Passamonti, Francesco

Introduction: Anemia is a cardinal feature of myelofibrosis (MF), along with splenomegaly and constitutional symptoms. Red blood cell (RBC) transfusions, often used to manage anemia in patients (pts) with MF, are a negative prognostic factor for overall survival and are associated with diminished quality of life and increased healthcare-related economic burden. Momelotinib (MMB), a Janus kinase (JAK) 1/JAK2/activin A receptor type 1 inhibitor, has demonstrated clinically meaningful and durable improvements in anemia, splenomegaly, and symptoms. Prespecified anemia endpoints in MMB phase 3 studies prioritized achievement of a strict transfusion independence response, defined as no transfusions for ≥12 wk immediately before the end of wk 24, with all hemoglobin levels ≥8 g/dL. Longitudinal analysis of transfusion intensity (units per 28 days) in a phase 2 trial of MMB in pts with transfusion-dependent MF demonstrated a reduction in transfusion burden in most (85%) pts (Harrison C, et al. EHA 2023). Here, we further characterize the impact of MMB and comparators on transfusion burden in pts with JAK inhibitor-naive and -experienced MF from the phase 3 SIMPLIFY-1 and MOMENTUM trials. Methods: This analysis evaluated time-dependent transfusion burden in pts enrolled in the phase 3 SIMPLIFY-1 (NCT01969838) and MOMENTUM (NCT04173494) trials. SIMPLIFY-1 included pts with JAK inhibitor-naive MF randomized (1:1) to receive MMB or ruxolitinib (RUX). In MOMENTUM, pts with symptomatic (Myelofibrosis Symptom Assessment Form Total Symptom Score ≥10), anemic (hemoglobin <10 g/dL), JAK inhibitor-experienced MF were randomized (2:1) to receive MMB or danazol (DAN). All RBC units transfused were collected during the 24-wk randomized treatment period of each study and during the 84 days before receipt of randomized treatment on study for baseline assessment. Time-dependent transfusion burden was quantified by number of RBC units administered, in a tabular display of baseline- and treatment-period intensity. Pts were grouped jointly based on the baseline- and treatment-period intensity of RBC units per 28 days into ordinal bins: exactly zero units, >0 to 1 unit, >1 to 2 units, >2 to 3 units, >3 to 4 units, and >4 units. Results: In SIMPLIFY-1 (JAK inhibitor-naive pts), 150 of 213 evaluable pts (70%) in the MMB arm and 163 of 216 evaluable pts (76%) in the RUX arm required zero units of RBC transfusion per 28 days at baseline. Of pts who required zero units of transfusion at baseline, a higher proportion in the MMB arm (142 of 150 [95%]) maintained a requirement of zero RBC transfusions during randomized treatment of 24 wks vs the RUX arm (93 of 163 [57%]). Overall, the mean RBC transfusion burden per 28 days declined 0.10 units (SD, 0.701) from baseline to randomized treatment in the MMB arm and increased 0.39 units (SD, 1.016) in the RUX arm. Using ordinal bins, 87% of pts in the MMB arm maintained (144 [67.6%]) or improved (41 [19.2%]) RBC transfusion intensity during randomized treatment compared with baseline vs 54% in the RUX arm (maintained, 94 [43.5%]; improved, 23 [10.6%]) (Figure). In MOMENTUM (JAK inhibitor-experienced pts), most pts had some transfusion requirement at baseline, with 26 of 130 (20%) in the MMB arm and 11 of 65 (17%) in the DAN arm requiring zero units of RBC transfusion per 28 days. During randomized treatment, a higher proportion of pts in the MMB arm (46 of 130 [35%]) required zero units of RBC transfusion vs the DAN arm (11 of 65 [17%]), including a higher proportion of those who had zero RBC transfusion requirement at baseline who maintained zero RBC transfusion requirement during randomized treatment (MMB, 92%; DAN, 64%). The mean RBC transfusion burden per 28 days declined 0.86 units (SD, 1.748) from baseline to randomized treatment in the MMB arm and declined 0.28 units (SD, 1.584) in the DAN arm. Using ordinal bins, 85% of pts in the MMB arm maintained (25 [19.2%]) or improved (85 [65.4%]) RBC transfusion intensity compared with baseline vs 63% in the DAN arm (maintained, 7 [10.8%]; improved, 34 [52.3%]). Conclusions: These data demonstrate that MMB was associated with better maintenance of RBC transfusion intensity and zero RBC transfusion status vs RUX in pts with MF who were JAK inhibitor naive and showed greater reduction in RBC transfusion burden from baseline vs DAN in pts with MF who were JAK inhibitor experienced. Across both trials, ≥85% of pts treated with MMB maintained or improved transfusion intensity.

