Ruxolitinib is effective in patients with intermediate-1 risk myelofibrosis: a summary of recent evidence

Real-World Use of Fedratinib for Myelofibrosis Following Prior Ruxolitinib Failure: Patient Characteristics, Treatment Patterns, and Clinical Outcomes

BACKGROUND

There is a lack of established clinical outcomes for patients with myelofibrosis (MF) receiving fedratinib following ruxolitinib failure. This study examined real-world patient characteristics, treatment patterns, and clinical outcomes of patients with MF treated with fedratinib following ruxolitinib failure in US clinical practice.

PATIENTS AND METHODS

This retrospective patient chart review included adults with a physician-reported diagnosis of MF, who initiated fedratinib after discontinuing ruxolitinib. Descriptive analyses characterized patient characteristics, clinical outcomes, and treatment patterns from MF diagnosis through ruxolitinib and fedratinib treatment.

RESULTS

Twenty-four physicians abstracted data for 150 eligible patients. Approximately 55.3% of the patients were male, 68.0% were White, and median age at MF diagnosis was 68 (range, 35-84) years. Median duration of ruxolitinib therapy was 7.6 (range, 0.7-65.5) months. At initiation of fedratinib, 88.0% of patients had palpable spleen and a mean spleen size of 16.0 (standard deviation [SD], 5.9) cm. Spleen size decreased by 19.4% to 13.2 (SD, 7.9) cm at month 3 (P = .0001) and by 53.4% to 7.2 (SD, 7.4) cm at month 6 (P = .01) of fedratinib treatment, respectively. Almost one-third (26.8%) of patients had achieved ≥ 50% spleen reduction by month 6. Mean number of symptoms also decreased significantly at month 3 (P < .0001) and month 6 (P = .01).

CONCLUSION

Fedratinib appears to deliver spleen and symptom benefits in real-world patients with MF previously treated with ruxolitinib.

Endothelial senescence in vascular diseases: current understanding and future opportunities in senotherapeutics

Senescence compromises the essential role that the endothelium plays in maintaining vascular homeostasis, so promoting endothelial dysfunction and the development of age-related vascular diseases. Their biological and clinical significance calls for strategies for identifying and therapeutically targeting senescent endothelial cells. While senescence and endothelial dysfunction have been studied extensively, distinguishing what is distinctly endothelial senescence remains a barrier to overcome for an effective approach to addressing it. Here, we review the mechanisms underlying endothelial senescence and the evidence for its clinical importance. Furthermore, we discuss the current state and the limitations in the approaches for the detection and therapeutic intervention of target cells, suggesting potential directions for future research.

Senolytics and senomorphics: Natural and synthetic therapeutics in the treatment of aging and chronic diseases

Cellular senescence is a heterogeneous process guided by genetic, epigenetic and environmental factors, characterizing many types of somatic cells. It has been suggested as an aging hallmark that is believed to contribute to aging and chronic diseases. Senescent cells (SC) exhibit a specific senescence-associated secretory phenotype (SASP), mainly characterized by the production of proinflammatory and matrix-degrading molecules. When SC accumulate, a chronic, systemic, low-grade inflammation, known as inflammaging, is induced. In turn, this chronic immune system activation results in reduced SC clearance thus establishing a vicious circle that fuels inflammaging. SC accumulation represents a causal factor for various age-related pathologies. Targeting of several aging hallmarks has been suggested as a strategy to ameliorate healthspan and possibly lifespan. Consequently, SC and SASP are viewed as potential therapeutic targets either through the selective killing of SC or the selective SASP blockage, through natural or synthetic compounds. These compounds are members of a family of agents called senotherapeutics divided into senolytics and senomorphics. Few of them are already in clinical trials, possibly representing a future treatment of age-related pathologies including diseases such as atherosclerosis, osteoarthritis, osteoporosis, cancer, diabetes, neurodegenerative diseases such as Alzheimer's disease, cardiovascular diseases, hepatic steatosis, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis and age-related macular degeneration. In this review, we present the already identified senolytics and senomorphics focusing on their redox-sensitive properties. We describe the studies that revealed their effects on cellular senescence and enabled their nomination as novel anti-aging agents. We refer to the senolytics that are already in clinical trials and we present various adverse effects exhibited by senotherapeutics so far. Finally, we discuss aspects of the senotherapeutics that need improvement and we suggest the design of future senotherapeutics to target specific redox-regulated signaling pathways implicated either in the regulation of SASP or in the elimination of SC.

