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Momelotinib; Myelofibrosis; Patient-reported outcomes Momelotinib; Mielofibrosi; Resultats informats pel pacient Momelotinib; Mielofibrosis; Resultados informados por el paciente Background Myelofibrosis (MF)-associated constitutional symptoms can severely impact health-related quality of life. Clinical trials in MF traditionally measure symptom response to treatment as a landmark endpoint of total symptom score (TSS) reduction ≥50% from baseline. However, this dichotomous assessment provides a limited view of clinically relevant symptomatic changes. Herein we evaluated longitudinal change from baseline in TSS over the continuous 24-week period and individual symptom scores to obtain a more comprehensive understanding of symptom benefits experienced by patients with MF receiving therapy. Methods Longitudinal symptom change was evaluated using mixed-effect model repeated measure (MMRM) methodology with individual item-level analyses to complement the interpretation of the landmark symptom results in the completed phase III SIMPLIFY studies of momelotinib in MF. MMRM compared mean change in TSS from baseline with Week 24 using data from all patient visits. Generalized estimating equations were used to estimate item-level odds ratios using multiple predictive imputations for missing data. Results Momelotinib and ruxolitinib groups reported similar overall symptom improvements, with a TSS difference of

MMB, an oral JAK1/2 and ACVR1/ALK2 inhibitor, was evaluated (vs DAN) in a pivotal phase 3 study of MF patients previously treated with a JAK inhibitor (JAKi). This subgroup analysis evaluated MOMENTUM patients with baseline platelet counts ≤150 × 10Eligibility: Primary or post-ET/PV MF; DIPSS high risk, Int-2, or Int-1; total symptom score (TSS) ≥10; hemoglobin10 g/dL; prior JAKi ≥90 days, or ≥28 days if RBC transfusions ≥4 units in 8 weeks or Grade 3/4 thrombocytopenia, anemia, or hematoma; palpable spleen ≥5 cm; platelets ≥25 × 10TSS response (≥50% reduction from baseline) rate at week 24. Secondary endpoints at week 24: transfusion independence (TI) rate, splenic response rate (SRR; ≥25% volume reduction from baseline), TSS change from baseline, SRR (≥35% reduction), and rate of zero transfusions since baseline.Mean baseline TSS: 29 MMB, 26 DAN, hemoglobin: 8.1 MMB, 7.8 DAN g/dL, and platelets: 74 × 10In symptomatic, anemic, and thrombocytopenic MF patients, MMB was superior to DAN for symptom responses, transfusion requirements, and spleen responses with comparable safety and favorable survival. MMB may address a critical unmet need in thrombocytopenic MF patients. NCT04173494.

