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

Janus Kinase Inhibitors and Non-Melanoma Skin Cancer

OPINION STATEMENT

JAK (janus kinase) inhibitors are becoming increasingly prescribed for various conditions from dermatologic diseases to graft versus host disease in bone marrow transplant recipients. This class of drugs has been found to be truly life-changing for many, though they are not without potential adverse effects. While JAK inhibitors have not been shown to significantly increase the risk of non-melanoma skin cancer (NMSC) in large scale clinical trials, NMSC is one of the most concerning possible adverse events, and there have been several reported cases of aggressive squamous cell carcinomas, especially in our already immunosuppressed patient populations. In these patients, it is incredibly important that patients are on the lowest possible dosage of the JAK inhibitor. In addition, these patients must be routinely screened by a dermatologist with a comprehensive skin exam to ensure early detection if skin cancer was to develop. For those patients diagnosed with skin cancer, early intervention is key to optimize outcomes, and at times, multi-disciplinary care coordination is needed. In the future, large-scale studies with longer follow-up of patients would help determine whether JAK inhibitors significantly increase the risk of NMSC.

COVID-19: High-JAKing of the Inflammatory "Flight" by Ruxolitinib to Avoid the Cytokine Storm

Since SARS-CoV-2 outbreak in December 2019, world health-system has been severely impacted with increased hospitalization, Intensive-Care-Unit (ICU) access and high mortality rates, mostly due to severe acute respiratory failure and multi-organ failure. Excessive and uncontrolled release of proinflammatory cytokines (cytokine release/storm syndrome, CRS) have been linked to the development of these events. The recent advancements of immunotherapy for the treatment of hematologic and solid tumors shed light on many of the molecular mechanisms underlying this phenomenon, thus rendering desirable a multidisciplinary approach to improve COVID-19 patients' outcome. Indeed, currently available therapeutic-strategies to overcome CRS, should be urgently evaluated for their capability of reducing COVID-19 mortality. Notably, COVID-19 shares different pathogenic aspects with acute graft-versus-host-disease (aGVHD), hemophagocytic-lymphohistiocytosis (HLH), myelofibrosis, and CAR-T-associated CRS. Specifically, similarly to aGVHD, an induced tissue damage (caused by the virus) leads to increased cytokine release (TNFα and IL-6) which in turn leads to exaggerated dendritic cells, macrophages (like in HLH) and lymphocytes (as in CAR-T) activation, immune-cells migration, and tissue-damage (including late-stage fibrosis, similar to myelofibrosis). Janus Kinase (JAK) signaling represents a molecular hub linking all these events, rendering JAK-inhibitors suitable to limit deleterious effects of an overwhelming inflammatory-response. Accordingly, ruxolitinib is the only selective JAK1 and JAK2-inhibitor approved for the treatment of myelofibrosis and aGVHD. Here, we discuss, from a molecular and hematological point of view, the rationale for targeting JAK signaling in the management of COVID-19 patients and report the clinical results of a patient admitted to ICU among the firsts to be treated with ruxolitinib in Italy.

Myeloproliferative Neoplasm Symptom Assessment Form - Total Symptom Score (MPN-SAF TSS) questionnaire: translation, cultural adaptation and validation to Brazilian Portuguese

Introduction

Constitutional symptoms and thrombohemorrhagic events are common in patients with myeloproliferative neoplasms (MPNs). Hence, the treatment’s primary goal is to control symptoms and improve the quality of life (QoL). In order to assess response to therapy, symptom burden, and QoL among patients with MPN, the “Myeloproliferative Neoplasm Symptom Assessment Form - Total Symptom Score (MPN-SAF TSS)” questionnaire was developed in the USA in 2012. Herein, we translated and validated the MPN-SAF TSS questionnaire to Brazilian Portuguese.

Methods

The ten-item questionnaire was translated from the English language and its psychometric properties (reliability, convergent and construct validities) were evaluated in 101 MPN patients.

Results

There were 41 patients with essential thrombocythemia, 39 with myelofibrosis and 21 with polycythemia vera. The median age of all patients at diagnosis was 68 years and 59% were female. The Cronbach's alpha coefficient for the overall questionnaire was 0.78, ranging from 0.73 to 0.79, if each item was deleted. Validity analyses showed that the strongest item-item correlation were between early satiety and abdominal discomfort. Strong correlations were also found between physician and patient perceptions of itching (r = 0.81) and fatigue (r = 0.70). The Pearson coefficient correlation between the MPN-SAF TSS global score and the EORTC QLQ-C30 functional scales ranged from 0.51 to 0.64. The exploratory factor analysis showed that seven of the ten symptoms loaded into one single factor.

Conclusion

The Brazilian Portuguese version of the MPN-SAF-TSS showed good psychometric properties and can be an available tool to assess symptom burden in this group of patients.

Primary myelofibrosis: 2021 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm (MPN) characterized by stem cell-derived clonal myeloproliferation that is often but not always accompanied by JAK2, CALR, or MPL mutations. Additional disease features include bone marrow reticulin/collagen fibrosis, aberrant inflammatory cytokine expression, anemia, hepatosplenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival.

DIAGNOSIS

Bone marrow morphology is the primary basis for diagnosis. Presence of JAK2, CALR, or MPL mutation, expected in around 90% of the patients, is supportive but not essential for diagnosis; these mutations are also prevalent in the closely related MPNs, namely polycythemia vera (PV) and essential thrombocythemia (ET). The 2016 World Health Organization classification system distinguishes "prefibrotic" from "overtly fibrotic" PMF; the former might mimic ET in its presentation. Furthermore, approximately 15% of patients with ET or PV might progress into a PMF-like phenotype (post-ET/PV MF) during their clinical course.

ADVERSE MUTATIONS

SRSF2, ASXL1, and U2AF1-Q157 mutations predict inferior survival in PMF, independent of each other and other risk factors. RAS/CBL mutations predicted resistance to ruxolitinib therapy.

ADVERSE KARYOTYPE

Very high risk abnormalities include -7, inv (3), i(17q), +21, +19, 12p-, and 11q-.

RISK STRATIFICATION

Two new prognostic systems for PMF have recently been introduced: GIPSS (genetically-inspired prognostic scoring system) and MIPSS70+ version 2.0 (MIPSSv2; mutation- and karyotype-enhanced international prognostic scoring system). GIPSS is based exclusively on mutations and karyotype. MIPSSv2 includes, in addition, clinical risk factors. GIPSS features four and MIPSSv2 five risk categories.

RISK-ADAPTED THERAPY

Observation alone is advised for MIPSSv2 "low" and "very low" risk disease (estimated 10-year survival 56%-92%); allogeneic hematopoietic stem cell transplant (AHSCT) is the preferred treatment for "very high" and "high" risk disease (estimated 10-year survival 0%-13%); treatment-requiring patients with intermediate-risk disease (estimated 10-year survival 30%) are best served by participating in clinical trials. In non-transplant candidates, conventional treatment for anemia includes androgens, prednisone, thalidomide, and danazol; for symptomatic splenomegaly, hydroxyurea and ruxolitinib; and for constitutional symptoms, ruxolitinib. Fedratinib, another JAK2 inhibitor, has now been FDA-approved for use in ruxolitinib failures. Splenectomy is considered for drug-refractory splenomegaly and involved field radiotherapy for non-hepatosplenic EMH and extremity bone pain.

NEW DIRECTIONS

A number of new agents, alone or in combination with ruxolitinib, are currently under investigation for MF treatment (ClinicalTrials.gov); preliminary results from some of these clinical trials were presented at the 2020 ASH annual meeting and highlighted in the current document.

