Disseminated tuberculosis in a patient treated with a JAK2 selective inhibitor: a case report

Ruxolitinib associated psoas muscle tuberculosis abscess in a primary myelofibrosis woman: A case report and literature review

RATIONALE

Primary myelofibrosis is a subtype of myeloproliferative neoplasm that leads to bone marrow fibrosis. Historically, the only curative option for primary myelofibrosis was allogeneic hematopoietic stem cell transplant. Ruxolitinib, a Janus kinase inhibitor, is now used for the treatment of primary myelofibrosis and polycythemia vera. It effectively improves symptoms related to splenomegaly and anemia. However, its association with the development of opportunistic infections has been observed in clinical studies and practical application.

PATIENT CONCERNS

A 64-year-old female with primary myelofibrosis and chronic hepatitis B infection who received ruxolitinib treatment. She was admitted for spiking fever and altered consciousness.

DIAGNOSIS

Tuberculosis meningitis was suspected but cerebrospinal fluid can't identify any pathogens. An abdominal computed tomography scan revealed a left psoas abscess and an enlarged spleen. A computed tomography-guided pus drainage procedure was performed, showing a strong positive acid-fast stain and a positive Mycobacterium tuberculosis polymerase chain reaction result.

INTERVENTIONS

antituberculosis medications were administered. The patient developed a psoas muscle abscess caused by tuberculosis and multiple dermatomes of herpes zoster during antituberculosis treatment.

OUTCOMES

The patient was ultimately discharged after 6 weeks of treatment without apparent neurological sequelae.

LESSONS

This case underscores the importance of clinicians evaluating latent infections and ensuring full vaccination prior to initiating ruxolitinib-related treatment for primary myelofibrosis.

Ruxolitinib and tuberculosis: A case report with brief review

JAK 2 inhibitors are widely used for the treatment of primary myelofibrosis. Ruxolitinib is the most commonly used JAK inhibitor in clinical practice. We report two cases of Primary Myelofibrosis who developed tuberculosis on active treatment with ruxolitinib. Our first case was a 48 year male who developed disseminated tuberculosis during fourth month of treatment and second case was a 50 year male developing tubercular lymphadenitis during second month of treatment respectively. These case reports indicate reactivation of underling tubercular infection as a very dreaded complication of this treatment. The prevalence of tuberculosis is much higher in India compared to the west. A thorough pretreatment evaluation should ideally be done using Mantoux test or interferon gamma release assay (IGRA) to rule out latent tuberculosis. Furthermore, the patients should be counselled regarding the possibility of reactivation of infections including tuberculosis. Also, proper follow up is the need of hour in all patients on any kind of immunomodulators.

Fatal Disseminated Tuberculosis and Concurrent Disseminated Cryptococcosis in a Ruxolitinib-treated Patient with Primary Myelofibrosis: A Case Report and Literature Review

Ruxolitinib, a Janus kinase inhibitor, improves symptoms in patients with myelofibrosis. However, its association with the development of opportunistic infections has been a concern. We herein report a 71-year-old man with primary myelofibrosis who developed disseminated tuberculosis and concurrent disseminated cryptococcosis during ruxolitinib treatment. We also reviewed the literature on disseminated tuberculosis and/or cryptococcosis associated with ruxolitinib treatment. This is the first case of disseminated tuberculosis and concurrent disseminated cryptococcosis during treatment with ruxolitinib. We therefore suggest considering not only disseminated tuberculosis but also cryptococcosis in the differential diagnosis of patients with abnormal pulmonary shadows during ruxolitinib treatment.

Adverse Effects of Immunosuppression: Infections

Immunosuppressive therapies are currently indicated for a wide range of diseases. As new agents emerge and indications evolve the landscape grows increasingly complex. Therapies can target pathologic immune system over-activation in rheumatologic or autoimmune disease, or conditioning and graft versus host disease (GVHD) prophylactic regimens may eliminate or inhibit host immune function to improve graft survival and risk of complication in solid organ transplantation (SOT) or hematopoietic stem cell transplantation (HSCT). With immunosuppressive therapy, infections occur. Complex disease states, host factors, and concomitant therapies contribute to a "net state" of immunosuppression that must be considered and may confound perceived increased infection risks in patients receiving treatment.

