n-(cyanomethyl)-4-(2-((4-(4-morpholinyl)phenyl)amino)-4-pyrimidinyl)benzamide and Myeloproliferative-Disorders

Ruxolitinib is the first FDA-approved JAK inhibitor for the treatment of myeloproliferative neoplasms and is an effective means of controlling symptom burden and improving splenomegaly. However, a majority of patients will develop disease progression with long-term use. Fedratinib, momelotinib, and pacritinib are three newer-generation JAK inhibitors being prospectively evaluated and we will discuss their roles in the treatment of myeloproliferative neoplasms.. Fedratinib has a role in both JAK-inhibitor naive intermediate-/high-risk myelofibrosis patients and in patients that have previously received ruxolitinib. It has recently received FDA approval for these indications as well. Momelotinib does not appear to have an advantage over ruxolitinib with regards to improving splenomegaly in intermediate-/high-risk JAK-inhibitor naive myelofibrosis. However, increased rates of transfusion independence have been noted with momelotinib. Pacritinib has been studied in myelofibrosis patients with significant baseline anemia and thrombocytopenia; these trials support the use of pacritinib in myelofibrosis patients with significant thrombocytopenia. While ruxolitinib is effective in reducing the symptom burden and splenomegaly of patients with myeloproliferative neoplasms, a majority of patients will ultimately progress on therapy. Newer-generation JAK inhibitors including fedratinib, momelotinib, and pacritinib are being prospectively evaluated to determine their appropriate roles in the management of myeloproliferative neoplasms. In addition, both combination therapies with JAK inhibitors and novel investigational therapies are being actively explored.

Topics: Antineoplastic Combined Chemotherapy Protocols; Benzamides; Biomarkers; Bridged-Ring Compounds; Clinical Trials as Topic; Disease Management; Disease Progression; Disease Susceptibility; Humans; Janus Kinase Inhibitors; Molecular Targeted Therapy; Myeloproliferative Disorders; Pyrimidines; Pyrrolidines; Sulfonamides; Treatment Outcome

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

Topics: Benzamides; Bridged-Ring Compounds; Clinical Trials as Topic; Fusion Proteins, bcr-abl; Humans; Janus Kinase Inhibitors; Myeloproliferative Disorders; Nitriles; Polycythemia Vera; Primary Myelofibrosis; Pyrazoles; Pyrimidines; Thrombocythemia, Essential

Myelofibrosis (MF) is a chronic malignancy of the blood-forming system caused by hyperactivation of JAK2/STAT signaling pathway. Small-molecule inhibitors of JAK2 can variably ameliorate MF-related symptoms caused by chronic inflammation and hepatosplenomegaly. Anemia is a significant problem and adverse prognostic factor in over a third of MF patients and is often worsened by JAK2 inhibitors. The JAK1/2 inhibitor momelotinib unexpectedly resulted in reduction of anemia in MF patients during Phase I/II trials. Current Phase III trials will be the basis for seeking regulatory approval of momelotinib during 2017. Studies to determine how momelotinib improves anemia are underway, potentially leading to expanded momelotinib use and/or development of other targeted therapies for treating anemia in MF and related diseases.

Topics: Anemia; Antineoplastic Agents; Benzamides; Clinical Trials as Topic; Drug Discovery; Humans; Janus Kinase 1; Janus Kinase 2; Myeloproliferative Disorders; Primary Myelofibrosis; Prognosis; Protein Kinase Inhibitors; Pyrimidines; Signal Transduction; Treatment Outcome

Individualized medicine is important for patients with myeloproliferative neoplasms (MPNs), including essential thrombocythemia, polycythemia vera, and myelofibrosis, which are heterogeneous in terms of genetic mutation profile, prognosis, disease burden, and symptoms. Status of MPN driver mutations in JAK2, CALR, and MPL (or lack of one of these mutations) and other myeloid mutations (ASXL1, SRSF2, CBL, and IDH1/2, among others) affects diagnosis and prognosis. Management begins with estimating the prognosis, disease burden including MPN symptoms, and prevention of vascular events. Allogeneic stem cell transplantation is the definitive therapy in a subset of patients with myelofibrosis, the majority of whom receive JAK inhibition with ruxolitinib to relieve splenomegaly and symptoms and to prolong survival. Ruxolitinib is now a second-line therapy in polycythemia vera, with pegylated interferon being evaluated as a potential front-line therapy compared with hydroxyurea. The therapeutic landscape is evolving to include new JAK inhibitors, which may affect cytopenias (pacritinib and momelotinib), combination therapies including ruxolitinib, and novel targets such as pentraxin and telomerase. Assessing the therapeutic efficacy (including symptom impact) and toxicity of these new approaches is necessary to determine longitudinal management of MPNs in clinical practice and is a key component of "individualizing" care for patients with MPNs.

