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

Development and validation of a novel clinical fluorescence in situ hybridization assay to detect JAK2 and PD-L1 amplification: a fluorescence in situ hybridization assay for JAK2 and PD-L1 amplification

The amplification of chromosome 9p24.1 encoding PD-L1, PD-L2, and JAK2 has been reported in multiple types of cancer and is associated with poor outcome, upregulation of PD-L1, and activation of the JAK/STAT pathway. We have developed a novel fluorescence in situ hybridization assay which combines 3 probes mapping to 9p24.1 with a commercial chromosome 9 centromere (CEN9) probe for detection of the JAK2/9p24.1 amplification. JAK2 fluorescence in situ hybridization was compared with array-based comparative genomic hybridization in 34 samples of triple negative breast cancer tumor. By array-based comparative genomic hybridization, 15 had 9p24.1 copy-number gain (log₂ratio>0.3) and 19 were classified as non-gain (log₂ratio≤0.3). Copy-number gain was defined as JAK2/CEN9 ratio ≥1.1 or average JAK2 signals≥3.0. Twelve of 15 samples with copy-number gain by array-based comparative genomic hybridization were also detected by fluorescence in situ hybridization. Eighteen of 19 samples classified as copy-number non-gain by array-based comparative genomic hybridization were concordant by array-based comparative genomic hybridization. The sensitivity and specificity of the fluorescence in situ hybridization assay was 80% and 95%, respectively (P=0.02). The sample with the highest level of amplification by array-based comparative genomic hybridization (log₂ratio=3.6) also scored highest by fluorescence in situ hybridization (ratio=8.2). There was a correlation between the expression of JAK2 and amplification status (Mean 633 vs 393, P=0.02), and there was a trend of association with PD-L1 RNA expression (Mean 46 vs 22, P=0.11). No significant association was observed between PD-L1 immunohistochemistry expression and copy-number gain status. In summary, the novel array-based comparative genomic hybridization assay for detection of chromosome 9p24.1 strongly correlates with the detection of copy-number gain by array-based comparative genomic hybridization. In triple negative breast cancer, this biomarker may identify a relevant subset of patients for targeted molecular therapies.

Evaluation of the dose and efficacy of ruxolitinib in Japanese patients with myelofibrosis

Ruxolitinib, a potent JAK1/JAK2 inhibitor, improved splenomegaly and myelofibrosis-associated symptoms and prolonged survival compared with placebo and best available therapy in the phase 3 COMFORT studies. Although cytopenias were the most common adverse events associated with ruxolitinib treatment, a COMFORT-I analysis showed that they were managed effectively with dose modifications, without a negative impact on the efficacy of ruxolitinib. Subsequently, studies A2202 and AJP01 showed that ruxolitinib is an effective treatment for Japanese patients with myelofibrosis. We conducted a pooled analysis of these two studies (N = 81) to evaluate the association between ruxolitinib dose and changes in spleen volume or symptoms in Japanese patients. Most patients began treatment at 15 or 20 mg twice daily (BID); 70% received a final titrated dose ≥ 10 mg BID. Overall, 91% of patients exhibited spleen volume reductions; patients with final titrated doses ≥ 10 mg BID had larger spleen volume reductions. Similarly, 83% of patients showed improvements in symptom scores; those with a final titrated dose of 20 or 25 mg BID had the greatest reductions. Consistent with COMFORT-I, this pooled analysis indicates that, despite dose adjustments, ruxolitinib provides spleen and symptom control in Japanese patients, with higher doses associated with better responses.

Ruxolitinib for the management of myelofibrosis: Results of an international physician survey

BACKGROUND

Ruxolitinib is established as treatment for symptomatic myeloproliferative neoplasm (MPN)-associated myelofibrosis. The strict inclusion and exclusion criteria and dose modification rules that applied to the COMFORTI and II studies that led to the licensing of ruxolitinib are not always applicable to routine clinical practice. Thus physicians now face decisions regarding ruxolitinib use that were not addressed in these pivotal trials.

METHODS

We performed an online survey of hematologists practicing in Europe, Israel, the United Kingdom and the United States. Demographic details regarding the physicians and their practice as relates to MPNs were collected. Management decisions pertaining to the use of ruxolitinib were obtained regarding 10 clinical scenarios relating to anemia, thrombocytopenia, frailty, infection and lack or loss of response to ruxolitnib in MF patients.

