Dynamic International Prognostic Scoring System Research Articles

Predictors of clinical outcome in myeloproliferative neoplasm, unclassifiable: A Bone Marrow Pathology Group study.

Myeloproliferative neoplasm, unclassifiable (MPN-U, revised to MPN, not otherwise specified in the fifth edition of the World Health Organization classification) is a heterogeneous category of primary marrow disorders with clinical, morphologic, and/or molecular features that preclude classification as a more specific MPN subtype due to stage at diagnosis, overlapping features between MPN subtypes, or the presence of coexisting disorders. Compared with other MPN subtypes, the contribution of the mutational landscape in MPN-U in conjunction with other clinical and morphologic biomarkers to prognosis has been less well investigated. We performed a multicenter, retrospective study of MPN-U (94 cases) to better define the clinicopathologic features, genetic landscape, and clinical outcomes, including subgroups of early-stage, advanced-stage, and coexisting disorders. The Dynamic International Prognostic Scoring System (DIPSS) plus scoring system was applied to assess its relevance to MPN-U prognosis. Multivariate analysis demonstrated bone marrow blast count and DIPSS plus score as statistically significant in predicting overall survival. Univariate analysis identified additional potential poor prognostic markers, including abnormal karyotype and absence of JAK2 mutation. Secondary mutations were frequent in the subset analyzed by next-generation sequencing (26/37 cases, 70.3%) with a borderline association between high molecular risk mutations and overall survival. This study, as one of the largest of MPN-U studies incorporating both clinicopathologic and molecular data, moves toward identification of biomarkers that better predict prognosis in this heterogeneous category.

Investigation of Serum Albumin as a Dynamic Treatment-Specific Surrogate for Outcomes in Patients With Myelofibrosis Treated With Ruxolitinib.

Ruxolitinib improves splenomegaly and disease-related symptoms in most patients with myelofibrosis (MF), and it has been associated with a survival benefit in higher-risk patients with splenomegaly. Spleen volume reduction has been associated with a survival benefit in ruxolitinib-treated patients; however, its use as a surrogate is limited. We hypothesized that an anti-inflammatory response to ruxolitinib would correlate with improved patient outcomes. We interrogated serum albumin, an acute phase reactant and marker of nutritional status in 590 patients with MF and analyzed differential trajectories of albumin on the basis of ruxolitinib treatment. Additionally, we assessed the prognostic role of baseline albumin and change in albumin. We found that serum albumin levels tend to decrease in patients with MF; however, this tendency is abrogated by ruxolitinib treatment. To that end, baseline serum albumin level correlates with overall survival (OS) in patients with MF, independent of the variables that comprise the dynamic international prognostic scoring system; however, this correlation is limited to ruxolitinib-naïve patients. In ruxolitinib-treated patients, the change in serum albumin after ruxolitinib treatment, rather than the baseline value, is associated with improved OS, a finding not seen in ruxolitinib-naïve patients. These findings suggest that serum albumin, a ubiquitously available laboratory value, has specific relevance in patients with MF and reflects therapeutic response to ruxolitinib.

Young patients with myelofibrosis have distinct clinicomolecular features, favorable prognosis, and commonly exhibit inflammatory comorbidities.

Myelofibrosis (MF) is commonly diagnosed in older individuals and has not been extensively studied in young patients. Given the infrequent diagnosis in young patients, analyzing this cohort may identify factors that predict for disease development/progression. We retrospectively analyzed clinical/genomic characteristics, treatments, and outcomes of patients with MF aged 18-50 years (YOUNG) at diagnosis. Sixty-three YOUNG patients were compared to 663 patients diagnosed at 51 or older (OLDER). YOUNG patients were more likely to be female, harbor driving CALR mutations, lack splicing gene mutations, and have low-risk disease by dynamic international prognostic scoring system (DIPSS) at presentation. Thirty-six patients (60%) presented with incidental lab findings and 19 (32%) with symptomatic disease. Median time to first treatment was 9.4 months (mo). Fourteen (22%) YOUNG patients underwent allogeneic hematopoietic stem cell transplant (median 57.4 mo post-diagnosis). Five (8%) developed blast-phase disease (median 99 mo post-diagnosis). Median overall survival (OS) for YOUNG patients was not reached compared to 62.8 mo in OLDER cohort (p < 0.001). The survival advantage for YOUNG patients lost significance when compared to OLDER patients lacking splicing mutations (p = 0.11). Thirty-one (49%) had comorbidities predating MF diagnosis. Presence of a comorbidity correlated with increased disease risk as measured by serial DIPSS (p=0.02). Increased disease risk correlated with decreased OS (p = 0.05). MF is rare in young adults, has distinct clinical/molecular correlates, and a favorable prognosis. The high frequency of inflammatory comorbidities and their correlation with progression of disease risk clinically highlights the role of inflammation in MF pathogenesis.

Ropeginterferon Alfa-2b for Pre-Fibrotic Primary Myelofibrosis and DIPSS Low/Intermediate-1 Risk Myelofibrosis: Durable Responses and Evidence of Disease Modification

Background Most patients with primary myelofibrosis (PMF) in pre-/early fibrotic stage (pre-PMF) and at low or intermediate-1 risk by the dynamic international prognostic scoring system (DIPSS) will progress to higher risks or overt MF. There is currently no consensus on the optimal treatment for these patients. Ropeginterferon alfa 2b (ropeg) is a next-generation monopegylated interferon alfa-2b developed specifically to treat myeloproliferative neoplasms (MPN). Aims P1101MF is an on-going multicenter phase 2 study of ropeg in patients with pre-PMF and DIPSS low/intermediate-risk PMF. Methods Key eligibility included morphologically confirmed pre-PMF, overt PMF, post-polycythemia vera MF (PPV-MF) or post-essential thrombocythaemia MF (PET-MF), DIPSS low/intermediate-1 risk, and the need for cytoreduction. The primary outcome were responses in haemoglobin (Hb, from 10 g/dL to upper reference range), white blood cell (WBC, &amp;lt; 10 x 10 9/L) and platelet (≤ 400 x 10 9/L) at 24 and 48 weeks. Secondary outcomes included adverse events (AEs), changes in mutant allele frequencies (MAF) of driver and non-driver genes as assessed by droplet digital polymerase chain reaction (ddPCR), quality-of-life (QOL), cytokine profiles and bone marrow morphology. Patients received ropeg at a dose of 250 mcg at week 1, followed by 350 mcg at week 2 and 500 mcg every 2 weeks from week 4 onwards. Results At the data cut-off of 30 June 2023, 37 men and 29 women with a median age of 59 (range: 30-86) years were enrolled. The diagnoses were pre-PMF (=46, 69.6%); overt PMF (N=6, 9.1%); PPV-MF (N=5, 7.5%); and PET-MF (N=9, 13.6%). Mutational profile of driver genes was JAK2V617F (N=46, 69.6%); CALR mutations (type 1/type-1 like, N=13, 19.7%; type 2/type 2-like, N=4, 6.1%); MPL mutation (N=1, 1.5%); and triple-negative (N=3, 4.5%). The median time from diagnosis to treatment was 5.8 (1-271) months. The median baseline parameters were white blood cell count (WBC): 6.49 (3.25-33.95) x 10 9/L; haemoglobin (Hb): 12.5 (7.1-15.9) g/dL; platelet count: 495 (113-1114) x 10 9/L; and lactate dehydrogenase: 277 (136-1146) IU/L. The median follow-up was 69 (4-69) weeks, with 61 patients (92%) and 51 patients (77%) having completed 24 and 48 weeks of treatment respectively. Responses in Hb, WBC and platelet were 75%, 82% and 74% respectively at 24 weeks, and 82%, 80% and 71% respectively at 48 weeks. Reduction of MAF at 24 and 48 weeks was achieved for JAK2V617F in 50% (19/38) of patients (≥50%, N=10, 26%; complete, N=3, 8%) and 79% (22/28) of patients (≥50%, N=6, 21%; complete, N=1, 4%) respectively; and for CALR in 44% (7/16) of patients (≥50%, N=1, 6%) and 50% (5/10) of patients (≥50%, N=1, 10%) respectively. Forty-six patients (69.6%) had bone marrow biopsies serially performed, with 42 patients (91%) having stable/improved marrow fibrosis. Eight patients (17.4%) had resolution of marrow fibrosis by 48 weeks. There were 5 discontinuations (personal reasons, N=1; intractable pruritus, N=1; symptom/spleen size progression, N=3). Disease progression (pre-PMF to overt PMF; development of accelerated/blast phase) was not observed. Non-haematological AEs included transaminitis (grade 1-2, N=34); malaise (grade 1-2, N=27; grade 3-4, N=1) and hair loss (grade 1-2, N=21). The most common haematological AE was anaemia (grade 1-2, N=15; grade 3-4, N=6). Conclusion: Ropeg was well-tolerated, effective in cytoreduction and induced molecular and morphologic responses in patients with pre-PMF and low/intermediate-1-risk MF.

