Long-term findings from COMFORT-II, a phase 3 study of ruxolitinib vs best available therapy for myelofibrosis

Recent advances and future perspectives in small molecule JAK2 inhibitors

The Janus kinase (JAK)/Signal Transducer and Activator of Transcription (STAT) signaling pathway is essential for controlling immune function, blood cell formation, and cell growth. Dysregulation of this pathway is implicated in various diseases, including hematologic malignancies, autoimmune disorders, and chronic inflammatory conditions. This review provides a comprehensive overview of the structural and functional aspects of JAK/STAT signaling, with a particular focus on the role of JAK2. This manuscript explores the primary regulators of the JAK/STAT pathway, such as Suppressors Of Cytokine Signaling (SOCS), Protein Inhibitors of Activated STATs (PIAS), and Protein Tyrosine Phosphatases (PTPs), which play a crucial role in maintaining cellular balance and stability. Additionally, the therapeutic landscape of JAK2 inhibitors is explored, covering both approved and investigational drugs, including their mechanisms of action, efficacy, and safety profiles. Emerging strategies such as drug repositioning using computational approaches and experimental validation are also highlighted. By integrating insights from molecular docking studies, machine learning models, and kinase assays, this review emphasizes the potential of JAK2 inhibitors in disease management.

Pelabresib plus ruxolitinib for JAK inhibitor-naive myelofibrosis: a randomized phase 3 trial

Janus kinase (JAK) inhibitors provide limited depth and durability of response in myelofibrosis. We evaluated pelabresib-a bromodomain and extraterminal domain (BET) inhibitor-plus ruxolitinib (a JAK inhibitor) compared with placebo plus ruxolitinib as first-line therapy. In this phase 3 study (MANIFEST-2), JAK inhibitor-naive patients with myelofibrosis were randomized 1:1 to pelabresib 125 mg once daily (QD; 50-175 mg QD permitted) for 14 days followed by a 7-day break (21-day cycle), or to placebo in combination with ruxolitinib 10 or 15 mg twice daily (BID; 5 mg QD-25 mg BID permitted). Primary endpoint was reduction in spleen volume of ≥35% from baseline at week 24. Key secondary endpoints were absolute change in total symptom score (TSS) and TSS50 response (≥50% reduction in TSS from baseline at week 24). The primary endpoint was met in 65.9% of patients randomized to pelabresib-ruxolitinib (n = 214) versus 35.2% to placebo-ruxolitinib (n = 216) (difference, 30.4%; 95% confidence interval (CI), 21.6, 39.3; P < 0.001). Absolute change in TSS was -15.99 versus -14.05 (difference, -1.94; 95% CI, -3.92, 0.04; P = 0.0545) and TSS50 was achieved in 52.3% versus 46.3% (difference, 6.0%; 95 CI, -3.5, 15.5) with pelabresib-ruxolitinib versus placebo-ruxolitinib. Exploratory analyses of proinflammatory cytokine amounts and bone marrow morphology showed greater improvement with the combination. Thrombocytopenia and anemia were the most common treatment-emergent adverse events, occurring in 52.8% (13.2% grade ≥3) versus 37.4% (6.1% grade ≥3) and 44.8% (23.1% grade ≥3) versus 55.1% (36.5% grade ≥3), respectively. Pelabresib in combination with ruxolitinib is well tolerated, improves signs of underlying myelofibrosis pathobiology and provides substantial clinical benefit over standard-of-care JAK inhibitor monotherapy. ClinicalTrials.gov identifier: NCT04603495 .

How I individualize selection of JAK inhibitors for patients with myelofibrosis

ABSTRACT

The advent of Janus kinase inhibitors (JAKis) inaugurated a novel era in the treatment of myelofibrosis (MF), a myeloproliferative neoplasm with heterogeneous clinical manifestations. Four JAKis have been approved for intermediate or high-risk MF, in the United States. Regulatory approval of the first JAK1/2 inhibitor, ruxolitinib, in 2011, transformed the landscape of MF by markedly controlling splenomegaly and constitutional symptoms, improving patients' quality of life, and prolonging survival. Fedratinib, the second approved JAKi, is preferred in the second-line setting. Ruxolitinib and fedratinib can cause myelosuppression and are recommended for patients with the myeloproliferative phenotype. The approval of 2 less-myelosuppressive JAKis, pacritinib and momelotinib, provided essential treatment options for patients with severe thrombocytopenia and anemia, respectively. Momelotinib and pacritinib are potent activin A receptor, type 1 inhibitors with consequent significant benefits for patients with anemia. Transfusion independence was achieved with momelotinib in patients who were severely anemic, and the association of transfusion independence with prolonged overall survival was demonstrated. Judicious treatment decisions regarding JAKis can be made with in-depth understanding of the pivotal clinical trials that evaluated JAKis and their therapeutic attributes and should be guided by the dominant clinical manifestations and the type/degree of cytopenia(s) (myeloproliferative/cytopenic phenotypes). This article reviews our clinical approach to treatment with JAKis and their sequencing in patients with MF by presenting 3 clinical vignettes.

How I treat anemia in myelofibrosis

ABSTRACT

Anemia is a common consequence of myelofibrosis. The treatment of myelofibrosis-associated anemia is complicated by a multifactorial pathobiology and a lack of therapies that result in normalization of the bone marrow and complete restoration of its function. Established agents that are used to treat anemia in other bone marrow failure states, such as myelodysplastic syndromes and aplastic anemia, are used for the treatment of myelofibrosis-associated anemia. However, there has been rapid development of new anemia-directed therapies, some of which have garnered regulatory approval. In addition to adopting therapies from other disease states, better understating of the root causes of myelofibrosis-associated anemia has positioned the field to be on the cutting edge of new anemia treatments, spearheading the advancement of agents that work on the hepcidin pathway to improve red cell production.

Impact of Ruxolitinib Interactions on JAK2 JH1 Domain Dynamics

Janus kinase 2 (JAK2) is an important intracellular mediator of cytokine signaling. Mutations in the JAK2 gene are associated with myeloproliferative neoplasms (MPNs) such as polycythemia vera (PV) and essential thrombocythemia (ET), while aberrant JAK2 activity is also associated with a number of immune diseases. The acquired somatic mutation JAK2 V617F (95% of cases of PV and in 55-60% of cases of ET), which constitutively activates the JAK2, is the most common molecular event in MPN. The development of specific JAK2 inhibitors is therefore of considerable clinical importance. Ruxolitinib is a JAK inhibitor recently approved by the FDA/EMA and effective in relieving symptoms in patients with MPN. Ruxolitinib binds to the JAK2 last domain, namely JH1; its action on the dynamics of the domain is still only partially known. Using Molecular Dynamics simulations, we have analyzed the JH1 domain in four different states as follows: (i) alone, (ii) with one phosphorylation, (iii) adding Ruxolitinib, and (iv) with five phosphorylations and Ruxolitinib. The ligand induces a dynamic behavior similar to the inactive form of JH1, with a less flexible state than the phosphorylated active form of JH1. This study highlights the inhibitory effect of Ruxolitinib on the JH1 domain, demonstrating the importance of dynamics in regulating JH1 activation.

What are the therapeutic options for previously treated myelofibrosis?

INTRODUCTION

The disruption of the JAK/STAT signaling pathway is a defining feature of myelofibrosis (MF). The introduction of JAK inhibitors (JAKi) has transformed the therapeutic approach to MF, becoming essential to treatment and reshaping the management landscape. While JAKi are now the preferred first-line treatment for most patients, various management options are available for those who do not respond to initial therapy.

AREAS COVERED

This review focuses on management options for patients with MF, with particular emphasis on therapeutic strategies following the failure of first-line JAKi. It provides a comprehensive overview of the current treatment landscape, including alternative JAKi and other approaches. The review is based on an extensive literature search using available databases (PubMed, Cochrane …) and relevant web resources (clinicaltrials.gov).

EXPERT OPINION

Ruxolitinib benefits in MF often diminish after 3-4 years, with complications like thrombocytopenia and anemia. Three newer JAKi offer alternatives with similar efficacy and varied side effects. Stem cell transplantation is a curative option for a minority, ideally timed at peak response to JAKi. Research aims to enhance first-line treatments and restore responses in resistant patients. Future therapies may include novel combinations or immunotherapies targeting specific mutations, requiring collaboration between patient, clinical, and pharmaceutical communities.