Challenges and Perspectives for Therapeutic Targeting of Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are hematopoietic stem cell disorders with dysregulated myeloid blood cell production and propensity for transformation to acute myeloid leukemia, thrombosis, and bleeding. Acquired mutations in JAK2, MPL, and CALR converge on hyperactivation of Janus kinase 2 (JAK2) signaling as a central feature of MPN. Accordingly, JAK2 inhibitors have held promise for therapeutic targeting. After the JAK1/2 inhibitor ruxolitinib, similar JAK2 inhibitors as fedratinib are entering clinical use. While patients benefit with reduced splenomegaly and symptoms, disease-modifying effects on MPN clone size and clonal evolution are modest. Importantly, response to ruxolitinib may be lost upon treatment suggesting the MPN clone acquires resistance. Resistance mutations, as seen with other tyrosine kinase inhibitors, have not been described in MPN patients suggesting that functional processes reactivate JAK2 signaling. Compensatory signaling, which bypasses JAK2 inhibition, and other processes contribute to intrinsic resistance of MPN cells restricting efficacy of JAK2 inhibition overall. Combinations of JAK2 inhibition with pegylated interferon-α, a well-established therapy of MPN, B-cell lymphoma 2 inhibition, and others are in clinical development with the potential to enhance therapeutic efficacy. Novel single-agent approaches targeting other molecules than JAK2 are being investigated clinically. Special focus should be placed on myelofibrosis patients with anemia and thrombocytopenia, a delicate patient population at high need for options. The extending range of new treatment approaches will increase the therapeutic options for MPN patients. This calls for concomitant improvement of our insight into MPN biology to inform tailored therapeutic strategies for individual MPN patients.

Current and Emerging Targeted Therapies for Acute Graft-Versus-Host Disease

Acute graft-versus-host disease (GVHD), the major complication after allogeneic hematopoietic cell transplant (HCT), develops in approximately 50% of patients. The primary treatment is high-dose systemic steroids, but treatment failure is common, and steroid-refractory (SR) GVHD is the leading cause of non-relapse mortality after allogeneic HCT. Ruxolitinib became the first treatment for SR GVHD to obtain US Food and Drug Administration approval, and other new treatments are actively being studied. We searched the literature using the PubMed database and clinical trials using ClinicalTrials.gov to identify the most promising new treatments for GVHD. In this review, we categorize potential new treatments for GVHD by their mechanism of action (e.g., antibodies that deplete T cells or prevent their trafficking to target tissues, proteasome inhibitors, tyrosine kinase inhibitors, and other agents) and summarize the results from clinical trials.

The safety of JAK kinase inhibitors for the treatment of myelofibrosis

INTRODUCTION

During the last decade, the development of small molecule inhibitors of Janus kinases (JAKi) contributed to revolutionize the therapeutic landscape of myelofibrosis (MF). JAKi proved to be effective in controlling disease-related symptoms and splenomegaly with remarkable inter-drug variability. However, in some cases the border between clinical efficacy of JAKi and dose-dependent toxicities is narrow leading to sub-optimal dose modifications and/or treatment discontinuation.

AREAS COVERED

In the current review, the authors aimed at providing a comprehensive review of the safety profile of JAKi that are currently approved or in advanced clinical development. Also, a short discussion of promising JAKi in early clinical evaluation and molecules 'lost' early in clinical development is provided. Finally, we discuss the possible strategies aimed at strengthening the safety of JAKi while improving the therapeutic efficacy.

EXPERT OPINION

Overall, JAKi display a satisfactory risk-benefit ratio, with main toxicities being gastrointestinal or related to the myelo/immunosuppressive effects, generally mild and easily manageable. However, JAKi may be associated with potentially life-threatening toxicities, such as neurological and infectious events. Thus, many efforts are needed in order to optimize JAKi-based therapeutic strategies without burdening patient safety. This could be attempted through drug combinations or the development of more selective molecules.

Metabolic Vulnerabilities and Epigenetic Dysregulation in Myeloproliferative Neoplasms

The Janus kinase 2 (JAK2)-driven myeloproliferative neoplasms (MPNs) are associated with clonal myelopoiesis, elevated risk of death due to thrombotic complications, and transformation to acute myeloid leukemia (AML). JAK2 inhibitors improve the quality of life for MPN patients, but these approved therapeutics do not readily reduce the natural course of disease or antagonize the neoplastic clone. An understanding of the molecular and cellular changes requisite for MPN development and progression are needed to develop improved therapies. Recently, murine MPN models were demonstrated to exhibit metabolic vulnerabilities due to a high dependence on glucose. Neoplastic hematopoietic progenitor cells in these mice express elevated levels of glycolytic enzymes and exhibit enhanced levels of glycolysis and oxidative phosphorylation, and the disease phenotype of these MPN model mice is antagonized by glycolytic inhibition. While all MPN-driving mutations lead to aberrant JAK2 activation, these mutations often co-exist with mutations in genes that encode epigenetic regulators, including loss of function mutations known to enhance MPN progression. In this perspective we discuss how altered activity of epigenetic regulators (e.g., methylation and acetylation) in MPN-driving stem and progenitor cells may alter cellular metabolism and contribute to the MPN phenotype and progression of disease. Specific metabolic changes associated with epigenetic deregulation may identify patient populations that exhibit specific metabolic vulnerabilities that are absent in normal hematopoietic cells, and thus provide a potential basis for the development of more effective personalized therapeutic approaches.

Genomics of MPN progression

The Philadelphia chromosome-negative (Ph-) myeloproliferative neoplasms (MPNs) are a heterogenous group of hematopoietic stem cell diseases characterized by activated JAK/STAT signaling and a variable propensity toward myelofibrotic and leukemic transformation. Acquisition of somatic mutations in addition to the canonical JAK2, MPL, and CALR mutations found in MPNs is an important catalyst in the clonal evolution and progression of these disorders. In recent years, our increasing understanding of the molecular landscape of Ph- MPNs has generated important prognostic information that informs our approach to risk stratification and therapeutic decision-making. This review will focus on the critical impact of genomics on our approach to management of advanced Ph- MPNs.

Myeloproliferative neoplasms treated with hydroxyurea, pegylated interferon alpha-2A or ruxolitinib: clinicohematologic responses, quality-of-life changes and safety in the real-world setting

Introduction: Real-world data of responses, quality-of-life (QOL) changes and adverse events in patients with myeloproliferative neoplasms (MPN) on conventional therapy (hydroxyurea ± anagrelide), pegylated interferon alpha-2A (PEG-IFNα-2A) or ruxolitinib are limited. Methods: We prospectively studied MPN patients receiving conventional therapy, PEG-IFNα-2A or ruxolitinib. Next-generation sequencing of 69 myeloid-related genes was performed. Clinicohematologic responses, adverse events, and QOL (determined by the Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score, MPN-SAF TSS) were evaluated. Results: Seventy men and fifty-five women with polycythemia vera (PV) (N = 23), essential thrombocythemia (ET) (N = 56) and myelofibrosis (MF) (N = 46) were studied for a median of 36 (range: 19-42) months. In PV, responses were comparable for different modalities. CREBBP mutations were associated with inferior responses. In ET, PEG-IFNα-2A resulted in superior clinicohematologic complete responses (CHCR) (P = 0.045). In MF, superior overall response rates (ORR) were associated with ruxolintib (P = 0.018) and JAK2V617F mutation (P = 0.04). For the whole cohort, ruxolitinib led to rapid and sustained reduction in spleen size within the first 6 months, and significant improvement of QOL as reflected by reduction in MPN-SAF TSS (P < 0.001). Adverse events of grades 1-2 were observed in 44%, 62% and 20% of patients receiving conventional therapy, PEG-IFNα-2A and ruxolitinib respectively; and of grade 3-4 in 7% and 9% of patients receiving PEG-IFNα-2A and ruxolitinib. Conclusions: Conventional therapy, PEG-IFNα-2A and ruxolitinib induced responses in all MPN subtypes. PEG-IFNα-2A led to superior CHCR in ET; whereas ruxolitinib resulted in superior ORR in MF, and significant reduction in spleen size and improvement in QOL.