Philadelphia-Negative Chronic Myeloproliferative Neoplasms during the COVID-19 Pandemic: Challenges and Future Scenarios

An outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) started in December 2019 in China and then become pandemic in February 2020. Several publications investigated the possible increased rate of COVID-19 infection in hematological malignancies. Based on the published data, strategies for the management of chronic Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) are provided. The risk of severe COVID-19 seems high in MPN, particularly in patients with essential thrombocythemia, but not negligible in myelofibrosis. MPN patients are at high risk of both thrombotic and hemorrhagic complications and this must be accounted in the case of COVID-19 deciding on a case-by-case basis. There are currently no data to suggest that hydroxyurea or interferon may influence the risk or severity of COVID-19 infection. Conversely, while the immunosuppressive activity of ruxolitinib might pose increased risk of infection, its abrupt discontinuation during COVID-19 syndrome is associated with worse outcome. All MPN patients should receive vaccine against COVID-19; reassuring data are available on efficacy of mRNA vaccines in MPNs.

Type I Interferons Suppress Anti-parasitic Immunity and Can Be Targeted to Improve Treatment of Visceral Leishmaniasis

Type I interferons (IFNs) play critical roles in anti-viral and anti-tumor immunity. However, they also suppress protective immune responses in some infectious diseases. Here, we identify type I IFNs as major upstream regulators of CD4⁺ T cells from visceral leishmaniasis (VL) patients. Furthermore, we report that mice deficient in type I IFN signaling have significantly improved control of Leishmania donovani, a causative agent of human VL, associated with enhanced IFNγ but reduced IL-10 production by parasite-specific CD4⁺ T cells. Importantly, we identify a small-molecule inhibitor that can be used to block type I IFN signaling during established infection and acts synergistically with conventional anti-parasitic drugs to improve parasite clearance and enhance anti-parasitic CD4⁺ T cell responses in mice and humans. Thus, manipulation of type I IFN signaling is a promising strategy for improving disease outcome in VL patients.

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.

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.

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.

Tuberculosis Peritonitis During Treatment of Polycythemia Vera with Ruxolitinib

Ruxolitinib is a selective JAK1/2 inhibitor that is widely used for the treatment of myeloproliferative neoplasms (MPNs), including myelofibrosis and polycythemia vera (PV). Despite its clinical efficacy for MPNs, ruxolitinib possesses immunosuppressive properties that potentially increase the risks for opportunistic infection, such as mycobacterium tuberculosis (MTB) infection, and reactivation of occult viral infection. Herein, we report the case of a 76-year-old male with PV who developed tuberculosis peritonitis under ruxolitinib therapy for 28 weeks. While previous studies and case reports have suggested an increased risk of MTB infection of various organs during ruxolitinib treatment of MPNs, this case is apparently the first of tuberculosis peritonitis in a patient with MPN treated with ruxolitinib. A review of previous case reports suggests the need for careful observation for MTB from the relatively early phase of ruxolitinib treatment, given that the median duration from the start of ruxolitinib treatment to the emergence of MTB was 20 weeks (range: 3-88 weeks). Clinicians should consider tuberculosis peritonitis as a differential diagnosis when patients with MPN treated with ruxolitinib develop infectious abdominal symptoms.

Reactivation of tuberculosis following ruxolitinib therapy for primary myelofibrosis: Case series and literature review

Primary myelofibrosis (PMF) is a subtype of BCR-ABL1 negative myeloproliferative neoplasm. Its characteristic features include clonal myeloproliferation, dysregulation of kinase signaling pathway, abnormal release of cytokines leading to fibrosis in the bone marrow, osteosclerosis, and extramedullary hematopoiesis. Approximately 20% of deaths occur because of disease progression, but death may also result occur because of cardiovascular complications or as a consequence of either infection or bleeding. The only and curative option for PMF is allogeneic hematopoietic stem cell transplant (allo-HSCT); however, the Janus kinase (JAK) 1/2 inhibitor ruxolitinib is highly effective in reducing constitutional symptoms and spleen volume, and has been found to improve survival. Ruxolitinib decreases the activity of type I T-helper cells, leading to decreased release of cytokines including tumor necrosis factor-α, interleukin-1 (IL-1), IL-6, interferon-γ, and production of IL-12, which can be a risk factor for opportunistic infections. In this report, we describe three cases of tuberculosis reactivation shortly after initiation of ruxolitinib therapy followed by a literature review.

A case report of cryptococcal meningitis associated with ruxolitinib

We herein report a 76-year-old Japanese man with myelofibrosis who developed cryptococcal meningitis. After treatment for 5 months with ruxolitinib, the patient presented with fever and disturbance of consciousness. Marked nuchal stiffness was noted. The magnetic resonance imaging results of the brain were normal. Lumbar puncture showed an opening cerebrospinal fluid (CSF) pressure of 110 mm H2O, pleocytosis (85 mononuclear cells and 222 polymorphonuclear cells/μL), decreased CSF/serum glucose ratio (43%), and elevated protein (194 mg/dL). Blood and CSF cultures grew no bacteria or fungi. However, cryptococcal antigen was detected in the blood and CSF samples. We discontinued ruxolitinib and started administration of amphotericin B. His condition improved gradually 1 week after initiation of treatment. There have been only a few reports on cryptococcal meningitis associated with ruxolitinib. Physicians should consider the possibility of cryptococcal meningitis in patients receiving ruxolitinib.