HMR Mutations Drive Poor Prognosis in Myelofibrosis Patients with Lower JAK2V617F Allele Burden but Not in Those with Higher Allele Burden: Results of a Multicenter Study

JAK2V617F is the most common driver mutation in myelofibrosis (MF), followed by CALR and MPL alterations. Clinical variables included in the International Prognostic Scoring System (IPSS), Dynamic IPSS (DIPSS), and DIPSS plus, as well as JAK2V617F allele burden are all well-established prognostic factors influencing the survival of MF patients. In addition, ASXL1, EZH2, SRSF2, IDH and U2AF1 mutations are classified as high-molecular risk (HMR) mutations in this context because of their close association with disease progression and leukemic transformation. However, the relationship between JAK2V617F allele burden and HMR mutations remains unclear. To address this, we recruited 122 MF patients (discovery cohort) diagnosed at the National Taiwan University Hospital (Taipei, Taiwan) who had available mutation profile determined by next-generation sequencing. For external validation, 82 MF patients from the Christie Hospital (Manchester, U.K.) and 51 MF patients from the Cleveland Clinic (Ohio, U.S.A.) and Vilnius University Hospital Santaros Klinikos (Vilnius, Lithuania) were enrolled. The median age of the discovery cohort was 61 years. JAK2V617F was the most common driver mutation (64.8%), followed by CALR (18%) and MPL mutations (9%). ASXL1 mutation was the most common (37%) genetic alteration other than driver mutations, followed by TET2 (16%) and EZH2 mutations (12%). Overall, 55 patients (45%) had at least one HMR mutation ( ASXL1, EZH2, SRSF2, IDH and U2AF1). With a median follow-up of 28.2 months, the median overall survival (OS) of the discovery cohort was not reached (NR) and was well risk-stratified by current prognostication systems, including IPSS, DIPSS plus, MIPSS70, and GIPSS. Notably, patients with at least one HMR mutation had significantly shorter leukemia-free survival (LFS) and OS than those without (both p&amp;lt;0.001). Next, we divided the 79 JAK2-mutated patients into lower- and higher-allele burden groups ( JAK2low and JAK2high) using the median (75%), as the cutoff. Concurring with previous reports ( Tefferi et al, Leukemia 2008; and Guglielmelli et al, Blood 2009), JAK2low patients had significantly inferior OS than JAK2high patients (median, 53 months vs NR, p=0.037). Among all JAK2-mutated patients, those with HMR mutations had a significantly shorter OS than those without (50 months vs NR, p&amp;lt;0.001). When considering HMR mutations and JAK2V617F allele burden together, the presence of HMR alterations conferred worse LFS and OS in JAK2low but not in JAK2high patients (HMR vs without HMR among JAK2low patients, p&amp;lt;0.001 and p&amp;lt;0.001; and JAK2high, p=0.822 and p=0.699, respectively). By and large, patients with concurrent HMR mutations and lower JAK2V617F allele burden had a distinctively inferior OS than those with other constellations of genomic lesions ( p&amp;lt;0.001, Figure 1A). This group of patients also had the shortest survival among the total cohort including both JAK2-mutated and wild patients ( p&amp;lt;0.001). The discriminating power of integrating HMR/ JAK2 allele burden for LFS and OS remained valid in the UK cohort (HMR vs without HMR: JAK2low, p=0.013 and p=0.012; and JAK2high, p=0.337 and p=0.600, respectively) and the US/Lithuania cohort (HMR vs without HMR: JAK2low, p=0.016 and p=0.013; and JAK2high, p=0.643 and p=0.446, respectively). Co-occurrence tests in the discovery and validation cohorts revealed that there was no shared mutational co-occurrence pattern among the 3 cohorts, excluding the potential confounding influence of specific concurrent mutations. More strikingly, time-dependent ROC curve analyses suggested that integrating JAK2 allele burden with HMR mutations could be complementary to current risk stratification systems in predicting LFS and OS of MF patients (Figure 1B) across 3 cohorts. Finally, HMR/ JAK2low was identified as an independent adverse prognostic factor by multivariable analysis, irrespective of age, risk stratification systems, and other mutations. In summary, we observe that HMR mutations accompanied by a lower mutant JAK2V617F allele burden identified a distinct MF population with significantly reduced survival and high risk of leukemic transformation, with independent prognostic relevance extrapolated to and validated in two independent cohorts. Experimental studies are ongoing to ascertain the underlying mechanistic basis and resolve the clonal architecture of this distinct MF genomic grouping.

Phase 1/2 Study of the Activin Receptor-like Kinase-2 Inhibitor Zilurgisertib (INCB000928, LIMBER-104) As Monotherapy or with Ruxolitinib in Patients with Anemia Due to Myelofibrosis

Introduction:Elevated levels of the iron regulator hepcidin can cause functional iron deficiency anemia. Hepcidin dysregulation is central to anemia of chronic inflammation observed in several malignancies including myelofibrosis (MF). Activin receptor-like kinase-2 (ALK2 [ie, ACVR1]) contributes to MF-associated anemia via hepcidin upregulation. We evaluated the safety, efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of zilurgisertib-a potent and selective oral ALK2 inhibitor-in patients (pts) with anemia due to MF. Methods:This ongoing open-label, multicenter, phase 1/2 dose-escalation/expansion INCB 00928-104 study (NCT04455841) is evaluating zilurgisertib alone (treatment group A [TGA]) or with ruxolitinib (RUX; treatment group B [TGB]). Eligible pts are ≥18 years old with primary/secondary MF of intermediate (Int)-1 (TGB only) or Int-2/high-risk (TGA and TGB) per the Dynamic International Prognostic Scoring System (DIPSS) and with anemia, including pts who are transfusion dependent (≥4 units of red blood cell transfusions during the 28 days or 8 weeks before Cycle [C] 1 Day [D] 1 for hemoglobin [Hb] &amp;lt;8.5 g/dL in the absence of bleeding or treatment-induced anemia) or are nontransfusion dependent with symptomatic anemia (Hb &amp;lt;10 g/dL during screening on 3 separate occasions ≥7 days apart and not meeting criteria for transfusion dependence). The zilurgisertib starting dose in TGA was 50 mg once daily (qd), with dose increases of ≤2-fold performed until a grade ≥2 toxicity with reasonable probability of being related to the treatment group was observed; subsequent dose increases were limited to ≤50% until the maximum tolerated dose (MTD) was reached or the recommended doses(s) for expansion were identified. In TGB, pts were on a stable regimen of RUX for ≥12 weeks before initiating zilurgisertib at 100 mg qd. The primary endpoints are safety and tolerability, including determination of dose-limiting toxicities (DLTs) and MTD. Secondary endpoints include efficacy (per anemia response parameters), PK, and PD (hepcidin measurement). Results:A total of36 pts were enrolled at the time of analysis (data cutoff, February 15, 2023), with 20 in TGA and 16 in TGB. Median (range) age was 73 (53-84) years for TGA and 75.5 (54-85) years for TGB; 65% of TGA pts had received prior RUX therapy. Overall, 89% had Int-2 risk DIPSS, and the remainder had high-risk DIPSS (1 in TGA, 3 in TGB). In total, 55% of pts in TGA and 25% in TGB were transfusion dependent at time of enrollment. Median (range) baseline Hb was 7.7 (7-10) g/dL in TGA and 8.0 (5-9) g/dL in TGB. Baseline median (range) hepcidin was high in both cohorts (TGA, 171 [18-535] ng/mL; TGB, 126 [7-421] ng/mL; normal range, 0-50 ng/mL). At the time of analysis, dose escalation was ongoing in both treatment groups. No DLTs occurred in either treatment group, and the MTD had not been reached. Treatment-emergent adverse events (TEAEs) were mainly low grade without apparent dose dependence. Grade ≥3 TEAEs occurred in 11 pts, with thrombocytopenia the most common (n=4). The PK profile for zilurgisertib at steady state was consistent with that observed with previous healthy volunteer studies, with observed time of maximum concentration at 2-4 hours after administration and predicted half-life of approximately 24 hours. Maximum reduction in hepcidin following zilurgisertib dosing in C1D1 was observed at 6-8 hours postdose; the highest doses tested in both TGA and TGB demonstrated more effective maintenance of hepcidin suppression over time compared with lower doses. Among non-transfusion-dependent pts, anemia improvement (Hb increase of ≥1.5 g/dL vs baseline) was observed in both treatment groups (Figure). Among transfusion-dependent pts, anemia response of transfusion independence had not been observed at data cutoff. All pts with anemia improvement have maintained Hb increase in the absence of transfusion and remain on study. Conclusions:Treatment with zilurgisertib monotherapy or in combination with RUX in this pt population was generally well tolerated, with predominantly grade 1/2 TEAEs. Reduced hepcidin levels were observed at all dose levels with both monotherapy and in combination with RUX, with greater control of hepcidin over time observed at higher zilurgisertib doses. Preliminary improvements in anemia were observed in non-transfusion-dependent pts during dose escalation, suggesting potential for therapeutic activity.