Impact of Mutational Profile on the Management of Myeloproliferative Neoplasms: A Short Review of the Emerging Data

Philadelphia-chromosome negative myeloproliferative neoplasms (MPN) are a heterogeneous group of clonal hematopoietic stem cell disorders characterized by an increased risk of thrombosis and progression to acute myeloid leukemia. MPN are associated with driver mutations in JAK2, CALR and MPL which are crucial for the diagnosis and lead to a constitutive activation of the JAK-STAT signaling, independent of cytokine regulation. Moreover, most patients have concomitant mutations in genes involved in DNA methylation, chromatin modification, messenger RNA splicing, transcription regulation and signal transduction. These additional mutations may arise before, in the context of clonal hematopoiesis of indeterminate potential (CHIP), or after the acquisition of the driver mutation. The clinical phenotype of MPN results from complex interactions between mutations and host factors. The increased application of next-generation sequencing (NGS) techniques to a large series of patients with MPN has expanded the knowledge of mutational landscape and contributed to define the clinical significance of mutations. This molecular information is being increasingly used to refine diagnosis, risk stratification, monitoring of residual disease and response to treatment. ASXL1, SRSF2, EZH2, IDH1/IDH2 and U2AF1 mutations are associated with a more advanced disease and reduced overall survival in primary myelofibrosis (PMF), whereas spliceosome mutations in Polycythemia vera (PV) and essential thrombocythemia (ET) adversely affect both overall (SF3B1, SRSF2 in ET and SRSF2 in PV) and myelofibrosis-free (U2AF1, SF3B1 in ET) survival. This review discusses current knowledge of the molecular landscape of MPN, and how the availability of those molecular information may impact patient management.

Health-Related Quality of Life in Patients with Philadelphia-Negative Myeloproliferative Neoplasms: A Nationwide Population-Based Survey in Denmark

Simple Summary

The aim of this research was to investigate the health-related quality of life (HRQoL) in patients with Philadelphia-negative myeloproliferative neoplasms (chronic blood cancers) in Denmark. A nationwide questionnaire survey covering functioning, symptom burden, symptom profile, QoL, and lifestyle was performed. Patients registered in the National Patient Register with a diagnosis of Philadelphia-negative myeloproliferative neoplasm were invited. A total of 2228 patients participated in the survey and these could be divided into groups of participants with different subtypes of Phildelphia-negative myeloproliferative neoplasms. The HRQoL across groups of participants with different subtypes of the disease was compared, and the HRQoL of all participants and the general population was compared in order to investigate for a potential difference. The participants reported their HRQoL to be inferior to the general population, but the difference was minor. The differences in HRQoL across groups of participants with different subtypes of the disease were subtle. Fatigue and sexual problems were prevalent and burdensome. Participants reported a slightly healthier lifestyle than the general population. Understanding HRQoL of these patients is a necessity to be able to provide the best treatment and rehabilitation activities.

Abstract

Previous studies have clarified that many patients with Philadelphia-negative myeloproliferative neoplasms (MPNs) have burdensome symptom profiles and accordingly impaired functioning and quality of life (QoL). In Denmark, all MPN patients are affiliated with public hospitals and because of a healthcare system financed by taxpayers these patients do not have any financial costs related to the hematological disease. Diagnoses are recorded for all patients in hospitals, and diagnosis codes are communicated to the National Patient Register (NPR). Owing to this, it was possible to contribute to the elucidation of Philadelphia-negative MPN patients’ health-related quality of life (HRQoL), by conducting a nationwide, population-based, cross-sectional HRQoL survey of these patients with cost-free access to the best available, suitable medical treatment. The survey contained validated questionnaires covering functioning, symptom burden, symptom profile, QoL, and additional questions on lifestyle. Information on comorbid diagnoses was obtained from the NPR. The participants’ HRQoL was compared to the general population. Moreover, differences in HRQoL across essential thrombocythemia, polycythemia vera, myelofibrosis, and unclassifiable MPN participants were investigated, adjusted for age, sex, comorbidity, and lifestyle. To the best of our knowledge this is the first survey of HRQoL in patients with unclassifiable MPN. A total of 2228 Philadelphia-negative MPN patients participated. The participants reported their HRQoL to be inferior to the general population, but the difference was minor. The differences in HRQoL across groups of participants with different MPN subtypes were subtle. Fatigue and sexual problems were prevalent and burdensome. Overall, participants reported a slightly healthier lifestyle compared to the general population.

Splicing factor YBX1 mediates persistence of JAK2-mutated neoplasms

Janus kinases (JAKs) mediate responses to cytokines, hormones and growth factors in haematopoietic cells^1,2. The JAK gene JAK2 is frequently mutated in the ageing haematopoietic system^3,4 and in haematopoietic cancers⁵. JAK2 mutations constitutively activate downstream signalling and are drivers of myeloproliferative neoplasm (MPN). In clinical use, JAK inhibitors have mixed effects on the overall disease burden of JAK2-mutated clones^6,7, prompting us to investigate the mechanism underlying disease persistence. Here, by in-depth phosphoproteome profiling, we identify proteins involved in mRNA processing as targets of mutant JAK2. We found that inactivation of YBX1, a post-translationally modified target of JAK2, sensitizes cells that persist despite treatment with JAK inhibitors to apoptosis and results in RNA mis-splicing, enrichment for retained introns and disruption of the transcriptional control of extracellular signal-regulated kinase (ERK) signalling. In combination with pharmacological JAK inhibition, YBX1 inactivation induces apoptosis in JAK2-dependent mouse and primary human cells, causing regression of the malignant clones in vivo, and inducing molecular remission. This identifies and validates a cell-intrinsic mechanism whereby differential protein phosphorylation causes splicing-dependent alterations of JAK2-ERK signalling and the maintenance of JAK2^V617F malignant clones. Therapeutic targeting of YBX1-dependent ERK signalling in combination with JAK2 inhibition could thus eradicate cells harbouring mutations in JAK2.

Determining the recommended dose of pacritinib: results from the PAC203 dose-finding trial in advanced myelofibrosis

PAC203 is a randomized dose-finding study of pacritinib, an oral JAK2/IRAK1 inhibitor, in patients with advanced myelofibrosis who are intolerant of or resistant to ruxolitinib. Patients were randomized 1:1:1 to pacritinib 100 mg once per day, 100 mg twice per day, or 200 mg twice per day. Enhanced eligibility criteria, monitoring, and dose modifications were implemented to mitigate risk of cardiac and hemorrhagic events. Efficacy was based on ≥35% spleen volume response (SVR) and ≥50% reduction in the 7-component total symptom score (TSS) through week 24. Of 161 patients, 73% were intolerant of and 76% had become resistant to ruxolitinib; 50% met criteria for both. Severe thrombocytopenia (platelet count <50 × 103/μL) was present in 44%. SVR rates were highest with 200 mg twice per day (100 mg once per day, 0%; 100 mg twice per day, 1.8%; 200 mg twice per day, 9.3%), particularly among patients with baseline platelet counts <50 × 103/μL (17%; 4 of 24). Although TSS response rate was similar across doses (100 mg once per day, 7.7%; 100 mg twice per day, 7.3%; 200 mg twice per day, 7.4%), median percent reduction in TSS suggested a dose-response relationship (-3%, -16%, and -27%, respectively). Pharmacokinetic and pharmacodynamic modeling based on all available data showed greatest SVR and TSS reduction at 200 mg twice per day compared with lower doses. Common adverse events were gastrointestinal events, thrombocytopenia, and anemia. There was no excess of grade ≥3 hemorrhagic or cardiac events at 200 mg twice per day. Pacritinib 200 mg twice per day demonstrated clinical activity and an acceptable safety profile and was selected as the recommended dose for a pivotal phase 3 study in patients with myelofibrosis and severe thrombocytopenia. This trial was registered at www.clinicaltrials.gov as #NCT03165734.