Topics: Adenylate Kinase; Benzamides; Bridged-Ring Compounds; Humans; Janus Kinase 2; Myeloproliferative Disorders; Polycythemia Vera; Precision Medicine; Primary Myelofibrosis; Pyrimidines; Stem Cell Transplantation; Thrombocythemia, Essential; Transplantation, Homologous

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.

Topics: Antineoplastic Combined Chemotherapy Protocols; Benzamides; Bridged-Ring Compounds; Clinical Trials, Phase III as Topic; Drug Delivery Systems; Hematologic Neoplasms; Humans; Janus Kinase 2; Myeloproliferative Disorders; Neoplasm Proteins; Nitriles; Pyrazoles; Pyrimidines; Quality of Life

In 2005, the description of the JAK2V617F mutation for the first time provided a molecular key to enable more rapid diagnosis and target for novel therapeutics in the myeloproliferative neoplasms. In 2007, the first-in-class agent INC18424, ruxolitinib, JAKafi, or JAKAVI was first tested in patients with intermediate-risk 2 or high-risk myelofibrosis regardless of whether they possessed the JAK2V617F mutation. Patients treated with this agent had major reduction in splenomegaly as well as impressive reduction, and in some cases resolution, of symptoms. This study was followed by the two Controlled Myelofibrosis Study with Oral JAK Inhibitor Therapy (COMFORT) trials (the first-ever phase III trials in myelofibrosis), which confirmed results in these aspects were superior to either placebo or standard care, and updated results show a survival advantage with this therapy. This paper discusses these results and data from other JAK inhibitors while speculating on the future of these therapies. It also reflects on the fact that the true targets and agents' mode of action are uncertain. Unlike targeted therapy for chronic myeloid leukemia (CML), these agents do not deliver molecular remission, and it is not clear whether their predominant benefit is mediated via JAK2, JAK1, or both. Nonetheless, the advent of the JAK inhibitor is a welcome advance and has made a dramatic improvement to the therapeutic landscape of these conditions.

Topics: Benzamides; Bridged-Ring Compounds; Humans; Janus Kinase 1; Janus Kinase 2; Molecular Targeted Therapy; Mutation; Myeloproliferative Disorders; Nitriles; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines; Pyrrolidines; Sulfonamides

Myeloproliferative neoplasms (MPNs) are diseases that carry the JAK2 (V617F) mutation in about 70% of the patients. The purpose of this review is to describe the recent advances in the therapy of MPNs with JAK2 inhibitors.. Many drugs are now under investigations targeting different pathways critical for MPN development, such as the JAK-STAT (JAK2 inhibitors: INCB018424 or ruxolitinib, TG101348 or SAR302503, CYT387, SB1518, CEP701 and LY2784544) and the PI3K/AKT/mTOR (everolimus) pathways, or act through remodeling of chromatin with a key role in epigenetics (givinostat, panobinostat and vorinostat). The most relevant effects were spleen size reduction and relief of constitutional symptoms.. Patients who might benefit from JAK2 inhibitors in clinical practice are mostly those with splenomegaly or with constitutional symptoms. We should alert patients with lower hemoglobin levels that these therapies might, although temporarily, favor the need for red blood cell transfusions.