High Rate of Disease Progression in Patients with Low-Risk Myelofibrosis (MF) Enrolled in the Prospective, Real-World MOST Study

Background: Patients (pts) with low-risk MF are typically excluded from interventional clinical trials, thus data regarding the prognosis of this pt population are largely derived from retrospective analyses. The Myelofibrosis and Essential Thrombocythemia Observational Study (MOST; NCT02953704) is a prospective observational study that enrolled pts with low-risk MF defined by Dynamic International Prognostic Scoring System (DIPSS) criteria. In this analysis, we report disease progression, defined by worsening of clinical or laboratory parameters, in MF pts during the MOST study. Methods: Criteria for enrollment in MOST were confirmed locally and centrally, and included a physician-reported diagnosis of MF (PMF, post-PV, or post-ET) and lack of any DIPSS risk factors except for age &amp;gt;65 y. Of the 232 MF pts enrolled, 205 met this criteria upon central review and were included in this analysis as Cohort A; the remaining 27 pts were enrolled despite having ≥1 DIPSS risk factor (other than age &amp;gt;65 y) and were analyzed separately as Cohort B. Data were collected as previously described (Gerds A. CLML. 2022;22:e532). Disease progression on study was defined as the acquisition of 1 of the following criteria: hemoglobin (Hb) &amp;lt;10 g/dL, platelets &amp;lt;100×10 9/L, presence of constitutional symptoms (weight loss, fever, or sweats), new or worsening splenomegaly, blasts &amp;gt;1%, WBC count &amp;gt;25×10 9/L, death due to disease progression, leukemic transformation (LT), or &amp;gt;1 RBC transfusion. Median (range) follow-up was 52.9 months (42-68). Results: In Cohort A, 120/205 pts (58.5%) had evidence of disease progression during the study. Baseline characteristics comparing pts with vs without disease progression were similar; although compared with pts without progression, those who progressed were older at diagnosis (median [range], 65.9 [21-88] vs 62.9 [35-86] y), older at enrollment (median [range], 70.5 [35-88] vs 66.0 [35-88] y), and had longer median (range) time from diagnosis to enrollment (1.9 [0-38] vs 1.4 [0-24] y). Similar percentages of pts with vs without progression were receiving MF-directed therapy at enrollment (59.2% vs 61.2%); most common treatments were ruxolitinib (33.3% vs 14.1%) and hydroxyurea (22.5% vs 36.5%). Of pts in Cohort A tested for JAK2 mutations, 66/93 (71.0%) with disease progression and 42/65 (64.6%) without were positive. Of pts tested for CALR mutations, 16/21 (76.2%) with disease progression and 17/23 (73.9%) without were positive. Among the 120 pts with progression, 64 (53.3%) met 1 criteria, 27 (22.5%) met 2 criteria, and 29 (24.2%) met ≥3 criteria during the study. The most common progression criteria met were Hb &amp;lt;10 g/dL (47.5%), platelets &amp;lt;100×10 9/L (31.7%), constitutional symptoms (30.8%), and new/worsening splenomegaly (28.3%) (Table 1). Median (95% CI) durations to 1st, 2nd, and 3rd progression criteria were 24.9 (19.2-34.7), 28.2 (14.3-NE), and 11.6 (8.9-26.5) months, respectively (Figure 1). Of pts who progressed, 6 (5.0%) developed LT and 12 (10.0%) died due to disease progression. In Cohort B at time of enrollment, 25/27 pts (92.6%) met 1 progression criteria. The most frequent was Hb &amp;lt;10 g/dL (13/27 [48.1%]), followed by WBC count &amp;gt;25×10 9/L (7/27 [25.9%]); constitutional symptoms (4/27 [14.8%]), and blasts &amp;gt;1% (1/27 [3.7%]); 1 pt (3.7%) met 2 progression criteria (Hb &amp;lt;10 g/dL and constitutional symptoms), and 1 pt (3.7%) met 3 progression criteria (blasts &amp;gt;1%, constitutional symptoms, and WBC count &amp;gt;25×10 9/L). Eight of 27 pts (29.6%) had evidence of further disease progression while on study (Table 1). The most common new progression criteria met were Hb &amp;lt;10 g/dL and platelets &amp;lt;100×10 9/L (each 5/8 [62.5%]) and constitutional symptoms and new/worsening splenomegaly (each 3/8 [37.5%]). Conclusions: This real-world observational analysis from MOST is the first prospective analysis of disease progression in low-risk myelofibrosis. The results show that with over 4 y of follow-up, nearly 60% of pts with low-risk MF had evidence of disease progression; 17/205 pts (8.3%) developed LT or died (both occurred in 1 pt). Median time to acquisition of 1st and 2nd disease progression criteria was approximately 2 y, respectively, decreasing to approximately 1 y for the 3rd criteria; this indicates a slow but increasing rate of progression over the course of the study. These data provide real-world insight into disease progression rate in pts with low-risk myelofibrosis.

Phase 2 Study to Assess the Safety and Efficacy of Bomedemstat (MK3543) in Combination with Ruxolitinib in Patients with Myelofibrosis