RESULTS

140 physicians responded to the survey. There were marked differences regarding their decisions for ruxolitinib administration in MF patients with or developing anemia or thrombocytopenia. Similarly there was little consensus regarding management of patients refractory or losing a response to ruxolitinib. There were differences between "MPN-focused" and "non-MPN-focused" physicians in certain areas.

CONCLUSION

Physician practices regarding management of MF patients experiencing ruxolitinib-related toxicities or in whom response to the drug is lost was variable. This was true of "MPN-focused" and "non-MPN-focused" physicians in certain cases. Physician education and experience in using ruxolitinib may improve patient management.

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.

Clonal evolution and outcomes in myelofibrosis after ruxolitinib discontinuation

Despite significant improvements in the signs and symptoms of myelofibrosis (MF), and possible prolongation of patients' survival, some have disease that is refractory to ruxolitinib and many lose their response over time. Furthermore, patients with ≥3 mutations are less likely to respond to ruxolitinib. Here we describe outcomes after ruxolitinib discontinuation in MF patients enrolled in a phase 1/2 study at our center. After a median follow-up of 79 months, 86 patients had discontinued ruxolitinib (30 of whom died while on therapy). The median follow-up after ruxolitinib discontinuation for the remaining 56 patients was 32 months, with median survival after discontinuation of 14 months. Platelets <260 × 10⁹/L at the start of therapy or <100 × 10⁹/L at the time of discontinuation were associated with shorter survival after discontinuation. Of 62 patients with molecular data at baseline and follow-up, 22 (35%) acquired a new mutation while receiving ruxolitinib (14 [61%] in ASXL1). Patients showing clonal evolution had significantly shorter survival after discontinuation (6 vs 16 months). Transfusion dependency was the only clinical variable associated with clonal evolution. These findings underscore the need for novel therapies and suggest that clonal evolution or decreasing platelet counts while on ruxolitinib therapy may be markers of poor prognosis.

Developmental Therapeutics in Myeloproliferative Neoplasms

The unprecedented success of the Janus kinase (JAK) 1/2 inhibitor ruxolitinib in myelofibrosis (MF) provided much-needed impetus for clinical drug development for the Philadelphia chromosome-negative myeloproliferative neoplasms. The survival benefit conferred by this agent, along with its marked efficacy with regard to spleen volume and symptom reduction, have made ruxolitinib the cornerstone of drug therapy in MF. However, there remain significant unmet needs in the treatment of patients with MF, and many novel classes of agents continue to be investigated in efforts to build on the progress made with ruxolitinib. These include inhibitors of histone deacetylases (HDACs) and DNA methyltransferases, phosphatidylinositol-3-kinase isoforms, heat shock protein 90, cyclin-dependent kinases 4/6, and Hedgehog signaling, among others. In parallel, other JAK inhibitors with potential for less myelosuppression or even improvement of anemia, greater selectivity for JAK1 or JAK2, and the ability to overcome JAK inhibitor persistence are in various stages of development. First-in-class agents such as the activin receptor IIA ligand trap sotatercept (for anemia of MF), the telomerase inhibitor imetelstat, and the antifibrotic agent PRM-151 (recombinant human pentraxin-2) are also in clinical trials. In polycythemia vera, a novel interferon administered every 2 weeks is being developed for front-line therapy in high-risk individuals, and inhibitors of human double minute 2 (HDM2) have shown promise in preclinical studies, as have HDAC inhibitors such as givinostat (both in the laboratory and in the clinic). Ruxolitinib is approved for second-line therapy of polycythemia vera and is being developed for essential thrombocythemia.

