scholarly journals JAK inhibitors for myeloproliferative neoplasms: clarifying facts from myths

Blood ◽  
2012 ◽  
Vol 119 (12) ◽  
pp. 2721-2730 ◽  
Author(s):  
Ayalew Tefferi

Abstract On November 16, 2011, the Food and Drug Administration approved ruxolitinib (a JAK1 and JAK2 inhibitor) for use in the treatment of high and intermediate risk myelofibrosis. This is welcome news for those patients in whom such therapy is indicated and treatment benefit outweighs attendant risk. The question is who are these patients, what should they expect in terms of both short-term effects and long-term impact, and why would they choose ruxolitinib over other JAK inhibitors that are freely available for use in a research setting. Ruxolitinib and most other JAK inhibitors exert a salutary effect on constitutional symptoms and splenomegaly but have yet to produce histopathologic or cytogenetic remissions, reverse bone marrow fibrosis, or improve survival over best supportive care. Furthermore, the palliative value of JAK inhibitors is diminished by notable side effects, including anemia, thrombocytopenia, gastrointestinal disturbances, metabolic abnormalities, peripheral neuropathy, and hyperacute relapse of symptoms during treatment discontinuation. Therefore, risk-benefit balance favors use of currently available JAK inhibitors in only a select group of patients with myelofibrosis, and their potential value in polycythemia vera, outside of special circumstances (eg, intractable pruritus), is undermined by the absence of evidence for a disease-modifying effect and presence of arguably superior alternatives.

Hematology ◽  
2013 ◽  
Vol 2013 (1) ◽  
pp. 529-537 ◽  
Author(s):  
Jason Gotlib

AbstractThe discovery of the JAK2 V617F mutation in the classic BCR-ABL1–negative myeloproliferative neoplasms in 2005 catalyzed a burst of research efforts that have culminated in substantial dividends for patients. Beyond JAK2 V617F, a more detailed picture of the pathobiologic basis for activated JAK-STAT signaling has emerged. In some patients with myelofibrosis (MF), next-generation sequencing technologies have revealed a complex clonal architecture affecting both genetic and epigenetic regulators of cell growth and differentiation. Although these bench-top findings have informed the clinical development of JAK inhibitors in MF, they have also provided scientific context for some of their limitations. The JAK1/JAK2 inhibitor ruxolitinib is approved for treatment of MF in North America and Europe and other lead JAK inhibitors discussed herein (fedratinib [SAR302503], momelotinib [CYT387], and pacritinib [SB1518]), have entered advanced phases of trial investigation. Uniformly, these agents share the ability to reduce spleen size and symptom burden. A major challenge for practitioners is how to optimize dosing of these agents to secure clinically relevant and durable benefits while minimizing myelosuppression. Suboptimal responses have spurred a “return to the bench” to characterize the basis for disease persistence and to inform new avenues of drug therapy.


2016 ◽  
Vol 157 (39) ◽  
pp. 1547-1556
Author(s):  
Zsófia Simon ◽  
Imelda Marton ◽  
Zita Borbényi ◽  
Árpád Illés

Primary myelofibrosis is one of the Philadelphia negative chronic myeloproliferative neoplasms. It is a rare disease featured by cytopenias and hepatosplenomegaly. Although the etiology of the disease is still unknown, our knowledge about its pathology and prognosis has been improving in the last few years. Furthermore, the JAK2 inhibitor ruxolitinib has become available in Hungary since 2015. Beside its high efficacy in spleen volume and in reduction of myelofibrosis-associated symptoms, this novel therapy also exerts a disease-modifying effect and, therefore, ruxolitinib may improve the life expectancy too. Treatment approach of myelofibrosis has been changed these years, which gives a reason for this summary. Orv. Hetil., 2016, 157(39), 1547–1556.


Hematology ◽  
2013 ◽  
Vol 2013 (1) ◽  
pp. 529-537 ◽  
Author(s):  
Jason Gotlib

The discovery of the JAK2 V617F mutation in the classic BCR-ABL1–negative myeloproliferative neoplasms in 2005 catalyzed a burst of research efforts that have culminated in substantial dividends for patients. Beyond JAK2 V617F, a more detailed picture of the pathobiologic basis for activated JAK-STAT signaling has emerged. In some patients with myelofibrosis (MF), next-generation sequencing technologies have revealed a complex clonal architecture affecting both genetic and epigenetic regulators of cell growth and differentiation. Although these bench-top findings have informed the clinical development of JAK inhibitors in MF, they have also provided scientific context for some of their limitations. The JAK1/JAK2 inhibitor ruxolitinib is approved for treatment of MF in North America and Europe and other lead JAK inhibitors discussed herein (fedratinib [SAR302503], momelotinib [CYT387], and pacritinib [SB1518]), have entered advanced phases of trial investigation. Uniformly, these agents share the ability to reduce spleen size and symptom burden. A major challenge for practitioners is how to optimize dosing of these agents to secure clinically relevant and durable benefits while minimizing myelosuppression. Suboptimal responses have spurred a “return to the bench” to characterize the basis for disease persistence and to inform new avenues of drug therapy.


