Perkins, Andrew C

ABSTRACT Myelofibrosis is characterized by perturbation of the JAK/STAT pathway and upregulation of anti‐apoptotic factors leading to myeloproliferation, bone marrow fibrosis (BMF), extramedullary hematopoiesis, splenomegaly, and cytopenias. Navitoclax, a potent oral B‐cell lymphoma (BCL)‐X L /BCL‐2 inhibitor, promotes apoptosis of malignant myelofibrosis cells. Herein, we present results of Cohort 3 of the Phase 2 REFINE study (NCT03222609), which evaluated efficacy and safety of navitoclax plus ruxolitinib in JAKi‐naïve patients with myelofibrosis. JAKi‐naïve patients with primary or secondary myelofibrosis (≥ 18 years with splenomegaly, DIPSS intermediate‐2 and high‐risk myelofibrosis, and ECOG 0–2) and platelet count > 100 × 10 9 /L were enrolled and treated with navitoclax 100 mg once daily (QD) or 200 mg QD according to platelet count (≤ 150 × 10 9 /L or > 150 × 10 9 /L, respectively). Ruxolitinib was given twice daily (dose per label). Primary endpoint: spleen volume reduction of ≥ 35% (SVR 35 ) at week 24. Secondary endpoints: ≥ 50% reduction in total symptom score (TSS 50 ) at week 24, change in grade of BMF, anemia response, and safety. Thirty‐two patients received ≥ 1 dose of navitoclax plus ruxolitinib. Median (range) duration of follow‐up was 44 months (5–58). 63% (20/32) of patients achieved SVR 35 at week 24; median (range) time to first SVR 35 was 12 weeks (11─48). Of 24 evaluable patients, 21% achieved ≥ 50% reduction in driver gene variant allele frequency (VAF). Of 27 evaluable patients, 11 (41%) achieved TSS 50 at week 24; median (range) time to first TSS 50 of 3 weeks (0─16). BMF improved from baseline by ≥ 1 grade in 13/27 patients (48%) at any time on study. Anemia response rates were 38% (5/13) for transfusion‐independent and 100% (2/2) for transfusion‐dependent patients. No bleeding events or deaths were attributed to navitoclax. These findings suggest navitoclax plus ruxolitinib has a tolerable safety profile and provides clinically meaningful improvements for JAKi‐naïve patients with myelofibrosis. Trial Registration NCT03222609.

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.

Myelofibrosis (MF) is a chronic myeloproliferative neoplasm that typically manifests with debilitating symptoms that progressively worsen, negatively impacting patients’ quality of life. Fatigue is a multifactorial and burdensome MF-related symptom due to its severity, persistence, and prevalence, with anemia a contributing factor and major unmet need. Clinical trials of the Janus kinase (JAK)1/JAK2/activin A receptor type 1 inhibitor momelotinib have shown consistent anemia benefits, in addition to improvements in MF-related symptoms. The phase 3 MOMENTUM trial in symptomatic and anemic patients met its primary end point, with a greater proportion having a Myelofibrosis Symptom Assessment Form (MFSAF) Total Symptom Score (TSS) reduction ≥50% at week 24 with momelotinib versus danazol. To support the positive primary end point result, we conducted longitudinal, responder, and time-to-event analyses of patient-reported outcomes from MOMENTUM, as measured by the MFSAF, European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30), and Patient-Reported Outcomes Measurement Information System (PROMIS) assessments. These analyses demonstrated rapid and durable response benefits with momelotinib, with achievement of first TSS response by day 29 and continued improvement over time. Improvements favored momelotinib versus danazol for each MFSAF individual item, and greater improvements were observed for disease- and cancer-related fatigue and physical functioning at week 24, with significant results for multiple items/domains across the 3 assessments. These findings are consistent in demonstrating that momelotinib provides substantial symptom benefit.