SOHO State of the Art Updates and Next Questions | Choosing and Properly Using a JAK Inhibitor in Myelofibrosis

Myelofibrosis (MF) is a chronic myeloid neoplasm characterized by myeloproliferation, bone marrow fibrosis, splenomegaly, and constitutional symptoms related to pro-inflammatory cytokine signaling. Biologically, MF is characterized by constitutive activation of JAK-STAT signaling; accordingly, JAK inhibitors have been rationally developed to treat MF. Following the initial approval of ruxolitinib in 2011, three additional agents have been approved: fedratinib, pacritinib, and momelotinib. As these therapies are noncurative, allogeneic stem cell transplantation remains a key treatment modality and patients with MF who are deemed candidates should be referred to a transplant center. This potentially curative but toxic approach is typically reserved for patients with higher-risk disease, and JAK inhibitors are recommended in the pretransplant setting. JAK inhibitors have proven effective at managing splenomegaly and constitutional symptoms and should be started early in the disease course in patients presenting with these clinical manifestations; asymptomatic patients may initially be followed with close surveillance. Drug-related myelosuppression has been a challenge with initial JAK inhibitors, particularly in patients presenting with a cytopenic phenotype. However, newer agents, namely pacritinib and momelotinib, have proven more effective in this setting and are approved for patients with significant thrombocytopenia and anemia, respectively. Resistance or disease progression is clinically challenging and may be defined by several possible events, such as increasing splenomegaly or progression to accelerated or blast phase disease. However, with multiple JAK inhibitors now approved, sequencing of these agents appears poised to improve outcomes. Additionally, novel JAK inhibitors and JAK inhibitor-based combinations are in clinical development.

Real World Management of Cytopenias and Infections in Patients With Myelofibrosis Treated With Ruxolitinib

Introduction

Ruxolitinib was the first JAK2 inhibitor approved for the treatment of primary and secondary myelofibrosis. It is currently used worldwide as first-line therapy for advanced disease (intermediate-2 and high-risk) and is effective in polycythaemia vera (PV) and essential thrombocythaemia (ET), but not funded for this indication in many countries. Ruxolitinib has proven benefits with respect to symptom control, reduction in spleen size and prolongation of survival; however, it rarely induces a substantial reduction in allele burden and never provides a cure. Moreover, there are frequently encountered adverse effects and dosing issues that require careful management to optimise its therapeutic benefit.

Methods and Results

In this case-based review, we use seven informative common clinical scenarios to discuss appropriate investigation and management of cytopenias and infection issues.

Conclusions

We make recommendations based on 15 years of experience in using ruxolitinib and other JAK inhibitors for the treatment of myelofibrosis. We discuss when allogeneic haematopoietic stem cell transplantation (AHSCT) should be considered and some of the currently available alternative JAK inhibitors and trial options when AHSCT is not an option.

Red Blood Cell Distribution Width May Predict Drug-Induced Anemia and Prognosis in Patients Affected by Primary/Secondary Myelofibrosis Treated with Ruxolitinib

INTRODUCTION

Myelofibrosis (MF) is often characterized by a multifactorial anemia determined, in part, by bone marrow (BM) fibrosis, extramedullary erythropoiesis and splenomegaly. Ruxolitinib (RUX) is the first-in-class janus kinase 2 (JAK2) inhibitor approved for treatment of MF, proved to reduce spleen volume and decrease symptom burden. The red cell distribution width (RDW) is the measure of erythrocyte volume variability (anisocytosis). RDW has been recognized as a marker of clinical and subclinical systemic inflammation, and its elevation has also been associated with poor outcome in a wide spectrum of benign disorders and in different types of neoplasms.

METHODS

We retrospectively evaluated RDW in a single-center series of 200 consecutive patients with primary and secondary MF at RUX treatment initiation and examined any possible correlation with adverse MF features or drug-related anemia and any prognostic impact.

RESULTS

We suggested 20.5% as the optimal cutoff point in RDW values at start of RUX to dichotomize patients in receiver operating characteristic (ROC) analysis for spleen response and for survival. Higher RDW values at RUX start were associated with clinical and laboratory features of an aggressive MF phenotype. Lower spleen response (p < 0.001) and greater odds of drug-related anemia at 3 (p = 0.006) and 6 months (p < 0.001) were also seen in patients with higher RDW. Both increased RDW (considered as a continuous variable) and RDW ≥ 20.5% were associated with shorter overall survival (OS) from RUX initiation in univariate and multivariate analysis: HR 1.25 (95% confidence interval [CI], 1.12-1.40) (p < 0.001) and HR 3.01 (95% CI 1.81-4.99) (p < 0.001), respectively. RDW ≥ 20.5% at RUX start seems to possibly improve patients' sub-stratification along with anemia and conventional prognostic scoring systems.

CONCLUSIONS

RDW at RUX start might represent a good indirect measure of MF features and might have prognostic significance for RUX-treated patients affected by MF, aiding in the rapid detection of patients with poor prognosis.

Treatment patterns and healthcare resource utilization in ruxolitinib-treated patients with myelofibrosis with and without anemia: a real-world analysis

Anemia affects many patients with myelofibrosis and is associated with poor prognosis. The Janus kinase inhibitor ruxolitinib is often used in myelofibrosis but may cause or worsen anemia. Using healthcare claims data from the IQVIA PharMetrics Plus database, this retrospective analysis evaluated healthcare resource utilization (HCRU), healthcare costs, and treatment patterns in ruxolitinib-treated patients with myelofibrosis stratified by anemia diagnosis prior to ruxolitinib initiation. Of 11,499 patients diagnosed with myelofibrosis between January 2011 and December 2022, 481 had ≥ 1 ruxolitinib claim on or after the myelofibrosis diagnosis date and were included in this analysis. Mean follow-up was 2.0 years. At baseline, anemic patients (n = 257) were older (mean age, 60.2 vs. 56.8 years; P < 0.001) and had a higher mean Charlson Comorbidity Index (1.0 vs. 0.5; P < 0.001) than nonanemic patients (n = 224). During follow-up, anemic patients exhibited higher median annual all-cause HCRU (inpatient admissions, 0.3 vs. 0.0 [P < 0.001]; outpatient visits, 40.0 vs. 20.0 [P < 0.001]; emergency department visits, 0.4 vs. 0.0 [P < 0.010]) and also had numerically higher median annual all-cause total healthcare costs ($198,491 vs. $170,419; P = 0.549) and medical costs ($44,830 vs. $12,017; P = 0.638) but significantly lower median annual total pharmacy costs ($129,381 vs. $136,686; P < 0.050), compared with nonanemic patients. Ruxolitinib discontinuation rates were higher and median time to discontinuation was approximately 1 year earlier in anemic patients (14.1 vs. 23.8 months; P < 0.010). In conclusion, patients with myelofibrosis and baseline anemia who are treated with ruxolitinib may be an HCRU-intensive population, suggesting a potential need for alternative treatments that reduce their medical resource burden.

Clinical and Immune Effects of Peri-Transplantation JAK Inhibition for Myelofibrosis

Despite the introduction of JAK inhibitors, allogeneic hematopoietic cell transplant remains the only potentially curative treatment for patients with myelofibrosis but has considerable treatment-related complications. Whether the incorporation of JAK inhibition into the transplant algorithm leads to improved outcomes is still unclear. Here, we analyzed different transplant platforms in myelofibrosis patients undergoing a first transplant, comparing immune profiles and outcomes of (1) 33 patients continuing JAK inhibition at start of conditioning until stable engraftment (PERI-group), (2) 38 patients receiving JAK inhibition prior to transplant until start of conditioning (PRE-group), and (3) 38 patients that had never received JAK inhibition (NON-group). Patients in the PERI-group showed significantly higher early B-cell recovery as well as significantly increased late recovery of gamma-delta T cells and NK cells. We observed excellent neutrophil and platelet engraftment (100% for both) in the PERI-group and no hematotoxic effects or increased rates of infections following peri-transplant JAK inhibition. Cumulative incidence of acute graft-versus-host disease (GvHD) grade II-IV at day 100 after transplant was 15% in the PERI-group versus 29% in the PRE-group versus 34% in the NON-group. Cumulative incidence of relapse at 1 year after transplant was 9% in the PERI-group compared with 16% in the PRE-group and 18% in the NON-group. In conclusion, peri-transplant JAK inhibition was feasible with promising engraftment and acute GvHD rates, though deserves further investigation.

