Reichard, Kaaren K.

ABSTRACT We examined the prognostic value of routine NGS data in newly diagnosed acute myeloid leukemia (AML) treated with intensive (7 + 3 backbone) induction, specified by AML subtype. A contemporary (2015–2025) series of 545 Mayo Clinic patients (median age 56 years, females 44%) was considered. Median follow‐up was 49 months with 341 (63%) allogeneic hematopoietic stem cell transplantations (AHSCT) recorded. AML subtypes included core‐binding factor (CBF; N = 72; 13%), primary non‐CBF ( N = 403; 74%), post‐myelodysplastic syndromes (MDS) or post‐myelodysplastic/myeloproliferative neoplasms (post‐MDS‐MDS/MPN; N = 28; 5%), post‐MPN ( N = 15; 3%), and therapy‐related (t‐AML; N = 27; 5%). Corresponding complete remission rates, with/without count recovery (CR/CRi), were 89%, 76%, 64%, 27%, and 78% ( p < 0.01) and 5‐year transplant‐censored survival rates 68%, 57%, 21%, 0%, and 55% ( p < 0.01). In multivariable analyses, the prognostic value of specific mutations was mostly limited to primary non‐CBF AML where adverse karyotype (OR 1.9; p = 0.04) predicted inferior and FLT3 ‐ITD (OR 0.4; p < 0.01) or NPM1 MUT / FLT3 WT (OR 0.1; p < 0.01) superior CR/CRi while KRAS MUT (HR 8.8; p < 0.01), TP53 MUT (HR 5.4; p < 0.01), and TET2 MUT (HR 2.3; p = 0.01) predicted inferior and NPM1 MUT / FLT3 WT (HR 0.3; p = 0.01) superior survival. Prognostication in intensively‐treated AML should start with subtype specification and recognition of the limited value of NGS in non‐primary AML. Post‐MPN AML is particularly associated with dismal outcomes and should be prognostically distinguished from post‐MDS‐MDS/MPN AML. In primary non‐CBF AML, in addition to previously established risk factors, the favorable impact of FLT3 ‐ITD on achieving CR/CRi and the unfavorable impact of KRAS MUT and TET2 MUT on transplant‐censored survival were noted and require confirmation from additional studies.

Myeloid sarcoma (MS) is a tumor mass involving any extramedullary site composed of myeloid-lineage blasts with myeloid, myelomonocytic, or monocytic differentiation. Distinguishing MS from malignant histiocytic neoplasms (MHNs) is diagnostically challenging due to morphologic and immunophenotypic overlap, particularly for MS with monocytic differentiation, which can mimic MHNs, especially the subtypes of histiocytic sarcoma and interdigitating dendritic cell sarcoma, leading to potential misdiagnosis and inappropriate management. Cyclin D1 overexpression is implicated in MHNs, but its utility in differentiating these entities has not been systematically characterized. We evaluated cyclin D1 immunostaining in 43 MS cases and 30 MHNs. The median age at MS diagnosis was 59 years (range: 0.1 to 90), while the median age at MHN diagnosis was 62 years (range: 9 to 90), with heterogeneous sites of involvement. Cyclin D1 evaluation showed 100% MHNs with strong cyclin D1 positivity in ≥50% tumor cells, compared with 7% MS with weak-to-intermediate positivity in a minor subset of tumor cells. Additional immunohistochemical evaluation showed no difference in PU.1 expression in MHNs (93%) versus MS (84%) but demonstrated a higher proportion of OCT2-positivity in MHNs over MS (52% vs. 23%, P <0.05). Our study demonstrates a high sensitivity (100%) and specificity (93%) in utilizing cyclin D1 to distinguish MHNs (mature phenotype) from MS (immature phenotype) in diagnostic practice. It is particularly valuable in challenging scenarios of MS with the absence of immature/myeloid lineage-defining markers (MPO, CD34, or CD117) and provides a cost-effective tool to resolve this diagnostic pitfall, ensuring an accurate subclassification.

