1 inhibition., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Janus kinase inhibitors (JAKis) ruxolitinib, fedratinib, and pacritinib are the current standard of care in symptomatic myelofibrosis (MF). However, progressive disease and toxicities frequently lead to JAKi discontinuation. Preclinical data indicate that combining JAK and bromodomain and extraterminal (BET) domain inhibition leads to overlapping effects in MF. Pelabresib (CPI-0610), an oral, small-molecule BET1,2 inhibitor (BETi), in combination with ruxolitinib showed improvements in spleen volume reduction (SVR35) and total symptom score reduction (TSS50) from baseline in the phase 2 MANIFEST study (NCT02158858) in patients with MF. Given the absence of a head-to-head clinical comparison between JAKi monotherapy and JAKi with BETi combination therapy, we performed an unanchored matching-adjusted indirect comparison analysis to adjust for differences between studies and allow for the comparison of SVR35, TSS50, and TSS measured at several timepoints in arm 3 of MANIFEST (pelabresib with ruxolitinib in JAKi treatment-naive patients with MF), with data from the following JAKi monotherapy studies in JAKi treatment-naive patients: COMFORT-I and COMFORT-II (ruxolitinib), SIMPLIFY-1 (ruxolitinib and momelotinib), and JAKARTA (fedratinib). Response rate ratios >1 were observed for pelabresib with ruxolitinib vs all comparators for SVR35 and TSS50 at week 24. Improvements in TSS were observed as early as week 12 and were durable. These results indicate that pelabresib with ruxolitinib may have a potentially higher efficacy than JAKi monotherapy in JAKi treatment-naive MF., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Background: The MOMENTUM study met all key endpoints at week 24, demonstrating symptom, spleen, and anaemia benefits with momelotinib versus danazol in patients with myelofibrosis. In this updated analysis, we report duration of week 24 responses and new responses with momelotinib through week 48., Methods: MOMENTUM is an international, double-blind, randomised, phase 3 study done at 107 sites across 21 countries. Patients were 18 years or older with primary, post-polycythaemia vera, or post-essential thrombocythaemia myelofibrosis, previously treated with an approved Janus kinase (JAK) inhibitor for 90 days or more (≥28 days with haematological complications), and had an Eastern Cooperative Oncology Group performance status of 2 or less. Patients were randomly assigned (2:1) to either the momelotinib group (200 mg orally once per day) or danazol group (300 mg orally twice per day) through week 24 via non-deterministic biased coin minimisation and an interactive response system. Stratification factors were Total Symptom Score (TSS; <22 vs ≥22), spleen size (<12 cm vs ≥12 cm), transfusion burden (0 units vs 1-4 units vs ≥5 units), and study site. After week 24, all patients initially randomly assigned to either group who remained on the study received open-label momelotinib. The primary endpoint, which has already been reported, was Myelofibrosis Symptom Assessment Form TSS response rate at week 24. Predefined secondary endpoints were duration of week 24 TSS and transfusion independence responses, safety, and survival, which are summarised post hoc at the week 48 data cutoff (May 17, 2022). TSS, transfusion independence, and splenic responses at week 48 were defined post hoc and assessed in all evaluable patients who entered the open-label period and provided sufficient data. The timing of this updated analysis was defined post hoc after all patients had the opportunity to complete their week 48 assessments, as most patients entered an extended access study (NCT03441113) after week 48. This study is registered with ClinicalTrials.gov, number NCT04173494, and is now complete., Findings: Between April 24, 2020, and Dec 3, 2021, a total of 195 patients were randomised (130 [67%] in the momelotinib group and 65 [33%] in the danazol group). 93 (72%) of 130 patients in the momelotinib group and 41 (63%) of 65 in the danazol group entered the momelotinib open-label extension period. Median follow-up was 48·4 weeks (IQR 40·6-55·7). Among TSS-evaluable patients at week 48, 30 (45%) of 67 patients in the momelotinib group who continued treatment and 15 (50%) of 30 in the danazol group who crossed over were responders. TSS responders at any time during the open-label period by week 48 were 46 (61%) of 75 evaluable patients in the momelotinib group who continued and 19 (59%) of 32 in the danazol group who crossed over, including most week 24 responders plus new responders after week 24. No new safety signals emerged with long-term follow-up. The most common non-haematological treatment-emergent adverse events in momelotinib-treated patients over the entire study period as of the data cutoff were diarrhoea (45 [26%] of 171) and asthenia (28 [16%]); the most common grades 3-4 treatment-emergent adverse events were thrombocytopenia (33 [19%]) and anaemia (19 [11%]). Serious treatment-emergent adverse events were reported in 79 (46%) of 171 patients, and fatal treatment-emergent adverse events were reported in 30 (18%); two fatal treatment-emergent adverse events were considered possibly related to momelotinib (rotaviral enteritis and Staphylococcus pneumonia)., Interpretation: Momelotinib was associated with durable symptom, spleen, and anaemia benefits, late responses after week 24, and favourable safety through week 48. These results highlight the potential benefits of treatment with momelotinib in patients with myelofibrosis, particularly those with anaemia., Funding: Sierra Oncology, a GSK company., Competing Interests: Declaration of interests ATG reports consulting fees from AbbVie, Bristol Myers Squibb, Constellation/MorphoSys, CTI Biopharma, Imago Biosciences/Merck, Incyte, Pharma Essentia, Sierra Oncology/GSK, and Telios. SV reports consulting fees from GSK. AMV reports payment or honoraria from AbbVie, AOP Health, Bristol Myers Squibb, GSK, Incyte, Novartis, and Roche. HKA-A reports research grants from Bristol Myers Squibb and Incyte; honoraria from AbbVie, Bristol Myers Squibb, GSK, and Novartis; and advisory board participation with AbbVie, Bristol Myers Squibb, GSK, and Novartis. DL reports consulting fees from AbbVie, Medisson, and Takeda; payment or honoraria from AbbVie, Novartis, Roche, and Takeda; travel support from AbbVie; and advisory board participation with AbbVie and Medisson. ATK reports consulting fees from CTI Biopharma, GSK, and Imago Biosciences; payment or honoraria from Bristol Myers Squibb, Incyte, and MorphoSys; travel support from AbbVie and MorphoSys; and advisory board participation with Incyte. AI reports payment or honoraria from Bristol Myers Squibb, GSK, Incyte, Novartis, and Pfizer; and advisory board participation with AOP Health, Incyte, and Novartis. YTG reports consulting fees from AstraZeneca, GSK, Novartis, and Pfizer; and payment or honoraria from AbbVie. MLF reports consulting fees from AbbVie, GSK, Novartis, and Sierra Oncology; payment or honoraria from Bristol Myers Squibb and Novartis; and travel support from AbbVie. DM reports a research grant from Imago Biosciences; payment or honoraria from AbbVie, Bristol Myers Squibb, Jazz Pharma, and Novartis; participation on a data safety monitoring board for the UK ALL-RIC trial; and a leadership or fiduciary role as a member of the EBMT Scientific Council and chair of the EBMT Chronic Malignancies Working Party. S-SY reports grants or contracts from Roche-Genentech, Kyowa Hakko Kirin, and Yuhan Pharma; payment or honoraria from Celgene, Janssen, and Novartis; and advisory board participation with Amgen, Antengene, and Takeda. VG reports consulting fees from AbbVie, Bristol Myers Squibb/Celgene, Constellation Biopharma, CTI Biopharma, GSK, Novartis, Pfizer, and Sierra Oncology; payment or honoraria from Bristol Myers Squibb/Celgene and Novartis; and advisory board participation with AbbVie, Bristol Myers Squibb/Celgene, CTI Biopharma, Pfizer, Roche, and Sierra Oncology. J-JK reports advisory board participation with AbbVie, AOP Health, Bristol Myers Squibb, GSK, Incyte, and Novartis. FP reports grants or contracts from Bristol Myers Squibb; consulting fees from AbbVie, AOP Orphan, Bristol Myers Squibb/Celgene, Kartos, Karyopharm, Kyowa Kirin and MEI, Novartis, Roche, Sierra Oncology, and Sumimoto; and payment or honoraria from AbbVie, AOP Orphan, Bristol Myers Squibb/Celgene, Novartis, and Roche. CNH reports payment for study conduct and advisory board participation, related to the present manuscript; consulting fees from DISC, Galecto, and Keros; payment or honoraria from Bristol Myers Squibb, CTI Biopharma, GSK, Novartis, and Sierra Oncology; advisory board participation with AOP, Keros, Sumimoto, and Telios; and a leadership or fiduciary role with EHA, HemaSphere, and MPN Voice. SO reports consulting fees from AbbVie, Bristol Myers Squibb, Cogent, Constellation, CTI Biopharma, Geron, Incyte, Protagonist, and Sierra Oncology. BJK and RD employment and stock/stock options with Sierra Oncology, a GSK company. JY reports employment and stock or stock options with GSK. JK reports employment and stock or stock options with Sierra Oncology, a GSK company; and stock or stock options with Gilead. RM reports consulting fees from AbbVie, Blueprint, Bristol Myers Squibb, CTI, Genentech, Geron, GSK, Incyte, MorphoSys, Novartis, Sierra Oncology, and Telios. All authors received medical writing support related to the present manuscript, funded by GSK. SG, MCL, ME, NG, AP, S-EL, and LO declare no other competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Momelotinib is the first inhibitor of Janus kinase 1 (JAK1) and JAK2 shown to also inhibit activin A receptor type 1 (ACVR1), a key regulator of iron homeostasis, and has demonstrated improvements in splenomegaly, constitutional symptoms, and anemia in myelofibrosis (MF). This long-term analysis pooled data from 3 randomized phase 3 studies of momelotinib (MOMENTUM, SIMPLIFY-1, and SIMPLIFY-2), representing MF disease from early (JAK inhibitor-naive) to late (JAK inhibitor-experienced) stages. Patients in the control arms (danazol in MOMENTUM, ruxolitinib in SIMPLIFY-1, and best available therapy in SIMPLIFY-2) could cross over to receive momelotinib at the end of the 24-week randomized period, and all patients could continue momelotinib treatment after the completion of these studies via an extended access protocol (XAP). Across these studies, 725 patients with MF received momelotinib; 12% remained on therapy for ≥5 years, with a median treatment exposure of 11.3 months (range, 0.1-90.4 months). The most common nonhematologic treatment-emergent adverse event (AE) occurring in ≥20% of patients was diarrhea (any grade, 27% and grade ≥3, 3%). Any-grade thrombocytopenia, anemia, and neutropenia occurred in 25%, 23%, and 7% of patients, respectively. The most common reason for momelotinib discontinuation was thrombocytopenia (4% discontinuation rate). The incidence of AEs of clinical importance (eg, infections, malignant transformation, peripheral neuropathy, and hemorrhage) did not increase over time. This analysis of one of the largest randomized trial databases for a JAK inhibitor to date in MF demonstrated a consistent safety profile of momelotinib without long-term or cumulative toxicity. These trials were registered at www.clinicaltrials.gov as: MOMENTUM (#NCT04173494), SIMPLIFY-1 (#NCT01969838), SIMPLIFY-2 (#NCT02101268), and XAP (#NCT03441113)., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Background: In a pooled analysis of the phase 3 Controlled Myelofibrosis Study With Oral JAK Inhibitor Treatment I (COMFORT-I) and COMFORT-II clinical trials, adult patients with intermediate-2 or high-risk myelofibrosis who received oral ruxolitinib at randomization or after crossover from placebo or best available therapy (BAT) had improved overall survival (OS)., Methods: This post hoc analysis of pooled COMFORT data examined relevant disease outcomes based on the disease duration (≤12 or >12 months from diagnosis) before ruxolitinib initiation., Results: The analysis included 525 patients (ruxolitinib: ≤12 months, n = 84; >12 months, n = 216; placebo/BAT: ≤12 months, n = 66; >12 months, n = 159); the median age was 65.0-70.0 years. Fewer thrombocytopenia and anemia events were observed among patients who initiated ruxolitinib treatment earlier. At Weeks 24 and 48, the spleen volume response (SVR) was higher for patients who initiated ruxolitinib earlier (47.6% vs. 32.9% at Week 24, p = .0610; 44.0% vs. 26.9% at Week 48, p = .0149). In a multivariable analysis of factors associated with spleen volume reduction, a logistic regression model that controlled for confounding factors found that a significantly greater binary reduction was observed among patients with shorter versus longer disease duration (p = .022). At Week 240, OS was significantly improved among patients who initiated ruxolitinib earlier (63% [95% CI, 51%-73%] vs. 57% [95% CI, 49%-64%]; hazard ratio, 1.53; 95% CI, 1.01-2.31; p = .0430). Regardless of disease duration, a longer OS was observed for patients who received ruxolitinib versus those who received placebo/BAT., Conclusions: These findings suggest that earlier ruxolitinib initiation for adult patients with intermediate-2 and high-risk myelofibrosis may improve clinical outcomes, including fewer cytopenia events, durable SVR, and prolonged OS., Plain Language Summary: Patients with myelofibrosis, a bone marrow cancer, often do not live as long as the general population. These patients may also have an enlarged spleen and difficult symptoms such as fatigue. Two large clinical trials showed that patients treated with the drug ruxolitinib lived longer and had improved symptoms compared to those treated with placebo or other standard treatments. Here it was examined whether starting treatment with ruxolitinib earlier (i.e., within a year of diagnosis) provided benefits versus delaying treatment. Patients who received ruxolitinib within a year of diagnosis lived longer and experienced fewer disease symptoms than those whose treatment was delayed., (© 2023 The Authors. Cancer published by Wiley Periodicals LLC on behalf of American Cancer Society.)