Treatment of Myeloproliferative Neoplasms With Janus Kinase Inhibitors: A Meta-Analysis of Cardiovascular Safety

BACKGROUND

Janus kinase inhibitors (JAKis) are an integral aspect of the management of myeloproliferative neoplasms (MPNs). Part of the clinical benefit derived from JAKis may be due to reductions in thrombosis, a potentially life-threatening complication of MPNs. However, evidence has emerged of adverse cardiovascular effects secondary to JAKis. We conducted a first-of-a-kind meta-analysis of the cardiovascular safety of JAKis in the treatment of MPNs.

METHODS

This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Systematic searches for studies comparing JAKi treatment to a control group were conducted. Studies reporting hypertension, major adverse cardiovascular events (MACE) and thromboembolic events were included in a meta-analysis using a random-effects model for the primary analysis, and fixed-effects model for any subgroup analyses performed.

RESULTS

A total of 23 publications, consisting of nine clinical trials and one retrospective analysis, met the inclusion criteria. This resulted in a pooled population of 2198 patients (JAKi n = 1145, Control n = 1053). In studies reporting thromboembolic events (n = 9), pooled analysis revealed a significantly lower rate of thromboembolic events in the JAKi group (incidence rate ratio (IRR): 0.52, 95% CI: 0.28-0.98, p = 0.04). This was primarily driven by ruxolitinib studies in myelofibrosis (MF) and polycythemia vera (PV) as when a subgroup analysis of these trials was performed (n = 7), an even more significant reduction in thromboembolic events with JAKi treatment was found (IRR: 0.41, 95%CI: 0.26-0.64, p < 0.001). There was no significant difference in MACE or hypertension between JAKi and control groups.

CONCLUSION

This meta-analysis suggests that JAKi treatment of MPN was associated with a reduced risk of thromboembolic events; primarily driven by studies of ruxolitinib in PV and MF. Further prospective clinical trials are warranted to confirm these findings and characterise the cardiovascular profile of other JAKis and other types of MPNs.

The impact of starting dose on overall survival in myelofibrosis patients treated with ruxolitinib: A prospective real-world study on AIFA monitoring registries

Ruxolitinib is a JAK1/JAK2 inhibitor approved for the treatment of myelofibrosis (MF)-related splenomegaly or symptoms. The recommended starting dose depends on platelet count, regardless of haemoglobin level at baseline. In the recent years, an overall survival (OS) advantage was reported in patients treated with ruxolitinib compared with best available therapy. We analysed a large Italian cohort of 3494 patients identified by Agenzia Italiana del Farmaco (AIFA) monitoring registries. Of them, 2337 (66.9%) started at reduced dose: these patients were older (median age 70 vs. 67), with increased incidence of large splenomegaly (longitudinal diameter 20 vs. 19.1 cm, median volume 1064 cm3 vs. 1016 cm3), with higher IPSS risk (30.9% vs. 26.1%), and worse ECOG score (more than 1 in 14.3% vs. 9.8%). After balancing for baseline characteristics, Kaplan-Meier analysis showed a median OS of 78.2 months (95% CI 65.9-89) for patients who started at full dose and 52.6 (95% CI 49-56.6) months for patients who started with reduced dose (p < 0.001). Group analysis also showed a substantial difference in patients with intermediate-2 and high IPSS risk. The majority of MF patients in real-world analysis started with a reduced dose of ruxolitinib, which is associated with less favourable outcomes.

Synergistic effect of concurrent high molecular risk mutations and lower JAK2 mutant variant allele frequencies on prognosis in patients with myelofibrosis-insights from a multicenter study

In addition to high-molecular risk (HMR) mutations (ASXL1, EZH2, SRSF2, IDH, and U2AF1Q157), lower JAK2V617F variant allele frequencies (VAF) have been demonstrated to be associated with poor prognosis of myelofibrosis (MF) patients. Nevertheless, the relationship between JAK2V617F VAF and HMR mutations remains inconclusive. To address this, we analyzed the mutation status of 54 myeloid neoplasm-relevant genes using targeted next-generation sequencing in 124 MF patients. Three cohorts from multiple international centers were analyzed for external validation. Among JAK2-mutated patients, the presence of HMR mutations drove poor prognosis in patients with lower JAK2V617F VAF but not in those with higher JAK2V617F VAF. Survival analyses showed consistent results across validation cohorts. In multivariable analysis, concurrent HMR and a lower JAK2V617F VAF was identified as an independent adverse prognostic factor for survival, irrespective of age, MIPSS70, MIPSS70 + v2, and GIPSS risk groups. Mutation co-occurrence tests revealed no shared mutational pattern over different cohorts, excluding potential confounding effect from other concurrent mutations. Importantly, the integration of HMR/JAK2V617F VAF (≤50%) status significantly enhanced existing prognostic models, as evidenced by higher c-indexes and time-dependent ROC analyses. Single-cell studies with sequential follow-ups are warranted to decipher the clonal evolution of MF and how it relates to JAK2V617F VAF dynamics.

Clinical outcomes of ruxolitinib treatment in 595 intermediate-1 risk patients with myelofibrosis: The RUX-MF Real-World Study

BACKGROUND

Ruxolitinib (RUX) is a JAK1/2 inhibitor approved for the therapy of myelofibrosis (MF) based on clinical trials including only intermediate2-high risk (INT2/HIGH) patients. However, RUX is commonly used in intermediate-1 (INT1) patients, with scarce information on responses and outcome.

METHODS

The authors investigated the benefit of RUX in 1055 MF patients, included in the "RUX-MF" retrospective study.

RESULTS

At baseline (BL), 595 (56.2%) patients were at INT1-risk according to DIPSS (PMF) or MYSEC-PM (SMF). The spleen was palpable at <5 cm, between 5 and 10 cm, and >10 cm below costal margin in 5.9%, 47.4%, and 39.7% of patients, respectively; 300 (54.1%) were highly symptomatic (total symptom score ≥20). High-molecular-risk (HMR) mutations (IDH1/2, ASXL-1, SRSF2, EZH2, U2AF1Q157) were detected in 77/167 patients. A total of 101 (19.2%) patients had ≥1 cytopenia (Hb < 10 g/dL: n.36; PLT <100 x 109/L: n = 43; white blood cells <4 x 109/L: n = 40). After 6 months on RUX, IWG-MRT-defined spleen and symptoms response rates were 26.8% and 67.9%, respectively. In univariate analysis, predictors of SR at 6 months were no HMR mutations odds ratio [OR], 2.0, p = .05], no cytopenia (OR, 2.10; p = .01), and blasts <1% (OR, 1.91; p = .01). In multivariate analysis, absence of HMR maintained a significant association (OR, 2.1 [1.12-3.76]; p = .01).

CONCLUSIONS

In INT1 patients, responses were more frequent and durable, whereas toxicity rates were lower compared to INT2/high-risk patients. Presence of HMR mutations, cytopenia, and peripheral blasts identified less-responsive INT1 patients, who may benefit for alternative therapeutic strategies.

Inhibition of RhoA-mediated secretory autophagy in megakaryocytes mitigates myelofibrosis in mice

Megakaryocytes (MKs) are large, polyploid cells that contribute to bone marrow homeostasis through the secretion of cytokines such as transforming growth factor β1 (TGFβ1). During neoplastic transformation, immature MKs accumulate in the bone marrow where they induce fibrotic remodeling ultimately resulting in myelofibrosis. Current treatment strategies aim to prevent MK hyperproliferation, however, little is understood about the potential of targeting dysregulated cytokine secretion from neoplastic MKs as a novel therapeutic avenue. Unconventional secretion of TGFβ1 as well as interleukin 1β (IL1β) via secretory autophagy occurs in cells other than MKs, which prompted us to investigate whether similar mechanisms are utilized by MKs. Here, we identified that TGFβ1 strongly co-localized with the autophagy marker light chain 3B in native MKs. Disrupting secretory autophagy by inhibiting the small GTPase RhoA or its downstream effector Rho kinase (ROCK) markedly reduced TGFβ1 and IL1β secretion in vitro . In vivo , conditional deletion of the essential autophagy gene Atg5 from the hematopoietic system limited megakaryocytosis and aberrant cytokine secretion in an MPL W515L -driven transplant model. Similarly, mice with a selective deletion of Rhoa from the MK and platelet lineage were protected from progressive fibrosis. Finally, disease hallmarks in MPL W515L -transplanted mice were attenuated upon treatment with the autophagy inhibitor hydroxychloroquine or the ROCK inhibitor Y27632, either as monotherapy or in combination with the JAK2 inhibitor ruxolitinib. Overall, our data indicate that aberrant cytokine secretion is dependent on secretory autophagy downstream of RhoA, targeting of which represents a novel therapeutic avenue in the treatment of myelofibrosis.