Necessity to screen and treat latent tuberculosis before ruxolitinib treatment—Ruxolitinib-associated disseminated tuberculosis: A case report and literature review

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Ruxolitinib, a JAK inhibitor, improves polycythemia vera and myelofibrosis symptoms.

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Tuberculosis (disseminated) reactivation reported after ruxolitinib treatment.

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Screening for/treating latent tuberculosis suggested before administering ruxolitinib.

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This is especially pertinent in areas where the risk of tuberculosis is high.

Ruxolitinib, a Janus kinase inhibitor, considerably improves symptoms of patients with polycythemia vera and primary or secondary myelofibrosis. However, its association with the development of infectious complications is a concern. Herein, we report the case of an 80-year-old man with primary myelofibrosis who developed disseminated tuberculosis during treatment with ruxolitinib at 15 mg twice daily and prednisone at 5 mg. We also reviewed the literature on patients who developed tuberculosis during treatment with ruxolitinib. There are 13 case reports of patients who developed tuberculosis during treatment with ruxolitinib, including our case. Disseminated tuberculosis manifestations were observed in 84.6 % of the patients and 50 % of them died. Although the interferon-gamma release assay was performed for seven of the patients with six positive results at the time of tuberculosis diagnosis, none were tested before the commencement of ruxolitinib. We suggest taking a history of tuberculosis and screening for and treating latent tuberculosis before administering ruxolitinib, especially in areas where the risk of tuberculosis is high.

Mechanisms Underlying the Anti-inflammatory and Immunosuppressive Activity of Ruxolitinib

The JAK-STAT signaling pathway plays a central role in signal transduction in hematopoietic cells, as well as in cells of the immune system. The occurrence in most patients affected by myeloproliferative neoplasms (MPNs) of driver mutations resulting in the constitutive activation of JAK2-dependent signaling identified the deregulated JAK-STAT signal transduction pathway as the major pathogenic mechanism of MPNs. It also prompted the development of targeted drugs for MPNs. Ruxolitinib is a potent and selective oral inhibitor of both JAK2 and JAK1 protein kinases. Its use in patients with myelofibrosis is associated with a substantial reduction in spleen volume, attenuation of symptoms and decreased mortality. With growing clinical experience, concerns about infectious complications, and increased risk of B-cell lymphoma, presumably caused by the effects of JAK1/2 inhibition on immune response and immunosurveillance, have been raised. Evidence shows that ruxolitinib exerts potent anti-inflammatory and immunosuppressive effects. Cellular targets of ruxolitinib include various components of both the innate and adaptive immune system, such as natural killer cells, dendritic cells, T helper, and regulatory T cells. On the other hand, immunomodulatory properties have proven beneficial in some instances, as highlighted by the successful use of ruxolitinib in corticosteroid-resistant graft vs. host disease. The objective of this article is to provide an overview of published evidence addressing the key question of the mechanisms underlying ruxolitinib-induced immunosuppression.

A journey through infectious risk associated with ruxolitinib

Ruxolitinib has proved to be effective for the treatment of patients with myelofibrosis (either primary or secondary) and polycythaemia vera, and its approval led to a significant change in the current treatment algorithm. Despite its efficacy and beyond its well described haematological toxicity, a peculiar immunosuppressive effect emerged as our clinical experience grew, both within and outside of a clinical trial setting. Definite and negative interactions with multiple pathways of the immune system of patients have been reported so far, involving both adaptive and innate immune responses. These pathophysiological mechanisms may contribute to the increased risk of reactivation of silent infections (e.g., tuberculosis, hepatitis B virus and varicella zoster virus) that have been associated with the drug. Even though such infectious events may be fatal or may lead to significant impairment of organ function, compromising the eligibility of patients for an allotransplant procedure, there are no dedicated guidelines that may help us in assessing and managing the risk of developing serious infections. On this basis, our aim for the present work was to review the current knowledge on the pathophysiological mechanisms through which ruxolitinib may exert its immunosuppressive effect, and to illustrate our personal approach to the management of three peculiar clinical scenarios, for which a risk-based algorithm is suggested.