Background: Myelofibrosis (MF)-associated constitutional symptoms can severely impact health-related quality of life. Clinical trials in MF traditionally measure symptom response to treatment as a landmark endpoint of total symptom score (TSS) reduction ≥50% from baseline. However, this dichotomous assessment provides a limited view of clinically relevant symptomatic changes. Herein we evaluated longitudinal change from baseline in TSS over the continuous 24-week period and individual symptom scores to obtain a more comprehensive understanding of symptom benefits experienced by patients with MF receiving therapy., Methods: Longitudinal symptom change was evaluated using mixed-effect model repeated measure (MMRM) methodology with individual item-level analyses to complement the interpretation of the landmark symptom results in the completed phase III SIMPLIFY studies of momelotinib in MF. MMRM compared mean change in TSS from baseline with Week 24 using data from all patient visits. Generalized estimating equations were used to estimate item-level odds ratios using multiple predictive imputations for missing data., Results: Momelotinib and ruxolitinib groups reported similar overall symptom improvements, with a TSS difference of <1.5 points between groups for each post-baseline visit in SIMPLIFY-1. In SIMPLIFY-2, the improvement in TSS observed in momelotinib-treated patients was consistent with that observed in SIMPLIFY-1, whereas progressive TSS deterioration was observed with control. Item-level scores were heterogeneous in both studies. A similar and greater proportion of momelotinib-treated patients were categorized as "improved" or "stable" compared with control in SIMPLIFY-1 and SIMPLIFY-2, respectively. Odds ratios for between-group comparison ranged from 0.75 to 1.21 in SIMPLIFY-1, demonstrating similarity in likelihood of symptom improvement. In SIMPLIFY-2, the likelihood of symptom improvement in each item was higher in the momelotinib arm., Conclusions: These findings suggest that momelotinib provides clinically relevant symptom benefits in the JAK inhibitor-naïve and JAK inhibitor-exposed settings., (© 2023 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Myelofibrosis (MF) is a myeloproliferative disorder that exhibits considerable biological and clinical heterogeneity. At the two ends of the disease spectrum are the myelodepletive or cytopenic phenotype and the myeloproliferative phenotype. The cytopenic phenotype has a high prevalence in primary MF (PMF) and is characterized by low blood counts. The myeloproliferative phenotype is typically associated with secondary MF (SMF), mild anemia, minimal need for transfusion support, and normal to mild thrombocytopenia. Differences in somatic driver mutations and allelic burden, as well as the acquisition of non-driver mutations further influences these phenotypic differences, prognosis, and response to therapies such as JAK2 inhibitors. The outcome of patients with the cytopenic phenotype are comparatively worse and frequently pose a challenge to treat given the inherent exacerbation of cytopenias. Recent data indicate that an innate immune deregulated state that hinges on the myddosome-IRAK-NFκB axis favors the cytopenic myelofibrosis phenotype and offers opportunity for novel treatment approaches. We will review the biological and clinical features of the MF disease spectrum and associated treatment considerations., (© 2022. The Author(s).)