Comparing the safety and efficacy of ruxolitinib in patients with Dynamic International Prognostic Scoring System low-, intermediate-1-, intermediate-2-, and high-risk myelofibrosis in JUMP, a Phase 3b, expanded-access study

Ruxolitinib, a potent Janus kinase 1/2 inhibitor, has demonstrated durable improvements in patients with myelofibrosis. In this analysis of the Phase 3b JUMP study, which included patients aged ≥18 years with a diagnosis of primary or secondary myelofibrosis, we assessed the safety and efficacy of ruxolitinib in patients stratified by Dynamic International Prognostic Scoring System (DIPSS) risk categories. Baseline characteristic data were available to assess DIPSS status for 1844 of the 2233 enrolled patients; 60, 835, 755, and 194 in the low‐, intermediate (Int)‐1‐, Int‐2‐, and high‐risk groups, respectively. Ruxolitinib was generally well tolerated across all risk groups, with an adverse‐event (AE) profile consistent with previous reports. The most common hematologic AEs were thrombocytopenia and anemia, with highest rates of Grade ≥3 events in high‐risk patients. Approximately, 73% of patients experienced ≥50% reductions in palpable spleen length at any point in the ≤24‐month treatment period, with highest rates in lower‐risk categories (low, 82.1%; Int‐1, 79.3%; Int‐2, 67.1%; high risk, 61.6%). Median time to spleen length reduction was 5.1 weeks and was shortest in lower‐risk patients. Across measures, 40%–57% of patients showed clinically meaningful symptom improvements, which were observed from 4 weeks after treatment initiation and maintained throughout the study. Overall survival (OS) was 92% at Week 72 and 75% at Week 240 (4.6 years). Median OS was longer for Int‐2‐risk than high‐risk patients (253.6 vs. 147.3 weeks), but not evaluable in low‐/Int‐1‐risk patients. By Week 240, progression‐free survival (PFS) and leukemia‐free survival (LFS) rates were higher in lower‐risk patients (PFS: low, 90%; Int‐1, 82%; Int‐2, 46%; high risk, 15%; LFS: low, 92%; Int‐1, 86%; Int‐2, 58%; high risk, 19%). Clinical benefit was seen across risk groups, with more rapid improvements in lower risk patients. Overall, this analysis indicates that ruxolitinib benefits lower‐risk DIPSS patients in addition to higher risk.

A phase 2 study of ruxolitinib in combination with azacitidine in patients with myelofibrosis

Ruxolitinib (RUX)-based combinations may provide benefit for patients with myelofibrosis (MF). In this open-label, nonrandomized, prospective phase 2 study, patients with MF initially received RUX twice per day continuously in 28-day cycles for the first 3 cycles. Azacitidine (AZA) 25 mg/m² (days 1-5) was added starting with cycle 4 and could be subsequently increased to 75 mg/m² (days 1-5). Forty-six patients were enrolled with a median follow-up of 28 months (range, 4-50+ months). An International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) response was achieved in 33 patients (72%), with a median time to response of 1.8 months (range, 0.7-19.0 months). One-fourth (7 of 33) of the IWG-MRT responses occurred after the addition of AZA. A reduction of >50% in palpable spleen length at 24 weeks and at any time on the study was achieved in 62% and 71% of the evaluable patients, respectively. Among patients who achieved a >50% reduction in spleen length at 24 weeks, 95% had maintained it at 48 weeks. Notably, improvements in bone marrow reticulin fibrosis grade occurred in 57% of the patients at 24 months. Treatment discontinuations as a result of drug-related toxicities occurred in 4 patients (9%), all as a result of cytopenias. New onset grade 3 to 4 anemia and thrombocytopenia occurred in 35% and 26% of patients, respectively. RUX and AZA were safe, with encouraging spleen response rates and improvement in bone marrow fibrosis in patients with MF. This trial was registered at www.clinicaltrials.gov as #NCT01787487.