Background Approximately 50% of patients with myelofibrosis (MF) discontinue ruxolitinib after 3 years, mostly due to disease progression, suboptimal response or cytopenia. Outcome after ruxolitinib discontinuation is poor with a median overall survival (OS) of approximately 14 months. Lysine-specific demethylase-1 (LSD1) is a histone demethylase critical for self-renewal of malignant hematopoietic stem cells and for maturation of progenitor cells. Bomedemstat is an oral LSD1 inhibitor clinically active in patients with myeloproliferative neoplasms (MPN) and has shown clinical activity as a single-agent in patients with MF. Aims This is an ongoing, open-label, Phase 2 study of the combination of bomedemstat and ruxolitinib in treatment-naïve patients with MF or those with a sub-optimal response to ruxolitinib. The objectives of this are to evaluate the safety and tolerability of the combination, the optimal dosing of bomedemstat in this regimen, and to assess the efficacy of the combination as assessed by spleen size reduction and symptom reduction using the Myelofibrosis Symptom Assessment Form (MFSAF). Methods Cohort A is comprised of patients with a sub-optimal response to an adequate trial of ruxolitinib defined as splenomegaly not reduced by &amp;gt;35% from baseline or symptoms scores that have not improved by &amp;gt;50%. Cohort A patients must have been on a stable dose of ruxolitinib for ≥8wks. Cohort B is comprised of treatment-naïve patients with MF who require treatment per guidelines. Patients in Cohort A remain on the entry dose of ruxolitinib while Cohort B patients received a starting ruxolitinib dose of 10 mg BID throughout the study. All patients received concomitantly, a starting dose of bomedemstat of 0.4mg/kg/d. Dose adjustments up were allowed every 4 weeks to achieve a target platelet count of 50 x 10 9/L (40-90 x 10 9/L range) Down titrations could be made at any time in the interest of patient safety. Results At the data cut-off of 30 June 2023, 16 men and 16 women with a median age of 64 (range: 47-81) years were enrolled. Case distribution was PMF, N=19 (59.4%); PPV-MF, N=7 (21.9%); and PET-MF, N=6 (18.8%). Mutational profile of driver genes was JAK2 V617F, N=24 (75%); JAK2 exon 12, N=1 (3.1%); and CALR mutations, N=7 (21.9%). Six patient (18.8%) harbored high-molecular risk (HMR) mutations ( ASXL N =4; EZH2, N=2). At enrollment, the median white blood cell count (WBC), hemoglobin (Hb), platelet count, and lactate dehydrogenase (LDH) were 10.21 x 10 9/L (2.4-50.8 x 10 9/L), 9.4 g/dL (6.7-12.1g/dL), 215 x 10 9/L (100-906 x 10 9/L) and 504 IU/L (107-2174 UL), respectively. Ten patients (31.2%), 19 patients (59.4%) and 3 patients (9.4%) belonged to the Dynamic International Prognostic Scoring System (DIPSS) high, intermediate-2 and intermediate-1 risk categories, respectively. The median spleen size was 5cm (5-16cm) below left costal margin (BLCM). Twenty-four patients were enrolled in Cohort A with a median treatment duration of ruxolitinib of 128 (13-668) weeks. Cohort B has enrolled 8 patients. The median duration of ruxolitinib + bomedemstat was 12 (1-26) weeks. In 20 evaluable patients at Week 12 (Cohort A, N=17; Cohort B, N=3), 12 patients (60%) had stable ( ∆&amp;lt;± 1.0 g/dL) or improved Hb (&amp;gt;1.0 g/dL) (Cohort A: 11/17, 64.7%; Cohort B: 1/3, 33.3%), 5 patients (25%) had ≥50% reduction in MF-SAF Total Symptom Score (TSS) (Cohort A: 4/17, 23.5%; Cohort B: 1/3, 33.3%) and 18 patients (65%) had ≥ 30% spleen length reduction (Cohort A: 15/17, 88.2%; Cohort: 3/3, 100%) (Figure 1A-C). In six patients evaluable for molecular responses by droplet-digital polymerase chain reaction at Week 12, 4 patients (67%) had reductions in JAK2 V617F allele frequencies with 1 patient (17%) having ≥50% reduction. The most common non-hematologic adverse events (AEs) were diarrhea (Grade 1-2, N=16; Grade 3-4, N=0); malaise (Grade 1-2, N= 6; Grade 3-4, N=0); oedema (Grade 1-2, N=7; Grade 3-4, N=0) and dysgeusia (Grade 1-2, N=5; Grade 3-4, N=0). There were no safety signals, dose-limiting toxicities, or deaths related to drug. Conclusions These early results suggest that the addition of bomedemstat to a ruxolitinib regimen is well tolerated, improves splenomegaly and symptom scores, and stabilizes hemoglobin both in the frontline and second-line setting. Enrollment in ongoing.

ATG/ATLG Improves GvHD-Free and Relapse-Free Survival in Myelofibrosis Undergoing Hematopoietic Stem Cell Transplantation

Background Despite recent improvements in the field of JAK inhibitors, allogeneic hematopoietic stem cell transplantation (HSCT) remains the only potentially curative treatment for patients with myelofibrosis. However, HSCT is associated with a non-negligible treatment-related morbidity and mortality, with graft-versus-host disease (GvHD) being one of the major complications for these patients. In vivo T-cell depletion with antithymocyte/antilymphocyte globulin (ATG/ATLG, short ATG) as part of the conditioning regimen prior to HSCT is widely used as a GvHD prophylaxis, but data on its role in the setting of myelofibrosis is scarce. The aim of this study was to evaluate the impact of ATG on clinical outcomes of patients with myelofibrosis undergoing HSCT in a large international retrospective study. Patients and Methods We leveraged a multicenter collaborative network of 7 European and US academic transplant centers to accrue myelofibrosis patients who underwent first HSCT. The primary endpoint was GvHD-free and relapse-free survival (GRFS), whereas secondary endpoints were acute and chronic GvHD, relapse incidence, non-relapse mortality (NRM), and overall survival (OS). We applied multivariate Cox and Fine &amp; Gray modelling to adjust for potential confounders. In addition, a Dependent Dirichlet Process model for censored data was developed, which can adjust for potential violations of the ubiquitous proportional hazards assumption. Finally, to check results and to obtain another reliable comparison, we applied a propensity score matching of the two groups. Results Overall, we identified 806 patients, of whom 513 received ATG and 293 received non-ATG GvHD prophylaxis. No significant differences were observed between the two groups with regards to median age at HSCT (57 years for both) nor for gender, disease ontogenesis (primary or secondary), frequency of driver mutations, and treatment with ruxolitinib prior to transplant. Patients in the ATG and the non-ATG group differed for other characteristics including splenectomy prior to transplant (8% vs. 20%), donor type (matched related donor (MRD): 21% vs. 39%), Karnofsky Performance Status (&amp;lt;90%: 39% vs. 26%), intensity of conditioning therapy (reduced intensity conditioning (RIC) in 80% vs. 40%) and the presence of constitutional symptoms (58% vs. 44%). Regarding the Dynamic International Prognostic Scoring System (DIPSS), the ATG cohort was more enriched in intermediate-2 and high-risk diseases (64% vs. 58%). Notably, the most common stem cell source in the ATG and the non-ATG cohort was in both cases peripheral blood (98% vs. 95%). The cumulative incidence of acute GvHD grade II-IV was 35% (95% CI, 31-39%) for the ATG group vs. 58% (95% CI, 52-64%) for the non-ATG group (P&amp;lt;0.001). No difference in incidence of chronic GvHD was observed, showing 53% (95% CI, 49-57%) for the ATG group vs. 52% (95% CI, 47-57%) for the non-ATG group (P=0.52). With a median follow-up of 6.5 years for the ATG group and 7 years for the non-ATG group (P=0.10), the 5-year estimates for GRFS were 47% (95% CI, 43-51%) vs. 44% (95% CI, 38-50%; P=0.007; Figure), respectively. The 5-year cumulative incidence of relapse was 14% (95% CI, 10-18%) vs. 13% (95% CI, 8-18%; P=0.62) and the 5-year cumulative incidence of death without relapse for both groups was 28%, respectively (P=0.59). Remarkably, 5-year OS was similar, being 63% (95% CI, 59-67%) for the ATG group vs. 62% (95% CI, 58-68%) for the non-ATG group (P=0.56). Multivariable modelling for GRFS (adjusting for donor type, performance status, conditioning intensity, and DIPSS categories) showed an independent significant reduction in risk for GvHD or relapse in the ATG group (HR=0.85, 95% CI 0.79-0.91; P=0.007). Propensity score matching of 150 pairs confirmed the significant effect of ATG on GRFS (HR 0.90, 95% CI, 0.82-0.98; P=0.03). No differences between the two groups were identified for secondary endpoints of relapse, non-relapse mortality, and overall survival. Conclusion The use of ATG as GvHD prophylaxis in patients with myelofibrosis undergoing HSCT resulted in significantly reduced GRFS. This effect was mainly driven by a significant reduction in acute GvHD.