Background: Janus kinase (JAK) inhibitors approved for myelofibrosis provide spleen and symptom improvements but do not meaningfully improve anaemia. Momelotinib, a first-in-class inhibitor of activin A receptor type 1 as well as JAK1 and JAK2, has shown symptom, spleen, and anaemia benefits in myelofibrosis. We aimed to confirm the differentiated clinical benefits of momelotinib versus the active comparator danazol in JAK-inhibitor-exposed, symptomatic patients with anaemia and intermediate-risk or high-risk myelofibrosis., Methods: MOMENTUM is an international, double-blind, randomised, controlled, phase 3 study that enrolled patients at 107 sites across 21 countries worldwide. Eligible patients were 18 years or older with a confirmed diagnosis of primary myelofibrosis or post-polycythaemia vera or post-essential thrombocythaemia myelofibrosis. Patients were randomly assigned (2:1) to receive momelotinib (200 mg orally once per day) plus danazol placebo (ie, the momelotinib group) or danazol (300 mg orally twice per day) plus momelotinib placebo (ie, the danazol group), stratified by total symptom score (TSS; <22 vs ≥22), spleen size (<12 cm vs ≥12 cm), red blood cell or whole blood units transfused in the 8 weeks before randomisation (0 units vs 1-4 units vs ≥5 units), and study site. The primary endpoint was the Myelofibrosis Symptom Assessment Form (MFSAF) TSS response rate at week 24 (defined as ≥50% reduction in mean MFSAF TSS over the 28 days immediately before the end of week 24 compared with baseline). MOMENTUM is registered with ClinicalTrials.gov, number NCT04173494, and is active but not recruiting., Findings: 195 patients were randomly assigned to either the momelotinib group (130 [67%]) or danazol group (65 [33%]) and received study treatment in the 24-week randomised treatment period between April 24, 2020, and Dec 3, 2021. A significantly greater proportion of patients in the momelotinib group reported a 50% or more reduction in TSS than in the danazol group (32 [25%] of 130 vs six [9%] of 65; proportion difference 16% [95% CI 6-26], p=0·0095). The most frequent grade 3 or higher treatment-emergent adverse events with momelotinib and danazol were haematological abnormalities by laboratory values: anaemia (79 [61%] of 130 vs 49 [75%] of 65) and thrombocytopenia (36 [28%] vs 17 [26%]). The most frequent non-haematological grade 3 or higher treatment-emergent adverse events with momelotinib and danazol were acute kidney injury (four [3%] of 130 vs six [9%] of 65) and pneumonia (three [2%] vs six [9%])., Interpretation: Treatment with momelotinib, compared with danazol, resulted in clinically significant improvements in myelofibrosis-associated symptoms, anaemia measures, and spleen response, with favourable safety. These findings support the future use of momelotinib as an effective treatment in patients with myelofibrosis, especially in those with anaemia., Funding: Sierra Oncology., Competing Interests: Declaration of interests SV reports consulting fees from Bristol Myers Squibb/Celgene, Incyte, Novartis, and Sierra Oncology. ATG reports consulting fees from AbbVie, Bristol Myers Squibb, Constellation/MorphoSys, CTI Biopharma, Novartis, Pharma Essentia, and Sierra Oncology. ATK reports grants from AbbVie, Bristol Myers Squibb, Prelude, and Sierra; consulting fees from AbbVie and Prelude; honoraria from Bristol Myers Squibb, Incyte, and Novartis; and participation on a data safety monitoring board or advisory board for AbbVie, Bristol Myers Squibb, CTI Biopharma, Geron, Imago, and Incyte. MLF reports payment for expert testimony from OncLive; meeting attendance or travel support from Novartis; and participation on a data safety monitoring board or advisory board for Bristol Myers Squibb, Novartis, and Sierra Oncology. DM reports research grants from Bristol Myers Squibb/Celgene, and Constellation Biopharma; honoraria from AbbVie, Celgene, Jazz, and Novartis; meeting attendance or travel support from Jazz; participation on a data safety monitoring board or advisory board for the ALL-RIC study; and leadership role with the European Society of Hematology and the EBMT Chronic Malignancies Working Party. AP reports honoraria, meeting attendance and travel support, and participation on an advisory board from Novartis Oncology. S-SY reports research grants from Kyowa Kirin and Roche/Genentech; consulting fees from Astellas, Amgen, Antengene, and Celgene; and honoraria from Novartis. VG reports consulting fees from AbbVie, Bristol Myers Squibb/Celgene, Constellation Biopharma, Novartis, Pfizer, and Sierra Oncology; honoraria from Bristol Myers Squibb, Constellation Biopharma, and Novartis; and participation on data safety monitoring board or advisory board for AbbVie, Bristol Myers Squibb/Celgene, Pfizer, and Roche. J-JK reports honoraria from Novartis; participation on a data safety monitoring board or advisory board for AbbVie, Bristol Myers Squibb, Incyte, and Novartis. NG reports consulting fees from Alexion, Bristol Myers Squibb/Celgene, Incyte, and Novartis; honoraria from Bristol Myers Squibb/Celgene, Janssen, and Novartis; leadership or fiduciary role for Alexion, Incyte, and Novartis; and meeting attendance or travel support from AbbVie, Genzyme, and Sanofi. FP reports research grant from Bristol Myers Squibb/Celgene; consulting fees from AbbVie, APO, Bristol Myers Squibb/Celgene, Karyopharm, Kyowa Kirin, MEI, Novartis, and Roche; and honoraria from Bristol Myers Squibb/Celgene, Janssen, and Novartis. CNH reports grant support from Bristol Myers Squibb/Celgene, Constellation Biopharma, and Novartis; consulting fees from AOP, Galecto, Keros, and Roche; honoraria from AbbVie, Celgene, Constellation Biopharma, CTI Biopharma, Janssen, and Novartis; participation in data safety monitoring board or advisory board for AbbVie, AOP, CTI Biopharma, Geron, Promedior, Roche, and Sierra Oncology; and leadership or fiduciary role in the European Hematology Association and MPN Voice. BJK, SR, and RD report employment and stock or stock options at Sierra Oncology. JK reports employment and stock or stock options at Sierra Oncology and former employment and stock and stock options from Gilead. RM reports research grants from AbbVie, Celgene, CTI Biopharma, Constellation Biopharma, Genotech, Incyte, Promedior, Samus, and the Mays Cancer Center P30 Cancer Center Support Grant from the National Cancer Institute (CA054174); and consulting fees from Constellation Biopharma, LaJolla, Novartis, and Sierra Oncology. All other authors declare no competing interests., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Myelofibrosis (MF) is a clonal hematologic malignancy with progressive bone marrow fibrosis. Clinical manifestations of MF include splenomegaly, constitutional symptoms, and anemia, whose pathogenesis is multifactorial and largely due to ineffective erythropoiesis and is clinically associated with poor quality of life and reduced overall survival. The only curative treatment for MF is allogenic stem cell transplantation; however, few patients are eligible. Disease management strategies for MF-related anemia have limited effectiveness, and Janus kinase (JAK) inhibitors may induce or worsen related anemia. Thus, there is a significant unmet need for the treatment of patients with MF-related anemia. This review summarizes current and emerging treatments for anemia in MF, including luspatercept and KER-050 (transforming growth factor-β ligand traps), momelotinib and pacritinib (JAK inhibitors), pelabresib (a bromodomain extra-terminal domain inhibitor), PRM-151 (an antifibrotic agent), imetelstat (a telomerase inhibitor), and navitoclax (a BCL-2/BCL-xL inhibitor). Therapeutic combinations with ruxolitinib may offer another treatment approach., Competing Interests: Declaration of Competing Interest Francesco Passamonti has been a member of a speakers’ bureau for AbbVie, BMS, Celgene, Janssen, and Novartis; has consulted for AbbVie, AOP Orphan, BMS, Celgene, Janssen, Karyopharma, Kyowa Kirin, MEI Pharma, Novartis, and Roche; and has received research grants from BMS. Claire N. Harrison has received honoraria from AbbVie, AOP Orphan, BMS, Constellation Pharmaceuticals, CTI BioPharma Corp, Janssen, Novartis, and Sierra Oncology; has consulted for AbbVie, AOP Orphan, CTI BioPharma Corp, Galecto, Geron, and Sierra Oncology; has received support for travel from BMS and Novartis; has been a member of an advisory board for Galecto; and has received research grants from BMS, Constellation Pharmaceuticals, and Novartis. Ruben A. Mesa has consulted for Constellation Pharmaceuticals, La Jolla Pharmaceutical, Novartis, Pharma, and Sierra Oncology; and has received research grants from AbbVie, Celgene, Constellation Pharmaceuticals, CTI BioPharma Corp, Genotech, Incyte, Mays Cancer Center P30 Cancer Center Support Grant from the National Cancer Institute (CA054174), Promedior, and Samus. Jean-Jacques Kiladjian received honoraria from Novartis; and has been a member of an advisory board for AbbVie, AOP Orphan, BMS, Incyte, and Novartis. Alessandro M. Vannucchi has been a member of an advisory board for AbbVie, AOP Orphan, Blueprint Medicines, Celgene, Incyte, and Novartis; and has received lecture fees from AbbVie, AOP Orphan, Blueprint Medicines, BMS, GSK, Incyte, and Novartis. Srdan Verstovsek has received research support for the conduct of clinical studies from BMS., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Patients with Philadelphia-negative myeloproliferative neoplasms are at high risk of thrombotic events (TEs). Predisposing factors have been identified in essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (primary MF, PMF), while yet not recognized in post PV/ET-MF (known as secondary MF, SMF). Within the 1258 SMF of the MYSEC (MYelofibrosis SECondary to PV and ET) dataset, 135 (10.7%) developed a TE at a median follow-up of 3.5 years (range, 1-21.4), with an incidence of 2.3% patients per year. Venous events accounted for two-thirds of the total. Cox multivariable analysis, supported by Fine-Gray models with death as competitive risk, showed that being on cytoreductive therapy at time of SMF evolution is associated with an absolute risk reduction of thrombosis equal to 3.3% within 3 years. Considering individually cytoreductive therapies, univariate regression model found that both conventional cytoreduction, mainly hydroxyurea, (HR 0.41, 95% CI: 0.26-0.65, p = 0.0001) and JAK inhibitors, mostly ruxolitinib, (HR 0.50, 95% CI: 0.24-1.02, p = 0.05) were associated with fewer thrombosis. Our study informs treating physicians of a non-low incidence of TEs in post PV/ET-MF and of the potential protective role of cytoreductive therapy in terms of thrombotic events., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Myeloproliferative neoplasms (MPNs) are uncommon in children/young adults. Here, we present data on unselected patients diagnosed before 25 years of age included from 38 centers in 15 countries. Sequential patients were included. We identified 444 patients, with median follow-up 9.7 years (0-47.8). Forty-nine (11.1%) had a history of thrombosis at diagnosis, 49 new thrombotic events were recorded (1.16% patient per year [pt/y]), perihepatic vein thromboses were most frequent (47.6% venous events), and logistic regression identified JAK2V617F mutation (P = .016) and hyperviscosity symptoms (visual disturbances, dizziness, vertigo, headache) as risk factors (P = .040). New hemorrhagic events occurred in 44 patients (9.9%, 1.04% pt/y). Disease transformation occurred in 48 patients (10.9%, 1.13% pt/y), usually to myelofibrosis (7.5%) with splenomegaly as a novel risk factor for transformation in essential thrombocythemia (ET) (P= .000) in logistical regression. Eight deaths (1.8%) were recorded, 3 after allogeneic stem cell transplantation. Concerning conventional risk scores: International Prognostic Score for Essential Thrombocythemia-Thrombosis and new International Prognostic Score for Essential Thrombocythemia-Thrombosis differentiated ET patients in terms of thrombotic risk. Both scores identified high-risk patients with the same median thrombosis-free survival of 28.5 years. No contemporary scores were able to predict survival for young ET or polycythemia vera patients. Our data represents the largest real-world study of MPN patients age < 25 years at diagnosis. Rates of thrombotic events and transformation were higher than expected compared with the previous literature. Our study provides new and reliable information as a basis for prospective studies, trials, and development of harmonized international guidelines for the specific management of young patients with MPN., (© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Myelofibrosis (MF) is a clonal myeloproliferative neoplasm, typically associated with disease-related symptoms, splenomegaly, cytopenias and bone marrow fibrosis. Patients experience a significant symptom burden and a reduced life expectancy. Patients with MF receive ruxolitinib as the current standard of care, but the depth and durability of responses and the percentage of patients achieving clinical outcome measures are limited; thus, a significant unmet medical need exists. Pelabresib is an investigational small-molecule bromodomain and extraterminal domain inhibitor currently in clinical development for MF. The aim of this article is to describe the design of the ongoing, global, phase III, double-blind, placebo-controlled MANIFEST-2 study evaluating the efficacy and safety of pelabresib and ruxolitinib versus placebo and ruxolitinib in patients with JAKi treatment-naive MF. Clinical Trial Registration: NCT04603495 (ClinicalTrials.gov).