VEXAS syndrome is a clonal hemato-inflammatory disorder impacting older, predominantly male patients, characterized by systemic inflammation and progressive bone marrow failure. It is caused by somatic mutations in UBA1, an X-linked gene, essential for initiating cellular ubiquitination. Loss-of-function mutations, most commonly M41 missense variants, lead to decreased expression of the cytoplasmic isoform, UBA1b, resulting in accumulation of misfolded proteins and activation of the endoplasmic reticulum stress pathway. Patients classically present with systemic and often refractory inflammation, requiring chronic glucocorticoid treatment and targeted immunosuppressive therapies. A central hallmark of this syndrome is progressive bone marrow failure and associated cytopenia, with a diagnosis of myelodysplastic syndromes (MDS) being reported in approximately 30-50% of patients while only 1% of unselected MDS patients have UBA1 mutations. This review examines current literature on distinct MDS features reported in VEXAS syndrome. We first summarize the defects and alterations in the hematopoietic system from UBA1 mutations, including associated peripheral blood and bone marrow findings. Next, we describe the histological and molecular characteristics of patients with VEXAS syndrome, with and without MDS, and review potential treatment strategies, including responses to hypomethylating agents. Finally, we highlight that VEXAS-associated MDS is a challenging diagnosis but one with unique clinical, laboratory, and morphological features, including prognostic implications.

ABSTRACT Hypomethylating agents (HMA) and allogeneic hematopoietic stem cell transplantation (alloHSCT) have both demonstrated remissions in VEXAS; however, comparative data is lacking. We conducted a multicenter, retrospective analysis of 66 patients diagnosed with VEXAS syndrome treated with HMA ( n = 35) or alloHSCT ( n = 31). Baseline characteristics such as genetics, co‐morbidities, and performance status were balanced between the groups, except older age in the HMA group. Median follow‐up from therapy initiation was 18 months (95% CI: 11–26), and 14 (21%) deaths were reported (alloHSCT n = 3; HMA n = 11). Among all evaluable patients within the alloHSCT cohort, all patients achieved molecular remission, and a substantial proportion of patients discontinued glucocorticoids (58%). In contrast, HMA therapy was associated with lower but meaningful rates of molecular remission (22%) and glucocorticoid discontinuation (6%). In a real‐world setting, HMA therapy was associated with a high discontinuation rate related to toxicity or lack of response. On multivariable analysis adjusted for age and Charlson Comorbidity Index, alloHSCT was associated with improved overall survival (HR = 0.20, 95% CI: 0.05–0.81; p = 0.024). This association remained consistent across multiple ancillary sensitivity analyses, including restriction to transplant‐eligible patients, patients aged ≤ 75 years, 1:1 matching, and propensity score‐based weighted analyses. Although limited by retrospective design, these findings suggest that alloHSCT remains an attractive and potentially curative strategy in selected patients with VEXAS. Prospective validation of these findings is warranted.

Abstract Introduction: CSF3R mutations (CSF3RMUT), most commonly T618I, represent the defining genomic alteration in chronic neutrophilic leukemia (CNL), present in ~80% of cases. Despite emerging real-world data, information on treatment outcomes and prognostic factors remains limited due to rarity of the disease. In this two-center retrospective study, we examined clinical and molecular predictors of treatment response, overall survival (OS), and blast transformation (BT) and outcome following allogeneic stem cell transplant (ASCT). Methods: The study was approved by the institutional review boards of the Mayo Clinic (USA) and the University of Montreal (Canada). Electronic medical records were reviewed to identify patients with CSF3R mutated CNL at both institutions and extract relevant data. Statistical analyses were conducted using JMP Pro 17.0.0 software (SAS Institute, Cary, NC, USA). Results: Forty-four patients (68% male, median age 68 years [range: 26-93]) were included. At diagnosis, 20 (56%) were asymptomatic, 13 (36%) presented with constitutional/non-specific symptoms, and 20 (50%) had antecedent leukocytosis at a median of 13 months(mo) prior. Splenomegaly (palpable or radiological) was observed in 28 (67%) patients, hepatomegaly in 7 (17%) and lymphadenopathy in 4 (9.8%). Median white blood cell count (WBC) was 52×10⁹/L (range: 17-390). CSF3RMUT/variants included 39 (89%) with T618I (7 of the 39 had additional CSF3RMUT), 2 (5%) with M696T, and 1 (2%) each for I598I, Q739* and T640N. Frequent co-mutations included ASXL1 in 25 (63%) patients, SETBP1 in 14 (36%), and SRSF2 in 8 (31%), with overlapping occurrence; 10 (38%) patients had ≥2 of these 3 mutations. Ten patients (median WBC 29 x10⁹/L [range: 19–58]), were initially observed without treatment for a median of 8.6 mo; 2 remained on observation alone at 46 and 77 mo. Hydroxyurea (HU) alone or in combinations excluding ruxolitinib (Ruxo) was the most common first-line treatment (68%). Second-line therapies included Ruxo (39%), HU (25%), and hypomethylating agents (14%). WBC response (≥50% reduction from baseline) was 78% with HU vs. 60% with Ruxo (p=0.2). WBC response to HU was lower with abnormal karyotype (40% vs. 94%; p=0.02). WBC response to Ruxo was lower with SETBP1MUT (0% vs. 72%; p=0.05) and with male sex (40% vs. 100%; p=0.04). Seven patients underwent ASCT, including 2 after BT; four (57%) of the 7 remain alive, including 2 without evidence of disease (both 45 mo post-ASCT; one harbored ASXL1MUT) and the other 2 with active disease (both harbored ASXL1MUT). Three patients died from veno-occlusive disease (Day+34), CNS relapse with AML (at 105 mo post-ASCT), or unrelated causes (at 44 mo post-ASCT). Median OS was longer in transplanted patients (115 vs 23 mo; p=0.03). At a median follow-up of 44 mo for living patients, disease transformation occurred in 10 patients, including 7 with BT (6 with T618I, 1 T640N) and 3 with chronic myelomonocytic leukemia (2 M696T, 1 T618I). BT rate at 2, 3, and 5 years was 15%, 31%, and 43%, respectively. Univariate analysis (UVA) identified male gender (p&lt;0.01), &gt;5% immature WBCs (p=0.02), platelets &lt;160×10⁹/L (p=0.04), higher WBC (p=0.02), and ASXL1 or SETBP1 mutation (p&lt;0.01) as risk factors for BT. On multivariable analysis (MVA), only the latter remained significant. Median OS was 26 mo (95% CI: 21-43) for the entire cohort; 24 mo for patients with T618I CSF3RMUT vs 53 mo with other CSF3RMUT, p=0.1. In UVA, age &gt;60 years (HR 5.0, p=0.03), platelets &lt;160×10⁹/L (HR 3.4, p=0.006), WBC &gt;50×10⁹/L (HR 2.6, p=0.02), and ASXL1 or SETBP1 mutations (HR 4.2, p=0.01) were associated with shorter OS. In MVA, age &gt;60 (HR 6, p=0.03), WBC &gt;50×10⁹/L (HR 12, p&lt;0.01), and the presence of ASXL1MUT or SETBP1MUT (HR 9.5, p=0.01) remained significant. Based on the HRs on MVA, one adverse point was allocated for age &gt;60 years, and two adverse points each for WBC &gt;50×10⁹/L and presence of ASXL1 or SETBP1 mutations. Patients were accordingly stratified into low (0-2 points), intermediate (3) and high (4-5) risk groups with corresponding median OS of “not reached”, 29 mo, and 16 mo (p&lt;0.01). Causes of death included disease progression (82%), infection/bleeding (9%), and ASCT complications (9%). Conclusion: The current study highlights the prognostic relevance of “SETBP1 or ASXL1” mutation for both overall survival and risk of blast transformation. The study also signifies variable natural history and potential benefit from ASCT.