2019 ◽  
Vol 26 (10) ◽  
pp. 1806-1832 ◽  
Author(s):  
Francesca Musumeci ◽  
Chiara Greco ◽  
Ilaria Giacchello ◽  
Anna Lucia Fallacara ◽  
Munjed M. Ibrahim ◽  
...  

Janus kinases (JAKs) are a family of non-receptor tyrosine kinases, composed by four members, JAK1, JAK2, JAK3 and TYK2. JAKs are involved in different inflammatory and autoimmune diseases, as well as in malignancies, through the activation of the JAK/STAT signalling pathway. Furthermore, the V617F mutation in JAK2 was identified in patients affected by myeloproliferative neoplasms. This knowledge prompted researchers from academia and pharmaceutical companies to investigate this field in order to discover small molecule JAK inhibitors. These efforts recently afforded to the market approval of four JAK inhibitors. Despite the fact that all these drugs are pyrrolo[2,3-d]pyrimidine derivatives, many compounds endowed with different heterocyclic scaffolds have been reported in the literature as selective or multi-JAK inhibitors, and a number of them is currently being evaluated in clinical trials. In this review we will report many representative compounds that have been published in articles or patents in the last five years (period 2013-2017). The inhibitors will be classified on the basis of their chemical structure, focusing, when possible, on their structure activity relationships, selectivity and biological activity. For every class of derivatives, compounds disclosed before 2013 that have entered clinical trials will also be briefly reported, to underline the importance of a particular chemical scaffold in the search for new inhibitors.


Hematology ◽  
2014 ◽  
Vol 2014 (1) ◽  
pp. 277-286 ◽  
Author(s):  
Holly L. Geyer ◽  
Ruben A. Mesa

Abstract Myeloproliferative neoplasms, including polycythemia vera (PV), essential thrombocythemia, and myelofibrosis (MF) (both primary and secondary), are recognized for their burdensome symptom profiles, life-threatening complications, and risk of progression to acute leukemia. Recent advancements in our ability to diagnose and prognosticate these clonal malignancies have paralleled the development of MPN-targeted therapies that have had a significant impact on disease burden and quality of life. Ruxolitinib has shown success in alleviating the symptomatic burden, reducing splenomegaly and improving quality of life in patients with MF. The role and clinical expectations of JAK2 inhibition continues to expand to a variety of investigational arenas. Clinical trials for patients with MF focus on new JAK inhibitors with potentially less myelosuppression (pacritinib) or even activity for anemia (momelotinib). Further efforts focus on combination trials (including a JAK inhibitor base) or targeting new pathways (ie, telomerase). Similarly, therapy for PV continues to evolve with phase 3 trials investigating optimal frontline therapy (hydroxyurea or IFN) and second-line therapy for hydroxyurea-refractory or intolerant PV with JAK inhibitors. In this chapter, we review the evolving data and role of JAK inhibition (alone or in combination) in the management of patients with MPNs.


2018 ◽  
Vol 10 ◽  
pp. e2018058
Author(s):  
Emmanouil Spanoudakis ◽  
Menelaos Papoutselis ◽  
Ioanna Bazntiara ◽  
Eleftheria Lamprianidou ◽  
Xrisa Kordella ◽  
...  

