David Morrall Ross

Purpose: Polycythemia vera (PV) is a myeloproliferative neoplasm characterized by erythrocytosis. Rusfertide is a subcutaneous, injectable, hepcidin mimetic peptide that suppresses erythrocytosis. The phase III VERIFY trial evaluated the efficacy and safety of rusfertide in phlebotomy-dependent patients with PV and poorly controlled hematocrit. Methods: In VERIFY Part 1a (32 weeks), patients requiring frequent phlebotomy were randomly assigned (1:1, double-blind) to receive rusfertide or placebo with or without cytoreductive therapy. The primary efficacy end point was clinical response (absence of phlebotomy eligibility; weeks 20-32). Key secondary end points (baseline to week 32) included mean number of phlebotomies, proportion of patients who maintained hematocrit P < .0001). Compared with placebo, rusfertide reduced mean ± standard deviation number of phlebotomies (0.5 ± 1.2 v 1.8 ± 1.5; P < .0001) and was superior in maintaining hematocrit v n = 21 [14%]; P < .0001). Rusfertide led to a significant improvement in the PROMIS Fatigue SF-8a T-score and MFSAF TSS7 versus placebo ( P = .0252 and .0240, respectively). Injection site reactions, anemia, and fatigue were the most common adverse events. No deaths were reported. Conclusion: Rusfertide significantly improved hematocrit control, reduced the need for phlebotomy, and improved patient-reported symptoms versus placebo in phlebotomy-dependent patients with PV who were also receiving standard-of-care therapy.

Novel therapies are needed for myelofibrosis (MF), particularly after Janus kinase (JAK) inhibitor failure. This open-label, phase 1/2 study evaluated bomedemstat, an irreversible inhibitor of lysine-specific demethylase 1, in participants with MF refractory or resistant to, inadequately controlled by, or intolerant of approved therapies. Eighty-nine participants initially received bomedemstat at doses 0.25, 0.5, or 0.6 mg/kg orally once per day, titrated to achieve a target platelet count of ≥50 × 109/L to ≤75 × 109/L. Primary end points were safety and change in spleen volume. Hematologic response and change in symptom burden, bone marrow fibrosis score, and variant allele frequency (VAF) were exploratory. Eighty-seven (97%) participants experienced ≥1 any-cause adverse event (AE), most commonly thrombocytopenia (48%) and dysgeusia (36%); 62 (69%) participants experienced ≥1 grade 3 to 5 AE. Three participants (3%) experienced AEs that led to death; none were related to treatment. Of 35 participants with spleen volume data at week 24, 23 (66%) had a reduction in spleen volume; 9 (26%) had a reduction of ≥20%. Mean platelet and white blood cell counts normalized over 24 weeks; hemoglobin levels remained stable. Participants reported improvement in most symptoms, including fatigue. Of 35 participants with baseline and week 24 data, 8 (23%) had improved bone marrow fibrosis by ≥1 grade per central review, and 21 (60%) were stable. Of 36 participants with CALR, JAK2, or MPL mutations and data at week 24, 56% had a reduction in VAF. Bomedemstat had manageable safety and clinical activity in participants with MF in need of an alternative therapy. This trial was registered at www.ClinicalTrials.gov as NCT03136185.