Baseline factors associated with response to ruxolitinib: an independent study on 408 patients with myelofibrosis

In patients with Myelofibrosis (MF) treated with ruxolitinib (RUX), the response is unpredictable at therapy start. We retrospectively evaluated the impact of clinical/laboratory factors on responses in 408 patients treated with RUX according to prescribing obligations in 18 Italian Hematology Centers. At 6 months, 114 out of 327 (34.9%) evaluable patients achieved a spleen response. By multivariable Cox proportional hazard regression model, pre-treatment factors negatively correlating with spleen response were: high/intermediate-2 IPSS risk (p=0.024), large splenomegaly (p=0.017), transfusion dependency (p=0.022), platelet count <200×10⁹/l (p=0.028), and a time-interval between MF diagnosis and RUX start >2 years (p=0.048). Also, patients treated with higher (≥10 mg BID) average RUX doses in the first 12 weeks achieved higher response rates (p=0.019). After adjustment for IPSS risk, patients in spleen response at 6 months showed only a trend for better survival compared to non-responders. At 6 months, symptoms response was achieved by 85.5% of 344 evaluable patients; only a higher (>20) Total Symptom Score significantly correlated with lower probability of response (p<0.001). Increased disease severity, a delay in RUX start and titrated doses <10 mg BID were associated with patients achievinglower response rates. An early treatment and higher RUX doses may achieve better therapeutic results.

Managing side effects of JAK inhibitors for myelofibrosis in clinical practice

INTRODUCTION

Myelofibrosis (MF) is characterized by bone marrow fibrosis, abnormalities in peripheral counts, extramedullary hematopoiesis, splenomegaly and an increased risk of transformation to acute myeloid leukaemia. The disease course is often heterogeneous and management can range from observation alone through to allogeneic stem cell transplantation. As of 2017, the only approved medication for MF remains the JAK Inhibitor (JAKi), ruxolitinib (Novartis Pharmaceuticals, Basel, Switzerland; Incyte, Wilmington, Detroit, USA) although several others have reached advanced stages of clinical trials. Areas covered: In this review, we focus on the management of both common and uncommon side effects arising from the use of currently approved and clinical trial JAKi. Most of the discussion concerns ruxolitinib although we also cover both pacritinib (CTI BioPharma) and momelotinib (Gilead Sciences, Foster City, California) which have been in recent large, multinational phase III trials. The various approaches to management of JAKi-related side effects are discussed - with particular emphasis to anaemia, thrombocytopaenia and infection risk. Expert commentary: JAK inhibitors are effective in many individuals with MF and have revolutionized the current treatment paradigm. The side effect profile, in the most, is predictable and manageable with high degrees of clinical surveillance and dose modifications.

Janus kinase-2 inhibitor fedratinib in patients with myelofibrosis previously treated with ruxolitinib (JAKARTA-2): a single-arm, open-label, non-randomised, phase 2, multicentre study

BACKGROUND

Myelofibrosis is a chronic myeloproliferative neoplasm characterised by splenomegaly, cytopenias, bone marrow fibrosis, and debilitating symptoms including fatigue, weight loss, and bone pain. Mutations in Janus kinase-2 (JAK2) occur in approximately 50% of patients. The only approved JAK2 inhibitor for myelofibrosis is the dual JAK1 and JAK2 inhibitor, ruxolitinib. 58-71% of patients treated with ruxolitinib in clinical trials so far have not achieved the primary endpoint of 35% or more reduction in spleen volume from baseline assessed by MRI or CT. Furthermore, more than 50% of patients discontinue ruxolitinib treatment after 3-5 years. On the basis of this unmet need, we investigated the efficacy and safety of fedratinib, a JAK2-selective inhibitor, in patients with ruxolitinib-resistant or ruxolitinib-intolerant myelofibrosis.

METHODS

This single-arm, open-label, non-randomised, phase 2, multicentre study, done at 31 sites in nine countries, enrolled adult patients with a current diagnosis of intermediate or high-risk primary myelofibrosis, post-polycythaemia vera myelofibrosis, or post-essential thrombocythaemia myelofibrosis, found to be ruxolitinib resistant or intolerant after at least 14 days of treatment. Other main inclusion criteria were palpable splenomegaly (≥5 cm below the left costal margin), Eastern Cooperative Oncology Group performance status of 2 or less, and life expectancy of 6 months or less. Patients received oral fedratinib at a starting dose of 400 mg once per day, for six consecutive 28-day cycles. The primary endpoint was spleen response (defined as the proportion of patients with a ≥35% reduction in spleen volume as determined by blinded CT and MRI at a central imaging laboratory). We did the primary analysis in the per-protocol population only (patients treated with fedratinib, for whom a baseline and at least one post-baseline spleen volume measurement was available) and the safety analysis in all patients receiving at least one dose of fedratinib. This trial was registered with ClinicalTrials.gov, number NCT01523171.