Janus kinase inhibitors (JAKi) approved for myelofibrosis provide spleen and symptom improvements but do not address anemia, a negative prognostic factor. Momelotinib, an inhibitor of ACVR1/ALK2, JAK1 and JAK2, demonstrated activity against anemia, symptoms, and splenomegaly in the phase 3 SIMPLIFY trials. Here, we report mature overall survival (OS) and leukemia-free survival (LFS) from both studies, and retrospective analyses of baseline characteristics and efficacy endpoints for OS associations. Survival distributions were similar between JAKi-naïve patients randomized to momelotinib, or ruxolitinib then momelotinib, in SIMPLIFY-1 (OS HR = 1.02 [0.73, 1.43]; LFS HR = 1.08 [0.78, 1.50]). Two-year OS and LFS were 81.6% and 80.7% with momelotinib and 80.6% and 79.3% with ruxolitinib then momelotinib. In ruxolitinib-exposed patients in SIMPLIFY-2, two-year OS and LFS were 65.8% and 64.2% with momelotinib and 61.2% and 59.7% with best available therapy then momelotinib (OS HR = 0.98 [0.59, 1.62]; LFS HR = 0.97 [0.59, 1.60]). Baseline transfusion independence (TI) was associated with improved survival in both studies (SIMPLIFY-1 HR = 0.474, p = 0.0001; SIMPLIFY-2 HR = 0.226, p = 0.0005). Week 24 TI response in JAKi-naïve, momelotinib-randomized patients was associated with improved OS in univariate (HR = 0.323; p < 0.0001) and multivariate (HR = 0.311; p < 0.0001) analyses. These findings underscore the importance of achieving or maintaining TI in myelofibrosis, supporting the clinical relevance of momelotinib's pro-erythropoietic mechanism of action, and potentially informing treatment decision-making., (© 2022. The Author(s).)