Topics: Animals; Benzamides; Clinical Trials as Topic; Disease Models, Animal; Drug Evaluation, Preclinical; Humans; Janus Kinase 2; Janus Kinases; Mice; Myeloproliferative Disorders; Nitriles; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines; Pyrrolidines; Sulfonamides

Discovery of the JAK2 V617F mutation in the myeloproliferative neoplasms (MPNs) essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF) has stimulated great interest in the underlying molecular mechanisms and treatment of these diseases. Along with acceleration of technologies, novel mutations in genes such as MPL, LNK, and CBL have been discovered that converge on the JAK-STAT pathway. Several additional novel mutations in genes involved in epigenetic regulation of the genome, including TET2, ASXL1, DNMT3A, and IDH1/2, have emerged, in addition to several mutations in cellular splicing machinery. While understanding of the pathogenetic mechanisms of these novel mutations in MPNs has improved, it is still lagging behind the pace of mutation discovery. Concurrent with molecular discoveries, especially with regard to JAK-STAT signaling, therapeutic development has accelerated in recent years. More than ten JAK kinase inhibitors have been advanced into clinical trials. Recently the first JAK2 inhibitor was approved for use in patients with PMF. Most JAK-targeting agents share similar characteristics with regard to clinical benefit, consisting of improvements in splenomegaly, constitutional symptoms, and cytopenias, for example. It remains to be determined if JAK2 inhibitors can considerably impact disease progression and bone marrow histologic features (e.g., fibrosis) or significantly impact the JAK2 allele burden. While JAK2 inhibitors appear to be promising in PV and ET, they need to be compared with standard therapies, such as hydroxyurea or interferon-based therapies. Future clinical development will focus on optimal combination partners and agents that target alternative mechanisms, deepen the response, and achieve molecular remissions.

Topics: Adaptor Proteins, Signal Transducing; Alleles; Benzamides; Bridged-Ring Compounds; Carbazoles; Chromatin; Dioxygenases; DNA (Cytosine-5-)-Methyltransferases; DNA Methyltransferase 3A; DNA-Binding Proteins; Enhancer of Zeste Homolog 2 Protein; Epigenesis, Genetic; Furans; Gene Expression Regulation; Humans; Ikaros Transcription Factor; Intracellular Signaling Peptides and Proteins; Isocitrate Dehydrogenase; Janus Kinase 2; Mutation; Myeloproliferative Disorders; Nitriles; Polycomb Repressive Complex 2; Proteins; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-cbl; Pyrazoles; Pyrimidines; Pyrrolidines; Receptors, Thrombopoietin; Repressor Proteins; Signal Transduction; Spliceosomes; Sulfonamides

The discovery of JAK2V617F and other JAK-STAT-activating mutations in BCR-ABL1-negative myeloproliferative neoplasms (MPN) has led to the development of small-molecule ATP-mimetics that inhibit wild-type and mutant JAK. Here, we review the current experience with JAK inhibitors used for the treatment of myelofibrosis and polycythemia vera/essential thrombocythemia.. Consistent with the clonal complexity of MPN, JAK inhibitors have not thus far shown disease-modifying activity; treatment with these agents has however shown clinically meaningful benefits, particularly decreased splenomegaly and improvement in constitutional symptoms, in myelofibrosis patients. Although these benefits accrue with both JAK-2 (TG101348) and JAK-1/2 (INCB018424, CYT387) inhibitors, the mode of action (predominant anticlonal versus anticytokine activity) may be different between the two groups. It is possible that an optimal balance between JAK-1-inhibitory and JAK-2-inhibitory activities may broaden the therapeutic activity (i.e. anemia improvement), as has been preliminarily seen (CYT387).. Although JAK inhibitors have important benefits in myelofibrosis therapy, their role in polycythemia vera/essential thrombocythemia treatment is still being defined. The optimal dosing strategy and feasibility for combination with other therapeutic agents remains to be established. Another challenge is the identification of robust primary end-points that will support labeling claims for JAK inhibitors for the aforementioned indications.

Topics: Benzamides; Humans; Janus Kinase 2; Mutation; Myeloproliferative Disorders; Nitriles; Polycythemia Vera; Primary Myelofibrosis; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines; Pyrrolidines; Sulfonamides; Thrombocythemia, Essential