FINDINGS

Between May 8, 2012, and Aug 29, 2013, 97 patients were enrolled and received at least one dose of fedratinib. Of 83 assessable patients, 46 (55%, 95% CI 44-66) achieved a spleen response. Common grade 3-4 adverse events included anaemia (37 [38%] of 97 patients) and thrombocytopenia (21 [22%] of 97), with 18 (19%) patients discontinuing due to adverse events. Seven (7%) patients died during the study, but none of the deaths was drug related. Suspected cases of Wernicke's encephalopathy in other fedratinib trials led to study termination.

INTERPRETATION

This phase 2 study met its primary endpoint, suggesting that patients with ruxolitinib-resistant or ruxolitinib-intolerant myelofibrosis might achieve significant clinical benefit with fedratinib, albeit at the cost of some potential toxicity, which requires further evaluation. Fedratinib development in this setting is currently being assessed.

FUNDING

Sanofi.

Gli1+ Mesenchymal Stromal Cells Are a Key Driver of Bone Marrow Fibrosis and an Important Cellular Therapeutic Target

Bone marrow fibrosis (BMF) develops in various hematological and non-hematological conditions and is a central pathological feature of myelofibrosis. Effective cell-targeted therapeutics are needed, but the cellular origin of BMF remains elusive. Here, we show using genetic fate tracing in two murine models of BMF that Gli1+ mesenchymal stromal cells (MSCs) are recruited from the endosteal and perivascular niche to become fibrosis-driving myofibroblasts in the bone marrow. Genetic ablation of Gli1+ cells abolished BMF and rescued bone marrow failure. Pharmacological targeting of Gli proteins with GANT61 inhibited Gli1+ cell expansion and myofibroblast differentiation and attenuated fibrosis severity. The same pathway is also active in human BMF, and Gli1 expression in BMF significantly correlates with the severity of the disease. In addition, GANT61 treatment reduced the myofibroblastic phenotype of human MSCs isolated from patients with BMF, suggesting that targeting of Gli proteins could be a relevant therapeutic strategy.

Inhibitors of the PI3K/mTOR pathway prevent STAT5 phosphorylation in JAK2V617F mutated cells through PP2A/CIP2A axis

Inhibition of the constitutively activated JAK/STAT pathway in JAK2V617F mutated cells by the JAK1/JAK2 inhibitor ruxolitinib resulted in clinical benefits in patients with myeloproliferative neoplasms. However, evidence of disease-modifying effects remains scanty; furthermore, some patients do not respond adequately to ruxolitinib, or have transient responses, thus novel treatment strategies are needed. Here we demonstrate that ruxolitinib causes incomplete inhibition of STAT5 in JAK2V617F mutated cells due to persistence of phosphorylated serine residues of STAT5b, that conversely are targeted by PI3K and mTORC1 inhibitors. We found that PI3K/mTOR-dependent phosphorylation of STAT5b serine residues involves Protein Phosphatase 2A and its repressor CIP2A. The levels of CIP2A were found increased in cells harboring the JAK2V617F mutation, and we provide evidence of a correlation between clinical responses and the extent of CIP2A downregulation in myelofibrosis patients receiving the mTOR inhibitor RAD001 in a phase II clinical trial. To achieve maximal inhibition of STAT5 phosphorylation, we combined ruxolitinib with BKM120, a PI3K inhibitor, and RAD001, an mTOR inhibitor, obtaining improved efficacy in JAK2V617F mutated cell lines, primary patients’ cells, and JAK2V617F knock-in mice. These findings contribute to understanding the effectiveness of PI3K/mTOR inhibitors in MPN and argue for the rationale to develop combination clinical trials.