T cell-directed IL-17 production by lung granular γδ T cells is coordinated by a novel IL-2 and IL-1β circuit

Immune-mediated lung is considered the result of an exacerbated innate injury immune response, although a role for adaptive lymphocytes is emerging. αβ T cells specific for S. aureus enterotoxin A orchestrate a Tγδ17 response during lung injury. However, the mechanism driving IL-17 production is unclear. Here, we show a role for IL-2 triggering IL-17 production by lung granular γδ T cells as IL-17 synthesis and neutrophil recruitment was reduced by IL-2 blocking mAbs in vitro and in vivo. Mass cytometry analysis revealed that lung γδ T cells responded directly to IL-2 as evident from STAT5 phosphorylation and RoRγt expression. IL-2 receptor blocking mAbs and JAK inhibition impaired STAT5 phosphorylation and IL-17 release. Moreover, inhalation of S. aureus enterotoxin A induced IL-2 secretion and caspase-1-dependent IL-1β activation to drive IL-17 production. This T-cell-mediated inflammasome-dependent IL-17 response is maximum when lung Tγδ17 cells were sequentially stimulated first with IL-2 then IL-1β. Interestingly, when IL-2 is given therapeutically to cancer patients it carries a known risk of lung injury that is largely indistinguishable from that seen in sepsis. Hence, this novel mechanism reveals therapeutic targets treating both acute lung injury and high-dose IL-2 toxicity in cancer.

Ruxolitinib therapy for myelofibrosis in Austria : Consensus on therapy management

The oral Janus associated kinase (JAK1/2) inhibitor ruxolitinib has been available for treatment of patients with intermediate or high-risk myelofibrosis in Europe since 2012. Since its introduction, the expertise of prescribing doctors with respect to ruxolitinib function, efficacy and adverse effects has consistently been augmented, resulting in therapy modalities that are better tailored to individual patients as well as in increased safety of the treatment. The present consensus on ruxolitinib therapy management has been elaborated by Austrian experts in myeloproliferative neoplasms in line with international treatment guidelines. Our recommendations aim to contribute to an improved management of patients with myelofibrosis treated with ruxolitinib.

Recommendations on the use of ruxolitinib for the treatment of myelofibrosis

OBJECTIVES

Myelofibrosis (MF) is a severe disease, with decreased life expectancy and heavy symptom burden. Ruxolitinib is the only approved pharmacotherapy for the treatment of MF patients. In Belgium, ruxolitinib is only reimbursed for MF patients with splenomegaly for whom the disease is categorized as intermediate-2 or high risk. The improvement of symptoms without spleen volume reduction is not considered sufficient to continue treatment. The aim of this manuscript is to provide guidance for the safe and effective administration of ruxolitinib, considering the particularities of the Belgian reimbursement criteria.

METHODS

Our recommendations are based on a consensus reached during two meetings, where available data and observations derived from clinical experience were discussed.

RESULTS AND DISCUSSION

We recommend changing the current Belgian reimbursement conditions to include the evaluation of disease-related symptoms along with splenomegaly to decide whether ruxolitinib treatment should be continued or not. Indeed, the decrease in disease-related symptoms seems to be an equally important parameter as the decrease in splenic volume in the evaluation of the response to ruxolitinib. We also advocate for the treatment with ruxolitinib of MF patients in lower-risk categories with severe disease-related symptoms, as this drug could greatly improve their quality of life. Optimization of the ruxolitinib dose is recommended to avoid an unnecessary decrease in platelet count or hemoglobin that may jeopardize treatment continuation.

CONCLUSION

With the aim to optimize the treatment of MF patients, the Belgian regulation for ruxolitinib should be revised in terms of reimbursement criteria, dose titration, stopping rules, and patient follow-up.

Treatment With JAK Inhibitors in Myelofibrosis Patients Nullifies the Prognostic Impact of Unfavorable Cytogenetics

INTRODUCTION

In the era before Janus kinase (JAK) inhibitors, cytogenetic information was used to predict survival in myelofibrosis patients. However, the prognostic value of cytogenetics in the setting of JAK inhibitor therapy remains unknown.