Thrombocytopenia is common in patients with myelofibrosis (MF) and is a well-established adverse prognostic factor. Both of the approved Janus kinase (JAK) inhibitors, ruxolitinib and fedratinib, can worsen thrombocytopenia and have not been evaluated in patients with severe thrombocytopenia (platelet counts <50×109/L). Pacritinib, a novel JAK2/interleukin-1 receptor-associated kinase 1 inhibitor, has been studied in two phase III trials (PERSIST-1 and PERSIST- 2), both of which enrolled patients with MF and severe thrombocytopenia. In order to better characterize treatment outcomes for this population with advanced disease, we present a retrospective analysis of efficacy and safety data in the 189 patients with severe thrombocytopenia treated in the PERSIST studies. The proportion of patients in the pacritinib group meeting efficacy endpoints was greater than in the BAT group for ≥35% spleen volume reduction (23% vs. 2%, P=0.0007), ≥50% modified Total Symptom Score reduction (25% vs. 8%, P=0.044), and self-reported symptom benefit ("much" or "very much" improved; 25% vs. 8%, P=0.016) at the primary analysis time point (week 24). The adverse event profile of pacritinib was manageable, and dose modification was rarely required. There was no excess in bleeding or death in pacritinib-treated patients. These results indicate that pacritinib is a promising treatment for patients with MF who lack safe and effective therapeutic options due to severe thrombocytopenia.

Fedratinib, an oral Janus kinase-2 (JAK2) inhibitor, is approved for patients with myelofibrosis (MF) and platelet counts ≥50 × 10 9 /l, based on outcomes from the phase 3, placebo-controlled JAKARTA trial in JAK-inhibitor-naïve MF, and the phase 2, single-arm JAKARTA2 trial in patients previously treated with ruxolitinib. We evaluated the efficacy and safety of fedratinib 400 mg/day in patients with baseline platelet counts 50 to <100 × 10 9 /l ("Low-Platelets" cohorts), including 14/96 patients (15%) in JAKARTA and 33/97 (34%) in JAKARTA2. At 24 weeks, spleen response rates were not significantly different between the Low-Platelets cohort and patients with baseline platelet counts ≥100 × 10 9 /l ("High-Platelets" cohort), in JAKARTA (36% vs. 49%, respectively; p = 0.37) or JAKARTA2 (36% vs. 28%; p = 0.41). Symptom response rates were also not statistically different between the Low- and High-Platelets cohorts. Fedratinib was generally well-tolerated in both platelet-count cohorts. New or worsening thrombocytopaenia was more frequent in the Low-Platelets (44%) versus the High-Platelets (9%) cohort, but no serious thrombocytopaenia events occurred. Thrombocytopaenia was typically managed with dose modifications; only 3/48 Low-Platelets patients discontinued fedratinib due to thrombocytopaenia. These data indicate that fedratinib 400 mg/day is safe and effective in patients with MF and low pretreatment platelet counts, and no initial fedratinib dose adjustment is required for these patients., (© 2022 The Authors. British Journal of Haematology published by British Society for Haematology and John Wiley & Sons Ltd.)

Imetelstat, a first-in-class telomerase inhibitor, demonstrated meaningful clinical benefit including a robust symptom response rate and potential overall survival benefit in IMbark, a phase II study in intermediate-2 or high-risk myelofibrosis (MF) patients who have relapsed after or are refractory to JAK inhibitors. We describe the rationale and design for the phase III trial, IMpactMF (NCT04576156), an open-label evaluation of imetelstat versus best available therapy, excluding JAK inhibitors, in MF patients refractory to JAK inhibitor. Imetelstat 9.4 mg/kg is administered as an intravenous infusion every 21 days. Primary objective is to assess overall survival. Secondary objectives include symptom and spleen responses, progression-free survival, clinical response assessment, bone marrow fibrosis reduction, safety and pharmacokinetics. Biomarker, cytogenetics and mutation analyses will be performed.