Practical Measures of Clinical Benefit With Ruxolitinib Therapy: An Exploratory Analysis of COMFORT-I

BACKGROUND

The phase III COMFORT (Controlled Myelofibrosis Study With Oral JAK inhibitor Treatment)-I and COMFORT-II trials in patients with intermediate-2 or high-risk myelofibrosis (MF) showed that ruxolitinib was superior to placebo and best available therapy, respectively, for improvements in spleen volume, MF-related symptoms, and overall survival (OS). However, patients managed in community settings might not have access to the methods used in the COMFORT trials. In this exploratory analysis we summarize efficacy findings of COMFORT-I using practical, community-oriented measures of patient outcomes.

PATIENTS AND METHODS

In this post hoc analysis of data from COMFORT-I we evaluated changes from baseline to week 12 in spleen size (palpable length and volume), patient-reported outcomes (Patient Global Impression of Change; Myelofibrosis Symptom Assessment Form; Patient-Reported Outcomes Measurement System Fatigue Scale), body weight, and serum albumin levels in 5 subgroups of ruxolitinib-treated patients on the basis of week 12 spleen length changes from baseline: (1-4) ≥ 50%, 25% to < 50%, 10% to < 25%, or < 10% reduction; and (5) worsening. OS was evaluated in ruxolitinib-treated patients with week 12 spleen length reductions from baseline ≥ 50%, 25% to < 50%, or < 25% (including worsening).

RESULTS

In all spleen length subgroups, including patients with worsening spleen length at week 12, ruxolitinib (n = 150) was associated with improvements in spleen volume, patient-reported symptom burden, body weight, and serum albumin levels. Greater reductions in spleen length were associated with prolonged OS.

CONCLUSION

A variety of assessment methods beyond palpable spleen length that are easily accessible in the community setting might be useful in evaluating the clinical benefit of ruxolitinib over time in patients with MF.

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.

Treatment of Myelofibrosis: Old and New Strategies

Myelofibrosis (MF) is a BCR-ABL1-negative myeloproliferative neoplasm that is mainly characterised by reactive bone marrow fibrosis, extramedullary haematopoiesis, anaemia, hepatosplenomegaly, constitutional symptoms, leukaemic progression, and shortened survival. As such, this malignancy is still orphan of curative treatments; indeed, the only treatment that has a clearly demonstrated impact on disease progression is allogeneic haematopoietic stem cell transplantation, but only a minority of patients are eligible for such intensive therapy. However, more recently, the discovery of JAK2 mutations has also led to the development of small-molecule JAK1/2 inhibitors, the first of which, ruxolitinib, has been approved for the treatment of MF in the United States and Europe. In this article, we report on old and new therapeutic strategies that proved effective in early preclinical and clinical trials, and subsequently in the daily clinical practice, for patients with MF, particularly concerning the topics of anaemia, splenomegaly, iron overload, and allogeneic stem cell transplantation.

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.

A nationwide population-based cross-sectional survey of health-related quality of life in patients with myeloproliferative neoplasms in Denmark (MPNhealthSurvey): survey design and characteristics of respondents and nonrespondents

OBJECTIVE

The Department of Hematology, Zealand University Hospital, Denmark, and the National Institute of Public Health, University of Southern Denmark, created the first nationwide, population-based, and the most comprehensive cross-sectional health-related quality of life (HRQoL) survey of patients with myeloproliferative neoplasms (MPNs). In Denmark, all MPN patients are treated in public hospitals and treatments received are free of charge for these patients. Therefore, MPN patients receive the best available treatment to the extent of its suitability for them and if they wish to receive the treatment. The aims of this article are to describe the survey design and the characteristics of respondents and nonrespondents.

MATERIAL AND METHODS

Individuals with MPN diagnoses registered in the Danish National Patient Register (NPR) were invited to participate. The registers of the Danish Civil Registration System and Statistics Denmark provided information regarding demographics. The survey contained 120 questions: validated patient-reported outcome (PRO) questionnaires and additional questions addressing lifestyle.

RESULTS

A total of 4,704 individuals were registered with MPN diagnoses in the NPR of whom 4,236 were eligible for participation and 2,613 (62%) responded. Overall, the respondents covered the broad spectrum of MPN patients, but patients 70-79 years old, living with someone, of a Danish/Western ethnicity, and with a higher level of education exhibited the highest response rate.