PATIENTS AND METHODS

We performed a retrospective analysis of 180 patients with bone marrow biopsy-proven myelofibrosis from 3 US academic medical centers. We fit Cox proportional hazards models for overall survival and transformation-free survival on the bases of 3 factors: JAK inhibitor therapy as a time-dependent covariate, dichotomized cytogenetic status (favorable vs. unfavorable), and statistical interaction between the two. The median follow-up time was 37.1 months.

RESULTS

Among patients treated with best available therapy, unfavorable cytogenetic status was associated with decreased survival (hazard ratio = 2.31; P = .025). At initiation of JAK inhibitor therapy, unfavorable cytogenetics was (nonsignificantly) associated with increased survival compared to favorable cytogenetics (hazard ratio = 0.292; P = .172). The ratio of hazard ratios was 0.126 (P = .034). These findings were similar after adjusting for standard clinical prognostic factors as well as when measured against transformation-free survival.

CONCLUSION

The initiation of JAK inhibitor therapy appears to change the association between cytogenetics and overall survival. There was little difference in survival between treatment types in patients with favorable cytogenetics. However, the use of JAK inhibitor therapy among patients with unfavorable cytogenetics was not associated with worse survival compared to favorable cytogenetics. Our analyses suggest that initiation of JAK inhibitor therapy nullifies the negative prognostic implication of unfavorable cytogenetics established in the pre-JAK inhibitor therapy era.

SOHO State-of-the-Art Update and Next Questions: MPN

The discovery of the activating Janus kinase (JAK)2V617F mutation in 2005 in most patients with the classic Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) spurred intense interest in research into these disorders, culminating in the identification of activating mutations in MPL in 2006 and indels in the gene encoding calreticulin (CALR) in 2013, thus providing additional mechanistic explanations for the universal activation of JAK-signal transducer and activator of transcription (JAK-STAT) observed in these conditions, and the success of the JAK1/2 inhibitor ruxolitinib, which first received regulatory approval in 2011. The field has continued to advance rapidly since then, and the past 2 years have witnessed important changes to the classification of MPN and diagnostic criteria for polycythemia vera (PV), novel insights into the mechanisms of bone marrow fibrosis in primary myelofibrosis (PMF), increasing appreciation of the biologic differences between essential thrombocythemia (ET), prefibrotic and overt PMF, and between primary and post-PV/ET myelofibrosis (MF). Additionally, the mechanisms through which mutant CALR drives JAK-STAT pathway activation and oncogenic transformation are now better understood. Although mastocytosis is no longer included under the broad heading of MPN in the 2016 revision to the World Health Organization classification, an important milestone in mastocytosis research was reached in 2017 with the regulatory approval of midostaurin for patients with advanced systemic mastocytosis (AdvSM). In this article, we review the major recent developments in the areas of PV, ET, and MF, and also briefly summarize the literature on midostaurin and other KIT inhibitors for patients with AdvSM.

The BCR-ABL1-negative myeloproliferative neoplasms: a review of JAK inhibitors in the therapeutic armamentarium

INTRODUCTION

The classical BCR-ABL1-negative myeloproliferative neoplasms (MPN) include primary myelofibrosis (PMF), polycythemia vera (PV) and essential thrombocythemia (ET). They are characterized by stem cell-derived clonal proliferation, harbor Janus kinase 2 (JAK2), or calreticulin (CALR), or myeloproliferative leukemia virus oncogene (MPL) driver mutations and exert an over activated JAK-signal transducer and activator of transcription (STAT) pathway. Therefore JAK inhibiting strategies have been successfully investigated in MPN clinical trials. Areas covered: The present review aims to provide a concise overview of the current and future role of JAK inhibitors in the therapeutic armamentarium of MPN. Expert opinion: The JAK1/JAK2 inhibitor ruxolitinib has clearly enriched the therapeutic armamentarium of MPN and is now licenced for more than five years in MF and over three years as second line in PV. Momelotinib, although of limited activity in MPN trials, demonstrated unique property of improving MF associated anemia. Less myelosuppressive or more selective JAK inhibitors like pacritinib, NS-01872 or Itacitinib are new promising agents tested in MF. JAK inhibition has become a cornerstone of MPN therapy and future efforts focus on ruxolitinib-based combinations and new JAK inhibitors.