Infections associated with immunotherapeutic and molecular targeted agents in hematology and oncology. A position paper by the European Conference on Infections in Leukemia (ECIL)

A multitude of new agents for the treatment of hematologic malignancies has been introduced over the past decade. Hematologists, infectious disease specialists, stem cell transplant experts, pulmonologists and radiologists have met within the framework of the European Conference on Infections in Leukemia (ECIL) to provide a critical state-of-the-art on infectious complications associated with immunotherapeutic and molecular targeted agents used in clinical routine. For brentuximab vedotin, blinatumomab, CTLA4- and PD-1/PD-L1-inhibitors as well as for ibrutinib, idelalisib, HDAC inhibitors, mTOR inhibitors, ruxolitinib, and venetoclax, a detailed review of data available until August 2018 has been conducted, and specific recommendations for prophylaxis, diagnostic and differential diagnostic procedures as well as for clinical management have been developed.

Ruxolitinib therapy for myelofibrosis in Austria : Consensus on therapy management

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

Fatal Disseminated Tuberculosis during Treatment with Ruxolitinib Plus Prednisolone in a Patient with Primary Myelofibrosis: A Case Report and Review of the Literature

A 73-year-old man with primary myelofibrosis (PMF) was being treated with hydroxyurea, which was changed to ruxolitinib treatment because of worsening constitutional symptoms. Although ruxolitinib rapidly induced relief, he developed a high-grade fever. A comprehensive fever work-up found no apparent cause of the fever, except for PMF. Therefore, we increased the dose of ruxolitinib and added prednisolone, which was gradually withdrawn with resolution of the fever. However, the patient subsequently developed disseminated tuberculosis and died eight months after initiation of ruxolitinib. Our case highlights the importance of assessing and monitoring the immune status of patients receiving ruxolitinib.

Epidemiology, outcome, and risk factors for infectious complications in myelofibrosis patients receiving ruxolitinib: A multicenter study on 446 patients

Infections represent one of the major concerns regarding the utilization of ruxolitinib (RUX) in patients with myelofibrosis. With the aim to investigate epidemiology, outcome and risk factors for infections in RUX-exposed patients, we collected clinical and laboratory data of 446 myelofibrosis patients treated with RUX between June 2011 and November 2016 in 23 European Hematology Centers. After a median RUX exposure of 23.5 months (range, 1-56), 123 patients (28%) experienced 161 infectious events (grades 3-4 32%, fatal 9%), for an incidence rate of 17 cases per 100 pts/y. The rate of infections tended to decrease over time: 14% of patients developed the first infection within 6 months, 5% between 6 and 12 months, 3.7% between 12 and 18 months, 3.4% between 18 and 24 months, and 7.9% thereafter (P < .0001). Respiratory tract infections were more frequently observed (81 events, 50%), and bacteria were the most frequent etiological agents (68.9%). However, also viral (14.9%) and fungal infections (2.5%) were observed. In multivariate analysis, previous infectious event (HR 2.54; 95% CI, 1.51-4.28; P = .0005) and high international prognostic score system category (IPSS) (HR 1.53; 95% CI, 1.07-2.20; P = .021) significantly correlated with higher infectious risk. On the contrary, spleen reduction ≥50% from baseline after 3 months of treatment (P = .02) was associated with better infection-free survival. Taken together, these findings reinforce the concept of disease severity as the most important risk factor for infections, and describe, for the first time, that a positive therapeutic effect in reducing splenomegaly may also reduce subsequent infectious complications.

Ruxolitinib-associated infections: A systematic review and meta-analysis

Ruxolitinib exerts immunosuppressive activity that may increase the risk of infectious complications. We performed a systematic review of the literature with the aim of estimating the risk of infections in patients treated with ruxolitinib. Studies were identified by electronic search of MEDLINE and EMBASE database. Differences in the incidence of infectious events between ruxolitinib and comparison groups were expressed as odds ratios (ORs) and 95% confidence intervals (95% CI). Five phase III randomized clinical trials (RCTs) (3 phase IIIa with their extended phase and 2 phase IIIb), 6 phase IV studies and 28 case reports were included in this systematic review. Ruxolitinib was associated with a statistically significant increased risk of herpes zoster infection compared to control group in 3 RCTs including patients with polycythemia vera (OR 7.39 [1.33, 41.07]) and in a pooled analysis of the extended phase IIIa RCTs (OR 5.20 [95%CI 1.27, 21.18]). In the larger phase IV post-marketing study, the incidence of the most frequent infections was 8% for herpes zoster, 6.1% for bronchitis and 6% for urinary tract infections. In the published case reports, the most frequent infections were tuberculosis (N = 10), hepatitis B reactivation (N = 5) and pneumocystis jeroveci infection (N = 2). Evidence is not solid enough to accurately estimate the risk of infection in ruxolitinib-treated patients. However, published data clearly suggest that the infection risk may be clinically relevant. Well-designed studies are warranted to evaluate the risk of ruxolitinib-associated infection, in order to identify the most appropriate antimicrobial prophylactic strategy.