In the MYF2001 trial, treatment of Janus kinase (JAK) inhibitor-relapsed/refractory intermediate-2 or high-risk myelofibrosis (MF) with imetelstat 9.4 mg/kg every 3 weeks demonstrated encouraging median overall survival of 29.9 months. To provide historical context, external real-world data (RWD) were collected from a study of 96 patients who had discontinued ruxolitinib and were subsequently treated with best available therapy (BAT) at Moffitt Cancer Center. A closely matched cohort was identified using the MYF2001 eligibility criteria, including patients with MF who had discontinued ruxolitinib due to lack or loss of response. Overall survival was measured from time of JAK inhibitor discontinuation to death or censored at last follow-up. To improve comparability, propensity score weighting approaches using average treatment effect for overlap population (ATO) and stabilized inverse probability treatment weighting (sIPTW) were used for 10 critical baseline covariates. Fifty-seven patients treated with imetelstat 9.4 mg/kg from MYF2001 and 38 patients treated with BAT from RWD were analyzed with improved balanced baseline covariates after propensity score adjustment, showing significantly lower risk of death with imetelstat compared with BAT (hazard ratio: 0.35; p = 0.0019). With sIPTW, results were similar. Results of sensitivity analyses were consistent with the primary analysis. In conclusion, treatment with imetelstat was associated with longer overall survival compared to BAT (30 vs 12 months, respectively) in closely matched patients with MF after JAK inhibitor failure, warranting further evaluation of imetelstat in this poor-prognosis patient population., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Patients with myelofibrosis who are relapsed or refractory (R/R) to Janus-associated kinase inhibitors (JAKis) have poor clinical outcomes including dismal overall survival (OS) that ranges between 13 and 16 months. Imetelstat, a telomerase inhibitor, was evaluated in patients with intermediate-2 or high-risk myelofibrosis R/R to JAKi in a phase II multicenter study (ClinicalTrials.gov identifier: NCT02426086)., Patients and Methods: Patients were randomly assigned to receive either imetelstat 9.4 mg/kg or 4.7 mg/kg intravenous once every 3 weeks. Spleen response (≥ 35% spleen volume reduction) and symptom response (≥ 50% reduction in total symptom score) rates at week 24 were coprimary end points. Secondary end points included OS and safety., Results: Study enrollment was closed early, and patients treated with 4.7 mg/kg were permitted to continue treatment with 9.4 mg/kg. At week 24, spleen and symptom response rates were 10.2% and 32.2% in the 9.4-mg/kg arm and 0% and 6.3% in the 4.7-mg/kg arm. Treatment with imetelstat 9.4 mg/kg led to a median OS of 29.9 months and bone marrow fibrosis improvement in 40.5% and variant allele frequency reduction of driver mutations in 42.1% of evaluable patients. Fibrosis improvement and variant allele frequency reduction correlated with OS. Target inhibition was demonstrated by reduction of telomerase activity and human telomerase reverse transcriptase level and correlated with spleen response, symptom response, and OS. Most common adverse events on both arms were grade 3 or 4 reversible cytopenias., Conclusion: In this phase II study of two imetelstat doses, 9.4 mg/kg once every 3 weeks demonstrated clinical benefits in symptom response rate, with an acceptable safety profile for this poor-risk JAKi R/R population. Biomarker and bone marrow fibrosis assessments suggested selective effects on the malignant clone. A confirmatory phase III study is currently underway., Competing Interests: John MascarenhasConsulting or Advisory Role: Incyte, Geron, Celgene/Bristol Myers Squibb, Novartis, CTI BioPharma Corp, Kartos Therapeutics, Constellation Pharmaceuticals, Sierra Oncology, AbbVie, Roche/GenentechResearch Funding: Incyte, Pharmaessentia, Merck, Forbius, Geron, AbbVie, Kartos Therapeutics, Roche/Genentech, CTI BioPharma Corp Rami KomrokjiStock and Other Ownership Interests: AbbVieConsulting or Advisory Role: Novartis, Bristol Myers Squibb, Jazz Pharmaceuticals, AbbVie, Geron, Acceleron PharmaSpeakers' Bureau: Jazz Pharmaceuticals, Bristol Myers Squibb, AgiosTravel, Accommodations, Expenses: Jazz Pharmaceuticals, Bristol Myers Squibb, Agios Dietger NiederwieserConsulting or Advisory Role: Cellectis, Amgen, NovartisSpeakers' Bureau: NovartisResearch Funding: Daiichi Sankyo Andreas ReiterHonoraria: Novartis, Blueprint Medicines, Incyte, Celgene/Bristol Myers Squibb, AOP Orphan PharmaceuticalsConsulting or Advisory Role: Novartis, Blueprint Medicines, Incyte, Celgene/Bristol Myers Squibb, AOP Orphan PharmaceuticalsResearch Funding: Blueprint Medicines, Deciphera, Novartis, Incyte, AOP Orphan PharmaceuticalsExpert Testimony: NovartisTravel, Accommodations, Expenses: Novartis, Deciphera, Blueprint Medicines, Incyte Bart ScottHonoraria: Bristol Myers SquibbConsulting or Advisory Role: Celgene, Acceleron Pharma, Astex Pharmaceuticals, NovartisSpeakers' Bureau: Alexion Pharmaceuticals, Celgene, Jazz Pharmaceuticals, NovartisResearch Funding: Celgene Maria BaerResearch Funding: AbbVie, AI Therapeutics, FORMA Therapeutics, Kite, a Gilead company, Oscotec, Takeda Ronald HoffmanConsulting or Advisory Role: Protagonist Therapeutics, NovartisResearch Funding: Novartis, Scholar Rock, Turning Point Therapeutics Olatoyosi OdenikeConsulting or Advisory Role: AbbVie, Impact Biomedicines, Celgene, Novartis, BMS, Taiho PharmaceuticalResearch Funding: Celgene, Incyte, Astex Pharmaceuticals, NS Pharma, AbbVie, Janssen Oncology, OncoTherapy Science, Agios, AstraZeneca, CTI BioPharma Corp, Kartos Therapeutics, Aprea AB Alessandro VannucchiConsulting or Advisory Role: Novartis, AbbVie, Roche, Incyte, CelgeneSpeakers' Bureau: Novartis, AOP Orphan Pharmaceuticals, Incyte, Roche, Celgene Jacqueline BussolariEmployment: Johnson & Johnson, Bristol Myers Squibb, HotSpot TherapeuticsLeadership: HotSpot TherapeuticsStock and Other Ownership Interests: Johnson & Johnson, Bristol Myers Squibb, HotSpot TherapeuticsTravel, Accommodations, Expenses: Johnson & Johnson Eugene ZhuEmployment: Johnson & JohnsonStock and Other Ownership Interests: Johnson & Johnson Esther RoseEmployment: Janssen Research & DevelopmentStock and Other Ownership Interests: Johnson & JohnsonConsulting or Advisory Role: Geron CorpTravel, Accommodations, Expenses: Janssen Research & Development Laurie ShermanEmployment: Geron, JanssenStock and Other Ownership Interests: Janssen, Geron Souria DoughertyEmployment: GeronStock and Other Ownership Interests: Geron Libo SunEmployment: GeronStock and Other Ownership Interests: Geron, Johnson & Johnson, Moderna TherapeuticsTravel, Accommodations, Expenses: Geron Fei HuangStock and Other Ownership Interests: Bristol Myers Squibb, Geron, Johnson & Johnson Ying WanEmployment: GeronStock and Other Ownership Interests: Geron Faye FellerEmployment: Geron, JanssenStock and Other Ownership Interests: Geron, JanssenTravel, Accommodations, Expenses: Geron, Janssen Aleksandra RizoLeadership: GeronStock and Other Ownership Interests: Geron, Johnson & Johnson Jean-Jacques KiladjianConsulting or Advisory Role: Novartis, Incyte, BMS, AOP Orphan Pharmaceuticals, AbbVie, PharmaessentiaNo other potential conflicts of interest were reported.