JAK2 inhibitors for myeloproliferative neoplasms: what is next?

Since its approval in 2011, the Janus kinase 1/2 (JAK1/2) inhibitor ruxolitinib has evolved to become the centerpiece of therapy for myelofibrosis (MF), and its use in patients with hydroxyurea resistant or intolerant polycythemia vera (PV) is steadily increasing. Several other JAK2 inhibitors have entered clinical testing, but none have been approved and many have been discontinued. Importantly, the activity of these agents is not restricted to patients with JAK2 V617F or exon 12 mutations. Although JAK2 inhibitors provide substantial clinical benefit, their disease-modifying activity is limited, and rational combinations with other targeted agents are needed, particularly in MF, in which survival is short. Many such combinations are being explored, as are other novel agents, some of which could successfully be combined with JAK2 inhibitors in the future. In addition, new JAK2 inhibitors with the potential for less myelosuppression continue to be investigated. Given the proven safety and efficacy of ruxolitinib, it is likely that ruxolitinib-based combinations will be a major way forward in drug development for MF. If approved, less myelosuppressive JAK2 inhibitors such as pacritinib or NS-018 could prove to be very useful additions to the therapeutic armamentarium in MF. In PV, inhibitors of histone deacetylases and human double minute 2 have activity, but their role, if any, in the future treatment algorithm is uncertain, given the availability of ruxolitinib and renewed interest in interferons. Ruxolitinib is in late-phase clinical trials in essential thrombocythemia, in which it could fill an important void for patients with troublesome symptoms.

Management of myelofibrosis: JAK inhibition and beyond

INTRODUCTION

Myelofibrosis (MF) is characterized by bone marrow fibrosis with subsequent extramedullary hematopoiesis and abnormal cytokine expression leading to splenomegaly, constitutional symptoms and cytopenias. The discovery of the JAK2 V617F mutation in the majority of MF patients has been followed by significant progress in drug development for MF. Areas covered: In this article, we review advances in the understanding of the underlying disease biology, prognostic assessment and therapeutic modalities for MF. We provide clinical trial evidence behind using the JAK2 inhibitor ruxolitinib, erythropoiesis stimulating agents, androgens, immunomodulatory drugs, interferon, cytoreductive drugs and hypomethylating agents in MF. Finally, we review novel therapeutic options for MF including the new JAK1/2 inhibitors, ruxolitinib based combination approaches as well as novel therapeutic agents. Expert commentary: Despite significant reduction of splenomegaly and improvement of symptom burden and a signal for survival improvement, ruxolitinib does not lead to major reductions in JAK2 V617F allele burden and bone marrow fibrosis. No ruxolitinib-based combination approach has so far demonstrated superiority over ruxolitinib monotherapy. The novel JAK2 inhibitors pacritinib and momelotinib, other JAK inhibitors, telomerase inhibitors, anti-fibrosis agents and hsp90 inhibitors are in different stages of development.

A case-based discussion of clinical problems in the management of patients treated with ruxolitinib for myelofibrosis

Ruxolitinib is a dual janus kinase 1 (JAK1)/JAK2 inhibitor used to treat splenomegaly and symptoms associated with myelofibrosis (MF). Current therapeutic options for symptomatic MF include supportive care, myelosuppressive therapy (such as hydroxycarbamide) and janus kinase (JAK) inhibitors (in particular ruxolitinib). Allogeneic stem cell transplantation remains the only potentially curative treatment for MF, and younger transplant-eligible patients should still be considered for allogeneic stem cell transplantation; however, this is applicable only to a small proportion of patients. There is now increasing and extensive experience of the efficacy and safety of ruxolitinib in MF, both in clinical trials and in 'real-world' practice. The drug has been shown to be of benefit in intermediate-1 risk patients with symptomatic splenomegaly or other MF-related symptoms, and higher risk disease. Optimal use of the drug is required to maximise clinical benefit, requiring an understanding of the balance between dose-dependent responses and dose-limiting toxicities. There is also increasing experience in the use of ruxolitinib in the pre-transplantation setting. This paper aims to utilise several 'real-life' cases to illustrate several strategies that may help to optimise clinical practice.