Clinical and Disease Characteristics of Patients with Myelofibrosis and Essential Thrombocythemia Who Harbor a Calreticulin (CALR) Gene Mutation: Subanalysis of the MOST Study

Background: Calreticulin(CALR)gene mutations are the second most frequent driver of disease in myelofibrosis (MF) and essential thrombocythemia (ET). Compared with patients with JAK2 mutations, those with CALR mutations are considered to have lower-risk disease; however, prospective data on clinical characteristics and disease progression for patients with CALR mutations are limited. This study compared the disease characteristics and treatment patterns of patients with MF or ET who had CALR mutations vs those who had JAK2 mutations at enrollment in the Myelofibrosis and Essential Thrombocythemia Observational Study (MOST; NCT02953704). Methods: Patients enrolled in MOST were aged≥18 years with clinical diagnoses of MF or ET at clinical practices within the United States. Patients with MF included those with primary or secondary MF who were low risk (or intermediate-1 by age &amp;gt;65 years alone) per the Dynamic International Prognostic Scoring System (Passamonti F, et al. Blood. 2010;115:1703-1708). Patients in the ET cohort had a clinical diagnosis of ET and were ≥60 years or had history of thromboembolic events or were receiving ET-directed therapy at enrollment. Descriptive statistics were used to summarize the data. The median (range) follow-up time for CALR- and JAK2-positive patients was 52.8 (43-68) months and 56.6 (42-70) months, respectively. ET progression was defined as transformation to MF; MF progression was defined as worsening of objective clinical and laboratory assessments of disease. Results: A total of 881 patients ( CALR-positive, n=137 [16%]; JAK2-positive, n=750 [85%]; 6 patients had both CALR and JAK2 mutations) were included in this study. A summary of patient and disease characteristics are presented in Table 1 and Table 2. At enrollment, 25% and 75% of CALR-positive patients had a diagnosis of MF and ET, respectively, vs 16% and 84% of JAK2-positive patients. The majority of patients in both groups were women ( CALR-positive, 56%; JAK2-positive, 65%). CALR-positive patients were younger at enrollment and at diagnosis compared with JAK2-positive patients (median age at enrollment, 63.0 [24.0-89.0] vs 70.0 [26.0-93.0] years, P&amp;lt;0.001; median age at diagnosis, 59.3 [21.0-87.0] vs 66.3 [22.0-93.0] years, P&amp;lt;0.001). The majority of patients in this analysis (79% of CALR-positive, 90% of JAK2-positive) were receiving MPN-directed therapy at enrollment. The most common therapies in the CALR cohort were hydroxyurea (51%), interferon (12%), and anagrelide (8%); the common therapies among patients in the JAK2 cohort were hydroxyurea (66%), aspirin only (10%), and ruxolitinib (8%). Disease burden at enrollment was also assessed. The percentages of patients with white blood cell (WBC) count &amp;gt;10×10 9/L or platelet count &amp;gt;400×10 9/L were similar for both CALR- and JAK2-positive patients (13% vs 20% and 53% vs 51%, respectively). Percentages of patients with splenomegaly (SPM) were similar for CALR- vs JAK2-positive patients at enrollment (11.0% vs 13%). The mean MPN-SAF TSS was similar at baseline for CALR- and JAK2-positive patients (15.1 vs 16.5). The percentage of patients with MPN-SAF TSS &amp;gt;25 was 12% in the CALR-positive and 16% in JAK2-positive cohorts. Disease complications and progression were also assessed. Thrombotic and hemorrhagic events during the study period were infrequent in both CALR- and JAK2-positive patients (2% vs 4% and 1% vs 3%, respectively). Rates of disease progression were similar for CALR- and JAK2-positive patients, both for MF progression (50% vs 61%) and for ET progression to MF (2% vs 5%). Leukemic transformation occurred in 6 (4%) CALR-positive patients and 43 (6%) JAK2-positive patients. Deaths due to disease progression occurred in no CALR-positive patients and in 18 (2%) JAK2-positive patients. Conclusions: The results of this real-world analysis of the MOST study demonstrate that despite nearly 80% of CALR-positive patients receiving MPN-directed treatment, a substantial percentage of this group did not meet treatment goals, including control of symptom burden, WBC and platelet counts, and SPM. In addition, disease progression was observed in 50% of the patients with MF in the CALR-positive cohort. Further analysis of the MOST study may provide insight into optimal management of patients with CALR mutations.

A Phase 2 Study to Evaluate the Efficacy and Safety of Selinexor Monotherapy in Patients with JAK Inhibitor-Naïve Myelofibrosis and Moderate Thrombocytopenia (XPORT-MF-044)

Background and Significance: Myelofibrosis (MF) is one of several myeloproliferative neoplasms (MPN) associated with somatic mutations in JAK2, CALR, or MPL. Thrombocytopenia is a common occurrence in patients with MF and associated with poor outcomes; the rate of moderate thrombocytopenia (platelet counts of &amp;lt;100 x 10 9 /L) in patients with JAK inhibitor (JAKi)-naïve MF is approximately 25%. While multiple JAKi therapies have been approved for MF, thrombocytopenia is an on-target side effect and suboptimal doses are often used in thrombocytopenic patients leading to suboptimal symptom and/or spleen response. Selinexor is an investigational oral XPO1 inhibitor that may inhibit MF-relevant pathways including STAT, extracellular signal-regulated kinase (ERK), and protein kinase B (AKT). Previously we reported that in a Phase 1 study of selinexor (using two different doses) and the JAKi ruxolitinib, the combination was generally tolerable and manageable in JAKi-naïve patients with MF (NCT04562389). In the cohort receiving 60 mg selinexor weekly in combination with ruxolitinib, 79% of the intent-to-treat (ITT) population achieved a ≥35% reduction in spleen volume from baseline (SVR35) at Week 24; SVR35 rates were consistent across subgroups, including gender and regardless of ruxolitinib starting dose (this includes patients treated with ruxolitinib 5mg BID, a dose associated with limited SVR and TSS responses). Robust symptom improvement was also observed with 58% of the ITT achieving a ≥50% reduction in total symptom score from baseline (TSS50) at Week 24. Additionally, a Phase 1 study of selinexor monotherapy in patients with MF refractory or intolerant to JAKi therapy (NCT03627403; ESSENTIAL) has reported a generally tolerable and manageable safety profile with improvements in SVR35. Single agent selinexor resulted in a robust rate of SVR35, achieved by 4 of 10 patients (40%) at ≥24 weeks; responses were durable with long term therapy beyond 2 years. Positive results of this monotherapy study provide rationale to further explore selinexor as a monotherapy in subpopulations with MF with high unmet need such as those with thrombocytopenia. XPORT-MF-044 will therefore evaluate the efficacy and safety of selinexor monotherapy (40 mg and 60 mg QW) in patients with JAKi-naïve MF and moderate thrombocytopenia in addition to assessing the performance of JAKi add-on treatments in those patients who achieve suboptimal response to selinexor monotherapy. Study Design and Methods: The XPORT-MF-044 trial is a two arm, sequential, multicenter, open-label, Phase 2 study with corresponding optional expansion to evaluate the efficacy of selinexor for up to 118 patients with JAKi-naïve MF and moderate thrombocytopenia ( Figure 1). Patients in Arm 1 will receive 60 mg of selinexor and those in Arm 2 will receive 40 mg of selinexor. Both arms will be able to enroll an additional 30 patients independently for the optional expansion arms after reaching 29 patients. Optional treatment of ruxolitinib or pacritinib, may be added for patients whose SVR is &amp;lt;10% at week 12 or &amp;lt;35% at week 24 when compared to baseline; and the choice of ruxolitinib or pacritinib will be considered based on platelet count. Select inclusion criteria are patients ≥18 years of age, measurable splenomegaly as demonstrated by spleen volume of ≥450 cm 3 by MRI or CT scan, dynamic international prognostic scoring system (DIPSS) of intermediate-1 with symptoms, intermediate-2, or high-risk, Eastern Cooperative Oncology Group (ECOG) performance status ≤2, platelet counts of 50 - 100 x 10 9 /L, and not eligible for stem cell transplantation. Major exclusion criteria are &amp;gt;10% blast in peripheral blood or bone marrow and previous treatment with JAKi for MF. The primary endpoint is SVR35 at week 24. Primary secondary endpoints are safety, TSS50 at week 24, anemia response at week 24, overall survival, and overall response rate. Efficacy and safety assessments will also be performed on patients who receive optional add-on treatment.

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.