7015 Background: Ruxolitinib (RUX), a Janus kinase (JAK) 1/2 inhibitor, is the current standard of care for patients (pts) with myelofibrosis (MF) that improves splenomegaly and disease symptoms with limited impact on disease biology. Many pts lose response over time, highlighting an unmet need for novel therapies. Navitoclax (NAV) is an oral, small-molecule inhibitor of BCL-XL and BCL-2 that has a synergistic effect when used in combination with JAK inhibitors to enhance apoptosis. This ongoing, open-label, multicenter, phase 2 trial (NCT03222609) is evaluating the efficacy and safety of NAV with/without RUX in pts with MF. Here, we report results from JAK inhibitor-naïve pts treated with NAV+RUX. Methods: Enrolled pts had primary or secondary MF with splenomegaly (DIPSS ≥INT-1) and did not receive prior JAK-2 therapy or bromodomain and extraterminal motif (BET) inhibitors. Pts initiated NAV at 100 mg QD or 200 mg QD if baseline (BL) platelet count was ≤150 × 109/L or >150 × 109/L, respectively. RUX was given BID with starting dose based on BL platelet count per local label. The primary endpoint was spleen volume reduction of ≥35% (SVR35) from BL at wk 24. Key secondary endpoints were ≥50% reduction in total symptom score (TSS50), bone marrow (BM) fibrosis reduction, and anemia response. Adverse events (AEs) were monitored throughout the study. Results: As of Oct 04, 2021, 32 pts received NAV+RUX. Median duration of f/u was 6.1 (range, 1.9 ─ 18.6) mos. 28 (88%) pts received NAV 200 mg and 4 (13%) received 100 mg OD. Median age was 69 (44 ─ 83) yrs, and median spleen volume was 1889.08 cm3 (645.6 ─ 7339.6). Median NAV and RUX exposures were 24.1 (5.1 ─ 80.9) and 20.1 (0.1 ─ 80.1) wks, respectively. 31 (97%) pts reported ≥1 AE (Grade ≥3 AEs, 25 [78%]; serious AEs, 6 [19%]). Most common Grade ≥3 AEs were anemia (34%), thrombocytopenia (31%), and neutropenia (19%). 3 (9%) and 2 (6%) pts reported an AE leading to NAV and RUX discontinuation, respectively, and 2 (6%; 1 PD, 1 cardiac disorder unrelated to NAV) AEs led to death ≤30 days after last NAV dose. SVR35 was achieved by 52% of evaluable pts at wk 24 (SVR35 in INT-2, 50%; HR, 33%) and by 76% at any time on treatment (Table). Median time to first SVR35 was 12.1 (11 ─ 47) wks. Conclusions: The combination of NAV+RUX was well tolerated and demonstrated early and robust reductions in spleen volume, anemia, and BM fibrosis in pts without prior JAK-2 inhibitor exposure. SVR35, TSS50, and BM fibrosis improved over time. Clinical trial information: NCT03222609. [Table: see text]

7061 Background: MMB, an oral JAK1/2 and ACVR1/ALK2 inhibitor, showed clinical activity on MF symptoms, RBC transfusion requirements (anemia), and spleen volume in the SIMPLIFY trials, including in MF patients (pts) with thrombocytopenia. MOMENTUM is a pivotal phase 3 study of symptomatic and anemic MF pts previously treated with a JAK inhibitor (JAKi) testing MMB vs DAN. This analysis evaluated MOMENTUM pts with baseline (BL) platelet counts (PLT) ≤150 x 109/L. Methods: Eligibility: Primary or post-ET/PV MF; DIPSS high risk, Int-2, or Int-1; MF Symptom Assessment Form Total Symptom Score (MFSAF TSS) ≥10; Hgb 9/L. JAKi taper and washout was ≥21 days. Randomization: 2:1 to MMB 200 mg QD plus DAN placebo or DAN 600 mg QD plus MMB placebo for 24 wks. Primary endpoint: TSS response (≥50% reduction from BL) rate at wk 24. Key secondary endpoints, assessed sequentially at wk 24: RBC transfusion independence (TI) rate, splenic response rate (SRR; ≥25% reduction in volume from BL), change from BL in TSS, SRR (≥35% reduction from BL) and rate of zero transfusions since BL. Results: 60 (74%) of 81 MMB pts and 25 (58%) of 43 DAN pts with BL PLT ≤150 x 109/L completed the 24-week randomized treatment (RT) phase. Median BL TSS were 29 (MMB) and 24 (DAN), Hgb were 7.9 (MMB) and 8.0 (DAN) g/dL, and PLT were 67 x 109/L (MMB) and 64 x 109/L (DAN). Prior JAKi was ruxolitinib in 124 pts (100%) and fedratinib in 6 pts (5%). Efficacy results are in Table. These results are consistent with the overall ITT analysis set (N=195). Most common Gr ≥3 TEAEs in the RT phase were thrombocytopenia (MMB, 31%; DAN, 16%) and anemia (MMB, 7%; DAN, 14%); Gr ≥3 bleeding events occurred in 9% of MMB and 5% of DAN pts. TEAEs led to study drug discontinuation in 15% of MMB and 19% of DAN pts in RT phase. A trend toward improved OS up to wk 24 was seen with MMB vs DAN [HR (95% CI)=0.490 (0.195, 1.235)]. Additional analyses of pts with BL PLT 9/L (N=100) and BL PLT 9/L (N=31) show similar treatment effects of MMB vs DAN. Conclusions: In thrombocytopenic MF pts who were symptomatic and anemic, MMB was superior to DAN for symptom responses, transfusion requirements, and spleen responses and showed comparable safety and favorable survival. MMB may address a critical unmet need in thrombocytopenic MF pts. Clinical trial information: NCT04173494. [Table: see text]