ESCMID Study Group for Infections in Compromised Hosts (ESGICH) Consensus Document on the safety of targeted and biological therapies: an infectious diseases perspective (Intracellular signaling pathways: tyrosine kinase and mTOR inhibitors)

BACKGROUND

The present review is part of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Infections in Compromised Hosts (ESGICH) Consensus Document on the safety of targeted and biologic therapies.

AIMS

To review, from an infectious diseases perspective, the safety profile of therapies targeting different intracellular signaling pathways and to suggest preventive recommendations.

SOURCES

Computer-based Medline searches with MeSH terms pertaining to each agent or therapeutic family.

CONTENT

Although BCR-ABL tyrosine kinase inhibitors modestly increase the overall risk of infection, dasatinib has been associated with cytomegalovirus and hepatitis B virus reactivation. BRAF/MEK kinase inhibitors do not significantly affect infection susceptibility. The effect of Bruton tyrosine kinase inhibitors (ibrutinib) among patients with B-cell malignancies is difficult to distinguish from that of previous immunosuppression. However, cases of Pneumocystis jirovecii pneumonia (PCP), invasive fungal infection and progressive multifocal leukoencephalopathy have been occasionally reported. Because phosphatidylinositol-3-kinase inhibitors (idelalisib) may predispose to opportunistic infections, anti-Pneumocystis prophylaxis and prevention strategies for cytomegalovirus are recommended. No increased rates of infection have been observed with venetoclax (antiapoptotic protein Bcl-2 inhibitor). Therapy with Janus kinase inhibitors markedly increases the incidence of infection. Pretreatment screening for chronic hepatitis B virus and latent tuberculosis infection must be performed, and anti-Pneumocystis prophylaxis should be considered for patients with additional risk factors. Cancer patients receiving mTOR inhibitors face an increased incidence of overall infection, especially those with additional risk factors (prior therapies or delayed wound healing).

IMPLICATIONS

Specific preventive approaches are warranted in view of the increased risk of infection associated with some of the reviewed agents.

Jak1 Integrates Cytokine Sensing to Regulate Hematopoietic Stem Cell Function and Stress Hematopoiesis

JAK1 is a critical effector of pro-inflammatory cytokine signaling and plays important roles in immune function, while abnormal JAK1 activity has been linked to immunological and neoplastic diseases. Specific functions of JAK1 in the context of hematopoiesis, and specifically within hematopoietic stem cells (HSCs), have not clearly been delineated. Here, we show that conditional Jak1 loss in HSCs reduces their self-renewal and markedly alters lymphoid/myeloid differentiation in vivo. Jak1-deficient HSCs exhibit decreased competitiveness in vivo and are unable to rescue hematopoiesis in the setting of myelosuppression. They exhibit increased quiescence, an inability to enter the cell cycle in response to hematopoietic stress, and a marked reduction in cytokine sensing, including in response to type I interferons and IL-3. Moreover, Jak1 loss is not fully rescued by expression of a constitutively active Jak2 allele. Together, these data highlight an essential role for Jak1 in HSC homeostasis and stress responses.

Recurrent Subcutaneous Sweet's Disease in a Myelofibrosis Patient Treated with Ruxolitinib before Allogeneic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-SCT) has a curative potential for myelofibrosis (MF) patients; however, its association with a high therapy-related mortality (TRM) remains a big obstacle that needs to be overcome. Ruxolitinib (RUXO), a novel JAK1/2 inhibitor, can be used as a bridging therapy until allo-SCT can be performed to reduce TRM. We herein report a RUXO-treated MF patient who developed recurrent subcutaneous Sweet's disease (SSD) that was successfully treated by the administration of systemic glucocorticoids. We performed allo-SCT as previously scheduled, resulting in a good clinical course without deterioration of SSD. RUXO administration, as well as MF itself, might therefore sometimes cause this rare non-infectious event.

Hematologic Complications of Tuberculosis

Tuberculosis (TB) affects the production and life span of all hematologic cellular components. In addition, plasma coagulation factors may be affected, resulting in sometimes life-threatening complications. Iron, folate, and vitamin B12 metabolism is derailed. The pharmacological agents used for TB therapy may also cause hematologic changes. There are some uncommon manifestations of TB in nontuberculous hematologic patients. There have been some exciting developments in the field of imaging to screen for TB, TB pathophysiology at the cellular level, and our understanding of immune response in TB. Advances have been made in pharmacologic therapeutic options, including discovery of new drugs in the fight against drug-resistant TB, bearing in mind their hematologic effects. This chapter reviews and updates known hematologic effects of TB and its therapy and some lesser known effects of TB in patients with nontuberculous hematologic conditions.