This multicenter prospective phase 2 trial analyzed disease-free survival (DFS) in myelofibrosis patients receiving ruxolitinib for 6 months before transplantation. Seventy-six patients were recruited. Age-adjusted dynamic international prognostic scoring system was intermediate-1, intermediate-2, and high in 27 (36%), 31 (41%), and 18 (24%) patients. All patients received ruxolitinib from inclusion to conditioning regimen (fludarabine-melphalan) or to progression. A donor was found in 64 patients: 18 HLA-matched sibling donor (MSD), 32 HLA-matched unrelated (UD10/10), and 14 HLA mismatched unrelated donor (UD9/10. Among 64 patients with a donor, 20 (31%) achieved a partial response before transplantation and 59 (92%) could be transplanted after ruxolitinib therapy (18/18 MSD, 30/21 UD10/10, 11/34 UD9/10), of whom 19 (32%) were splenectomized. Overall survival from inclusion was 68% at 12 months. One-year DFS after transplantation was 55%: 83%, 40%, and 34% after MSD, UD10/10 or UD9/10, respectively. Cumulative incidence of grade 2-4 acute graft-versus-host disease (GVHD) was 66% and non-relapse-mortality was 42% at 12 months. Short course of ruxolitinib before transplantation is followed by a high rate of transplantation. With the platform used in this protocol, outcome was much better in patients transplanted with HLA-matched sibling donor as compared to unrelated donor., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Myelofibrosis is a myeloproliferative neoplasm associated with constitutional symptoms, increasing splenomegaly, and worsening cytopenias. Janus kinase (JAK) inhibitors have been used for the treatment of myelofibrosis for several years, but there is a lack of comparative information between those treatments. A systematic review and network meta-analysis was performed on randomized controlled trials in patients with myelofibrosis receiving JAK inhibitor or placebo or control. Primary outcomes were efficacy on spleen volume reduction and total symptom score reduction. Additional analyses were conducted on anemia and thrombopenia events. Seven studies were included in the network meta-analysis including 1953 patients randomly assigned to four JAK inhibitors-ruxolitinib, fedratinib, pacritinib, momelotinib-or control. In first-line therapy, momelotinib and fedratinib were associated with comparable efficacy to ruxolitinib, and with less toxicity on erythrocytes and platelets, respectively. Pacritinib was less effective on splenomegaly than ruxolitinib as a first-line treatment but seemed effective in second line, after ruxolitinib exposure. Fedratinib and ruxolitinib that are FDA approved in myelofibrosis have both confirmed being valuable option to treat splenomegaly and constitutional symptoms, and their slightly different tolerance-profiles can guide therapeutic choice for first-line treatment, according to patient profile. Momelotinib could be another option especially due to its positive effect on anemia., (© 2021. The Author(s).)

Myelofibrosis (MF) is a non-BCR-ABL myeloproliferative neoplasm associated with poor outcomes. Current treatment has little effect on the natural history of the disease. MF results from complex interactions between (a) the malignant clone, (b) an inflammatory context, and (c) remodeling of the bone marrow (BM) microenvironment. Each of these points is a potential target of PPARγ activation. Here, we demonstrated the therapeutic potential of PPARγ agonists in resolving MF in 3 mouse models. We showed that PPARγ agonists reduce myeloproliferation, modulate inflammation, and protect the BM stroma in vitro and ex vivo. Activation of PPARγ constitutes a relevant therapeutic target in MF, and our data support the possibility of using PPARγ agonists in clinical practice.

Hallmark features of myelofibrosis (MF) are cytopenias, constitutional symptoms and splenomegaly. Anemia and transfusion dependency are among the most important negative prognostic factors and are exacerbated by many JAK inhibitors (JAKi). Momelotinib (MMB) has been investigated in over 820 patients with MF and possesses a pharmacological and clinical profile differentiated from other JAKi by inhibition of JAK1, JAK2 and ACVR1. MMB is designed to address the complex drivers of iron-restricted anemia and chronic inflammation in MF and should improve constitutional symptoms and splenomegaly while maintaining or improving hemoglobin in JAKi-naive and previously JAKi-treated patients. The MOMENTUM Phase III study is designed to confirm and extend observations of safety and clinical activity of MMB.

We aimed to study the prognostic impact of the mutational landscape in primary and secondary myelofibrosis. The study included 479 patients with myelofibrosis recruited from 24 French Intergroup of Myeloproliferative Neoplasms (FIM) centers. The molecular landscape was studied by high-throughput sequencing of 77 genes. A Bayesian network allowed the identification of genomic groups whose prognostic impact was studied in a multistate model considering transitions from the 3 conditions: myelofibrosis, acute leukemia, and death. Results were validated using an independent, previously published cohort (n = 276). Four genomic groups were identified: patients with TP53 mutation; patients with ≥1 mutation in EZH2, CBL, U2AF1, SRSF2, IDH1, IDH2, NRAS, or KRAS (high-risk group); patients with ASXL1-only mutation (ie, no associated mutation in TP53 or high-risk genes); and other patients. A multistate model found that both TP53 and high-risk groups were associated with leukemic transformation (hazard ratios [HRs] [95% confidence interval], 8.68 [3.32-22.73] and 3.24 [1.58-6.64], respectively) and death from myelofibrosis (HRs, 3.03 [1.66-5.56] and 1.77 [1.18-2.67], respectively). ASXL1-only mutations had no prognostic value that was confirmed in the validation cohort. However, ASXL1 mutations conferred a worse prognosis when associated with a mutation in TP53 or high-risk genes. This study provides a new definition of adverse mutations in myelofibrosis with the addition of TP53, CBL, NRAS, KRAS, and U2AF1 to previously described genes. Furthermore, our results argue that ASXL1 mutations alone cannot be considered detrimental., (© 2021 by The American Society of Hematology.)

Myeloproliferative neoplasm (MPN)-associated myelofibrosis (MF) is characterized by cytopenias, marrow fibrosis, constitutional symptoms, extramedullary hematopoiesis, splenomegaly, and shortened survival. Constitutive activation of the janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway in MF leads to cell proliferation, inhibition of cell death, and clonal expansion of myeloproliferative malignant cells. Fedratinib is a selective oral JAK2 inhibitor recently approved in the United States for treatment of adult patients with intermediate-2 or high-risk MF. In mouse models of JAK2V617F-driven myeloproliferative disease, fedratinib blocked phosphorylation of STAT5, increased survival, and improved MF-associated disease features, including reduction of white blood cell counts, hematocrit, splenomegaly, and fibrosis. Fedratinib exerts off-target inhibitory activity against bromodomain-containing protein 4 (BRD4); combination JAK/STAT and BRD4 inhibition was shown to synergistically block NF-kB hyperactivation and inflammatory cytokine production, attenuating disease burden and reversing bone marrow fibrosis in animal models of MPNs. In patients, fedratinib is rapidly absorbed and dosed once daily (effective half-life 41 h). Fedratinib showed robust clinical activity in JAK-inhibitor-naïve patients and in patients with MF who were relapsed, refractory, or intolerant to prior ruxolitinib therapy. Fedratinib is effective regardless of JAK2 mutation status. Onset of spleen and symptom responses are typically seen within the first 1-2 months of treatment. The most common adverse events (AEs) with fedratinib are grades 1-2 gastrointestinal events, which are most frequent during early treatment and decrease over time. Treatment discontinuation due to hematologic AEs in clinical trials was uncommon (~3%). Suspected cases of Wernicke's encephalopathy were reported during fedratinib trials in ~1% of patients; thiamine levels should be monitored before and during fedratinib treatment as medically indicated. Phase III trials are ongoing to assess fedratinib effects on long-term safety, efficacy, and overall survival. The recent approval of fedratinib provides a much-needed addition to the limited therapeutic options available for patients with MF.