AbstractBackgroundMyelofibrosis (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.MethodsLongitudinal 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.ResultsMomelotinib and ruxolitinib groups reported similar overall symptom improvements, with a TSS difference of <1.5 points between groups for each post‐baseline visit in SIMPLIFY‐1. In SIMPLIFY‐2, the improvement in TSS observed in momelotinib‐treated patients was consistent with that observed in SIMPLIFY‐1, whereas progressive TSS deterioration was observed with control. Item‐level scores were heterogeneous in both studies. A similar and greater proportion of momelotinib‐treated patients were categorized as “improved” or “stable” compared with control in SIMPLIFY‐1 and SIMPLIFY‐2, respectively. Odds ratios for between‐group comparison ranged from 0.75 to 1.21 in SIMPLIFY‐1, demonstrating similarity in likelihood of symptom improvement. In SIMPLIFY‐2, the likelihood of symptom improvement in each item was higher in the momelotinib arm.ConclusionsThese findings suggest that momelotinib provides clinically relevant symptom benefits in the JAK inhibitor‐naïve and JAK inhibitor‐exposed settings.

e19040 Background: Clinical trials investigating JAK1/JAK2 inhibitors for myelofibrosis (MF) subjects have measured symptom improvement as a minimum 50% reduction in total symptom score (TSS) at the end of a 24-week treatment period. This landmark analysis is based on post-baseline score changes from Weeks 21 (W21) to 24 and requires vastly different absolute TSS improvements for patients with very high or low baseline (BL) TSS to reach responder status. A phase 3 clinical study, SIMPLIFY-1, randomized 432 intermediate and high risk JAK inhibitor (JAKi) naive MF patients 1:1 to momelotinib (MMB) or ruxolitinib (RUX). Non-inferiority on the MPN-SAF TSS response rate endpoint at W24 was not met (MMB: 28% vs RUX: 42%); however, improvement in each of the 7 TSS items was similar for MMB vs RUX. To understand the discrepancy, we applied item analysis and mixed effect models for repeated measures (MMRM) to SIMPLIFY-1. Methods: Analyses were conducted in the intention-to-treat (ITT) population and in a symptomatic subset (selected as subjects with BL TSS ≥ 10). The distributions of TSS items were examined at BL and shift in scores at W24 (health state shifts) were assessed. GEE models were used to estimate item-level odds ratios using multiple predictive imputations for missing data. MMRM compared mean change in TSS from BL to W24 using data from all visits. The meaningful change threshold (MCT) was determined using Patient Global Impression of Change. Results: BL scores across items were heterogenous in the MMB and RUX groups; the proportion of subjects with no or mild symptoms (0–3 on a 0-10 point scale) ranged from 44% (tiredness) to 81% (itching). Distributions of BL scores were different across arms with 6 out of 7 items in the MMB arm reporting more severe or very severe symptoms (scores of 7-10) at BL. Despite the imbalance in BL scores, item-level health state shifts showed similar improvements for MMB and RUX. Categorical responder analysis showed no significant differences on any items. Odds ratios for each between-group comparison ranged from 0.74 to 1.20. MMRM mean TSS change at W24 was 6.35 (MMB) vs 7.87 (RUX) in the ITT and 8.80 (MMB) vs 10.46 (RUX) in the symptomatic subset. Mean TSS were near the within-subject MCT of 8 points in the ITT and exceeded the MCT in the symptomatic subset. The between-group difference was 1.52 (95% CI: (0.196, 2.847)) in the ITT and 1.67 (95% CI: -0.134, 3.468) in the symptomatic subset. Conclusions: Comparable item health state shifts at W24 and similar improvements in mean TSS as shown by MMRM, with a minimal between-group difference of 1.52 on the 70 point scale in context of an 8-point MCT suggest MMB provides clinically relevant and comparable symptom improvements to RUX; these analyses require further validation in independent data sets. Imbalance in BL symptom scores in MMB subjects may have contributed to the inability to demonstrate non-inferiority in TSS response rate at W24. Clinical trial information: NCT01969838.