7019 Background: High-risk essential thrombocythemia (HR ET) is characterized by thrombocytosis, thrombohemorrhagic events and systemic symptoms. Pts can experience intolerance, inadequate response or loss of response to first-line cytoreductive therapies (hydroxyurea [HU] or interferon alfa-2a). BET protein inhibition is a novel therapeutic strategy that downregulates inflammatory cytokines and may inhibit differentiation and proliferation of abnormal megakaryocytes involved in ET pathogenesis. Results from the Phase 2 MANIFEST study (NCT02158858) suggested potentially encouraging clinical efficacy in pts with myelofibrosis treated with Pelabresib (PELA), an oral, small-molecule, investigational BET inhibitor. Here we present preliminary results from MANIFEST Arm 4 investigating PELA monotherapy in HR ET refractory or intolerant to HU. Methods: Eligible pts had platelets > 600 x 109/L and ≥ 2 symptoms (average score ≥3/ TSS≥15). Pts received PELA monotherapy 225 mg QD. The primary endpoint was complete hematologic response (CHR; normalization of platelet count (≤400 x 109/L), WBC count (≤10 x 109/L) confirmed after one cycle [after 3 weeks]) and normal spleen size. Secondary endpoints included partial HR (PHR; platelets 400–600 x 109/L and WBC ≤10 x 109/L), symptom improvement (≥50% TSS reduction) and safety. Results: As of July 2022, 20 pts with HR ET were treated: median age 64 yrs (42–83), median Hgb 13 (10–16) g/dL, median platelet count 772 (418–1255) x 109/L and median TSS 32.7 (6.9–123). The majority of pts had a hematologic response (90% [18/20] unconfirmed CHR or PHR); confirmed CHR was observed in 40% (8/20) (Table). Median platelet and WBC count at Wk 12 was 446 x109/L and 8.2 x 109/L, respectively. TSS reduction was reported in 86% (12/14 pts); median TSS reduction at Wk 12 was –31%. Hgb levels remained stable through Wk 24. The most common nonhematologic AEs were nausea (60%; 10% Gr 3), diarrhea (35%; 5% Gr 3) and dysgeusia (35%; no Gr 3). Hemorrhagic or thromboembolic events were reported in 30% pts (15% Gr 3). No events of thrombocytopenia and no Gr 4 events or higher were reported. Conclusions: Preliminary results from Arm 4 of the MANIFEST study suggest potential clinical benefit with PELA monotherapy in pts with HR ET refractory or intolerant to HU as supported by hematologic responses and symptom improvement. Safety results are consistent with the known safety profile of PELA and as expected in the underlying study population. Clinical trial information: NCT02158858 . [Table: see text]

7016 Background: Many patients (pts) with myelofibrosis (MF) experience anemia resulting from disease or JAK inhibitor therapy. The open-label, phase 2 ACE-536-MF-001 study (NCT03194542) evaluated the safety and efficacy of luspatercept (LUSPA) for the treatment of MF-related anemia. Methods: Eligible pts comprised 4 cohorts based on transfusion dependence (TD, defined as receiving 4–12 red blood cell [RBC] units/84 days [d] immediately up to cycle 1 d 1) and stable ruxolitinib (RUX) treatment; cohort 1: no TD, no RUX; cohort 2: TD, no RUX; cohort 3A: no TD, RUX; cohort 3B: TD, RUX. Pts received subcutaneous LUSPA 1.0 mg/kg (1.33 mg/kg for pts in cohort 3B expansion) with titration up to 1.75 mg/kg in 21-d cycles. Disease response was assessed at d 169 and treatment extended for pts showing clinical benefit; pts were followed for ≥ 3 years (y) post last dose. The primary endpoint was anemia response (defined as 84 consecutive d: ≥ 1.5 g/dL hemoglobin [Hgb] from baseline without transfusion [cohorts 1 and 3A] or RBC transfusion-free [cohorts 2 and 3B]); secondary endpoints included duration of response (DOR), transfusion frequency, change in Hgb level, and symptom response. Results: Of 95 pts in the ITT group, the most common reason for treatment discontinuation was lack of clinical benefit at d 169 (n = 28). Median (range) age was 71.0 (50–89) y. Most (54.7%) pts had primary MF, intermediate-risk 2 disease (75.8%), and > 2 y since initial diagnosis (74.7%). Median prior RUX therapy was 18.1 months (cohorts 3A/3B) and 84.7% of pts had baseline transfusion burden 6–12 units/84 d (cohorts 2/3B). Mean treatment duration was 42.8 weeks. Cohort 3B had the highest anemia response rate with 26.3% (95% CI, 13.4–43.1) of pts transfusion independent during the primary treatment period and 31.6% (95% CI, 17.5–48.7) transfusion independent during the entire treatment period; median (range) DOR was 448 d (85–1582). In cohort 3B: 19 (50.0%) pts had reduced transfusion burden by ≥ 50% during the primary treatment period; 8 (21.1%) pts achieved mean Hgb increase ≥ 1.5 g/dL from baseline throughout the entire treatment period and 6 (15.8%) achieved a mean ≥ 50% reduction in symptom score from baseline. Overall, 47.4% of pts had ≥ 1 treatment-related adverse event (TRAE), most frequently hypertension (17.9%, 5.3% grade ≥ 3); 3.2% of pts had a serious TRAE. One TRAE led to LUSPA discontinuation. Two (2.1%) pts had transformation to acute myeloid leukemia. Nine pts died on treatment from: post-procedural hemorrhage, pneumonia, intracranial hemorrhage, septic shock, ischemic stroke, multiple organ dysfunction syndrome, renal failure, pneumonitis, and myelofibrosis (n = 1 each); no deaths were considered related to the study drug. Conclusions: In pts with MF, the safety profile of LUSPA was consistent with previous studies and efficacy results showed promising improvements in anemia and transfusion burden in all cohorts. Clinical trial information: NCT03194542 .

Abstract The classification of myeloid neoplasms and acute leukemias was last updated in 2016 within a collaboration between the World Health Organization (WHO), the Society for Hematopathology, and the European Association for Haematopathology. This collaboration was primarily based on input from a clinical advisory committees (CACs) composed of pathologists, hematologists, oncologists, geneticists, and bioinformaticians from around the world. The recent advances in our understanding of the biology of hematologic malignancies, the experience with the use of the 2016 WHO classification in clinical practice, and the results of clinical trials have indicated the need for further revising and updating the classification. As a continuation of this CAC-based process, the authors, a group with expertise in the clinical, pathologic, and genetic aspects of these disorders, developed the International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias. Using a multiparameter approach, the main objective of the consensus process was the definition of real disease entities, including the introduction of new entities and refined criteria for existing diagnostic categories, based on accumulated data. The ICC is aimed at facilitating diagnosis and prognostication of these neoplasms, improving treatment of affected patients, and allowing the design of innovative clinical trials.