The value of pretransplant splenectomy in patients with myelofibrosis (MF) is subject to debate, since the procedure may preclude subsequent allogeneic hematopoietic cell transplantation (allo-HCT). To determine the impact of pretransplant splenectomy on the incidence of allo-HCT, we conducted a comprehensive retrospective study of all patients with MF for whom an unrelated donor search had been initiated via the French bone marrow transplantation registry (RFGM) between 1 January 2008 and 1 January 2017. Additional data were collected from the patients' medical files and a database held by the French-Language Society for Bone Marrow Transplantation and Cell Therapy (SFGM-TC). We used a multistate model with four states ("RFGM registration"; "splenectomy"; "death before allo-HCT", and "allo-HCT") to evaluate the association between splenectomy and the incidence of allo-HCT. The study included 530 patients from 57 centers. With a median follow-up time of 6 years, we observed 81 splenectomies, 99 deaths before allo-HCT (90 without splenectomy and nine after), and 333 allo-HCTs (268 without splenectomy and 65 after). In a bivariable analysis, the hazard ratio [95% confidence interval (CI)] for the association of splenectomy with allo-HCT was 7.2 [5.1-10.3] in the first 4 months and 1.18 [0.69-2.03] thereafter. The hazard ratio [95% CI] for death associated with splenectomy was 1.58 [0.79-3.14]. These reassuring results suggest that splenectomy does not preclude allo-HCT in patients with MF., (© 2020 Wiley Periodicals LLC.)

PAC203 is a randomized dose-finding study of pacritinib, an oral JAK2/IRAK1 inhibitor, in patients with advanced myelofibrosis who are intolerant of or resistant to ruxolitinib. Patients were randomized 1:1:1 to pacritinib 100 mg once per day, 100 mg twice per day, or 200 mg twice per day. Enhanced eligibility criteria, monitoring, and dose modifications were implemented to mitigate risk of cardiac and hemorrhagic events. Efficacy was based on ≥35% spleen volume response (SVR) and ≥50% reduction in the 7-component total symptom score (TSS) through week 24. Of 161 patients, 73% were intolerant of and 76% had become resistant to ruxolitinib; 50% met criteria for both. Severe thrombocytopenia (platelet count <50 × 103/μL) was present in 44%. SVR rates were highest with 200 mg twice per day (100 mg once per day, 0%; 100 mg twice per day, 1.8%; 200 mg twice per day, 9.3%), particularly among patients with baseline platelet counts <50 × 103/μL (17%; 4 of 24). Although TSS response rate was similar across doses (100 mg once per day, 7.7%; 100 mg twice per day, 7.3%; 200 mg twice per day, 7.4%), median percent reduction in TSS suggested a dose-response relationship (-3%, -16%, and -27%, respectively). Pharmacokinetic and pharmacodynamic modeling based on all available data showed greatest SVR and TSS reduction at 200 mg twice per day compared with lower doses. Common adverse events were gastrointestinal events, thrombocytopenia, and anemia. There was no excess of grade ≥3 hemorrhagic or cardiac events at 200 mg twice per day. Pacritinib 200 mg twice per day demonstrated clinical activity and an acceptable safety profile and was selected as the recommended dose for a pivotal phase 3 study in patients with myelofibrosis and severe thrombocytopenia. This trial was registered at www.clinicaltrials.gov as #NCT03165734., (© 2020 by The American Society of Hematology.)

Myeloproliferative neoplasms (MPNs) are the most frequent underlying causes of splanchnic vein thromboses (SVTs). MPN patients with SVTs (MPN-SVT) often have a unique presentation including younger age, female predominance, and low Janus kinase 2 (JAK2) mutation allele burden. This study aimed at identifying risk factors for adverse hematologic outcomes in MPN-SVT patients. We performed a retrospective study of a fully characterized cohort of MPN-SVT patients. The primary outcome was the incidence of evolution to myelofibrosis, acute leukemia, or death. Eighty patients were included in the testing cohort. Median follow-up was 11 years. Most of the patients were women with a mean age of 42 years and a diagnosis of polycythemia vera. The primary outcome was met in 13% of the patients and was associated with a JAK2V617F allele burden ≥50% (odds ratio [OR], 14.7) and presence of additional mutations in genes affecting chromatin/spliceosome (OR, 9). We identified high-risk patients (29% of the cohort) as those harboring at least 1 molecular risk factor: JAK2-mutant allele burden ≥50%, presence of chromatin/spliceosome/TP53 mutation. High-risk patients had worse event-free survival (81% vs 100%; P = .001) and overall survival at 10 years (89% vs 100%; P = .01) than low-risk patients. These results were confirmed in an independent validation cohort of 30 MPN-SVT patients. In conclusion, molecular profiling identified MPN-SVT patients with dismal outcome. In this high-risk population, a disease-modifying therapy should be taken into consideration to minimize the probability of transformation., (© 2020 by The American Society of Hematology.)

Fedratinib is an oral, selective Janus kinase 2 (JAK2) inhibitor. The phase II JAKARTA2 study assessed fedratinib in patients with intermediate- or high-risk myelofibrosis (MF) who were resistant or intolerant to prior ruxolitinib per investigator assessment. Patients received fedratinib 400 mg/day in 28-day cycles. The JAKARTA2 outcomes were initially reported using a last-observation-carried forward (LOCF) analysis in a "Per Protocol" population. This updated analysis of JAKARTA2 employs intention-to-treat analysis principles without LOCF for all treated patients (ITT Population; N = 97), and for a patient subgroup who met more stringent definitions of prior ruxolitinib failure (Stringent Criteria Cohort; n = 79). Median duration of prior ruxolitinib exposure was 10.7 months. The primary endpoint was spleen volume response rate (SVRR; ≥35% spleen volume decrease from baseline to end of cycle 6 [EOC6]). The SVRR was 31% in the ITT Population and 30% in the Stringent Criteria Cohort. Median duration of spleen volume response was not reached. Symptom response rate (≥50% reduction from baseline to EOC6 in total symptom score [TSS] on the modified Myelofibrosis Symptom Assessment Form [MFSAF]) was 27%. Grade 3-4 anemia and thrombocytopenia rates were 38% and 22%, respectively. Patients with advanced MF substantially pretreated with ruxolitinib attained robust spleen responses and reduced symptom burden with fedratinib., (© 2020 The Authors. American Journal of Hematology published by Wiley Periodicals, Inc.)

Patients with myeloproliferative neoplasms (MPN) are known to have higher incidence of nonhematological second primary malignancies (SPM) compared to general population. In the MYSEC study on 781 secondary myelofibrosis (SMF) patients, the incidence of SPM after SMF diagnosis resulted 0.98/100 patient-years. When including non-melanoma skin cancers (NMSC), the incidence arose to 1.56/100 patient-years. In SMF, JAK inhibitor treatment was associated only with NMSC occurrence. Then, we merged the MYSEC cohort with a large dataset of PV and ET not evolving into SMF. In this subanalysis, we did not find any correlation between SPM and SMF occurrence. These findings highlight the need of studies aimed at identifying MPN patients at higher risk of SPM., (© 2019 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)