One Sentence Summary

TGFβ1 is released from megakaryocytes via RhoA-mediated secretory autophagy, and targeting this process can alleviate fibrosis progression in a preclinical mouse model of myelofibrosis.

JAK Inhibitors for Myelofibrosis: Strengths and Limitations

PURPOSE OF REVIEW

The landscape of myelofibrosis (MF) has changed since the discovery of the JAK2 V617F mutation and subsequent development of JAK inhibitors (JAKis). However, treatment with JAKis remain a challenge. In this review we critically analyze the strengths and limitations of currently available JAK inhibitors.

RECENT FINDINGS

In MF patients, JAK inhibitors have been associated with reduced symptom burden and spleen size, as well as improved survival. However, durability of response and development of treatment resistance remain an issue. Recently, there has been increased efforts to optimize treatment with the development of highly selective JAK inhibitors, as well as use of combination agents to counter disease resistance through targeting aberrant signaling pathways. Treatment of MF patients with JAKi therapy can be challenging but the development of more potent and selective JAK inhibitors, as well as combination therapies, represent exciting treatment advances in this field.

Janus kinase inhibitor monotherapy and combination therapies for myelofibrosis: what's the current standard of care?

INTRODUCTION

JAK inhibitors (JAKi) have changed the treatment paradigm of myelofibrosis (MF). Currently, 4 JAKis are approved in the US as monotherapy (mono) to treat patients with MF. JAKis are also being studied in combination (combo) with novel agents. Herein, we review some of the key studies that evaluated JAKi as mono and combo in MF.

AREAS COVERED

We performed a Pubmed search for 'JAK inhibitors' and 'myelofibrosis' from 1/2010 to 12/2023. For mono, we included only the unique phase II/III studies of the approved JAKi. Selective studies that evaluated JAKi in combo with the novel agents were also included.

EXPERT OPINION

JAKis aim to provide clinical benefit to patients via spleen size reduction and MPN symptom improvement. In order to potentially increase clinical benefit for patients with MF, several novel agents are being partnered with ruxolitinib (RUX) with the ongoing hypothesis to augment greater measures of MF disease modification. The novel agents are either 'added-on' to RUX or as a combo in JAKi naïve patients. Also, the mutant-targeting era of therapies is now beginning with novel CALR-mutated, novel JAK2 V617F mutation-specific and type II JAK2i in the initial stages of drug development, representing a new approach to treatment.

Consistency of Spleen and Symptom Reduction Regardless of Cytopenia in Patients With Myelofibrosis Treated With Pacritinib

BACKGROUND

Pacritinib is a JAK2/IRAK1/ACVR1 inhibitor that is approved in the United States for the treatment of patients with myelofibrosis who have a platelet count < 50 × 109/L. Phase 3 clinical studies of pacritinib included patients across a wide range of baseline platelet and hemoglobin levels.

PATIENTS AND METHODS

In order to assess the impact of baseline blood counts on pacritinib efficacy, an analysis of efficacy outcomes by baseline platelet and hemoglobin levels was performed using data pooled from 2 Phase 3 studies of pacritinib in patients with MF (PERSIST-1 and PERSIST-2).

RESULTS

Of 276 patients evaluable for spleen response, spleen volume reduction occurred consistently across platelet subgroups (< 100 × 109/L or ≥ 100 × 109/L) and hemoglobin subgroups (< 8 g/dL, ≥ 8 to < 10 g/dL, or > 10 g/dL), with no diminution in treatment effect in patients with severe thrombocytopenia or anemia. Among 159 patients evaluable for symptoms response, improvement in total symptom score (TTS) was similar across platelet subgroups. A ≥ 50% improvement of TSS occurred more frequently in patients with baseline hemoglobin < 8 g/dL compared with those with baseline hemoglobin ≥ 8 to < 10 g/dL or > 10 g/dL. Patients with baseline hemoglobin < 8 g/dL also experienced improved hemoglobin sustained over 24 weeks, whereas subgroups with less severe anemia had stable hemoglobin levels over time. Symptom improvement as assessed using the Patient Global Impression of Change instrument was generally consistent across platelet and hemoglobin subgroups.

CONCLUSION

Pacritinib demonstrates consistent efficacy in patients with MF regardless of baseline platelet and hemoglobin counts.

Decision analysis for transplant candidates with primary myelofibrosis in the ruxolitinib era

The recent progress with ruxolitinib treatment might improve quality of life as well as overall survival in patients with primary myelofibrosis. Therefore, the optimal timing of allogeneic hematopoietic cell transplantation (HCT) in the ruxolitinib era remains to be elucidated. We constructed a Markov model to simulate the 5-year clinical course of transplant candidates with primary myelofibrosis and compared outcomes between those who underwent immediate HCT and those whose HCT was delayed until after ruxolitinib failure. Since older age was associated with an increased risk of mortality, we analyzed patients aged <60 and ≥60 years separately in subgroup analyses. Life expectancy was consistently longer in the groups undergoing delayed HCT after ruxolitinib failure regardless of the patients' age. Regarding quality-adjusted life years, a baseline analysis showed that immediate HCT was inferior to delayed HCT after ruxolitinib failure (2.19 vs. 2.26). In patients aged <60 years, immediate HCT was equivalent to delayed HCT after ruxolitinib failure (2.31 vs. 2.31). On the other hand, in patients aged ≥60 years, immediate HCT was inferior to delayed HCT after ruxolitinib failure (1.98 vs. 2.21). A one-way sensitivity analysis showed that the utility of being alive without chronic graft-versus-host disease after immediate HCT was the most influential parameter for quality-adjusted life years, and that a value higher than 0.836 could reverse the superiority of delayed HCT after ruxolitinib failure. As a result, delayed HCT after ruxolitinib failure is expected to be superior to immediate HCT, especially in patients aged ≥60 years, and is also a promising strategy even in those aged <60 years.

Treatment Strategies Used in Treating Myelofibrosis: State of the Art

BACKGROUND

Current drug therapy for myelofibrosis does not alter the natural course of the disease or prolong survival, and allogeneic stem cell transplantation is the only curative treatment modality. For over a decade, the Janus kinase (JAK) inhibitor ruxolitinib has been the standard of care. More recently, newer-generation JAK inhibitors have joined the ranks of accepted treatment options.

OBJECTIVES

The primary goal of treatment is to reduce spleen size and minimize disease-related symptoms. Prognostic scoring systems are used to designate patients as being at lower or higher risk. For transplant-eligible patients, transplant is offered to those with a bridge of a JAK inhibitor; patients who are not eligible for transplant are usually offered long-term therapy with a JAK inhibitor. Limited disease-modifying activity, dose-limiting cytopenias, and other adverse effects have contributed to discontinuation of JAK inhibitor treatment.

CONCLUSIONS

Novel JAK inhibitors and combination approaches are currently being explored to overcome these shortcomings. Further research will be essential to establish optimal therapeutic approaches in first-line and subsequent treatments.

Identifying disease-modifying potential in myelofibrosis clinical trials

ABSTRACT

The ultimate goal of bringing most new drugs to the clinic in hematologic malignancy is to improve overall survival. However, the use of surrogate end points for overall survival is increasingly considered standard practice, because a well validated surrogate end point can accelerate the outcome assessment and facilitate better clinical trial design. Established examples include monitoring minimal residual disease in chronic myeloid leukemia and acute leukemia, and metabolic response assessment in lymphoma. However, what happens when a clinical trial end point that is not a good surrogate for disease-modifying potential becomes ingrained as an expected outcome, and new agents are expected or required to meet this end point to demonstrate "efficacy"? Janus kinase (JAK) inhibitors for myelofibrosis (MF) have a specific impact on reducing symptom burden and splenomegaly but limited impact on the natural history of the disease. Since the introduction of ruxolitinib more than a decade ago there has been modest incremental success in clinical trials for MF but no major leap forward to alter the natural history of the disease. We argue that the clinical development of novel agents for MF will be accelerated by moving away from using end points that are specifically tailored to measure the beneficial effects of JAK inhibitors. We propose that specific measures of relevant disease burden, such as reduction in mutation burden as determined by molecular end points, should replace established end points. Careful reanalysis of existing data and trials in progress is needed to identify the most useful surrogate end points for future MF trials and better serve patient interest.