A Global, Phase 3, Randomized, Double-Blind Study to Evaluate Safety and Efficacy of Selinexor, an XPO-1 Inhibitor, in Combination with Ruxolitinib in JAK Inhibitor-Naïve Myelofibrosis (XPORT-MF-034)

Background and Significance: Myelofibrosis (MF) is a myeloproliferative neoplasm that commonly harbors somatic gene driver mutations in Janus kinase 2 ( JAK2), calreticulin ( CALR), and myeloproliferative leukemia virus ( MPL) genes. Selinexor is an investigational oral XPO1 inhibitor that may inhibit MF-relevant pathways including STAT, extracellular signal-regulated kinase (ERK), protein kinase B (AKT) and p53. Furthermore, in vivo preclinical studies have shown potential synergy between selinexor and ruxolitinib treatment. The Phase 3 trial was initiated based on data from the Phase 1 portion of XPORT-MF-034 evaluating the combination of selinexor and ruxolitinib in JAKi-naïve patients with MF. Previously we reported that the combination of selinexor and ruxolitinib was generally tolerable and manageable and that the 60 mg selinexor dose cohort showed 71% and 79% of the intent-to-treat (ITT) population achieving a ≥35% reduction in spleen volume from baseline (SVR35) at Week 12 and Week 24, respectively; SVR35 rates were consistent across subgroups, including gender and regardless of ruxolitinib starting dose. Robust symptom improvement was also observed with 58% of the ITT achieving a ≥50% reduction in total symptom score from baseline (TSS50) at Week 24 (Ali et al., ASCO 2023; Ali et al., AACR 2023). These data provided strong support to further evaluate selinexor (60 mg) and ruxolitinib in patients with JAKi-naïve MF. Study Design and Methods: The XPORT-MF-034 (NCT04562389) trial includes a global, Phase 3 randomized, double-blind, placebo-controlled study designed to evaluate the combination of 60 mg selinexor and ruxolitinib. Patients will be randomized 2:1 to receive oral selinexor 60 mg or placebo once weekly (28-day cycle) and twice daily ruxolitinib. Select eligibility criteria include patients ≥18 years of age, with a spleen volume of ≥450 cm 3 by MRI or CT, dynamic international prognostic scoring system (DIPSS) of intermediate-1, intermediate-2, or high-risk, active symptoms of MF as determined by presence of at least 2 symptoms with a score ≥3 or total score of ≥10 at screening using the MFSAF v4.0, currently not eligible for stem cell transplantation, ECOG PS ≤2, platelet count ≥100 x 10 9/L, and creatinine clearance &amp;gt;15mL/min. Patients will be excluded if more than 10% blasts are present in peripheral blood or bone marrow; received previous treatment with JAK inhibitors for MF, or previous treatment with selinexor or other XPO1 inhibitors. The co-primary study endpoints are SVR35 at Week 24 as measured by MRI or CT scan and TSS50 at Week 24 as measured by the Myelofibrosis Symptom Assessment Form (MFSAF) V4.0. The key secondary endpoint is anemia response as per the International Working Group Myeloproliferative Neoplasms Research and Treatment and European Leukemia Network (IWG-MRT and ELN) criteria at Week 24. Results: TheXPORT-MF-034 Phase 3 trial is currently open for enrollment; a total of 306 JAKi-naïve MF patients will be enrolled and the study was initiated on June 28, 2023.

Efficacy and Safety of Fedratinib in Patients with Myelofibrosis Previously Treated with Ruxolitinib: Results from the Phase 3 Randomized FREEDOM2 Study

Introduction Patients (pts) with myelofibrosis (MF) treated with the Janus kinase inhibitor (JAKi) ruxolitinib (RUX) show spleen volume reduction (SVR) and symptom reduction. However, most develop RUX intolerance or relapsed/refractory (R/R) disease and survival rates after RUX discontinuation are poor. Fedratinib (FEDR) delivered SVR and symptom reduction in the JAKARTA2 and FREEDOM studies (C Harrison et al. Am J Hematol 2020; V Gupta et al. Blood 2022). FREEDOM2 (NCT03952039) was a phase 3, open-label, randomized study to evaluate the safety and efficacy of FEDR compared with best available therapy (BAT) in pts with MF previously treated with RUX. Methods Pts aged ≥ 18 years with primary, post-polycythemia vera, or post-essential thrombocythemia MF with Dynamic International Prognostic Scoring System (DIPSS) score ≥ intermediate-2, splenomegaly (≥ 450 cm 3), platelets ≥ 50 x 10 9/L, peripheral blood myeloblasts &amp;lt; 5%, and normal baseline thiamine, R/R or intolerant to RUX, were randomized 2:1 to FEDR 400 mg/day or BAT in 28-day cycles, with stratification by spleen size, platelet count, and RUX R/R vs intolerant. Crossover to FEDR was permitted for progressive disease or after cycle 6 (EOC6) response assessment. Pts were treated until intolerance or lack of efficacy and followed-up every 3 months until death, withdrawal of consent, or study closure. The primary endpoint was SVR ≥ 35% (SVR35) at EOC6; secondary endpoints included symptom response (≥ 50% reduction in total symptom score measured by Myelofibrosis Symptom Assessment Form), SVR ≥ 25% (SVR25), durability of SVR and symptom response, and safety. Results Overall, 201 pts were initially randomized and treated, 134 and 67 pts in the FEDR and BAT arms, respectively; subsequently, 46 (68.7%) pts from the BAT arm crossed over to FEDR. Median (interquartile range) age was 70 (64-74) years, 52.2% were male, and most had primary MF (54.7%) and intermediate-2 DIPSS risk (76.1%). Assessed by aggregated group, most pts in the BAT arm received RUX (70.1%), hydroxyurea (10.4%), or RUX plus hydroxyurea (7.5%). At the data cutoff of December 27, 2022 (median follow-up, 15 months), pts receiving FEDR had significantly higher rates of SVR35 at EOC6 compared with BAT (35.8% vs 6.0%; P &amp;lt; 0.0001), as well as superior SVR25 at EOC6 and SVR35 during the full treatment course ( Table, Figure). SVR35 benefit with FEDR was observed across subgroups. The FEDR arm also showed higher rates of symptom response at EOC6 compared with BAT (34.1% vs 16.9%; P = 0.0033; Table). Median treatment duration was 43 weeks of FEDR and 24.7 weeks of BAT. During the first 6 cycles in the safety population: 70 (52.2%) pts on FEDR and 20 (29.9%) pts on BAT had dose interruption/reduction; median time to first reduction/interruption was 44.0 days for FEDR and 56.5 days for BAT. Treatment-emergent adverse events (TEAEs) leading to permanent treatment discontinuation occurred in 13 (9.7%) and 4 (6.0%) pts in the FEDR and BAT arms, respectively, during the first 6 cycles. During the first 6 cycles, 132 (98.5%) pts on FEDR and 65 (97.0%) pts on BAT had ≥ 1 TEAE; treatment-related AEs (TRAEs) occurred in 109 (81.3%) and 23 (34.3%) pts in the FEDR and BAT arms, respectively. The most frequently occurring TRAEs with FEDR were diarrhea (38.1% FEDR vs 0.0% BAT) and nausea (32.1% FEDR vs 1.5% BAT); most cases were grade 1/2. Grade 3/4 TRAEs occurred in 52 (38.8%) pts in FEDR and 8 (11.9%) pts in BAT arms, most frequently thrombocytopenia (11.9% FEDR vs 3.0% BAT) and anemia (9.0% FEDR vs 9.0% BAT). In the FEDR arm, 22 (16.4%) pts had thiamine levels below normal range, compared with 2 (3.0%) pts receiving BAT; most cases occurred prior to the study amendment of prophylactic thiamine supplementation. There was a single grade 1 case of suspected Wernicke's encephalopathy in the FEDR arm during cycle 3, which resolved fully 24 hours after thiamine supplementation (0 cases in BAT arm). Two pts each in FEDR and BAT arms had TRAEs of infection. Conclusions In this phase 3 randomized study in pts with MF and prior RUX treatment, FEDR demonstrated superior SVR and symptom response rates compared with BAT. Most pts on BAT received RUX, highlighting a clinical need for an alternative JAKi. Differences in AE and discontinuation rates in the first 6 cycles are consistent with other studies comparing JAKi with BAT. AE mitigation strategies were effective and no new safety concerns for FEDR were identified. Study support Bristol Myers Squibb

First-in-Class JAK/Rock Inhibitor Rovadicitinib in Myeloproliferative Neoplasms: A Single Arm, Multicenter, Open-Label, Phase I/Ib Study