Abstract Background: The International Consensus Classification (ICC) for systemic mastocytosis (SM) recognizes mast cell leukemia (MCL) and SM with associated myeloid neoplasm (SM-AMN) as distinct categories of advanced SM (SM-Adv; Arber et al. Blood 2022;140:1200). Contemporary risk models in SM, including the Mayo Alliance Prognostic System (MAPS), do not account for the prognostic heterogeneity among ICC-defined SM-Adv subcategories. Methods: Mayo Clinic databases were utilized to access patient information. Diagnoses of SM and its morphological subcategories were confirmed through clinical evaluations and review of BM pathology. Diagnostic criteria were retrospectively fitted to be consistent with those of the ICC (Arber et al. Blood 2022;140:1200); diagnosis of MCL required the presence of immature cytomorphology of mast cells and only myeloid neoplasms were listed under the category of SM-AMN.Next-generation sequencing and cytogenetic studies was performed in a subset of the study patients according to previously described methodologies. Statistical analyses were conducted on clinical and laboratory data collected at the time of initial diagnosis while survival analysis was censored at the time of allogeneic stem cell transplant (ASCT). Results: A total of 910 Mayo Clinic patients with SM (median age 56 years, range 12-89; males 50%) were accessed in order to conduct a series of multivariable analyses (MVA) in search of independent risk factors for transplant-censored overall survival (OS). All patients were evaluable for assignment to specific ICC categories of SM: indolent (ISM; N=553), aggressive (ASM; N=114), SM-AMN (N=235), and MCL (N=8); the AMN components in SM-AMN included acute myeloid leukemia (N=18), chronic myelomonocytic leukemia (N=70), myelodysplastic syndromes (N=32), MDS/myeloproliferative overlap (N=81), myelofibrosis (N=7), polycythemia vera or essential thrombocythemia (PV/ET; N=19), and others (N=8). In addition, subsets of patients were evaluable for hemoglobin level (N= 865), white blood cell count (WBC; N=858), platelet count (N= 859), serum alkaline phosphatase (ALP; N=761), serum tryptase level (N=706), karyotype (N=574), and mutations (N=240). Median follow-up for living patients was 70 months (range, 0-520); during this time 346 (38%) deaths, 16 leukemic transformations, and 20 ASCTs were documented. ROC analysis-determined optimal cutoff levels for predicting OS included age at ≥60 years, platelet count &lt;150 x 109/L, tryptase level ≥100 ng/mL, WBC ≥10 x 109/L, hemoglobin below sex-adjusted lower limit of normal (anemia), and ALP &gt;210 U/L in women or &gt;170 U/L in men (increased). All except WBC ≥10 x 109/L retained significance during MVA that included ICC-specified SM categories: MCL (HR 74.8, 26.0-215.3; p&lt;0.01); SM-AMN (HR 3.9, 2.5-6.0; p&lt;0.01); ASM (HR 2.2, 1.4-3.5; p&lt;0.01); age ≥60 years (HR 3.3, 2.2-4.7; p&lt;0.01); platelets &lt;150 x 109/L (HR 2.8, 2.0-3.9; p&lt;0.01); tryptase ≥100 ng/mL (HR 2.1, 1.5-2.9; p&lt;0.01); anemia (HR 1.7, 1.1-2.4; p&lt;0.01); and increased ALP (HR1.5, 1.1-2.0; p=0.01). A subsequent HR-weighted risk model effectively delineated 5 risk levels ranging in median survivals from 11 months to 372 months (Figure 1). Figure 2 outlines complementary subtype-specific risk models; to that end, risk factors for ISM included age ≥60 years (HR 4.5, 2.5-7.9), tryptase ≥100 ng/mL (HR 3.5, 2.1-6.0); platelets &lt;150 x 109/L (HR 3.4, 1.5-7.9), and anemia (HR 2.4, 1.2-4.8); for ASM age ≥60 years (HR 2.3, 1.3-4.3), platelets &lt;150 x 109/L (HR 2.4, 1.4-4.0), and anemia (HR 2.0, 1.2-3.4); and for SM-AMN age ≥60 years (HR 2.9, 1.6-5.2), platelets &lt;150 x 109/L (HR 2.5, 1.6-3.9), and tryptase ≥100 ng/mL (HR 2.5, 1.6-3.9) [Figure 2]. In SM-AMN, additional prognostic relevance from subcategorization into PV/ET vs. all other types of AMN was appreciated (Figure 3; HR 4.0, 1.6-3.9) and incorporated into the risk model for SM-AMN (Figure 2). Abnormal karyotype (AK) and high risk mutations(HRM; ASXL1, SRSF2, RUNX1, NRAS)clustered withSM-AMN with AK and ASXL1MUT displaying independent prognostic relevance that was most apparent in SM-AMN. Conclusions : MAPS-R relies on the prognostic eminence of ICC-defined morphologic subcategories and allows for additional SM subtype-specific risk stratification. SM associated with ET or PV is a prognostically unique subcategory of SM-AMN and should be recognized as such in future classification schemes. SM-AMN must be thoroughly ruled out in the presence of AK or HRM.