PRMT5 Inhibition Modulates E2F1 Methylation and Gene-Regulatory Networks Leading to Therapeutic Efficacy in JAK2V617F-Mutant MPN

We investigated the role of PRMT5 in myeloproliferative neoplasm (MPN) pathogenesis and aimed to elucidate key PRMT5 targets contributing to MPN maintenance. PRMT5 is overexpressed in primary MPN cells, and PRMT5 inhibition potently reduced MPN cell proliferation ex vivo. PRMT5 inhibition was efficacious at reversing elevated hematocrit, leukocytosis, and splenomegaly in a model of JAK2V617F+ polycythemia vera and leukocyte and platelet counts, hepatosplenomegaly, and fibrosis in the MPLW515L model of myelofibrosis. Dual targeting of JAK and PRMT5 was superior to JAK or PRMT5 inhibitor monotherapy, further decreasing elevated counts and extramedullary hematopoiesis in vivo. PRMT5 inhibition reduced expression of E2F targets and altered the methylation status of E2F1 leading to attenuated DNA damage repair, cell-cycle arrest, and increased apoptosis. Our data link PRMT5 to E2F1 regulatory function and MPN cell survival and provide a strong mechanistic rationale for clinical trials of PRMT5 inhibitors in MPN. SIGNIFICANCE: Expression of PRMT5 and E2F targets is increased in JAK2V617F+ MPN. Pharmacologic inhibition of PRMT5 alters the methylation status of E2F1 and shows efficacy in JAK2V617F/MPLW515L MPN models and primary samples. PRMT5 represents a potential novel therapeutic target for MPN, which is now being clinically evaluated.This article is highlighted in the In This Issue feature, p. 1611.

Ruxolitinib-Associated Infections in Polycythemia Vera: Review of the Literature, Clinical Significance, and Recommendations

Simple Summary

Polycythemia vera (PV) is a chronic blood disease characterized by elevated red blood cells and splenomegaly. About 98% of all PV patients harbor the JAK2 mutation. Ruxolitinib (RUX), a JAK1/JAK2 inhibitor, received approval as a second-line indication in PV patients who are resistant or intolerant to standard therapy hydroxyurea in both the United States (2014) and Europe (2015). In the studies relevant to approval, RUX achieved excellent PV control. Due to its mechanism of action, RUX also has immunosuppressive effects. As expected, an increased rate of infection was observed in clinical studies and in practical application. In this overview, we have compiled all previous literature references on RUX and infections in PV. However, apart from a few individual cases with special infections and an increased rate of zoster infections, there are no exceptional high infection problems. Recommendations are given on how infections in RUX treated PV patients can be avoided.

Abstract

Ruxolitinib (RUX), a JAK1/JAK2 inhibitor, is approved for second-line therapy in patients with polycythemia vera (PV) who are resistant or intolerant to hydroxyurea. Due to the immunomodulatory and immunosuppressive effect of RUX, there is an increased susceptibility to infections. However, an increased risk of infection is inherent to even untreated myeloproliferative neoplasms (MPN). To obtain more information on the clinical significance of RUX-associated infections in PV, we reviewed the available literature. There is no evidence-based approach to managing infection risks. Most data on RUX-associated infections are available for MF. In all studies, the infection rates in the RUX and control groups were fairly similar, with the exception of infections with the varicella zoster virus (VZV). However, individual cases of bilateral toxoplasmosis retinitis, disseminated molluscum contagiosum, or a mycobacterium tuberculosis infection or a hepatitis B reactivation are reported. A careful assessment of the risk of infection for PV patients is required at the initial presentation and before the start of RUX. Screening for hepatitis B is recommended in all patients. The risk of RUX-associated infections is lower with PV than with MF, but compared to a normal population there is an increased risk of VZV infection. However, primary VZV prophylaxis for PV patients is not recommended, while secondary prophylaxis can be considered individually. As early treatment is most effective for VZV, patients should be properly informed and trained to seek medical advice immediately if cutaneous signs of VZV develop. Vaccination against influenza, herpes zoster, and pneumococci should be considered in all PV patients at risk of infection, especially if RUX treatment is planned. Current recommendations do not support adjusting or discontinuing JAK inhibition in MPN patients to reduce the risk of COVID-19.

Hypertensive Cardiotoxicity in Cancer Treatment-Systematic Analysis of Adjunct, Conventional Chemotherapy, and Novel Therapies-Epidemiology, Incidence, and Pathophysiology

Cardiotoxicity is the umbrella term for cardiovascular side effects of cancer therapies. The most widely recognized phenotype is left ventricular dysfunction, but cardiotoxicity can manifest as arrhythmogenic, vascular, myocarditic and hypertensive toxicities. Hypertension has long been regarded as one of the most prevalent and modifiable cardiovascular risk factors in the general population, but its relevance during the cancer treatment journey may be underestimated. Hypertensive cardiotoxicity occurs de novo in a substantial proportion of treated cancer patients. The pathology is incompletely characterized—natriuresis and renin angiotensin system interactions play a role particularly in conventional treatments, but in novel therapies endothelial dysfunction and the interaction between the cancer and cardiac kinome are implicated. There exists a treatment paradox in that a significant hypertensive response not only mandates anti-hypertensive treatment, but in fact, in certain cancer treatment scenarios, hypertension is a predictor of cancer treatment efficacy and response. In this comprehensive review of over 80,000 patients, we explored the epidemiology, incidence, and mechanistic pathophysiology of hypertensive cardiotoxicity in adjunct, conventional chemotherapy, and novel cancer treatments. Conventional chemotherapy, adjunct treatments, and novel targeted therapies collectively caused new onset hypertension in 33–68% of treated patients. The incidence of hypertensive cardiotoxicity across twenty common novel therapies for any grade hypertension ranged from 4% (imatinib) to 68% (lenvatinib), and high grade 3 or 4 hypertension in <1% (imatinib) to 42% (lenvatinib). The weighted average effect was all-grade hypertension in 24% and grade 3 or 4 hypertension in 8%.

Novel Concepts of Treatment for Patients with Myelofibrosis and Related Neoplasms

Simple Summary

Myelofibrosis (MF) is an advanced form of a group of rare, related bone marrow cancers termed myeloproliferative neoplasms (MPNs). Some patients develop myelofibrosis from the outset, while in others, it occurs as a complication of the more indolent MPNs, polycythemia vera (PV) or essential thrombocythemia (ET). Patients with PV or ET who require drug treatment are typically treated with the chemotherapy drug hydroxyurea, while in MF, the targeted therapies termed Janus kinase (JAK) inhibitors form the mainstay of treatment. However, these and other drugs (e.g., interferons) have important limitations. No drug has been shown to reliably prevent the progression of PV or ET to MF or transformation of MPNs to acute myeloid leukemia. In PV, it is not conclusively known if JAK inhibitors reduce the risk of blood clots, and in MF, these drugs do not improve low blood counts. New approaches to treating MF and related MPNs are, therefore, necessary.

Abstract

Janus kinase (JAK) inhibition forms the cornerstone of the treatment of myelofibrosis (MF), and the JAK inhibitor ruxolitinib is often used as a second-line agent in patients with polycythemia vera (PV) who fail hydroxyurea (HU). In addition, ruxolitinib continues to be studied in patients with essential thrombocythemia (ET). The benefits of JAK inhibition in terms of splenomegaly and symptoms in patients with MF are undeniable, and ruxolitinib prolongs the survival of persons with higher risk MF. Despite this, however, “disease-modifying” effects of JAK inhibitors in MF, i.e., bone marrow fibrosis and mutant allele burden reduction, are limited. Similarly, in HU-resistant/intolerant PV, while ruxolitinib provides excellent control of the hematocrit, symptoms and splenomegaly, reduction in the rate of thromboembolic events has not been convincingly demonstrated. Furthermore, JAK inhibitors do not prevent disease evolution to MF or acute myeloid leukemia (AML). Frontline cytoreductive therapy for PV generally comprises HU and interferons, which have their own limitations. Numerous novel agents, representing diverse mechanisms of action, are in development for the treatment of these three classic myeloproliferative neoplasms (MPNs). JAK inhibitor-based combinations, all of which are currently under study for MF, have been covered elsewhere in this issue. In this article, we focus on agents that have been studied as monotherapy in patients with MF, generally after JAK inhibitor resistance/intolerance, as well as several novel compounds in development for PV/ET.

Tuberculosis in Patients with Primary Myelofibrosis During Ruxolitinib Therapy: Case Series and Literature Review

Background

The selective Janus-activated kinase inhibitor ruxolitinib (rux) is now widely used to treat myelofibrosis and polycythemia vera due to its remarkable effect of reducing splenomegaly and improving constitutional symptoms. With opportunistic infections secondary to rux constantly reported; however, an increasing number of studies have begun to investigate the mechanism and underlying immunosuppressive effect of rux.