CONCLUSION

A nationwide, population-based, and comprehensive HRQoL survey of MPN patients in Denmark was undertaken (MPNhealthSurvey). We believe that the respondents broadly represent the MPN population in Denmark. However, the differences between respondents and nonrespondents have to be taken into consideration when examining PROs from the respondents. The results of the investigation of the respondents' HRQoL in this survey will follow in future articles.

Long-term treatment with ruxolitinib for patients with myelofibrosis: 5-year update from the randomized, double-blind, placebo-controlled, phase 3 COMFORT-I trial

Background

The randomized, double-blind, placebo-controlled, phase 3 COMFORT-I trial evaluated the JAK1/JAK2 inhibitor ruxolitinib in patients with intermediate-2/high-risk myelofibrosis. The primary and planned 3-year analyses of COMFORT-I data demonstrated that ruxolitinib—the first myelofibrosis-approved therapy—reduced splenomegaly and prolonged overall survival versus placebo. Here, we present the final 5-year results.

Methods

Patients managed in Australia, Canada, and the USA were randomized centrally (interactive voice response system) 1:1 to oral ruxolitinib twice daily (15 or 20 mg per baseline platelet counts) or placebo. Investigators and patients were blinded to treatment. The secondary endpoints evaluated in this analysis were durability of a ≥35% reduction from baseline in spleen volume (spleen response) and overall survival, evaluated in the intent-to-treat population. Safety was evaluated in patients who received study treatment.

Results

Patients were randomized (September 2009–April 2010) to ruxolitinib (n = 155) or placebo (n = 154). At termination, 27.7% of ruxolitinib-randomized patients and 25.2% (28/111) who crossed over from placebo were on treatment; no patients remained on placebo. Patients randomized to ruxolitinib had a median spleen response duration of 168.3 weeks and prolonged median overall survival versus placebo (ruxolitinib group, not reached; placebo group, 200 weeks; HR, 0.69; 95% CI, 0.50–0.96; P = 0.025) despite the crossover to ruxolitinib. The ruxolitinib safety profile remained consistent with previous analyses. The most common new-onset all-grade nonhematologic adverse events starting <12 versus ≥48 months after ruxolitinib initiation were fatigue (29.0 vs 33.3%) and diarrhea (27.8 vs 14.6%). New-onset grade 3 or 4 anemia and thrombocytopenia both primarily occurred within the first 6 months, with no cases after 42 months. The most common treatment-emergent adverse event-related deaths in the ruxolitinib-randomized group were sepsis (2.6%), disease progression (1.9%), and pneumonia (1.9%).

Conclusion

The final COMFORT-I results continue to support ruxolitinib as an effective treatment for patients with intermediate-2/high-risk MF.

Trial registration

ClinicalTrials.gov, NCT00952289

Ruxolitinib in myelofibrosis: to be or not to be an immune disruptor

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm classified according to the 2016 revision of World Health Organization Classification of Tumors and Haematopoietic and Lymphoid Tissue. Ruxolitinib is an oral inhibitor of Janus kinase approved in the USA for the treatment of intermediate or high-risk PMF and approved in Europe for the treatment of splenomegaly and constitutional symptoms of the disease. More recently, case reports described serious opportunistic infections in this neoplasm treated with ruxolitinib. Research studies demonstrated the immunological derangement of this compound mainly based on T, dendritic, and natural killer cell defects. The purpose of this review of the literature was to analyze the relationship among ruxolitinib, immune system and bacterial, viral, fungal, and protozoan infections. A literature search was conducted using PubMed articles published between January 2010 and November 2016. The efficacy of drug in patients with PMF was demonstrated in two phase III studies, Controlled MyeloFibrosis Study with ORal Jak inhibitor Treatment (COMFORT-I and COMFORT-II). Grade 3 and 4 neutropenia were recognized in 7.1% and 2% of patients in the ruxolitinib and placebo arm of COMFORT-I. Grade 3 or 4 neutropenia or leukopenia were observed in 8.9% and 6.3% of ruxolitinib treated patients of 5-year follow-up of COMFORT-II. In addition, leukocyte subpopulations, lymphocyte functions, or antibody deficiency were not documented in either of the studies. The complex interactions between ruxolitinib, bone marrow, immune system, and infections in PMF need further investigation, robust data from a randomized clinical trial, registry, or large case-series.