Pulmonary cryptococcosis in a ruxolitinib-treated patient with primary myelofibrosis

We present the case of a 79-year-old man who showed multiple pulmonary nodules on chest computed tomography (CT) after being treated for 6 months with ruxolitinib, an inhibitor of Janus kinase (JAK) 1 and 2, to treat primary myelofibrosis. We examined the lesions by bronchoscopy, and the biopsy specimen revealed fungus bodies of Cryptococcus with granulomatous inflammation. As a result, the patient was diagnosed with pulmonary cryptococcosis. The patient was treated with fluconazole (200 mg daily for 2 weeks) with concomitant ruxolitinib administration, but the pulmonary lesions progressed. Subsequently, the patient was treated with voriconazole (300 mg daily for 3 weeks), but the lesions worsened further. The administration of ruxolitinib was therefore discontinued, and the dosage of voriconazole was increased to 400 mg daily. Three months later, the pulmonary lesions diminished in size. The present case of pulmonary cryptococcosis occurred in a patient treated with ruxolitinib. Treatment of pulmonary cryptococcosis with concomitant JAK inhibitor administration may result in poor treatment efficacy. It might be better to stop administration of JAK inhibitors, if possible, in patients being treated for pulmonary cryptococcosis.

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.

Reactivation of Pulmonary Tuberculosis following Treatment of Myelofibrosis with Ruxolitinib

Ruxolitinib is widely in use for treatment of myeloproliferative disorders. It causes inhibition of the Janus kinase (JAK) signal transducer and activation of transcription (STAT) pathway, which plays a key role in the underlying pathophysiology of myeloproliferative diseases. We describe a case of reactivation pulmonary tuberculosis in a retired physician while on treatment with ruxolitinib. We also review the literature on opportunistic infections following use of ruxolitinib. Our case highlights the importance of screening for latent tuberculosis in patients from highly endemic areas prior to start of therapy with ruxolitinib.

Risk of Infectious Complications in Hemato-Oncological Patients Treated with Kinase Inhibitors

Infectious complications are a major cause of morbidity and mortality in patients with hemato-oncological diseases. Although disease-related immunosuppression represents one factor, aggressive treatment regimens, such as chemotherapy, stem cell transplantation, or antibody treatment, account for a large proportion of infectious side effects. With the advent of targeted therapies affecting specific kinases in malignant diseases, the outcome of patients has further improved. Nonetheless, dependent on the specific pathway targeted or off-target activity of the kinase inhibitor, therapy-associated infectious complications may occur. We review the most common and approved kinase inhibitors targeting a variety of hemato-oncological malignancies for their immunosuppressive potential and evaluate their risk of infectious side effects based on preclinical evidence and clinical data in order to raise awareness of the potential risks involved.

Historical views, conventional approaches, and evolving management strategies for myeloproliferative neoplasms

The classical Philadelphia chromosome-negative myeloproliferative neoplasms (MPN), which include essential thrombocythemia, polycythemia vera, and myelofibrosis (MF), are in a new era of molecular diagnosis, ushered in by the identification of the JAK2(V617F) and cMPL mutations in 2005 and 2006, respectively, and the CALR mutations in 2013. Coupled with increased knowledge of disease pathogenesis and refined diagnostic criteria and prognostic scoring systems, a more nuanced appreciation has emerged of the burden of MPN in the United States, including the prevalence, symptom burden, and impact on quality of life. Biological advances in MPN have translated into the rapid development of novel therapeutics, culminating in the approval of the first treatment for MF, the JAK1/JAK2 inhibitor ruxolitinib. However, certain practical aspects of care, such as those regarding diagnosis, prevention of vascular events, choice of cytoreductive agent, and planning for therapies, present challenges for hematologists/oncologists, and are discussed in this article.

Elevation of the Hepatitis B Virus DNA during the Treatment of Polycythemia Vera with the JAK Kinase Inhibitor Ruxolitinib

Ruxolitinib is a useful treatment option for myelofibrosis since it effectively resolves splenomegaly and constitutional symptoms. After the widespread use of ruxolitinib outside of clinical trials, a series of case reports indicated a potential risk of ruxolitinib-associated opportunistic infections, including the reactivation of the hepatitis B virus (HBV). We herein report the case of a polycythemia vera patient who showed an elevation of HBV-DNA viral DNA with an elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) after the initiation of ruxolitinib. Anti-viral therapy with entecavir was immediately started and the HBV viral load thereafter decreased with an improvement of the liver function. Physicians should thus be aware of the potential risk of ruxolitinib-associated HBV reactivation.