The role of corticosteroids in the current treatment paradigm for myelofibrosis

INTRODUCTION

Myelofibrosis (MF) is a clonal hematological disorder characterized by bone marrow fibrosis, splenomegaly, and inflammatory cytokine dysregulation. While the role of steroids in MF is not fully defined, their anti-inflammatory properties may offer therapeutic benefits, particularly in managing anemia and other cytopenias. Steroids exert their effects by suppressing pro-inflammatory cytokines such as IL1, IL6, and TNF, and by enhancing anti-inflammatory cytokines like IL4 and IL10. Elevated levels of IL6 and other cytokines in MF are associated with anemia and poor prognosis, suggesting that steroid therapy could mitigate these effects.

AREAS COVERED

In this manuscript, we review clinical studies which evaluated the safety and efficacy of steroids in MF patients. Moreover, we examine clinical data of the combination of steroids with immunomodulatory agents and JAK inhibitors. Our literature search consisted of an extensive review of PubMed and clinicaltrials.gov.

EXPERT OPINION

The role of steroids in the management of MF remains poorly defined, though emerging evidence suggests a potential therapeutic benefit, particularly in managing anemia and other cytopenias. The combination with IMIDs has also yielded positive outcomes as demonstrated in several studies. Steroids may also play a crucial role in managing cytopenias in MF patients receiving JAKi.

Efficacy and safety of fedratinib in patients with myelofibrosis previously treated with ruxolitinib (FREEDOM2): results from a multicentre, open-label, randomised, controlled, phase 3 trial

BACKGROUND

Most patients with myelofibrosis develop ruxolitinib intolerance or disease that is relapsed or refractory, and survival rates after ruxolitinib discontinuation are poor. We aimed to evaluate the safety and efficacy of fedratinib versus best available therapy (BAT) in patients with myelofibrosis previously treated with ruxolitinib.

METHODS

FREEDOM2 was a multicentre, open-label, randomised, controlled, phase 3 trial in 86 clinics in 16 countries, in which patients aged at least 18 years with intermediate-2 or high-risk myelofibrosis that was relapsed or refractory or intolerant to ruxolitinib with Eastern Cooperative Oncology Group performance status 0-2 were stratified by spleen size by palpation, platelet count, and previous ruxolitinib treatment, and randomly assigned 2:1 by interactive response technology to receive fedratinib 400 mg per day (4 × 100 mg capsules orally once daily, open-label) or BAT. Patients received prophylactic antiemetics and thiamine supplementation, and symptomatic antidiarrhoeals as required. Primary endpoint was proportion of patients reaching spleen volume reduction (SVR) of at least 35% (SVR35) at end of cycle 6 in the intention-to-treat population. This manuscript reports the primary analysis of the trial; follow-up is ongoing. This trial is registered at clinicaltrials.gov, NCT03952039.

FINDINGS

Between Sept 9, 2019 and June 24, 2022, of 316 patients screened, 201 were randomly assigned and treated (134 to fedratinib, 67 to BAT [including 52 receiving ruxolitinib]); 46 patients from the BAT group crossed over to fedratinib. Approximately half of enrolled patients were male (fedratinib 75 [56%] of 134; BAT 30 [45%] of 67) and most were White (fedratinib 106 [79%] of 134; BAT 58 [87%] of 67). At data cutoff (Dec 27, 2022), median survival follow-up was 64·5 weeks (IQR 37·9-104·9). SVR35 at end of cycle 6 was seen in 48 (36%) of 134 patients receiving fedratinib versus four (6%) of 67 patients receiving BAT (30% difference; 95% CI 20-39; one-sided p-value <0·0001). During the first six cycles 53 (40%) of 134 patients in the fedratinib group and 8 (12%) of 67 patients in the BAT group had grade 3 or greater treatment-related adverse events, most frequently anaemia (fedratinib 12 [9%] of 134; BAT 6 [9%] of 67) and thrombocytopenia (fedratinib 16 [12%] of 134; BAT 2 [3%] of 67); one patient in the fedratinib group died from acute kidney injury suspected to be related to study drug (no treatment-related deaths in the BAT group). Gastrointestinal adverse events occurred more frequently in the fedratinib group compared with the BAT group, but were mostly grade 1-2 in severity and more frequent in early cycles, and were less frequent than in prior clinical trials. A total of 28 (21%) of 134 patients in the fedratinib group and 3 (4%) of 67 patients in the BAT group had thiamine levels below lower limit of normal per central laboratory assessment, with only one case of low thiamine in the fedratinib arm after the introduction of prophylactic thiamine supplementation.

INTERPRETATION

Findings from FREEDOM2 support fedratinib as a second-line Janus kinase inhibitor option to reduce spleen size after ruxolitinib failure or intolerance in patients with myelofibrosis, and shows effective strategies for management of gastrointestinal adverse events and low thiamine concentrations through prophylaxis, monitoring, and treatment.

FUNDING

Bristol Myers Squibb.

Safety and efficacy of luspatercept for the treatment of anemia in patients with myelofibrosis

ABSTRACT

The ACE-536-MF-001 trial enrolled patients with myelofibrosis (n = 95) into 4 cohorts: patients in cohorts 1 and 3A were non-transfusion dependent (NTD) and had anemia; patients in cohorts 2 and 3B were transfusion dependent (TD); and patients in cohort 3A/3B had stable ruxolitinib treatment before and during the study. All patients received luspatercept (1.0-1.75 mg/kg, 21-day cycles). Treatment was extended if clinical benefit was observed at day 169. The primary end point was anemia response rate (NTD, ≥1.5 g/dL hemoglobin increase from baseline; TD, transfusion-independence) over any 12-week period during the primary treatment period (weeks 1-24). Overall, 14% of patients in cohorts 1 and 3A, 10% in cohort 2, and 26% in cohort 3B met the primary end point. In cohorts 1 and 3A (NTD), 27% and 50% of patients, respectively, had mean hemoglobin increase of ≥1.5 g/dL from baseline. Among TD patients, ∼50% had ≥50% reduction in transfusion burden. Reduction in total symptom score was observed in all cohorts, with the greatest response rate seen in cohort 3A. Overall, 94% of patients had ≥1 adverse event (AE); 47% had ≥1 treatment-related AE (TRAE; 11% grade ≥3), most frequently hypertension (18%), managed with medical intervention. One patient had a serious TRAE leading to luspatercept discontinuation. Nine patients died on treatment (unrelated to study drug). In most patients, ruxolitinib dose and spleen size remained stable. In patients with myelofibrosis, luspatercept improved anemia and transfusion burden across cohorts; the safety profile was consistent with previous studies. This trial was registered at www.ClinicalTrials.gov as #NCT03194542.

Safety and efficacy of fedratinib in patients with myelofibrosis previously treated with ruxolitinib: primary analysis of FREEDOM trial

The phase 3b FREEDOM trial (ClinicalTrials.gov: NCT03755518) evaluates efficacy/safety of fedratinib in intermediate- or high-risk myelofibrosis patients with platelet count ≥50 × 109/L, previously treated with ruxolitinib. The trial design included protocol specified strategies to mitigate the risk for gastrointestinal (GI) adverse events (AEs), thiamine supplementation, and encephalopathy surveillance. Due to COVID-19, accrual was cut short with 38 patients enrolled. In the efficacy evaluable population (n = 35), nine (25.7%; 95% confidence interval 12.5-43.3) patients achieved primary endpoint of ≥35% spleen volume reduction (SVR) at end of cycle (EOC) 6; and 22 (62.9%) patients showed best overall response of ≥35% SVR up to end of treatment. Sixteen (44.4%) patients showed ≥50% reduction in total symptom score at EOC6 (n = 36). Compared to previously reported JAKARTA-2 trial, rates of GI AEs were lower, and no patient developed encephalopathy. Overall, FREEDOM study showed clinically relevant spleen and symptom responses with fedratinib, and effective mitigation of GI AEs.