Case Presentation

We report two cases of tuberculosis (TB) in primary myelofibrosis patients during rux therapy. The first patient received rux soon after diagnosis, and tracheobronchial TB (TBTB) and bronchoesophageal fistula were found after 4 months. After discontinuation of rux, antituberculosis therapy (ATT) was introduced. The second patient initiated rux due to progressive splenomegaly after 7.5 years of interferon therapy and was diagnosed with disseminated TB after 2 months. He received ATT as well. His rux was maintained due to the high burden of systematic symptoms and splenomegaly. Both myelofibrosis and TB were well controlled in these patients.

Conclusion

This is the first case report that describes rux-related TBTB accompanied by a bronchoesophageal fistula. Through a review of the literature, we provide supporting evidence to the finding that intrinsic disorders of myeloproliferative neoplasms and rux-induced immunologic deregulation together lead to TB. We highlight the importance of screening for latent TB infection and timely chemoprophylaxis before rux therapy. Once TB is diagnosed during treatment, rux is recommended to be stopped and active ATT should begin quickly.

Modification of the Histone Landscape with JAK Inhibition in Myeloproliferative Neoplasms

Dysregulation of epigenetic processes is increasingly understood to play a role in the pathogenesis of myeloproliferative neoplasms (MPNs). Ruxolitinib, a JAK/STAT inhibitor, has proved a useful addition to the therapeutic arsenal for these disorders, but has limited disease modifying activity. We determined the effect of JAK inhibition on the histone landscape of MPN cells in cell line models of MPNs and validated using samples from the MAJIC randomised clinical trial of ruxolitinib in polycythaemia vera and essential thrombocythaemia. We demonstrated an epigenetic modifying effect of ruxolitinib using a histone modification assay. The majority of 21 histone H3 modifications were upregulated, with H3K27me3 and H3K36me2 significant in the combined cell line results. Chromatin immunoprecipitation and sequencing (CHIP-seq) for three marks of interest, H3K4me1, H3K4me3 and H3K27ac, was consistent with the histone modification assay showing a significant increase in H3K4me3 and H3K27ac peaks at promoter regions, both marks of active transcription. In contrast, RNA sequencing demonstrates a coordinated reduction in gene expression in a number of cell pathways including PI3K-AKT signalling, transcriptional misregulation in cancer and JAK-STAT signalling in spite of these histone changes. This highlights the complex mechanisms of transcriptional control within the cells which was reflected in analysis of the histone landscape in patient samples following ruxolitinib treatment.

Overview of the Side-Effects of FDA- and/or EMA-Approved Targeted Therapies for the Treatment of Hematological Malignancies

In the last decade there has been tremendous effort in offering better therapeutic management strategies to patients with hematologic malignancies. These efforts have ranged from biological to clinical approaches and resulted in the rapid development of new approaches. The main “problem” that comes with the high influx of newly approved drugs, which not only influences hematologists that frequently work with these drugs but also affects other healthcare professionals that work with hematologists in patient management, including intensive care unit (ICU) physicians, is they have to keep up within their specialty and, in addition, with the side-effects that can occur when encountering hematology-specific therapies. Nonetheless, there are few people that have an in-depth understanding of a specialty outside theirs. Thus, this manuscript offers an overview of the most common side-effects caused by therapies used in hematology nowadays, or that are currently being investigated in clinical trials, with the purpose to serve as an aid to other specialties. Nevertheless, because of the high amount of information on this subject, each chapter will offer an overview of the side-effects of a drug class with each reference of the section being intended as further reading.

[The prognostic value of ASXL1 mutation in primary myelofibrosis. Literature review and clinical case description]

Primary myelofibrosis is a myeloproliferative neoplasm that occurs de novo, characterized by clonal proliferation of stem cells, abnormal expression of cytokines, bone marrow fibrosis, hepatosplenomegaly as a result of extramedullary hematopoiesis, symptoms of tumor intoxication, cachexemia, peripheral blood leukoerythroblastosis, leukemic progression and low survival. Primary myelofibrosis is a chronic incurable disease. The aims of therapy: preventing progression, increasing overall survival, improving quality of life. The choice of therapeutic tactics is limited. Allogenic hematopoietic stem cell transplantation is the only method that gives a chance for a cure. The role of mutations in a number of genes in the early identification of candidates for allogeneic hematopoietic stem cell transplantation is being actively studied. The article describes the clinical case of the detection ofASXL1gene mutations in a patient with prefibrous primary myelofibrosis. The diagnosis was established on the basis of WHO criteria 2016. The examination revealed a mutation ofASXL1. Interferon alfa therapy is carried out, against the background of which clinico-hematological remission has been achieved. Despite the identified mutation, the patient is not a candidate for allogeneic hematopoietic stem cell transplantation. Given the unfavorable prognostic value of theASXL1mutation, the patient is subject to active dynamic observation and aggressive therapeutic tactics when signs of disease progression appear.

Targeting the JAK/STAT pathway in solid tumors

Aberrant activation of signal transducer and activator of transcription (STAT) proteins is associated with the development and progression of solid tumors. However, as transcription factors, these proteins are difficult to target directly. In this review, we summarize the role of targeting Janus kinases (JAKs), upstream activators of STATs, as a strategy for decreasing STAT activation in solid tumors. Preclinical studies in solid tumor cell line models show that JAK inhibitors decrease STAT activation, cell proliferation, and cell survival; in in vivo models, they also inhibit tumor growth. JAK inhibitors, particularly the JAK1/2 inhibitor ruxolitinib, sensitize cell lines and murine models to chemotherapy, immunotherapy, and oncolytic viral therapy. Ten JAK inhibitors have been or are actively being tested in clinical trials as monotherapy or in combination with other agents in patients with solid tumors; two of these inhibitors are already Food and Drug Administration (FDA) approved for the treatment of myeloproliferative disorders and rheumatoid arthritis, making them attractive agents for use in patients with solid tumors as they are known to be well-tolerated. Four JAK inhibitors (two of which are FDA approved for other indications) have exhibited promising anti-cancer effects in preclinical studies; however, clinical studies specifically assessing their activity against the JAK/STAT pathway in solid tumors have not yet been conducted. In summary, JAK inhibition is a viable option for targeting the JAK/STAT pathway in solid tumors and merits further testing in clinical trials.

Finding a Jill for JAK: Assessing Past, Present, and Future JAK Inhibitor Combination Approaches in Myelofibrosis

Myelofibrosis (MF) is a myeloproliferative neoplasm hallmarked by the upregulation of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway with associated extramedullary hematopoiesis and a high burden of disease-related symptoms. While JAK inhibitor therapy is central to the management of MF, it is not without limitations. In an effort to improve treatment for MF patients, there have been significant efforts to identify combination strategies that build upon the substantial benefits of JAK inhibition. Early efforts to combine agents with additive therapeutic profiles have given way to rationally designed combinations hoping to demonstrate clinical synergism and modify the underlying disease. In this article, we review the preclinical basis and existing clinical data for JAK inhibitor combination strategies while highlighting emerging strategies of particular interest.