Abstract Background: The primary goal of induction therapy in acute myeloid leukemia (AML) is to induce complete remission with (CR) or without (CRi) hematologic recovery. In order to accomplish this, re-induction might be necessary based on D14-residual AML. The current study examines the impact of re-induction on relapse, transplant-censored survival, and post-transplant survival in a consecutive series of AML patients who have achieved CR/CRi following intensive chemotherapy. The study also examined the impact of variations in consolidation chemotherapy including the use of anthracycline-based chemotherapy (AC) in the first consolidation cycle and the use of high (HiDAC) vs. intermediate (IDAC) dose cytarabine. Methods: The current study was conducted under IRB-approved minimum risk protocols that allowed retrospective collection and analysis of patient data. Formal criteria were used for AML diagnosis, genetic risk stratification, and adjudication of response (Blood 2022;140:1345). Patients who received less intensive induction regimens or failed to achieve CR/CRi were excluded. Relapse-free (RFS) and overall survival (OS) analysis was calculated from the date of documented CR/CRi. Patients who underwent allogeneic stem cell transplant (ASCT) were censored at the time of transplant. Conventional statistical methods were utilized (JMP Pro 17.1.0, SAS Institute, Cary, NC, USA). Results: A total of 279 AML patients diagnosed between 2004 and 2020 were included: median age 58 years, males 60%, de novo 75%, post-chronic myeloid neoplasm (post-CMN) 16%, and therapy-related 9%. Induction regimens included idarubicin (Ida) + cytarabine (Cyt) in 183 (66%) patients, daunorubicin (Da) 60 mg/m² + Cyt in 76 (27%), and Da 90 mg/m2 + Cyt in 19 (7%). Re-induction was utilized to achieve CR/CRi in 72 (27%) at a median of 18 days from start of first induction regimen. The indication for re-induction was based on residual bone marrow blast (median 30%; range 4-90) on day14 (N=53) or day 21-28 (N=15), persistent extramedullary disease (N=2) or the presence of circulating blast (N=2). At a median transplant censored follow-up of 26 months (mos), 93 (33%) deaths, 117 (42%) relapses, and 134 (48%) ASCTs were documented; ASCTs were performed in CR1 (50%) or CR2 (50%). Median RFS was 18 mos, with respective 1-, 2-, 3- year RFS of 63%, 42% and 35%. In multivariable analysis (MVA), age ≥65 years (HR 1.5, p=0.04), European LeukemiaNet (ELN) adverse karyotype (vs. intermediate HR 1.7, p=0.02; vs. favorable HR 2.8, p&lt;0.01), and the need for re-induction to achieve CR/CRi (HR 1.7, p=0.01) were independently predictive of relapse. RFS was not impacted by NPM1 mutation ( HR 0.5, p=0.09) or FLT3-ITD (HR 1.3, p=0.3). The median OS was 80 mos, with 5-year OS of 53%. In MVA, age ≥65 years (HR 2, p=0.01), ELN adverse karyotype (vs. intermediate HR 3.3, p&lt;0.01; vs. favorable HR 4.7, p&lt;0.01), FLT3-ITD (HR 1.9, p=0.04), and the need for re-induction (HR 1.9, p=0.03) independently predicted inferior OS. RFS was similar among patients who received AC (N=84; Idarubicin 9 mg/m2 or Da 60 mg/m2 days 1 to 2/3 + 100 mg/m2 Cyt days 1 to 5/7; median 18 mos) as their first consolidation cycle vs. those who received HiDAC (N=99; 3 g/m2 q12 hours on days 1,3 and 5; median 16 mos) or IDAC (N=58; IDAC; 1-2 g/m2 q12 hours on days 1, 3 and 5; median 24 mos; p=0.9); the corresponding median OS were 125, 85, and 40 mos (p=0.4). In patients aged ≥65 years, but not younger patients, both RFS (p&lt;0.01; median 23 (N=36) vs. 8 (N=24) mos) and OS (median 40 vs. 12 mos, p&lt;0.01) were significantly longer with IDAC vs. AC as their first consolidation cycle. In the AC consolidation cohort, patients who received 2-3 additional HiDAC/IDAC cycles displayed longer OS (p&lt;0.01) and RFS (p=0.047), compared to those who received less. In both the HiDAC and IDAC cohorts, RFS and OS were not significantly different between those who received 3-4 versus 1-2 consolidation cycles. The need for re-induction did not affect post-transplant survival (p=0.5), which was superior in patients receiving Ida + Cyt induction (vs. Da 60mg/m2 + Cyt, HR 0.6, p=0.04) and in those transplanted in CR1 (HR 0.5, p&lt;0.01). Conclusions: The current study signals the need for re-induction to achieve CR1 as a negative predictor of outcome in AML patients achieving CR/CRi following intensive induction chemotherapy. The particular information is potentially actionable in terms of the choice of consolidation strategy.

