Search

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]