Novel treatments that can improve outcomes of essential thrombocythemia (ET) are needed. In a phase 2 trial, participants with ET who required cytoreduction and had inadequate response to, or were intolerant of, ≥1 standard therapy received bomedemstat at a starting dose of 0.6 mg/kg per day, titrated to achieve a target platelet count (200 × 109/L to 400 × 109/L). Primary end points were safety and response, defined as a platelet count of ≤400 × 109/L without new thromboembolic events. Of 73 who received bomedemstat, at 24 weeks, 49 of 64 evaluable participants (77%) achieved a response. Durable reductions in platelet count (≤400 × 109/L for ≥12 weeks) were observed in 52 of 72 participants (72%). Durable reduction in white blood cell count (<10 × 109/L for ≥12 weeks) was observed in 61 of 72 participants (85%); of 10 participants with elevated white blood cell count at baseline, 9 had normal white blood cell count (<10 × 109/L) at week 24. Hemoglobin levels remained stable. After 24 weeks of treatment, a decrease in variant allele frequency of CALR, JAK2, or MPL was observed in 39 of 46 (85%) evaluable participants. By week 24, 2 of 73 participants (3%) had experienced ≥1 thrombotic event, and 15 of 73 (21%) experienced ≥1 hemorrhagic event. During overall treatment period, grade 3 or 4 adverse events (AEs) occurred in 34 of 73 participants (47%). AEs led to temporary treatment interruption in 29 participants (40%) and permanent discontinuation in 11 (15%). No participants died due to AEs. Bomedemstat had clinically relevant activity and manageable safety in participants with ET. This trial was registered at www.clinicaltrials.gov as #NCT04254978.

Myeloproliferative neoplasms (MPNs) are caused by acquired mutations in hematopoietic stem and progenitor cells (HSPCs). The acquisition of additional mutations like TP53 and the overall mutational burden influence a patient's risk of disease progression toward lethal post-MPN acute myeloid leukemia (AML). Recent technological advancements in linking single-cell gene expression with genotype have improved our understanding of tumor heterogeneity. However, current methodologies have limitations in simultaneously genotyping low-expression genes (such as JAK2) alongside other pathogenic loci. To address this, we developed a novel long read genotyping pipeline of cDNA transcripts called LOTR-Seq, which can genotype the full length of expressed transcripts of 30 genes at once. Using LOTR-Seq, we genotyped HSPCs at the JAK2V617 locus in 9,075 single cells from eight patients with chronic phase MPN (CP-MPN) and in 5,016 cells from four patients with post-MPN AML. We then linked the mutations to the single cell transcriptome of 29,712 JAK2V617F-driven CP-MPN cells and 16,895 post-MPN AML cells. In our analysis of post-MPN AMLs, we identified nine mutated loci across six genes (JAK2, IDH1/2, TP53, SRSF2, U2AF1) and linked these mutations to specific transcriptional phenotypes. Overall, LOTR-Seq provides novel insights into the evolution of post-MPN AML.

PURPOSE: Myelofibrosis (MF) is a complex and clinically heterogeneous myeloproliferative neoplasm, presenting significant challenges for patient care and clinical decision making. Although global guidelines exist for MF management and continue to evolve with the advent of novel therapies, they do not consider regional variations in drug accessibility nor the availability of diagnostic tools and resources. The notable gap in regional guidance for managing patients with MF in the Asia-Pacific (APAC) region has led to regional disparities in patient care practices. To bridge this gap, a steering committee (SC) of 14 expert hematologists from the APAC region collaborated to develop evidence- and consensus-based consensus statements (CSs) for MF management in the APAC region. MATERIALS AND METHODS: On the basis of evidence from a systematic literature review and their own clinical experience, the SC drafted 13 clinical practice recommendations across four consensus themes: (1) defining the thresholds for anemia and when to initiate or modify treatment; (2) defining when to initiate or modify treatment for thrombocytopenia; (3) defining Janus kinase inhibitor failure and what would warrant switching treatment; and (4) defining the most appropriate risk stratification model for MF in the APAC region. The SC and an extended faculty (EF) of 47 hematologists and two patients voted on the CSs in a modified Delphi process using a 9-point scale (1 = strongly disagree, 9 = strongly agree), with consensus achieved when 75% agreed within the range of 7-9. RESULTS: Following amendments to align with EF feedback, consensus was achieved for all 13 CSs. CONCLUSION: These CSs offer pragmatic guidance tailored to the MF landscape in the APAC region, which aims to enhance the quality of patient care and outcomes. The CSs in this study are formally endorsed by the Asian Myeloid Working Group.