The application of JAK inhibitors in the peri-transplantation period of hematopoietic stem cell transplantation for myelofibrosis

Myelofibrosis (MF) is a myeloproliferative neoplasm (MPN) with a poor prognosis, and allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only treatment with curative potential. Ruxolitinib, a JAK1/2 inhibitor, has shown promising results in improving patients' symptoms, overall survival, and quality of life, and can be used as a bridging therapy to HSCT that increases the proportion of transplantable patients. However, the effect of this and similar drugs on HSCT outcomes is unknown, and the reports on their efficacy and safety in the peri-transplantation period vary widely in the published literature. This paper reviews clinical data related to the use of JAK inhibitors in the peri-implantation phase of hematopoietic stem cell transplantation for primary myelofibrosis and discusses their efficacy and safety.

Oral Decitabine/Cedazuridine Is an Effective Ambulatory Therapy for Patients With Myelofibrosis Refractory to JAK2 Inhibitor Therapy

BACKGROUND

Outcomes are dismal for patients with myelofibrosis (MF) who are no longer responsive to JAK2 inhibitors (JAKi) and/or have increasing blast cell numbers. Although prior reports have suggested the benefits of intravenous decitabine (DAC) combined with ruxolitinib for patients with Myeloproliferative Neoplasm (MPN) accelerated/blast phase (AP/BP), decitabine-cedazuridine (DEC-C), an oral fixed-dose combination providing equivalent pharmacokinetic exposure, has not been evaluated in MF.

METHODS

We conducted a retrospective analysis of 14 patients with high-risk MF refractory to ruxolitinib or MPN-AP (10-19% blasts) treated with DEC-C +/- JAKi at Mount Sinai Hospital from 2021 to 2024.

RESULTS

The cohort was elderly (median age,76 years) and almost uniformly possessed high risk mutations with 13 of the 14 patients progressing on JAKi therapy. With a median follow-up of 9.4 months, the median overall survival (OS) was 29 months for the entire cohort. Median OS was 10.8 months for MPN-AP and was not reached for ruxolitinib refractory MF patients. All patients (n = 9) receiving > 4 cycles of DEC-C had clinical benefit exemplified by a reduction in blast cell numbers, spleen size, and lack of progression to MPN-BP (78%). Furthermore, 3/14 patients proceeded to allogeneic stem cell transplant. Myelosuppression was a common adverse event which was managed by reducing the number of days of administration of DEC-C from 5 to 3 per cycle.

CONCLUSIONS

This report demonstrates the feasibility, tolerability, and clinical benefit of an exclusively ambulatory regimen for high-risk, elderly patients with advanced MF which warrants further evaluation in a prospective clinical trial.

Comparative efficacy and hematologic safety of different dosages of JAK inhibitors in the treatment of myelofibrosis: a network meta-analysis

Background

Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by bone marrow fibrosis associated with substantial morbidity and mortality. The therapeutic landscape for MF has advanced with the development of Janus kinase inhibitors (JAKis) like ruxolitinib (RUX), fedratinib (FED), pacritinib (PAC), and momelotinib (MMB), aiming to alleviate symptoms and enhance patient comfort.

Methods

A network meta-analysis was conducted to assess the efficacy and safety of eleven JAKi treatment regimens across nine randomized controlled trials (RCTs) with a total of 2340 participants. Outcomes were evaluated in terms of spleen volume reduction (SVR), total symptom score reduction (TSSR), hematological safety profiles, and overall survival (OS).

Results

RUX and MMB were superior in achieving SVR and TSSR, with significant dose-response relationships observed. PAC and MMB were associated with a decreased risk of grade 3/4 anemia and thrombocytopenia compared to other JAKis. However, no substantial benefits in OS were observed with newer JAKis compared to RUX. The poorer OS outcomes with certain PAC dosages were likely influenced by baseline patient characteristics, particularly severe cytopenias.

Conclusion

The introduction of JAKis significantly changed the treatment of MF. This meta-analysis reaffirms the core role of RUX and positions MMB as a potentially powerful alternative for treating symptoms and reducing spleen size. Meanwhile, MMB and PAC have a positive effect on anemia in MF while FED is more tolerable for patients with thrombocytopenia. However, it should be noted that these results are influenced by baseline patient characteristics, particularly cytopenias, which affects both management and overall survival. Therefore, there is an urgent need for personalized dosing strategies to optimize the balance between efficacy and safety, with careful consideration of patient-specific factors.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023424179.

Advances with janus kinase inhibitors for the treatment of myeloproliferative neoplasms: an update of the literature

INTRODUCTION

The hallmark discovery of hyperactivation of the janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway was a sentinel moment in the history of myeloproliferative neoplasms (MPNs). This finding paved the way for the development of JAK inhibitors, which now represent the foundation of myelofibrosis therapy. With four JAK inhibitors now approved for myelofibrosis, awareness of their clinical efficacy and safety data and recognition of their unique pharmacologic attributes are of critical importance. Additionally, ruxolitinib represents an integral part of the therapeutic arsenal for polycythemia vera.

AREAS COVERED

This review provides a broad overview of the published literature supporting JAK inhibitor therapy for MPNs. Primarily focusing on myelofibrosis, each of the four available JAK inhibitors is reviewed in detail, including pharmacology, efficacy, and safety data. Failure of JAK inhibitors and future directions in JAK inhibitor therapy are also discussed.

EXPERT OPINION

JAK inhibitors revolutionized the treatment of MPNs and have dramatically improved patient outcomes. However, data informing selection between currently available JAK inhibitors is limited. These agents are not curative and eventually fail most patients with myelofibrosis. Combining JAK inhibitors with novel targeted agents appears to be the most promising path to further improve outcomes.

Recent advances in JAK2 inhibition for the treatment of myelofibrosis

INTRODUCTION

Myelofibrosis (MF) is a BCR-ABL-negative myeloproliferative neoplasm characterized by splenomegaly, constitutional symptoms, cytopenias, a potential for leukemic transformation, and increased mortality. Patients who are ineligible for stem cell transplant rely on pharmacologic therapies of noncurative intent, whose cornerstone consists of JAK inhibitors (JAKi). While current JAKi are efficacious in controlling symptoms and splenic volume, none meaningfully reduce clonal burden nor halt disease progression, and patients oftentimes develop JAKi intolerant, relapsed, or refractory MF. As such, there remains an urgent necessity for second-line options and novel therapies with disease-modifying properties.

AREAS COVERED

In this review, we delineate the mechanistic rationale, along with the latest safety and efficacy data, of investigational JAKi-based MF treatment strategies, with a focus on JAKi monotherapies and combinations of novel agents with approved JAKi. Our literature search consisted of extensive review of PubMed and clinicaltrials.gov.

EXPERT OPINION

A myriad of promising MF-directed therapies are in late-phase studies. Following their approval, treatment selection should be tailored to patient-specific treatment goals and disease characteristics, with an emphasis on combination therapies of JAKi with novel agents of differing mechanistic targets that possess anti-clonal properties, in attempt to alter disease course and concurrently limit dose-dependent JAKi toxicities.

Ruxolitinib Adherence in Myelofibrosis and Polycythemia Vera: the "RAMP" Italian multicenter prospective study

Ruxolitinib is beneficial in patients with myelofibrosis (MF) and polycythemia vera (PV). Information on ruxolitinib adherence is scant. The Ruxolitinib Adherence in Myelofibrosis and Polycythemia Vera (RAMP) prospective multicenter study (NCT06078319) included 189 ruxolitinib-treated patients. Patients completed the Adherence to Refills and Medications Scale (ARMS) and Distress Thermometer and Problem List (DTPL) at the earliest convenience, after registration in the study, and at later timepoints. At week-0, low adherence (ARMS > 14) and high distress (DT ≥ 4) were declared by 49.7% and 40.2% of patients, respectively. The main reason for low adherence was difficult ruxolitinib supply (49%), intentional (4.3%) and unintentional (46.7%) non-take. In multivariable regression analysis, low adherence was associated to male sex (p = 0.001), high distress (p < 0.001), and treatment duration ≥ 1 year (p = 0.03). Over time, rates of low adherence and high distress remained stable, but unintentional non-take decreased from 47.9% to 26.0% at week-48. MF patients with stable high adherence/low distress were more likely to obtain/maintain the spleen response at week-24. Low adherence to ruxolitinib represents an unmet clinical need that require a multifaceted approach, based on reason behind it (patients characteristics and treatment duration). Its recognition may help distinguishing patients who are truly refractory and those in need of therapy optimization.