RAS/CBL mutations predict resistance to JAK inhibitors in myelofibrosis and are associated with poor prognostic features

The dysregulation of the JAK/STAT pathway drives the pathogenesis of myelofibrosis (MF). Recently, several JAK inhibitors (JAKis) have been developed for treating MF. Select mutations (MTs) have been associated with impaired outcomes and are currently incorporated in molecularly annotated prognostic models. Mutations of RAS/MAPK pathway genes are frequently reported in cancer and at low frequencies in MF. In this study, we investigated the phenotypic, prognostic, and therapeutic implications of NRASMTs, KRASMTs, and CBLMTs (RAS/CBLMTs) in 464 consecutive MF patients. A total of 59 (12.7%) patients had RAS/CBLMTs: NRASMTs, n = 25 (5.4%); KRASMTs, n = 13 (2.8%); and CBLMTs, n = 26 (5.6%). Patients with RAS/CBLMTs were more likely to present with high-risk clinical and molecular features. RAS/CBLMTs were associated with inferior overall survival compared with patients without MTs and retained significance in a multivariate model, including the Mutation-Enhanced International Prognostic Score System (MIPSS70) risk factors and cytogenetics; however, inclusion of RAS/CBLMTs in molecularly annotated prognostic models did not improve the predictive power of the latter. The 5-year cumulative incidence of leukemic transformation was notably higher in the RAS/CBLMT cohort. Among 61 patients treated with JAKis and observed for a median time of 30 months, the rate of symptoms and spleen response at 6 months was significantly lower in the RAS/CBLMT cohort. Logistic regression analysis disclosed a significant inverse correlation between RAS/CBLMTs and the probability of achieving a symptom or spleen response that was retained in multivariate analysis. In summary, our study showed that RAS/CBLMTs are associated with adverse phenotypic features and survival outcomes and, more important, may predict reduced response to JAKis.

Next Generation Sequencing in MPNs. Lessons from the Past and Prospects for Use as Predictors of Prognosis and Treatment Responses

The myeloproliferative neoplasms (MPNs) are acquired hematological stem cell neoplasms characterized by driver mutations in JAK2, CALR, or MPL. Additive mutations may appear in predominantly epigenetic regulator, RNA splicing and signaling pathway genes. These molecular mutations are a hallmark of diagnostic, prognostic, and therapeutic assessment in patients with MPNs. Over the past decade, next generation sequencing (NGS) has identified multiple somatic mutations in MPNs and has contributed substantially to our understanding of the disease pathogenesis highlighting the role of clonal evolution in disease progression. In addition, disease prognostication has expanded from encompassing only clinical decision making to include genomics in prognostic scoring systems. Taking into account the decreasing costs and increasing speed and availability of high throughput technologies, the integration of NGS into a diagnostic, prognostic and therapeutic pipeline is within reach. In this review, these aspects will be discussed highlighting their role regarding disease outcome and treatment modalities in patients with MPNs.

JAK Inhibition for the Treatment of Myelofibrosis: Limitations and Future Perspectives

The 2011 approval of ruxolitinib ushered in the Janus kinase (JAK) inhibitor era in the treatment of myelofibrosis (MF), and 2019 saw the US approval of fedratinib. The first therapeutic agents approved by regulatory authorities for MF, these drugs attenuate the overactive JAK-signal transducer and activator of transcription (STAT) signaling universally present in these patients, translating into major clinical benefits in terms of spleen shrinkage and symptom improvement. These, in turn, confer a survival advantage on patients with advanced disease, demonstrated in the case of ruxolitinib, for which long-term follow-up data are available. However, JAK inhibitors do not improve cytopenias in most patients, have relatively modest effects on bone marrow fibrosis and driver mutation allele burden, and clinical resistance eventually develops. Furthermore, they do not modify the risk of transformation to blast phase; indeed, their mechanism of action may be more anti-inflammatory than truly disease-modifying. This has spurred interest in rational combinations of JAK inhibitors with other agents that may improve cytopenias and drugs that could potentially modify the natural history of MF. Newer JAK inhibitors that are distinguished from ruxolitinib and fedratinib by their ability to improve anemia (eg, momelotinib) or safety and efficacy in severely thrombocytopenic patients (eg, pacritinib) are in phase 3 clinical trials. There is also interest in developing inhibitors that are highly selective for mutant JAK2, as well as "type II" JAK2 inhibitors. Overall, although current JAK inhibitors have limitations, they will likely continue to form the backbone of MF therapy for the foreseeable future.

Management of myelofibrosis after ruxolitinib failure

Over the last decade, the Janus kinase1/2 (JAK1/2) inhibitor ruxolitinib has emerged as a cornerstone of myelofibrosis (MF) management. Ruxolitinib improves splenomegaly and symptoms regardless of driver mutation status, and confers a survival advantage in patients with intermediate-2/high risk MF. However, cytopenias remain problematic, and evidence for a robust anti-clonal effect is lacking. Furthermore, the median duration of spleen response to ruxolitinib in clinical trials is approximately 3 years, and ruxolitinib does not appear to affect the risk of leukemic transformation. There is no therapy approved specifically for patients whose disease 'progresses' on ruxolitinib, defining which remains challenging. The recent regulatory approval of the JAK2 inihibitor fedratinib partially fulfills this unmet need, but much remains to be done. Other JAK inhibitors and a plethora of novel agents are being studied in the ruxolitinib 'failure' setting, as well as 'add-on' therapies to ruxolitinib in patients having a 'sub-optimal' response.

The Rationale for Immunotherapy in Myeloproliferative Neoplasms

PURPOSE OF REVIEW

The classic, chronic Philadelphia chromosome negative myeloproliferative neoplasms (MPN)-essential thrombocythemia (ET), polycythemia vera (PV), and myelofibrosis (MF)-are clonal malignancies of hematopoietic stem cells and are associated with myeloproliferation, organomegaly, and constitutional symptoms. Expanding knowledge that chronic inflammation and a dysregulated immune system are central to the pathogenesis and progression of MPNs serves as a driving force for the development of agents affecting the immune system as therapy for MPN. This review describes the rationale and potential impact of anti-inflammatory, immunomodulatory, and targeted agents in MPNs.

RECENT FINDINGS

The advances in molecular insights, especially the discovery of the Janus kinase 2 (JAK2) V617F mutation and its role in JAK-STAT pathway dysregulation, led to the development of the JAK inhibitor ruxolitinib, which currently represents the cornerstone of medical therapy in MF and hydroxyurea-resistant/intolerant PV. However, there remain significant unmet needs in the treatment of these patients, and many agents continue to be investigated. Novel, more selective JAK inhibitors might offer reduced myelosuppression or even improvement of blood counts. The recent approval of a novel, long-acting interferon for PV patients in Europe, might eventually lead to its broader clinical use in all MPNs. Targeted immunotherapy involving monoclonal antibodies, checkpoint inhibitors, or therapeutic vaccines against selected MPN epitopes could further enhance tumor-specific immune responses. Immunotherapeutic approaches are expanding and hopefully will extend the therapeutic armamentarium in patients with myeloproliferative neoplasms.

Prognostic value of blasts in peripheral blood in myelofibrosis in the ruxolitinib era

BACKGROUND

Circulating blasts (peripheral blood [PB] blasts) ≥1% have long been considered an unfavorable feature for patients with primary myelofibrosis. Whether further quantification of PB blasts and their correlation with bone marrow (BM) blasts have incremental value with regard to patient prognostication is unclear. Similarly, the role of the JAK1/JAK2 inhibitor ruxolitinib (RUX) is not well defined in patients who have increased blasts.

METHODS

The authors retrospectively studied 1316 patients with myelofibrosis who presented at their institution between 1984 and 2018 and had available PB and BM blasts.

RESULTS

The PB blast percentage influenced overall survival (OS) only among patients who had BM blasts <5%, with a median OS of 64 months for patients with 0% PB blasts, 48 months for those with 1% to 3% PB blasts, and 22 months for those with 4% PB blasts (P < .01). Patients who had 4% PB blasts and 5% to 9% BM/PB blasts had clinical features similar to those of patients who had 10% to 19% blasts. Although the OS of the former patients was longer than in patients who had 10% to 19% blasts, it was not statistically different (median OS: 22, 26, and 13 months, respectively; P > .05). Forty-four percent of patients received RUX throughout their disease course. All patients who had <10% blasts (PB or BM) and received treatment with RUX had superior OS compared with those who did not receive RUX within the same group. PB blasts ≥4% and BM blasts ≥5% were significant for predicting inferior survival in multivariate analysis.

CONCLUSIONS

The current results provide comprehensive insight into the role of peripheral blasts in patients with myelofibrosis and indicates that patients who have PB blasts ≥4% have an unfavorable prognosis. RUX provides a survival benefit to patients who have PB blasts <10%.