JAK2V617F is a gain of function point mutation that occurs in Myeloproliferative Neoplasm (MPN) patients and deranges their hemopoiesis at cellular level. We speculate that hyperfunctioning JAK2 can modify osteoclast (OCL) homeostasis in MPN patients. We studied 18 newly diagnosed MPN patients and four age-matched normal donors (ND). Osteoclast forming assays started from selected monocytes also and under titrated concentrations of the JAK2 Inhibitor AG-490 (Tyrphostin). Genomic DNA was extracted from the formed osteoclasts, and the JAK2V617F/JAK2WT genomic DNA ratio was calculated. OCLs formed from monocytes derived from heterozygous (Het) for the JAK2V617F mutation MPN patients, were three times more compared to those from JAK2 wild type (WT) MPN patients (p=0,05) and from ND as well (p=0,03). The ratio of JAK2V617F/JAK2WT genomic DNA was increased in OCLs compared to the input monocyte cells showing a survival advantage of the mutated clone. In comparison to ND and JAK2 WT MPN patients, OCLs from patients JAK2V617F (Het) were more susceptible to JAK2 inhibition. These alterations in osteoclast homeostasis, attributed to mutated JAK2, can deregulate the hemopoietic stem cell niche in MPN patients.


2017 ◽  
Vol 55 ◽  
pp. S63
Author(s):  
F.M. Hernández Mohedo ◽  
J. Falantes González ◽  
J. Sanchez García ◽  
A. Medina Pérez ◽  
M. Expósito Ruiz ◽  
...  

Hematology ◽  
2017 ◽  
Vol 2017 (1) ◽  
pp. 470-479 ◽  
Author(s):  
Jyoti Nangalia ◽  
Anthony R. Green

Abstract Substantial progress has been made in our understanding of the pathogenetic basis of myeloproliferative neoplasms. The discovery of mutations in JAK2 over a decade ago heralded a new age for patient care as a consequence of improved diagnosis and the development of therapeutic JAK inhibitors. The more recent identification of mutations in calreticulin brought with it a sense of completeness, with most patients with myeloproliferative neoplasm now having a biological basis for their excessive myeloproliferation. We are also beginning to understand the processes that lead to acquisition of somatic mutations and the factors that influence subsequent clonal expansion and emergence of disease. Extended genomic profiling has established a multitude of additional acquired mutations, particularly prevalent in myelofibrosis, where their presence carries prognostic implications. A major goal is to integrate genetic, clinical, and laboratory features to identify patients who share disease biology and clinical outcome, such that therapies, both existing and novel, can be better targeted.


Hematology ◽  
2017 ◽  
Vol 2017 (1) ◽  
pp. 480-488 ◽  
Author(s):  
Alessandro M. Vannucchi ◽  
Paola Guglielmelli

Abstract Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic myeloproliferative neoplasms that are characterized by thrombohemorrhagic complications, symptom burden, and impaired survival mainly due to thrombosis, progression to myelofibrosis, and transformation to acute leukemia. In this manuscript, we will review the most recent changes in diagnostic criteria, the improvements in risk stratification, and the “state of the art” in the daily management of these disorders. The role of conventional therapies and novel agents, interferon α and the JAK2 inhibitor ruxolitinib, is critically discussed based on the results of a few basic randomized clinical studies. Several unmet needs remain, above all, the lack of a curative approach that might overcome the still burdensome morbidity and mortality of these hematologic neoplasms, as well as the toxicities associated with therapeutic agents.


Blood ◽  
2020 ◽  
Vol 135 (3) ◽  
pp. 191-207 ◽  
Author(s):  
Lanzhu Yue ◽  
Vasundhara Sharma ◽  
Nathan P. Horvat ◽  
Afua A. Akuffo ◽  
Matthew S. Beatty ◽  
...  

Abstract Protein acetylation is an important contributor to cancer initiation. Histone deacetylase 6 (HDAC6) controls JAK2 translation and protein stability and has been implicated in JAK2-driven diseases best exemplified by myeloproliferative neoplasms (MPNs). By using novel classes of highly selective HDAC inhibitors and genetically deficient mouse models, we discovered that HDAC11 rather than HDAC6 is necessary for the proliferation and survival of oncogenic JAK2-driven MPN cells and patient samples. Notably, HDAC11 is variably expressed in primitive stem cells and is expressed largely upon lineage commitment. Although Hdac11is dispensable for normal homeostatic hematopoietic stem and progenitor cell differentiation based on chimeric bone marrow reconstitution, Hdac11 deficiency significantly reduced the abnormal megakaryocyte population, improved splenic architecture, reduced fibrosis, and increased survival in the MPLW515L-MPN mouse model during primary and secondary transplantation. Therefore, inhibitors of HDAC11 are an attractive therapy for treating patients with MPN. Although JAK2 inhibitor therapy provides substantial clinical benefit in MPN patients, the identification of alternative therapeutic targets is needed to reverse MPN pathogenesis and control malignant hematopoiesis. This study establishes HDAC11 as a unique type of target molecule that has therapeutic potential in MPN.


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