7002 Background: MMB, an oral JAK1/2 and ACVR1/ALK2 inhibitor, showed clinical activity on MF symptoms, RBC transfusion requirements (anemia), and spleen volume in the SIMPLIFY trials. This pivotal phase 3 study of MF patients (pts) previously treated with a JAK inhibitor (JAKi) tested MMB vs DAN on key symptom, anemia, and spleen volume endpoints at 24 weeks (wks). Methods: Eligibility: Primary or post-ET/PV MF; DIPSS high risk, Int-2, or Int-1; MF Symptom Assessment Form Total Symptom Score (MFSAF TSS) ≥10; Hgb 9/L. BL TI was 13% (MMB) and 15% (DAN). Prior JAKi was ruxolitinib in 195 pts (100%) and fedratinib in 9 pts (5%). All primary and key secondary endpoints were met (Table). Most common Gr ≥3 TEAEs in the RT phase of the study were thrombocytopenia (MMB, 22%; DAN, 12%) and anemia (MMB, 8%; DAN, 11%). Gr ≥3 infections occurred in 15% of MMB and 17% of DAN pts. Peripheral neuropathy occurred in 5 (4%) of MMB (all Gr ≤2) and 1 (2%) of DAN (Gr ≤2) pts in the RT phase, and none discontinued study drug. Overall, TEAEs led to study drug discontinuation in 18% of MMB and 23% of DAN pts in RT phase. A trend toward improved OS up to wk 24 was seen with MMB vs DAN (HR=0.506, p=0.0719). Conclusions: In symptomatic and anemic MF pts, MMB was superior to DAN for symptom responses, transfusion requirements, and spleen responses with comparable safety and favorable survival. MMB may address a critical unmet need, particularly in MF pts with anemia. Clinical trial information: NCT04173494. [Table: see text]

Acute myeloid leukaemia (AML) is characterized by the accumulation of transformed immature myeloid blasts. While most AML patients treated with standard therapy have poor outcomes, in the APL disease subtype retinoic acid induces leukaemia maturation and can be curative in combination with arsenic trioxide. Recently approved mutant IDH1/2 inhibitors also induce AML maturation, renewing interest in AML differentiation therapy. To examine differentiation therapy dynamics in vivo we have generated a novel mouse AML model driven by reversible RNAi-mediated knockdown of the myeloid transcription factor PU.1. Restoration of endogenous PU.1 in established AML in vivo triggers synchronous differentiation of leukemic blasts and disease clearance. However, despite near-complete remission, mice reproducibly relapse with immature AML. Notably, in vivo time course studies reveal that one week after PU.1 restoration leukemic blasts differentiate into two mature myeloid lineages with distinct immunophenotype and morphology. AML-derived SSClowLy6G+ cells resembling neutrophils initially predominate but are rapidly eradicated in vivo. In contrast, high resolution flow and imaging indicates that mature AML-derived SSChighF4/80+SigF+ eosinophil-like cells persist at low numbers in specific organs during disease remission and appear to seed relapse. In mice transplanted with AML blasts lacking the essential eosinophil lineage transcription factor GATA1, in vivo PU.1 restoration triggers neutrophil but not eosinophil lineage differentiation and thereby eliminates residual disease. These results demonstrate that AML differentiation therapy can produce long-lived sublineages of mature AML-derived cells from which relapse can originate. Understanding the multilineage potential of AML blasts in individual patients may inform new strategies to improve differentiation therapy outcomes.