Favorable COVID-19 course despite significant comorbidities in a ruxolitinib-treated patient with primary myelofibrosis

COVID‐19 carries a high risk of severe disease course, particularly in patients with comorbidities. Therapy of severe COVID‐19 infection has relied on supportive intensive care measures. More specific approaches including drugs that limit the detrimental “cytokine storm”, such as Janus‐activated kinase (JAK) inhibitors, are being discussed. Here, we report a compelling case of a 55‐yo patient with proven COVID‐19 pneumonia, who was taking the JAK1/2 inhibitor ruxolitinib in‐label for co‐existing primary myelofibrosis for 15 months prior to coronavirus infection. The patient had significant comorbidities, including chronic kidney disease, arterial hypertension, and obesity, and our previous cohort suggested that he was thus at high risk for acute respiratory distress syndrome (ARDS) and death from COVID‐19. Since abrupt discontinuation of ruxolitinib may cause fatal cytokine storm and ARDS, ruxolitinib treatment was continued and was well tolerated, and the patient´s condition remained stable, without the need for mechanical ventilation or vasopressors. The patient became negative for SARS‐CoV‐2 and was discharged home after 15 days. In conclusion, our report provides clinical evidence that ruxolitinib treatment is feasible and can be beneficial in patients with COVID‐19 pneumonia, preventing cytokine storm and ARDS.

Management of challenging myelofibrosis after JAK inhibitor failure and/or progression

The myeloproliferative neoplasms (MPNs) encompass a heterogenous set of diseases that have variable survival, but in the setting of treatment refractory and progressive disease, prognosis has been characteristically poor. JAK inhibition with ruxolitinib or fedratinib therapy has become the first line treatment for symptomatic or intermediate to high risk myelofibrosis. However, after three years of ruxolitinib therapy, approximately half of all patients with myelofibrosis will likely have stopped treatment. JAK inhibition failure represents a mixture of etiologies, including drug intolerance, suboptimal dosing, drug resistance, or progression of disease. JAK inhibition failure and accelerated/blast phase have now become the primary clinical challenges in the treatment of myelofibrosis and high risk polycythemia vera, and no phase III trials or clear treatment guidelines exist to guide management strategies in this setting. On the other hand, this represents an exciting time in treatment of JAK inhibitor failure and accelerated phase MPNs due to the advent of recently approved drugs as well as new targeted agents currently under investigation. In this article, we review the management options for these challenging clinical scenarios. We discuss the options for JAK inhibitor dose optimization and overcoming resistance by utilizing combinations of JAK inhibition, primarily ruxolitinib, with alternative commercially available therapies. For patients who have progressed, we discuss recent data regarding targeted therapy options approved for AML that represent potentially efficacious options in the progressive MPN setting. We also discuss the new clinical agents under development in MF and accelerated MPNs that may offer new therapeutic options in the years to come.

Infectious Complications of Biological and Small Molecule Targeted Immunomodulatory Therapies

The past 2 decades have seen a revolution in our approach to therapeutic immunosuppression. We have moved from relying on broadly active traditional medications, such as prednisolone or methotrexate, toward more specific agents that often target a single receptor, cytokine, or cell type, using monoclonal antibodies, fusion proteins, or targeted small molecules. This change has transformed the treatment of many conditions, including rheumatoid arthritis, cancers, asthma, and inflammatory bowel disease, but along with the benefits have come risks. Contrary to the hope that these more specific agents would have minimal and predictable infectious sequelae, infectious complications have emerged as a major stumbling block for many of these agents. Furthermore, the growing number and complexity of available biologic agents makes it difficult for clinicians to maintain current knowledge, and most review articles focus on a particular target disease or class of agent. In this article, we review the current state of knowledge about infectious complications of biologic and small molecule immunomodulatory agents, aiming to create a single resource relevant to a broad range of clinicians and researchers. For each of 19 classes of agent, we discuss the mechanism of action, the risk and types of infectious complications, and recommendations for prevention of infection.

Insights into the role of the JAK/STAT signaling pathway in graft-versus-host disease

Allogeneic hematopoietic transplantation (allo-HCT) is a curative therapy for a variety of hematologic malignancies, primarily through immune-mediated clearance of malignant cells. This graft-versus-leukemia (GvL) effect is mediated by alloreactive donor T-cells against recipient malignant cells. Unfortunately, graft versus host disease is a potentially lethal complication of this procedure, also mediated by alloreactive donor T-cells against recipient normal tissues. Graft-versus-host disease (GVHD) remains a key contributor to nonrelapse mortality and long-term morbidity in patients undergoing allo-HCT. Reducing GVHD without interfering with - or ideally while enhancing - GvL, would improve outcomes and increase patient eligibility for allo-HCT. The JAK/STAT signaling pathway acts downstream of over 50 cytokines and is central to a wide variety of inflammatory pathways. These pathways play a role in the development and maintenance of GVHD throughout the disease process and within T-cells, B-cells, macrophages, neutrophils, and natural killer cells. Agents targeting JAK/STAT signaling pathways have shown clinical efficacy and gained US Food and Drug Administration approval for numerous diseases. Here, we review the preclinical and clinical evidence for the role of JAK/STAT signaling in the development and maintenance of GVHD and the utility of blocking agents at preventing and treating GVHD.

Management of myelofibrosis after ruxolitinib failure

Myelofibrosis is a BCR-ABL1-negative myeloproliferative neoplasm characterized by anemia, progressive splenomegaly, extramedullary hematopoiesis, bone marrow fibrosis, constitutional symptoms, leukemic progression, and shortened survival. Constitutive activation of the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathway, and other cellular pathways downstream, leads to myeloproliferation, proinflammatory cytokine expression, and bone marrow remodeling. Transplant is the only curative option for myelofibrosis, but high rates of morbidity and mortality limit eligibility. Several prognostic models have been developed to facilitate treatment decisions. Until the recent approval of fedratinib, a JAK2 inhibitor, ruxolitinib was the only available JAK inhibitor for treatment of intermediate- or high-risk myelofibrosis. Ruxolitinib reduces splenomegaly to some degree in almost all treated patients; however, many patients cannot tolerate ruxolitinib due to dose-dependent drug-related cytopenias, and even patients with a good initial response often develop resistance to ruxolitinib after 2-3 years of therapy. Currently, there is no consensus definition of ruxolitinib failure. Until fedratinib approval, strategies to overcome ruxolitinib resistance or intolerance were mainly different approaches to continued ruxolitinib therapy, including dosing modifications and ruxolitinib rechallenge. Fedratinib and two other JAK2 inhibitors in later stages of clinical development, pacritinib and momelotinib, have been shown to induce clinical responses and improve symptoms in patients previously treated with ruxolitinib. Fedratinib induces robust spleen responses, and pacritinib and momelotinib may have preferential activity in patients with severe cytopenias. Reviewed here are strategies to ameliorate ruxolitinib resistance or intolerance, and outcomes of clinical trials in patients with myelofibrosis receiving second-line JAK inhibitors after ruxolitinib treatment.

Current and future therapies for myelofibrosis

Myelofibrosis is classified as a 'Philadelphia-chromosome negative' clonal myeloproliferative disorder. The heterogeneity of this condition and patient population and array of often challenging clinical manifestations can frequently make therapeutic decisions challenging. Despite many advances in therapy with targeted and combination approaches, following an enhanced understanding of underlying disease pathogenesis, cure only remains achievable with allogeneic stem cell transplant. This option is often limited to a small group of younger transplant-eligible patients with more advanced disease who have both a suitable donor and no or few co-morbidities. In this article, we will discuss up-to-date disease prognostication, common clinical challenges associated with myelofibrosis and both standard and novel therapeutic approaches. Increasingly complex prognostic modelling utilises patient-specific, haematological and genomic parameters to improve the accuracy of risk assessment and predict disease progression. We will also focus on difficult clinical scenarios such as disease-associated anaemia, thrombocytopenia and extremes of age. Future and evolving therapies within this field are highly anticipated and novel JAK inhibitor and non-JAK inhibitor-based therapy will also be discussed, including the new challenge of how to switch from one JAK inhibitor therapy to another.