Secondary myelofibrosis (SMF) represents a late stage of polycythemia vera and essential thrombocythemia, with overall survival (OS) currently defined by the MYelofibrosis SECondary to PV and ET (MYSEC) Prognostic Model (MYSEC-PM). To identify additional myeloid neoplasm-associated cancer gene variants (CGVs) associated with SMF outcome, we evaluated next-generation sequencing panel testing in 644 patients within the MYSEC cohort. Overall, 429 (66.6%) subjects reported at least one CGV, with ASXL1, TET2 and DNMT3A being the most frequently involved. Specific molecular profiles affected OS (p < .001): U2AF1, TP53 or SRSF2 variants (UTS, 9.3% of cases, median OS 4.1 years) and ASXL1 without UTS (25.3%, median OS 8.4 years). By integrating these genetic signatures within the MYSEC-PM through penalized Cox regressions, we identified the following independent predictors (p from < .0001 to .02) and weighted: hemoglobin <11 g/dl (1 point), circulating blasts ⩾3% (2), platelets <150 × 109/l (2), age (0.21 points/year), ASXL1 without UTS mutations (1) and any UTS mutations (3). Finally, we developed the MYSEC-molecular prognostic model (MYSEC-mPM) allocating 582 SMF patients into four categories with different OS (p < .001): low (median OS 18.0 years, 95%CI: 14.2-not reached; score <14), intermediate-1 (8.8. years, 95%CI: 7.7-9.7; score 14-16), intermediate-2 (4.6 years, 95%CI: 3.1-7.2; score 17-18), and high risk (1.9 years, 95%CI: 1.2-2.5; score ⩾19). Additionally, in 381 SMF with available cytogenetics, the MYSEC-mPM was implemented with complex/monosomal karyotype, generating the karyotype-enhanced MYSEC-kmPM. Our study shows that genomic and cytogenetic profiling improve survival prediction in SMF, outperforming the MYSEC-PM.

Genomic profiling in patients with chronic-phase chronic myeloid leukemia (CP-CML) demonstrated somatic variants in blood cancer-related gene variants (CGVs) and rearrangements associated with the formation of the Philadelphia chromosome (Ph-associated rearrangements) at diagnosis, collectively termed additional genetic abnormalities (AGAs). AGAs had a negative impact on failure-free survival (FFS) and molecular response in imatinib-treated patients. We investigated whether treatment with more potent therapies could overcome the negative impact of AGAs at diagnosis. Targeted RNA-based next-generation sequencing was performed on diagnostic samples of 315 patients consecutively enrolled in 4 clinical trials of frontline potent tyrosine kinase inhibitors (TKIs) in CP-CML. AGAs were present in 34% of patients at diagnosis, including 20% harboring CGVs and 18% with Ph-associated rearrangements (4% had both). Although the negative impact of Ph-associated rearrangements was overcome by more potent inhibitors, patients with CGVs continued to experience inferior outcomes. This result was largely attributable to patients with ASXL1 variants, observed in 7% overall. Patients harboring ASXL1 variants also had inferior outcomes compared with those with wild-type ASXL1 in terms of 12-month major molecular response (55% vs 83%; P = .001), 2-year FFS (61% vs 91%; P < .001), and notably, the development of treatment-emergent BCR::ABL1 kinase domain mutations at 2 years (35% vs 1%; P < .001). In multivariable models, both CGVs and ASXL1 variants were predictors of each outcome. Treatment with frontline potent TKIs overcame the negative impact of Ph-associated rearrangements observed with frontline imatinib. However, inferior outcomes were still associated with the presence of CGVs. The acquisition of TKI-resistant BCR::ABL1 mutations was almost exclusively associated with mutated ASXL1 at diagnosis.

Supplementary Information: Figure S1 X-ray crystal structure of JNJ-77006621(ball and stick, C-atoms in green) bound to JAK2-PK domain (cartoon, yellow). Key residues are displayed in sticks [C-atoms in green near the optimisation domain (Peuleo et al. 2017, Liosi et al 2020) and C-atoms in yellow at the dimerization domain]. Supplementary Methods.

Figure showing X-ray crystal structure of pseudokinase domain inhibitor