Ruxolitinib Associated Tuberculosis Presenting as a Neck Lump

Tuberculosis is an opportunistic infection with protean clinical manifestations. We describe a case of Ruxolitinib induced miliary tuberculosis presenting as a neck lump. A 78-year-old female presented with a two-month history of right-sided neck lump associated with fever, night sweats, and significant weight loss. She had a past medical history that included myelofibrosis, being treated with Ruxolitinib. Examination demonstrated 4 × 4 cm right-sided cervical lymphadenopathy. A chest radiograph showed extensive shadowing in both lungs. CT scan demonstrated perilymphatic nodes in addition to the cervical mass. An ultrasound-guided biopsy of a cervical lymph node demonstrated confirmed Mycobacterium tuberculosis infection. It was hypothesized that use of Ruxolitinib through its selective inhibition of Janus-activated kinases 1 and 2 resulted in immunosuppression and miliary tuberculosis in this patient. The medication was stopped and a 12-month regime of antituberculosis therapy commenced. She remained well at one-year follow-up with resolution of lung involvement. Clinicians should consider tuberculosis as a differential diagnosis for patients presenting with a neck lump, particularly in those taking immunosuppressant medication such as Ruxolitinib. A multidisciplinary approach is needed to promptly treat the tuberculosis and consider discontinuation of Ruxolitinib.

Clinical potential of pacritinib in the treatment of myelofibrosis

Myelofibrosis (MF) is a myeloid disorder caused by a clonal hematopoietic stem-cell proliferation associated with activation of the Janus kinase (JAK) signal transducer and activator of transcription (STAT) signaling pathways. Patients with MF often develop severe splenomegaly, marked symptom burden and significant cytopenias, with a consequent marked negative impact on quality of life and survival. The management of MF patients has dramatically improved with the development of a group of drugs that inhibit JAK signaling. The first of these agents to be approved was ruxolitinib, a JAK1/JAK2 inhibitor, which has been shown to improve both spleen size and symptoms in patients with MF. However, myelotoxicity, particularly of the platelet lineage, significantly limits the patient population who can benefit from this agent. Thus, there is an unmet need for novel agents with limited myelotoxicity to treat MF. Pacritinib, a JAK2 and FMS-like tyrosine kinase 3 (FLT3) inhibitor, has shown promising results in early phase trials with limited myelotoxicity and clinical responses that are comparable with those seen with ruxolitinib, even in patients with severe thrombocytopenia. Currently there are two large phase III clinical trials of pacritinib in MF, including patients with thrombocytopenia, and those previously treated with ruxolitinib. If the encouraging results observed in early phase clinical trials are confirmed, pacritinib will represent a new and exciting treatment option for patients with MF and particularly patients with significant cytopenias.

JAK Inhibition Impairs NK Cell Function in Myeloproliferative Neoplasms

Ruxolitinib is a small-molecule inhibitor of the JAK kinases, which has been approved for the treatment of myelofibrosis, a rare myeloproliferative neoplasm (MPN), but clinical trials are also being conducted in inflammatory-driven solid tumors. Increased infection rates have been reported in ruxolitinib-treated patients, and natural killer (NK) cells are immune effector cells known to eliminate both virus-infected and malignant cells. On this basis, we sought to compare the effects of JAK inhibition on human NK cells in a cohort of 28 MPN patients with or without ruxolitinib treatment and 24 healthy individuals. NK cell analyses included cell frequency, receptor expression, proliferation, immune synapse formation, and cytokine signaling. We found a reduction in NK cell numbers in ruxolitinib-treated patients that was linked to the appearance of clinically relevant infections. This reduction was likely due to impaired maturation of NK cells, as reflected by an increased ratio in immature to mature NK cells. Notably, the endogenous functional defect of NK cells in MPN was further aggravated by ruxolitinib treatment. In vitro data paralleled these in vivo results, showing a reduction in cytokine-induced NK cell activation. Further, reduced killing activity was associated with an impaired capacity to form lytic synapses with NK target cells. Taken together, our findings offer compelling evidence that ruxolitinib impairs NK cell function in MPN patients, offering an explanation for increased infection rates and possible long-term side effects associated with ruxolitinib treatment.