Drug-Related Cutaneous Adverse Events in Philadelphia Chromosome-Negative Myeloproliferative Neoplasms: A Literature Review

Since myeloproliferative neoplasms (MPN) pose a significant risk for vascular and thrombotic complications, cytoreductive therapies, such as hydroxyurea (HU), interferon (IFN) inhibitors, and Janus kinase (JAK) inhibitors are recommended for patients at high risk. However, these agents also place patients at increased risk for drug-related cutaneous adverse events. Herein, we review the literature on skin toxicity related to the use of drugs for the treatment of MPN. Overall, the cytoreductive agents used for MPN are generally well tolerated and considered to be safe, except IFN, for which dropout rates as high as 25% have been reported. While IFN is known to give rise to flu syndrome, it rarely leads to hematological alterations. The most common hematological side effects of HU are mild and include granulocytopenia, anemia, and thrombocytopenia. The JAK inhibitor ruxolitinib has been associated with cytopenia and a higher incidence of viral infections, as well as increased risk for basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Based on the present analysis, it can be concluded that cutaneous toxicity is not a negligible complication of commonly used treatments for MPN. While further research is needed, patients on these agents, and especially those with a history of cutaneous malignancies, should undergo thorough skin examination before and during therapy. In addition, detailed history is critical since many patients who develop non-melanoma skin cancer have multiple preexisting risk factors for cutaneous carcinogenesis.

Maintenance Strategies After Hematopoietic Cell Transplantation

Hematopoietic cell transplantation (HCT) is an essential component of potentially curative therapy for patients with hematologic malignancies. High-dose chemotherapy with autologous (auto) stem cell rescue is used to overcome chemoresistance in multiple myeloma, non-Hodgkin lymphoma, and Hodgkin lymphoma. Alternatively, poor-risk acute leukemias rely on the graft versus leukemia effect of allogeneic (allo) products. Long-term remissions are feasible with both auto- and allo-HCT; however, disease relapse is the leading cause of death after HCT for many patients. In recognition of this, novel therapies are being investigated in the upfront, relapsed/refractory, and post-HCT maintenance settings to deepen response and maintain disease control. To date, the most robust data to support this approach are in multiple myeloma, where post-transplant maintenance therapy has improved clinical outcomes. In Hodgkin lymphoma, patients with high-risk features may benefit from post-auto-HCT vedotin (BV) regardless of pre-HCT BV exposure. Apart from mantle cell lymphoma, where rituximab maintenance is generally accepted, post-auto-HCT maintenance in other forms of NHL is less established. In patients who undergo allo-HCT, the utilization of maintenance therapy is an important component of improving post-HCT outcomes, however, an individualized approach that considers patient factors such as residual toxicity from HCT, an immature graft with poor graft function, infection, and graft-versus-host disease create a complex environment for aggressive interventions. Initiation of directed agents in patients with identified mutations prior to allo-HCT, including FLT3 in acute myeloid leukemia and Philadelphia chromosome in acute lymphoid leukemia have generally improved post-HCT outcomes. Ongoing studies are exploring the safety and efficacy of additional maintenance strategies post-allo-HCT in an effort to further improve post-HCT outcomes.

Modern management of splenomegaly in patients with myelofibrosis

Myelofibrosis (MF) is a chronic myeloproliferative neoplasm which can lead to massive splenomegaly secondary to extramedullary hematopoiesis. Patients frequently exhibit debilitating symptoms including pain and early satiety, in addition to cellular sequestration causing severe cytopenias. JAK 1/2 inhibitors, such as ruxolitinib and fedratinib, are the mainstay of therapy and produce significant and durable reductions in spleen volume. However, many patients are not eligible for JAK 2 inhibitor therapy or become refractory to treatment over time. Novel therapies are in development that can reduce the degree of splenomegaly for some of these patients. However, splenectomy, splenic irradiation, and partial splenic artery embolization remain valuable therapeutic options in select patients. In this review, we will discuss currently available pharmacologic therapies and describe promising drugs currently in development. We will also delve into the efficacy and safety concerns of splenectomy, splenic irradiation, and partial splenic artery embolization. Finally, we will propose a treatment algorithm to help guide clinicians in the management of symptomatic splenomegaly in patients with MF.

Real-world risk assessment and treatment initiation among patients with myelofibrosis at community oncology practices in the United States

Myelofibrosis (MF) is a chronic myeloproliferative neoplasm with a prevalence of 4 to 6 per 100,000 people in the USA. Treatment recommendations are risk-adapted. This study was conducted to evaluate how physicians risk-stratify patients at the time of MF diagnosis, the accuracy of the risk stratification, and its effect on treatment selection. Medical charts were reviewed at US community hematology/oncology practices in the Cardinal Health Oncology Provider Extended Network; patient clinical characteristics, risk stratification, and treatment data were collected. Physician-assigned risk categorizations were compared with data-derived risk categorizations based on the International Prognostic Scoring System, the system recommended at diagnosis. A total of 491 patients diagnosed with MF between 2012 and 2016 (mean [SD] age at diagnosis, 65.4 [11.8] years; 54.8% male, 69.2% with primary MF) were included. Risk categorization was not assigned for 30.1% of patients. Of the patients with a physician-assigned risk categorization (n = 343), a scoring system was used in 49.9%. Compared with data-derived risk categorizations, 42.9% of physician-assigned risk categorizations were incorrect; 85.0% of incorrect physician-assigned risk categorizations were underestimations. Notably, 38.5% of patients with data-derived intermediate- or high-risk categorizations did not initiate treatment within 120 days of diagnosis. Among patients with data-derived intermediate risk, those with an underestimated physician-assigned risk categorization were significantly less likely to receive treatment within 120 days of diagnosis (51.6% with correct physician-assigned categorization vs 18.5% with underestimated risk categorization; P = 0.0023). These results highlight the gap in risk assessment and the importance of accurate risk stratification at diagnosis.

Recommendations for the use of pegylated interferon-α in the treatment of classical myeloproliferative neoplasms

The classical myeloproliferative neoplasms (MPN) are uncommon clonal haemopoietic malignancies characterised by excessive production of mature blood cells. Clinically, they are associated with thrombosis, haemorrhage, varying degrees of constitutional disturbance and a risk of progression to myelofibrosis or acute myeloid leukaemia. Many of the disease manifestations may be ameliorated by treatment with interferon-α (IFN), but its use in Australian MPN patients has been limited due to the inconvenience of frequent injections and side-effects. The pegylated form of IFN is a long-acting preparation, which is better tolerated, and its Pharmaceutical Benefits Scheme listing is likely to lead to increased usage. We review the literature on risks and benefits of IFN treatment for MPN, suggest criteria for patient selection in each of these diseases and discuss strategies to manage the side-effects of pegylated IFN.

Patterns of Ruxolitinib Therapy Failure and Its Management in Myelofibrosis: Perspectives of the Canadian Myeloproliferative Neoplasm Group

Ruxolitinib improves splenomegaly and other disease-related symptoms in patients with myelofibrosis, but over time, many patients lose this benefit. It is difficult to determine whether this is due to resistance or intolerance to the drug; thus, we have used the more inclusive term of ruxolitinib failure. The survival of patients with myelofibrosis after ruxolitinib failure is poor but varies significantly by the pattern of the failure, underlining the need for a clinically appropriate classification. In this review, we propose diagnostic guidance for early recognition of the pattern of ruxolitinib failure and we recommend treatment options. The most frequent patterns of ruxolitinib failure are loss or failure to obtain a significant reduction in splenomegaly or symptom response, and the development or persistence of clinically significant cytopenias. Ruxolitinib dose modification and other ancillary therapies are sometimes helpful, and splenectomy is a palliative option in selected cases. Stem-cell transplantation is the only curative option for these patterns of failure, but its restricted applicability due to toxicity highlights the importance of ongoing clinical trials in this area. Recent approval of fedratinib by the US Food and Drug Administration provides an alternative option for patients with suboptimal or loss of spleen response. The transformation of myelofibrosis to accelerated or blast phase is an infrequent form of failure with an extremely poor prognosis, whereby patients who are ineligible for transplantation have limited treatment options.