Introduction: Rovadicitinib (TQ05105) is a first-in-class, oral, small molecule JAK/ROCK inhibitor which inhibits cell proliferation, induces cell apoptosis and decreases inflammatory cytokines by affecting the JAK-STAT signaling pathway in preclinical studies. Here we report the primary results of the phase I/Ib study of rovadicitinib in Myeloproliferative Neoplasms (MPN) patients. Methods: We conducted a single arm, multicenter, open-label, phase I/Ib trial (NCT04339400) at 9 sites in China. The study included dose-escalation cohort (phase I) and dose-expansion cohort (phase Ib). Aged ≥18 with MPN, dynamic international prognostic scoring system (DIPSS) Int-1 or higher risk of MF, naïve or resistant/intolerant to hydroxyurea and/or interferon therapy of PV or ET, were enrolled. Patients with MF must have palpable splenomegaly (≥5 cm below the left costal margin). Eligible patients received escalating doses of oral rovadicitinib 5 mg QD, 5 mg BID,10 mg BID, 15 mg BID, 20 mg BID of each 28-day cycle, and a modified “3 + 3” design was used in phase I. Treatment continued until progressive disease or unacceptable toxicity. The primary outcomes were the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) in phase I, and the proportion of patients whose reduction of at least 35% in spleen volume (SVR35) at week 24 compared with baseline in phase Ib. The main secondary end point was proportion of patients whose Total Symptom Score decreased ≥ 50% (TSS50) at week 24 in phase Ib. Results: Between November 20, 2018, and September 22, 2022, 102 patients were assessed for eligibility across two cohorts, 79 were enrolled and treated with rovadicitinib including, 15 patients in t phase I and 64 in phase Ib. 50 (63%) patients were male. The median age was 59 years (IQR 50-65), and 16 (20%) patients were aged 65 years or older. All patients had a definite diagnosis during the screening period, 64 (81%) patients were MF (55 were PMF, five were post-PV MF, four were post-ET MF), 10 (13%) patients were ET, five (6%) patients were PV. Mutations of JAK2, CALR, and MPL were analyzed, 60 (76%) of 79 patients with JAK2 V617F mutations, 10 (13%) patients with CALR mutations, four (5%) patients with MPL mutations. The median spleen volume was 1907 cm 3 (IQR 964-2994). In phase I, the number of patients enrolled per dose level was one at 5 mg QD, three at 5 mg BID, four at 10 mg BID, three at 15 mg BID, and four at 20 mg BID. The dose-limiting toxicities (DLTs) were experienced by two patients at 20 mg BID (one patient experienced grade 3 platelet count decrease with bleeding, one patient experienced grade 4 platelet count decrease). Given the safety profile and shrinking spleen, 15 mg BID was identified as MTD and RP2D. Rovadicitinib plasma peak concentrations and areas under the concentration versus time curve increased proportionally with dose. Terminal half-life was 1.3 h. No accumulation trend was noted. In phase Ib, 58 patients were included spleen volume set, 56 patients were included TSS set. 63.79% (37/58) patients achieved SVR35 during the study period (Figure 1A). The proportion of patients who had SVR35 was 37.93% (22/58) at week 24 and 39.66% (23/58) at week 48, respectively. The mean duration of splenic response was approximately 16 months. 87.5% (49/56) patients achieved TSS50 during the study period. The proportion of patients who had TSS50 was 71.43% (40/56) at week 24 and 48.21% (27/56) at week 48, respectively. Patients had durable splenic responses and significant symptom responses. The most common treatment-emergent adverse events (TEAEs) were 1~2 grade (Table 1). Grade ≥3 TEAEs were reported in 39 (49%) patients, the most common grade ≥3 hematological TEAE (≥10%) were platelet count decrease (17.72%) and anemia (16.46%). Occurrence of other grade ≥3 non-hematologic TEAEs was very low. There was only one death, due to disease progression and not related to rovadicitinib. TEAEs were generally manageable. Conclusions: Rovadicitinib was generally safe, well-tolerated and showed meaningful clinical activity in patients with MF, especially with palpable splenomegaly. Rovadicitinib may be a new treatment option for myelofibrosis patients. Furthermore, a randomized double-blind phase 2 study is ongoing, aiming to assess the efficacy and safety of rovadicitinib compared to hydroxyurea in patients with intermediate-2 or high-risk myelofibrosis in China (NCT05020652).

BMS-986158, a Potent BET Inhibitor, in Combination with Ruxolitinib or Fedratinib in Patients (pts) with Intermediate- or High-Risk Myelofibrosis (MF): Updated Results from a Phase 1/2 Study

Introduction Bromodomain and extra-terminal (BET) inhibitors in combination with Janus kinase inhibitors (JAKi) have demonstrated clinical benefits in pts with MF. BMS-986158 is an orally bioavailable, potent, and selective small molecule BET inhibitor with a dose-proportional pharmacokinetic profile with linear increases in exposure, which has shown time- and dose-dependent modulation of BET target gene expression. BMS-986158 in combination with JAKi ruxolitinib (RUX) or fedratinib (FED) is being evaluated in pts with MF in the CA011-023 study (NCT04817007). Previous analyses showed that BMS-986158+RUX in first-line (1L; RUX-naïve) MF and BMS-986158+FED in second-line (2L; relapsed, refractory, or intolerant to prior RUX treatment) MF was well tolerated, with most pts remaining on treatment, and had promising preliminary efficacy (Ayala R et al. EHA 2023. S213). Updated results with longer follow-up will be presented. Methods Eligible pts had primary or secondary MF and were either RUX-naïve (1L) or relapsed, refractory, or intolerant to RUX (2L), with splenomegaly (spleen volume [SV] ≥ 450 cm 3), ECOG PS ≤ 2, and Dynamic International Prognostic Scoring System risk scores of intermediate-1 with symptoms, intermediate-2, or high. In dose escalation, pts with 1L MF received BMS-986158 2.0, 3.0, or 3.75 mg QD 5d on/2d off + RUX 15 mg BID; pts with 2L MF received BMS-986158 0.5, 0.75, 1.0, or 1.25 mg QD 5d on/2d off (alternative schedule for 1.0-mg dose: 5d on/2d off, 3 wks on/1 wk off) + FED 400 mg QD. Primary objectives in dose escalation were safety, tolerability, and determination of the maximum tolerated dose and/or recommended phase 2 dose (RP2D) of BMS-986158+RUX and BMS-986158+FED. Secondary objectives included spleen volume reduction (SVR) from baseline and response rate (SVR35) at wk 24. Assessment of JAK2 variant allele frequency (VAF) was an exploratory objective. JAK2V617 VAF was measured longitudinally in peripheral blood CD34+ stem cells using next-generation sequencing. Results As of May 18, 2023, 16 pts with 1L MF received BMS-986158+RUX (median age 66 y [range, 36-81]) and 24 pts with 2L MF received BMS-986158+FED (median age 68 y [range, 34-81]). At baseline, median SV was 1504 cm 3 (range, 524-4379) in pts treated with BMS-986158+RUX and 2222 cm 3 (range, 581-6598) in pts treated with BMS-986158+FED. Any grade (G) treatment-related adverse events (TRAEs) were reported in 15 (94%) pts treated with BMS-986158+RUX; G 3/4 TRAEs were thrombocytopenia (n = 7, 44%), neutropenia (n = 2, 13%), anemia, leukopenia, herpes zoster, hyperbilirubinemia, and hypertension (n = 1 each, 6%). Any G TRAEs were reported in 18 (75%) pts treated with BMS-986158+FED; G 3/4 TRAEs were thrombocytopenia and anemia (n = 6 each, 25%), hyperbilirubinemia (n=2, 8%), leukocytosis, and diarrhea (n = 1 each, 4%). No TRAEs led to discontinuation of BMS-986158+RUX; 2 TRAEs (G4 thrombocytopenia and G3 hyperbilirubinemia) led to discontinuation of BMS-986158+FED. SVR was observed at wk 12 in all evaluable pts in both treatment regimens and continued to deepen at wk 24 (Figure). Median SV at wk 24 was 603 cm 3 (range, 170-2532) and 1826 cm 3 (range, 1079-5288) in evaluable pts with 1L MF and 2L MF, respectively. In pts with 1L MF, 8/11 (73%) treated with BMS-986158 (2.0, 3.0 or 3.75 mg)+RUX met SVR35 at wk 12; 9/10 (90%) pts met SVR35 at wk 24. In pts with 2L MF, 7/12 (58%) pts treated with BMS-986158 (0.5, 0.75, 1.0, or 1.25 mg)+FED met SVR35 at wk 12; 3/7 (43%) pts met SVR35 at wk 24. At the time of reporting, 32/40 (80%) pts remained on treatment: 14/16 (88%) receiving BMS-986158+RUX and 18/24 (75%) receiving BMS-986158+FED. Available analysis of JAK2 VAF showed reductions in the frequency of JAK2V617F with BMS-986158+RUX (52% max. reduction by C10, n = 7) and BMS-986158+FED (29% max. reduction by C4, n = 4). Conclusions These updated analyses of study CA011-023 show that BMS-986158+RUX in 1L MF and BMS-986158+FED in 2L MF continue to be well tolerated, with most patients remaining on treatment. TRAEs were mostly low-grade and transient. Thrombocytopenia, an on-target effect, was manageable and did not result in clinically significant bleeding. Both treatment regimens produced early and deep SVR by wk 12, which continued and deepened at wk 24 and beyond. The reductions observed in JAK2 VAF provide promising preliminary data of potential disease modification. Dose expansion with BMS-986158+RUX in 1L MF has opened and is actively enrolling patients.