Novel therapies for myelofibrosis

Myelofibrosis (MF), including primary, post-essential thrombocythemia and post-polycythemia vera MF, associates with a reduced quality of life and shortened life expectancy. Dysregulation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway is prominent, even in the absence of the JAK2(V617F) mutation. Therefore, all symptomatic MF patients may potentially derive benefit from JAK inhibitors. Despite the efficacy of JAK inhibitors in controlling signs and symptoms of MF, they do not eradicate the disease. Therefore, JAK inhibitors are currently being tested in combination with other novel therapies, a strategy which may be more effective in reducing disease burden, either by overcoming JAK inhibitor resistance or targeting additional mechanisms of pathogenesis. Additional targets include modulators of epigenetic regulation, pathways that work downstream from JAK/STAT (i.e. mammalian target of rapamycin/AKT/phosphoinositide 3-kinase) heat shock protein 90, hedgehog signaling, pro-fibrotic factors, abnormal megakaryocytes and telomerase. In this review, we discuss novel MF therapeutic strategies.

Definition and management of ruxolitinib treatment failure in myelofibrosis

Ruxolitinib, a Janus kinase (JAK)-1 and JAK-2 inhibitor, is the first-in-class drug to be licensed in the United States for the treatment of high- and intermediate-risk myelofibrosis (MF). Several other JAK inhibitors are in development with some currently undergoing phase-3 clinical trial testing. None of the currently available JAK inhibitors are specific to mutant JAK2; their mechanism of action involves attenuation of JAK-STAT signaling with downregulation of proinflammatory cytokines, rather than selective suppression of the disease clone. Accordingly, while ruxolitinib and other JAK inhibitors are effective in controlling splenomegaly and alleviating constitutional symptoms, their benefit in terms of reversing bone marrow fibrosis or inducing complete or partial remissions appears to be limited. The experience to date with ruxolitinib shows that despite its salutary effects on quality of life, over half of the patients discontinue treatment within 2-3 years. In the current perspective, we examine the incidence and causes of ruxolitinib 'treatment failure' in MF patients based on our personal experience as well as a review of the published literature. We also discuss the challenges in defining and classifying ruxolitinib failure, and within the context of several clinical scenarios, we provide recommendations for the post-ruxolitinib management of MF patients.

Ruxolitinib for the treatment of disease-related splenomegaly or symptoms in adult patients with myelofibrosis

SUMMARY 

Myelofibrosis is characterized by progressive splenomegaly, cytopenias and debilitating constitutional symptoms. It has the worst prognosis and poorest quality of life of all the chronic myeloproliferative neoplasms. Allogeneic stem cell transplantation is the only curative therapy, but it carries high treatment-related risks and is thus available to only a small subset of patients. All other interventions merely palliate either anemia or splenomegaly. Ruxolitinib, a JAK1/2 inhibitor, has recently been shown to be effective in reducing splenomegaly and improving constitutional symptoms to a degree that has not been achieved with conventional therapy. However, treatment with ruxolitinib can often worsen anemia, and its ability to change the natural history of myelofibrosis has not been definitively established.

Pneumocystis jiroveci pneumonitis complicating ruxolitinib therapy

Ruxolitinib is a novel inhibitor of the Janus kinase (JAK) pathway that has become available for the treatment of myelofibrosis. There are increasing reports of opportunistic infections associated with ruxolitinib therapy. We present a case of Pneumocystis jiroveci pneumonitis complicating ruxolitinib therapy. Clinicians should consider the use of pneumocystis prophylaxis when using ruxolitinib.

Efficacy of ruxolitinib for myelofibrosis

INTRODUCTION

The discovery of the activating JAK2 V617F mutation in patients with myelofibrosis (MF) led to the development of JAK2 inhibitors. The first such inhibitor to enter clinical trials was ruxolitinib . This review summarizes preclinical and clinical data of ruxolitinib in MF.

AREAS COVERED

A literature search through Medline employing the terms 'ruxolitinib,' 'INCB018424' and 'myelofibrosis' was undertaken. The results from Phase I/II studies in patients with MF showed that ruxolitinib led to durable improvements in splenomegaly, and symptoms associated with MF. Two Phase III trials have compared ruxolitinib against placebo and best available therapy, and in both studies ruxolitinib demonstrated superior rates of spleen control and symptom improvement, and additional analysis demonstrated a survival benefit with ruxolitinib treatment. The main toxicities seen with ruxolitinib are cytopenias, which are managed with dose adjustments. Recent reports documented sporadic cases of immunosuppression-related infections. Ruxolitinib is the first drug ever approved for the therapy of patients with MF.

EXPERT OPINION

Understanding the factors that predict the rate and duration of response to ruxolitinib would improve our ability to manage patients treated with this medication. Clinical trials combining ruxolitinib with novel compounds that are also active in MF will further improve therapy for this disease.