The role of the extracellular matrix in primary myelofibrosis

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm that arises from clonal proliferation of hematopoietic stem cells and leads to progressive bone marrow (BM) fibrosis. While cellular mutations involved in the development of PMF have been heavily investigated, noteworthy is the important role the extracellular matrix (ECM) plays in the progression of BM fibrosis. This review surveys ECM proteins contributors of PMF, and highlights how better understanding of the control of the ECM within the BM niche may lead to combined therapeutic options in PMF.

Safety and efficacy of ruxolitinib in splanchnic vein thrombosis associated with myeloproliferative neoplasms

Splanchnic vein thrombosis (SVT) is one of the vascular complications of myeloproliferative neoplasms (MPN). We designed a phase 2 clinical trial to evaluate safety and efficacy of ruxolitinib in reducing splenomegaly and improving disease-related symptoms in patients with MPN-associated SVT. Patients diagnosed with myelofibrosis (12 cases), polycythemia vera (5 cases) and essential thrombocythemia (4 cases) received ruxolitinib for 24 weeks in the core study period. Spleen volume was assessed by magnetic resonance imaging (MRI) and splanchnic vein circulation by echo-Doppler analysis. Nineteen patients carried JAK2V617F, one had MPLW515L, and one CALRL367fs*46 mutation. Eighteen patients had spleno-portal-mesenteric thrombosis, two had Budd-Chiari syndrome, and one had both sites involved; 16 patients had esophageal varices. Ruxolitinib was well tolerated with hematological toxicities consistent with those of patients without SVT and no hemorrhagic adverse events were recorded. After 24 weeks of treatment, spleen volume reduction ≥35% by MRI was achieved by 6/21 (29%) patients, and a ≥50% spleen length reduction by palpation at any time up to week 24 was obtained by 13/21 (62%) patients. At week 72, 8 of the 13 (62%) patients maintained the spleen response by palpation. No significant effect of treatment on esophageal varices or in splanchnic circulation was observed. MPN-related symptoms, evaluated by MPN-symptom assessment form (SAF) TSS questionnaire, improved significantly during the first 4 weeks and remained stable up to week 24. In conclusion, this trial shows that ruxolitinib is safe in patients with MPN-associated SVT, and effective in reducing spleen size and disease-related symptoms.

Emerging treatments for classical myeloproliferative neoplasms

There has been a major revolution in the management of patients with myeloproliferative neoplasms (MPN), and in particular those with myelofibrosis and extensive splenomegaly and symptomatic burden, after the introduction of the JAK1 and JAK2 inhibitor ruxolitinib. The drug also has been approved as second-line therapy for polycythemia vera (PV). However, the therapeutic armamentarium for MPN is still largely inadequate for coping with patients' major unmet needs, which include normalization of life span (myelofibrosis and some patients with PV), reduction of cardiovascular complications (mainly PV and essential thrombocythemia), prevention of hematological progression, and improved quality of life (all MPN). In fact, none of the available drugs has shown clear evidence of disease-modifying activity, even if some patients treated with interferon and ruxolitinib showed reduction of mutated allele burden, and ruxolitinib might extend survival of patients with higher-risk myelofibrosis. Raised awareness of the molecular abnormalities and cellular pathways involved in the pathogenesis of MPN is facilitating the development of clinical trials with novel target drugs, either alone or in combination with ruxolitinib. Although for most of these molecules a convincing preclinical rationale was provided, the results of early phase 1 and 2 clinical trials have been quite disappointing to date, and toxicities sometimes have been limiting. In this review, we critically illustrate the current landscape of novel therapies that are under evaluation for patients with MPN on the basis of current guidelines, patient risk stratification criteria, and previous experience, looking ahead to the chance of a cure for these disorders.