Prognostic Significance of the Myelodysplastic Syndrome-Specific Comorbidity Index (MDS-CI) in Patients with Myelofibrosis: A Retrospective Study.

In myelofibrosis, comorbidities (CMs) add prognostic information independently from the Dynamic International Prognostic Scoring System (DIPSS). The Myelodysplastic Syndrome-Specific Comorbidity Index (MDS-CI) offers a simple tool for CM assessment as it is calculable after having performed a careful history and physical examination, a small routine chemistry panel (including creatinine and liver enzymes) and a limited set of functional diagnostics. To assess the prognostic impact of the MDS-CI in addition to the DIPSS and the Mutation-Enhanced International Prognostic Scoring System (MIPSS)-70, we performed a retrospective chart review of 70 MF patients who had not received allogeneic stem cell transplantation (primary MF, n = 51; secondary MF, n = 19; median follow-up, 40 months) diagnosed at our institution between 2000 and 2020. Cardiac diseases (23/70) and solid tumors (12/70) were the most common CMs observed at MF diagnosis. Overall survival (OS) was significantly influenced by the MDS-CI (median OS MDS-CI low (n = 38): 101 months; MDS-CI intermediate (n = 25): 50 months; and high (n = 7): 8 months; p < 0.001). The MDS-CI added prognostic information after inclusion as a categorical variable in a multivariate model together with the dichotomized DIPSS or the dichotomized MIPSS70: MDS-CI high HR 14.64 (95% CI 4.42; 48.48), p = 0.0002, and MDS-CI intermediate HR 1.97 (95% CI 0.96; 4.03), p = 0.065, and MDS-CI high HR 19.65 (95% CI 4.71; 81.95), p < 0.001, and MDS-CI intermediate HR 1.063 (95% CI 0.65; 4.06), p = 0.2961, respectively. The analysis of our small and retrospective MF cohort suggests that the MDS-CI represents a useful tool to identify MF patients with an increased vulnerability due to comorbidities. However, analyses of larger cohorts are necessary to define the value of the MDS-CI as a prognostic tool in comparison with other comorbidity indices.

25-hydroxy vitamin D levels in patients with myelofibrosis and potential relationships with disease severity: A case-control study

Background/Aim: Although vitamin D deficiency has been associated with cancer and its prognosis, data is unclear regarding associations with myelofibrosis. This study aimed to measure 25-hydroxy vitamin D levels in patients with myelofibrosis and to evaluate its relationship with prognoses. Methods: This case-control study consisted of 72 patients with myelofibrosis and 75 controls. The Dynamic International Prognostic Scoring System was used to determine prognostic risk groups, and patients were divided into two subgroups: intermediate-1 (low risk) and intermediate-2 (high risk). Results: The median 25-OHD levels were decreased in the myelofibrosis group more so than in the controls (13.05 vs. 23.0 ng/mL, P&lt;0.001). A cut-off value of ≤ 16.5 ng/mL yielded a sensitivity of 84.72% and a specificity of 80% for the identification of patients with myelofibrosis. This impact was also evident when adjusted for age and sex, showing that patients with low 25-hydroxy vitamin D (≤16.5) had a 23.787-fold higher probability to have myelofibrosis (OR: 23.787, 95% CI: 9.676-58.479, P&lt;0.001). When examined for the two prognostic subgroups, 25-hydroxy vitamin D was found to be significantly lower in the intermediate-2 and high subgroup (P=0.017). For a cut-off value of ≤13.7 ng/mL, 25-hydroxy vitamin D level was able to discriminate patients in the intermediate-2 and high subgroup from those with lower risk (sensitivity: 77.8%, specificity: 55.6%). Conclusion: A serum 25-hydroxy vitamin D level may serve as a biomarker associated with myelofibrosis diagnosis and prognosis; however, the discriminatory value for prognostic groups was low, indicating the need for larger and longitudinally-designed studies.

Detection of primary myelofibrosis in blood serum via Raman spectroscopy assisted by machine learning approaches; correlation with clinical diagnosis

Primary myelofibrosis (PM) is one of the myeloproliferative neoplasm, where stem cell-derived clonal neoplasms was noticed. Diagnosis of this disease is based on: physical examination, peripheral blood findings, bone marrow morphology, cytogenetics, and molecular markers. However, the molecular marker of PM, which is a mutation in the JAK2V617F gene, was observed also in other myeloproliferative neoplasms such as polycythemia vera and essential thrombocythemia. Therefore, there is a need to find methods that provide a marker unique to PM and allow for higher accuracy of PM diagnosis and consequently the treatment of the disease. Continuing, in this study, we used Raman spectroscopy, Principal Components Analysis (PCA), and Partial Least Squares (PLS) analysis as helpful diagnostic tools for PM. Consequently, we used serum collected from PM patients, which were classified using clinical parameters of PM such as the dynamic international prognostic scoring system (DIPSS) for primary myelofibrosis plus score, the JAK2V617F mutation, spleen size, bone marrow reticulin fibrosis degree and use of hydroxyurea drug features. Raman spectra showed higher amounts of C-H, C-C and C-C/C-N and amide II and lower amounts of amide I and vibrations of CH3 groups in PM patients than in healthy ones. Furthermore, shifts of amides II and I vibrations in PM patients were noticed. Machine learning methods were used to analyze Raman regions: (i) 800 cm−1 and 1800 cm−1, (ii) 1600 cm−1–1700 cm−1, and (iii) 2700 cm−1–3000 cm−1 showed 100 % accuracy, sensitivity, and specificity. Differences in the spectral dynamic showed that differences in the amide II and amide I regions were the most significant in distinguishing between PM and healthy subjects. Importantly, until now, the efficacy of Raman spectroscopy has not been established in clinical diagnostics of PM disease using the correlation between Raman spectra and PM clinical prognostic scoring. Continuing, our results showed the correlation between Raman signals and bone marrow fibrosis, as well as JAKV617F. Consequently, the results revealed that Raman spectroscopy has a high potential for use in medical laboratory diagnostics to quantify multiple biomarkers simultaneously, especially in the selected Raman regions.

Systemic inflammatory indices for predicting prognosis of myelofibrosis

The impact of inflammatory markers such as systemic immune-inflammation (SII) index and systemic inflammation response index (SIRI) on myelofibrosis (MF) prognosis was evaluated for the first time in this study. Data from 60 patients diagnosed with MF between March 2011 and September 2022 were retrospectively analyzed. In addition to disease-related markers, the impact of SII and SIRI on prognosis was evaluated. In our study, the overall median survival (OS) was 64 months. OS was significantly shorter in patients older than 65 years, with high ferritin and lymphocyte levels, transfusion dependence at diagnosis, platelet count below 100 × 109/L, Hb level below 8 g/dl, and high risk according to the dynamic international prognostic scoring system (DIPSS)-Plus score. When these variables were included in the multivariate Cox regression model, it was found that being older than 65 years, having a high ferritin value, being at high risk according to the DIPSS-plus score and Hb values below 8 increased the risk of death. Platelet-to-lymphocyte ratio (PLR) and SII index were lower in patients with a fatal outcome. No statistically significant relationship was found between SIRI and mortality. The findings of this study showed that low PLR and high ferritin were associated with poor prognosis in MF. Elevated SII and SIRI, evaluated for the first time in patients with myelofibrosis, did not predict prognosis. Since non-inflammatory variables play a role in the pathogenesis of MF, bone marrow indicators and systemic inflammation indicators derived from hematologic parameters may not be accurate.