Skin Malignancies Due to Anti-Cancer Therapies

Skin cancers involve a significant concern in cancer therapy due to their association with various treatment modalities. This comprehensive review explores the increased risk of skin cancers linked to different anti-cancer treatments, including classic immunosuppressants such as methotrexate (MTX), chemotherapeutic agents such as fludarabine and hydroxyurea (HU), targeted therapies like ibrutinib and Janus Kinase inhibitors (JAKi), mitogen-activated protein kinase pathway (MAPKP) inhibitors, sonic hedgehog pathway (SHHP) inhibitors, and radiotherapy. MTX, a widely used immunosuppressant in different fields, is associated with basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and cutaneous melanoma (CM), particularly at higher dosages. Fludarabine, HU, and other chemotherapeutic agents increase the risk of non-melanoma skin cancers (NMSCs), including cSCC and BCC. Targeted therapies like ibrutinib and JAKi have been linked to an elevated incidence of NMSCs and CM. MAPKP inhibitors, particularly BRAF inhibitors like vemurafenib, are associated with the development of cSCCs and second primary melanomas (SPMs). SHHP inhibitors like vismodegib have been linked to the emergence of cSCCs following treatment for BCC. Additionally, radiotherapy carries carcinogenic risks, especially for BCCs, with increased risks, especially with younger age at the moment of exposure. Understanding these risks and implementing appropriate screening is crucial for effectively managing patients undergoing anti-cancer therapies.

Neuropilin2 in Mesenchymal Stromal Cells as a Potential Novel Therapeutic Target in Myelofibrosis

Bone marrow fibrosis in myeloproliferative neoplasm (MPN), myelodysplastic syndromes (MDS), MPN/MDS overlap syndromes and acute myeloid leukemia (AML) is associated with poor prognosis and early treatment failure. Myelofibrosis (MF) is accompanied by reprogramming of multipotent bone marrow mesenchymal stromal cells (MSC) into osteoid and fiber-producing stromal cells. We demonstrate NRP2 and osteolineage marker NCAM1 (neural cell adhesion molecule 1) expression within the endosteal niche in normal bone marrow and aberrantly in MPN, MDS MPN/MDS overlap syndromes and AML (n = 99), as assessed by immunohistochemistry. Increased and diffuse expression in mesenchymal stromal cells and osteoblasts correlates with high MF grade in MPN (p < 0.05 for NRP2 and NCAM1). Single cell RNA sequencing (scRNAseq) re-analysis demonstrated NRP2 expression in endothelial cells and partial co-expression of NRP2 and NCAM1 in normal MSC and osteoblasts. Potential ligands included transforming growth factor β1 (TGFB1) from osteoblasts and megakaryocytes. Murine ThPO and JAK2V617F myelofibrosis models showed co-expression of Nrp2 and Ncam1 in osteolineage cells, while fibrosis-promoting MSC only express Nrp2. In vitro experiments with MC3T3-E1 pre-osteoblasts and analysis of Nrp2-/- mouse femurs suggest that Nrp2 is functionally involved in osteogenesis. In summary, NRP2 represents a potential novel druggable target in patients with myelofibrosis.

Jak2V617F Reversible Activation Shows Its Essential Requirement in Myeloproliferative Neoplasms

Gain-of-function mutations activating JAK/STAT signaling are seen in the majority of patients with myeloproliferative neoplasms (MPN), most commonly JAK2V617F. Although clinically approved JAK inhibitors improve symptoms and outcomes in MPNs, remissions are rare, and mutant allele burden does not substantively change with chronic therapy. We hypothesized this is due to limitations of current JAK inhibitors to potently and specifically abrogate mutant JAK2 signaling. We therefore developed a conditionally inducible mouse model allowing for sequential activation, and then inactivation, of Jak2V617F from its endogenous locus using a combined Dre-rox/Cre-lox dual-recombinase system. Jak2V617F deletion abrogates MPN features, induces depletion of mutant-specific hematopoietic stem/progenitor cells, and extends overall survival to an extent not observed with pharmacologic JAK inhibition, including when cooccurring with somatic Tet2 loss. Our data suggest JAK2V617F represents the best therapeutic target in MPNs and demonstrate the therapeutic relevance of a dual-recombinase system to assess mutant-specific oncogenic dependencies in vivo.

SIGNIFICANCE

Current JAK inhibitors to treat myeloproliferative neoplasms are ineffective at eradicating mutant cells. We developed an endogenously expressed Jak2V617F dual-recombinase knock-in/knock-out model to investigate Jak2V617F oncogenic reversion in vivo. Jak2V617F deletion abrogates MPN features and depletes disease-sustaining MPN stem cells, suggesting improved Jak2V617F targeting offers the potential for greater therapeutic efficacy. See related commentary by Celik and Challen, p. 701. This article is featured in Selected Articles from This Issue, p. 695.

Advances in pharmacotherapy for myelofibrosis: what is the current state of play?

INTRODUCTION

The introduction of the first JAK inhibitor (JAKi) ruxolitinib 10 years ago represented a pivotal advancement in myelofibrosis (MF) treatment, mostly in terms of spleen and symptoms response. Nowadays three more JAKi, fedratinib, pacritinib, and momelotinib, are available for both ruxolitinib-resistant and naïve patients. Moreover, many drugs are currently being investigated, both alone and in combination with JAKi.

AREAS COVERED

In this review we discuss the long-term data of ruxolitinib and more recent evidence coming from clinical trials of fedratinib, pacritinib, and momelotinib, used as first- or second-line MF therapy. More, focus is set on data from non-JAKi drugs, such as the quite extensively studied BET-inhibitors (pelabresib) and BCL-inhibitors (navitoclax), novel target therapies, and drugs aimed to improve anemia, still representing a major determinant of reduced survival in MF.

EXPERT OPINION

It's now evident that JAKi monotherapy, though clinically effective, is rarely able to change MF natural history; novel drugs are promising but long-term data are inevitably lacking. We feel that soon MF treatment will require clinicians to select the most appropriate JAKi inhibitor, based on patient characteristics, associating either front-line or in case of early suboptimal response, non-JAKi drugs with the aim to pursue disease modification.

Momelotinib in myelofibrosis

INTRODUCTION

Myelofibrosis (MF) is a hematologic disease characterized by bone marrow fibrosis, cytopenias, splenomegaly, and constitutional symptoms. Recent years have seen the emergence of novel therapeutic agents, notably ruxolitinib and fedratinib, which target the Janus kinases (JAK) pathway. However, their myelosuppressive effect coupled with the persistence, and even worsening anemia remains a significant challenge, leading usually to treatment discontinuation.

AREAS COVERED

This review focuses on Momelotinib (MMB), a unique JAK inhibitor that has shown promise in MF treatment, particularly in improving anemia. MMB inhibits type 1 kinase activin A receptor or activin receptor-like kinase-2 (ACVR1/ALK2), with consequent rebalancing of the SMAD pathways and reduced transcription of hepcidin. Moreover, it seems that MMB could reduce the serum levels of several inflammatory cytokines responsible for anemia. Clinical trials have demonstrated MMB's efficacy in reducing spleen size, alleviating symptoms, and improving anemia, with a favorable safety profile compared to other JAK inhibitors, both in treatment-naïve and in pre-treated patients.

EXPERT OPINION

Due to its mechanism of action, MMB represents a valuable therapeutic option in MF, addressing the clinical challenge of anemia and potentially improving outcomes for patients with hematologic malignancies. Ongoing research explores MMB's potential in acute myeloid leukemia and combination therapies.

Disseminated Histoplasmosis in a Patient with Myelofibrosis on Ruxolitinib: A Case Report and Review of the Literature on Ruxolitinib-Associated Invasive Fungal Infections

Ruxolitinib, a selective inhibitor of Janus kinases, is a standard treatment for intermediate/high-risk myelofibrosis (MF) but is associated with a predisposition to opportunistic infections, especially herpes zoster. However, the incidence and characteristics of invasive fungal infections (IFIs) in these patients remain uncertain. In this report, we present the case of a 59-year-old woman with MF who developed disseminated histoplasmosis after seven months of ruxolitinib use. The patient clinically improved after ten weeks of combined amphotericin B and azole therapy, and ruxolitinib was discontinued. Later, the patient received fedratinib, a relatively JAK2-selective inhibitor, without relapse of histoplasmosis. We also reviewed the literature on published cases of proven IFIs in patients with MF who received ruxolitinib. Including ours, we identified 28 such cases, most commonly due to Cryptococcus species (46%). IFIs were most commonly disseminated (39%), followed by localized lung (21%) infections. Although uncommon, a high index of suspicion for opportunistic IFIs is needed in patients receiving JAK inhibitors. Furthermore, the paucity of data regarding the optimal management of IFIs in patients treated with JAK inhibitors underscore the need for well-designed studies to evaluate the epidemiology, pathobiology, early diagnosis, and multimodal therapy of IFIs in patients with hematological malignancies receiving targeted therapies.