Abstract Background Momelotinib, a small-molecule Janus kinase 1 and 2 (JAK1/2) inhibitor (JAKi), is FDA-approved (September 15, 2023) for use in anemic patients with myelofibrosis (MF). The drug appears to have an edge over other FDA-approved JAKis in regard to its unique erythropoietic effect that has been attributed to its inhibitory activity on activin A receptor type-1 (ACVR1). In clinical trials, anemia response to momelotinib in JAKi-naïve MF patients has been reported in more than a third of patients with or without transfusion-dependent anemia (TDA). The current study examines the drug's efficacy and toxicity in JAKi-naïve patients treated outside of clinical trials and after the drug was commercially approved. Methods The current study was conducted under an institutional review board approved minimum risk protocol. Diagnostic criteria were according to the International Consensus Classification (Arber et al. Blood 2022; 140:1200). Study inclusion criteria included a hemoglobin level of &lt;10 g/dL and absence of previous treatment with JAKi. Responses were adjudicated by the Revised International Working Group-European LeukemiaNet criteria (IWG-ELN; Blood 2024; 144:1813). Conventional statistical methods were used (JMP Pro 18.0.0 software SAS Institute, Cary, NC, USA). Results A Mayo Clinic enterprise-wide search identified 60 patients (median age 73 years; 55% males) with primary or secondary MF who received momelotinib outside of clinical trials as their first JAKi for treatment of anemia and associated symptoms. Driver mutation distribution included JAK2 42%, CALR 30%, MPL 18%, and triple-negative 10%. Table 1 outlines clinical and laboratory findings at the time of momelotinib treatment initiation; Dynamic International Prognostic Scoring System (DIPSS)-plus risk distribution included high (72%) and intermediate 1/2 (28%) risk. Twenty-seven (45%) patients were transfusion-requiring, 24 (40%) displayed peripheral blood (PB) blast ≥2%, 10 (17%) platelet count &lt;100 x 109/L, and 14 (25%) marked palpable splenomegaly (≥20cm). Unfavorable karyotype was seen in 9 (16%) of 58 patients. NGS-derived mutations were assessed in 57 cases and included ASXL1 (35%), TET2 (19%), SF3B1 (16%), SRSF2 (14%) and 7% (N=4) each for EZH2, IDH2, SH2B3, and ZRSR2. Baseline plasma cytokine levels were assessed in 17 patients with elevated TNF-a in 88%, IL-2 soluble 65%, IL-6 29% and IL-18 53%. Anemia response and predictors Fourteen (23%) patients met revised IWG-ELN criteria for anemia response (TDA 15% and non-TDA 30%; p=0.15). The anemia response was within 3 months in 10 (71%) patients. Median (range) durations of momelotinib exposure and anemia response were 8 (1-23) and 5 (1-13) months, respectively. The drug was discontinued in 29 (48%) patients (39% due to side effects; Table 2). In age-adjusted univariate analysis, predictors of anemia response included circulating blasts &lt;2% (33% [12/36] vs. 8% [2/24]; p=0.02), presence of SH2B3 mutation (100% [4/4] vs. 19% [10/53]; p&lt;0.01), and elevated IL-2 soluble (36% [4/11] vs. 0% [0/6]; p=0.02). The correlation with SH2B3 mutation remained significant (p&lt;0.01) after accounting for circulating blasts. Treatment emergent neuropathy and nephropathy Sensory peripheral neuropathy (PN) was reported by 12 (20%) patients with a median onset of 2 months (range 1-7); CTCAE v5.0 grades 1 (N=8), 2 (N=3), and 3 (N=1); reversibility was documented only for grade 1 severity and did not appear to be consistently affected by drug discontinuation or dose reduction (Table 3). Seventeen (29%) patients experienced a &gt;20% treatment-emergent decrease in estimated glomerular filtration rate from baseline, including 14 (23%) whose serum creatinine level crossed from the normal to abnormal range with pre- and post-treatment median (range) values of 1.05 (0.60-1.26) and 1.53 (1.1-3.31), respectively, with the majority reverting back to the normal range upon drug discontinuation. Conclusion In routine practice, momelotinib therapy might alleviate anemia in about a quarter of JAKi-naive patients with MF but is associated with non-trivial rates of treatment-emergent peripheral neuropathy and nephropathy. The latter appeared to be reversible on treatment discontinuation. Our novel observation regarding association of anemia response with SH2B3 mutation requires validation in a larger group of informative cases.