Austrian recommendations for the management of primary myelofibrosis, post-polycythemia vera myelofibrosis and post-essential thrombocythemia myelofibrosis: an expert statement

The entity "myelofibrosis" represents a subgroup of the Philadelphia chromosome-negative myeloproliferative neoplasms. It comprises primary myelofibrosis, post-polycythemia vera myelofibrosis and post-essential thrombocythemia myelofibrosis. This heterogeneous disease is characterized by clonal myeloproliferation, dysregulated kinase signalling and the abnormal expression of several proinflammatory cytokines. Clinically, patients present with symptoms related to thrombocytosis/leukocytosis, anemia and/or progressive splenomegaly. Mutations in Janus kinase 2, an enzyme that is essential for the normal development of erythrocytes, granulocytes, and platelets, notably the V617F mutation, have been identified in approximately 60% of patients with primary myelofibrosis. Recent molecular advances have not only elucidated critical pathways in the pathogenesis of the disease, but also contributed to a more precise assessment of a patient's individual risk. While allogeneic stem cell transplantation remains the only curative treatment, the natural course of the disease and the patient's survival and quality of life may be improved by new treatments, notably ruxolitinib, the first Janus kinase 1/2 inhibitor approved for the management of myelofibrosis. Additional treatment options are being explored.

Myeloproliferative Neoplasms, Version 2.2017, NCCN Clinical Practice Guidelines in Oncology

Myelofibrosis (MF), polycythemia vera (PV), and essential thrombocythemia (ET) are a group of heterogeneous disorders of the hematopoietic system collectively known as Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs). The diagnosis and the management of patients with MPNs have evolved since the identification of mutations that activate the JAK pathway (JAK2, CALR, and MPL mutations) and the development of targeted therapies has resulted in significant improvements in disease-related symptoms and quality of life. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnostic workup of MPN (MF, PV, and ET), risk stratification, treatment, and supportive care strategies for the management of MF.

Myelofibrosis: an update on drug therapy in 2016

INTRODUCTION

Primary myelofibrosis (PMF) is the least common but the most aggressive of the classic Philadelphia chromosome-negative myeloproliferative neoplasms. Survival is much shorter in PMF than in polycythemia vera (PV) or essential thrombocythemia (ET). Post-PV/ET myelofibrosis (MF) is clinically indistinguishable from PMF and approached similarly. Areas covered: Current pharmacologic therapy of MF revolves around the Janus kinase 1/2 (JAK1/2) inhibitor ruxolitinib, which dramatically improves constitutional symptoms and splenomegaly in the majority of patients, and improves overall survival (OS). However, allogeneic stem cell transplantation remains the only potential cure. Other JAK inhibitors continue to be developed for MF, and momelotinib and pacritinib are in phase III clinical trials. Anemia is common in MF, and initially worsened by ruxolitinib. Momelotinib and pacritinib may prove advantageous in this regard. Current strategies for managing anemia of MF include danazol, immunomodulatory drugs and erythroid stimulating agents, either alone or in combination with ruxolitinib. Expert opinion: A number of other agents, representing diverse drug classes, are in various stages of development for MF. These include newer JAK inhibitors, other signaling inhibitors, epigenetic modifiers, anti-fibrotic agents, telomerase inhibitors, and activin receptor ligand traps (for anemia). Hopefully, these novel therapies will further extend the clinical benefits of ruxolitinib.

Myeloproliferative Neoplasms: Molecular Drivers and Therapeutics

Activating mutations in genes that drive neoplastic cell growth are numerous and widespread in cancer, and specific genetic alterations are associated with certain types of cancer. For example, classic myeloproliferative neoplasms (MPNs) are hematopoietic stem cell disorders that affect cells of the myeloid lineage, including erythrocytes, platelets, and granulocytes. An activating mutation in the JAK2 tyrosine kinase is prevalent in these diseases. In MPN patients that lack such a mutation, other genetic changes that lead to activation of the JAK2 signaling pathway are present, indicating deregulation of JAK2 signaling plays an etiological driving role in MPNs, a concept supported by significant evidence from in vivo experimental MPN systems. Thus, small molecules that inhibit JAK2 activity are ideal drugs to impede the progression of disease in MPN patients. However, even though JAK inhibitors provide significant symptomatic relief, they have failed as a remission-inducing therapy. Nonetheless, the progress made understanding the molecular etiology of MPNs since 2005 is significant and has provided insight for the development and testing of novel molecular targeted therapeutic approaches. The current understanding of driver mutations in MPNs and an overview of current and potential therapeutic strategies for MPN patients will be discussed.