Phase 2 study of add-on parsaclisib for patients with myelofibrosis and suboptimal response to ruxolitinib: final results

ABSTRACT

Ruxolitinib reduces spleen volume, improves symptoms, and increases survival in patients with intermediate- or high-risk myelofibrosis. However, suboptimal response may occur, potentially because of signaling via the phosphoinositide 3-kinase (PI3K)/protein kinase B pathway. This phase 2 study evaluated dosing, efficacy, and safety of add-on PI3Kδ inhibitor parsaclisib for patients with primary or secondary myelofibrosis with suboptimal response to ruxolitinib. Eligible patients remained on a stable ruxolitinib dose and received add-on parsaclisib 10 or 20 mg, once daily for 8 weeks, and once weekly thereafter (daily-to-weekly dosing; n = 32); or parsaclisib 5 or 20 mg, once daily for 8 weeks, then 5 mg once daily thereafter (all-daily dosing; n = 42). Proportion of patients achieving a ≥10% decrease in spleen volume at 12 weeks was 28% for daily-to-weekly dosing and 59.5% for all-daily dosing. Proportions of patients achieving ≥50% decrease at week 12 in Myelofibrosis Symptom Assessment Form and Myeloproliferative Neoplasms Symptom Assessment Form symptom scores were 14% and 18% for daily-to-weekly dosing, and 28% and 32% for all-daily dosing, respectively. Most common nonhematologic treatment-emergent adverse events were nausea (23%), diarrhea (22%), abdominal pain and fatigue (each 19%), and cough and dyspnea (each 18%). New-onset grade 3 and 4 thrombocytopenia were observed in 19% of patients, each dosed daily-to-weekly, and in 26% and 7% of patients dosed all-daily, respectively, managed with dose interruptions. Hemoglobin levels remained steady. The addition of parsaclisib to stable-dose ruxolitinib can reduce splenomegaly and improve symptoms, with manageable toxicity in patients with myelofibrosis with suboptimal response to ruxolitinib. This trial was registered at www.clinicaltrials.gov as #NCT02718300.

Serious infections in patients with VEXAS syndrome: data from the French VEXAS registry

INTRODUCTION

Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome is an acquired autoinflammatory monogenic disease with a poor prognosis whose determinants are not well understood. We aimed to describe serious infectious complications and their potential risk factors.

METHODS

Retrospective multicentre study including patients with VEXAS syndrome from the French VEXAS Registry. Episodes of serious infections were described, and their risk factors were analysed using multivariable Cox proportional hazards models.

RESULTS

Seventy-four patients with 133 serious infections were included. The most common sites of infection were lung (59%), skin (10%) and urinary tract (9%). Microbiological confirmation was obtained in 76%: 52% bacterial, 30% viral, 15% fungal and 3% mycobacterial. Among the pulmonary infections, the main pathogens were SARS-CoV-2 (28%), Legionella pneumophila (21%) and Pneumocystis jirovecii (19%). Sixteen per cent of severe infections occurred without any immunosuppressive treatment and with a daily glucocorticoid dose ≤10 mg. In multivariate analysis, age >75 years (HR (95% CI) 1.81 (1.02 to 3.24)), p.Met41Val mutation (2.29 (1.10 to 5.10)) and arthralgia (2.14 (1.18 to 3.52)) were associated with the risk of serious infections. JAK inhibitors were most associated with serious infections (3.84 (1.89 to 7.81)) compared with biologics and azacitidine. After a median follow-up of 4.4 (2.5-7.7) years, 27 (36%) patients died, including 15 (56%) due to serious infections.

CONCLUSION

VEXAS syndrome is associated with a high incidence of serious infections, especially in older patients carrying the p.Met41Val mutation and treated with JAK inhibitors. The high frequency of atypical infections, especially in patients without treatment, may indicate an intrinsic immunodeficiency.

Neutrophil to lymphocyte ratio in myelofibrosis patients treated with ruxolitinib may predict prognosis and rate of discontinuation

BACKGROUND

Myelofibrosis (MF) is a clonal Philadelphia chromosome negative myeloproliferative neoplasm (Ph-MPN). MF is featured by an inflammatory condition that can also drive the progression of disease. Ruxolitinib (ruxo) is the-first-in-class Jak1/2 inhibitor approved for treatment of MF, proved to reduce spleen volume and decrease symptom burden. In various malignancies neutrophil-to-lymphocyte ratio (NLR) has been indicated as predictor of progression free survival (PFS) and overall survival (OS). NLR might reflect the balance between systemic inflammation and immunity and is emerging as a prognostic biomarker in several neoplasms, including the hematological ones.

METHODS

We analyzed a cohort of 140 MF patients treated with ruxo to validate baseline NLR (as a continuous variable and as a cut-off 2) as predictor of OS and of ruxo treatment discontinuation.

RESULTS

We found that both baseline NLR as a continuous variable [HR 0.8 (95% CI: 0.7-0.9) (p = .006)] and NLR (<2 vs. ≥2) [HR 3.4 (95% CI: 1.6-7.0) (p = .001)] were significantly associated with OS. Censoring for patients undergone allotransplant, baseline NLR <2 was predictive of an earlier ruxo any-other-cause discontinuation [HR 3.7 (95%CI 1.7-8.3) (p < .001)].

CONCLUSIONS

NLR before starting ruxo treatment may be used as a simple and early predictor of OS and earlier ruxo discontinuation in clinical practice.

Preclinical and clinical evaluation of the Janus Kinase inhibitor ruxolitinib in multiple myeloma

Multiple myeloma (MM) is the most common primary malignancy of the bone marrow. No established curative treatment is currently available for patients diagnosed with MM. In recent years, new and more effective drugs have become available for the treatment of this B-cell malignancy. These new drugs have often been evaluated together and in combination with older agents. However, even these novel combinations eventually become ineffective; and, thus, novel therapeutic approaches are necessary to help overcome resistance to these treatments. Recently, the Janus Kinase (JAK) family of tyrosine kinases, specifically JAK1 and JAK2, has been shown to have a role in the pathogenesis of MM. Preclinical studies have demonstrated a role for JAK signaling in direct and indirect growth of MM and downregulation of anti-tumor immune responses in these patients. Also, inhibition of JAK proteins enhances the anti-MM effects of other drugs used to treat MM. These findings have been confirmed in clinical studies which have further demonstrated the safety and efficacy of JAK inhibition as a means to overcome resistance to currently available anti-MM therapies. Additional studies will provide further support for this promising new therapeutic approach for treating patients with MM.

Upfront allogeneic transplantation versus JAK inhibitor therapy for patients with myelofibrosis: a North American collaborative study

Allogeneic hematopoietic cell transplantation (HCT) is the only curative therapy for myelofibrosis (MF) and is recommended for patients with higher risk disease. However, there is a risk of early mortality, and optimal timing is unknown. JAK inhibitor (JAKi) therapy may offer durable improvement in symptoms, splenomegaly and quality of life. The aim of this multicentre, retrospective observational study was to compare outcomes of patients aged 70 years or below with MF in chronic phase who received upfront JAKi therapy vs. upfront HCT in dynamic international prognostic scoring system (DIPSS)-stratified categories. For the whole study cohort, median overall survival (OS) was longer for patients who received a JAKi vs. upfront HCT, 69 (95% CI 57-89) vs. 42 (95% CI 20-not reached, NR) months, respectively (p = 0.01). In patients with intermediate-2 and high-risk disease, median OS was 55 (95% CI 36-73) months with JAKi vs. 36 (95% CI 20-NR) months for HCT (p = 0.27). An upfront HCT strategy was associated with early mortality and difference in median OS was not observed in any risk group by 5 years of follow-up. Within the limitations of a retrospective observational study, we did not observe any benefit of a universal upfront HCT approach for higher-risk MF.