Abstract Background: The majority of pts with MF present with a mutation in exon 14 of the JAK2 gene (JAK2V617F). Studies have suggested that in pts with MF and this mutation, a lower AB is associated with a myelodepletive phenotype and shortened survival (Tefferi, Leukemia 2008; Guglielmelli Blood 2009; reviewed in Vannucchi, Ther Adv Hematol 2011). For example, in a Cox proportional hazard model for factors predictive of overall survival (OS) in pts with primary MF, a JAK2V617F AB of <25% was associated with a shortened OS (p=0.002; Guglielmelli, Blood 2009). In the phase III trials of ruxolitinib (RUX) therapy in JAK inhibitor-naïve MF, RUX-treated pts had a median decrease in AB of 16% (maximal) in COMFORT-I followed up to 216 weeks and 7% in COMFORT-II at 48 weeks. The median AB at the start of therapy was not reported for COMFORT-I and in COMFORT-II was 84.5% (Cervantes, Blood 2013; Deininger, Blood2015). Methods: In this communication, we report on clinical correlates of quantitative baseline JAK2 mutational status and the effect of treatment on JAK2V617Fmutational burden in the PERSIST-1 trial. This trial enrolled JAK inhibitor-naïve pts with primary or secondary MF without restrictions on baseline platelet counts, randomized 2:1 between PAC and BAT (excluding JAK2 inhibitors) arms. Stratifications included Dynamic International Prognostic Scoring System (DIPSS) risk category, and baseline platelet counts (<50,000/μL, 50,000-100,000/μL, >100,000/μL). Following the 24-week primary analysis, crossover was allowed by physician/pt choice and 90/107 BAT-treated pts (84%) crossed over to receive PAC. Baseline characteristics have been previously reported (Mesa, ASCO 2016) and included 203/327 (62%) pts with Primary MF, 42 (13%) with post-essential thrombocythemia MF and 81 (25%) with post-polycythemia vera MF. 320 of 327 pts had informative PCR testing for JAK2V617F. We report the baseline characteristics of pts with high (≥50%) AB of JAK2V617F, low (<50%) AB of JAK2V617Fand those without a detectable mutation at baseline (<0.1%), as well as the effect of PAC and BAT on AB and correlation with outcome measures. Results: 131 (40.9%) had AB >50% (high AB), 115 (35.9%) had an AB ≥0.1% and ≤50% (low AB), and 74 (23.1%) had AB <0.1% (wild-type JAK2). Median AB values were 80.3% for the high AB group and 30.3% for the low AB group. Baseline characteristics that were significantly different between high and low AB pts are shown in the Table. No differences were noted in the DIPSS risk category or baseline percentage of blasts between pts with low or high AB. There were a higher percentage of pts with a lower AB in the PAC arm (64% vs. 48%; p=0.01). PAC therapy resulted in a median decrement in AB at Week 24 of −15.8% vs −7.9% for pts in the BAT arm (Figure). The median greatest reduction from baseline in AB in PAC-treated pts was −31.6%. Decrease in AB was strongly correlated with spleen volume reduction (p=0.003) and trended towards correlation with improvement in total symptom score (p=0.07) in PAC-treated, but not in BAT-treated pts. Overall survival was shorter in PAC-treated pts with a minimal AB reduction vs pts with greater decreases in AB. Conclusions: In the PERSIST-1 trial, pts with a JAK2V617FAB of <50% had substantially different disease and demographic characteristics when compared with those pts with a >50% AB despite similar distribution of DIPSS scores. In this trial, reduction in AB associated with PAC, but not BAT correlated with clinical benefit. Disclosures Vannucchi: Novartis: Consultancy, Research Funding, Speakers Bureau; Baxalta: Speakers Bureau; Shire: Speakers Bureau. Mead:Baxalta: Consultancy, Honoraria. Perkins:Novartis Oncology: Consultancy, Honoraria; Bristol-Myers Squibb: Other: Travel, Accommodations, Expenses. Mayer:CTI BioPharma Corp.: Other: Travel, Accommodations, Expenses, Research Funding. Schouten:Sanofi: Consultancy; Novartis: Consultancy. Farber:Alexion: Equity Ownership; Celgene: Honoraria, Research Funding, Speakers Bureau; Genentech: Research Funding, Speakers Bureau; Acerta: Research Funding; Gilead: Research Funding, Speakers Bureau; TG Therapeutics: Research Funding; Seattle Genetics: Speakers Bureau; Pharmacyclics: Speakers Bureau. Kiladjian:Novartis: Honoraria, Research Funding; AOP Orphan: Consultancy, Research Funding. Nangalia:Novartis: Consultancy, Other: Travel, Accommodations, Expenses. Dean:CTI BioPharma Corp.: Employment, Equity Ownership. Zhou:CTI BioPharma Corp.: Employment, Equity Ownership. Singer:CTI BioPharma Corp.: Employment, Equity Ownership, Other: Leadership . Mesa:Novartis: Consultancy, Honoraria; Incyte: Research Funding; Gilead: Research Funding; CTI BioPharma: Research Funding; Celgene: Research Funding; Genetech: Research Funding; Promedior: Research Funding. Harrison:Novartis: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Research Funding, Speakers Bureau; CTI BioPharma: Consultancy, Honoraria, Speakers Bureau; Baxter: Consultancy, Honoraria; Shire: Speakers Bureau; Gilead: Speakers Bureau; Incyte: Speakers Bureau.