Janus kinase (JAK) 2 inhibitors are now part of the therapeutic armamentarium for primary and secondary myelofibrosis (MF). Patients with MF endure shortened survival and poor quality of life. Allogeneic stem cell transplantation (ASCT) is currently the only treatment modality in MF with the potential to cure the disease or prolong survival. By contrast, current drug therapy in MF targets quality of life and does not modify the natural history of the disease. The discovery of JAK2 and other JAK-STAT activating mutations (i.e., CALR and MPL) in myeloproliferative neoplasms, including MF, has facilitated the development of several JAK inhibitors that are not necessarily specific to the oncogenic mutations themselves but have proven effective in countering JAK-STAT signaling, resulting in suppression of inflammatory cytokines and myeloproliferation. This non-specific activity resulted in clinically favorable effects on constitutional symptoms and splenomegaly and, consequently, approval by the Food and Drug Administration (FDA) of three small molecule JAK inhibitors: ruxolitinib, fedratinib, and pacritinib. A fourth JAK inhibitor, momelotinib, is poised for FDA approval soon and has been shown to provide additional benefit in alleviating transfusion-dependent anemia in MF. The salutary effect of momelotinib on anemia has been attributed to inhibition of activin A receptor, type 1 (ACVR1) and recent information suggests a similar effect from pacritinib. ACRV1 mediates SMAD2/3 signaling which contributes to upregulation of hepcidin production and iron-restricted erythropoiesis. Targeting ACRV1 raises therapeutic prospects in other myeloid neoplasms associated with ineffective erythropoiesis, such as myelodysplastic syndromes with ring sideroblasts or SF3B1 mutation, especially those with co-expression of a JAK2 mutation and thrombocytosis.

Topics: Activin Receptors, Type I; Anemia; Humans; Janus Kinase 2; Janus Kinase Inhibitors; Myeloproliferative Disorders; Neoplasms; Nitriles; Primary Myelofibrosis; Protein Kinase Inhibitors; Quality of Life

Small molecule inhibitors targeting JAK2 provide symptomatic benefits for myeloproliferative neoplasm (MPN) patients and are among first-line therapeutic agents. However, despite all having potent capacity to suppress JAK-STAT signaling, they demonstrate distinct clinical profiles suggesting contributory effects in targeting other ancillary pathways. Here, we performed comprehensive profiling on four JAK2 inhibitors either FDA-approved (ruxolitinib, fedratinib, and pacritinib) or undergoing phase 3 studies (momelotinib) to better outline mechanistic and therapeutic efficacy. Across JAK2-mutant in vitro models, all four inhibitors demonstrated similar anti-proliferative phenotypes, whereas pacritinib yielded greatest potency on suppressing colony formation in primary samples, while momelotinib exhibited unique erythroid colony formation sparing. All inhibitors reduced leukemic engraftment, disease burden, and extended survival across patient-derived xenograft (PDX) models, with strongest effects elicited by pacritinib. Through RNA-sequencing and gene set enrichment analyses, differential suppressive degrees of JAK-STAT and inflammatory response signatures were revealed, which we validated with signaling and cytokine suspension mass cytometry across primary samples. Lastly, we assessed the capacity of JAK2 inhibitors to modulate iron regulation, uncovering potent suppression of hepcidin and SMAD signaling by pacritinib. These comparative findings provide insight into the differential and beneficial effects of ancillary targeting beyond JAK2 and may help guide the use of specific inhibitors in personalized therapy.

Topics: Bone Marrow Neoplasms; Humans; Janus Kinase 2; Janus Kinase Inhibitors; Myeloproliferative Disorders; Protein Kinase Inhibitors

Topics: Animals; Benzamides; Cells, Cultured; Disease Models, Animal; Graft vs Host Disease; Humans; Janus Kinases; Mice; Mice, Inbred BALB C; Myeloproliferative Disorders; Protein Kinase Inhibitors; Pyrimidines; T-Lymphocytes

Although clinically tested JAK inhibitors reduce splenomegaly and systemic symptoms, molecular responses are not observed in most myeloproliferative neoplasm (MPN) patients. We previously demonstrated that MPN cells become persistent to type I JAK inhibitors that bind the active conformation of JAK2. We investigated whether CHZ868, a type II JAK inhibitor, would demonstrate activity in JAK inhibitor persistent cells, murine MPN models, and MPN patient samples. JAK2 and MPL mutant cell lines were sensitive to CHZ868, including type I JAK inhibitor persistent cells. CHZ868 showed significant activity in murine MPN models and induced reductions in mutant allele burden not observed with type I JAK inhibitors. These data demonstrate that type II JAK inhibition is a viable therapeutic approach for MPN patients.

Topics: Animals; Antineoplastic Agents; Benzamides; Cell Line, Tumor; Cell Proliferation; Humans; Janus Kinase 2; Mice; Mice, Inbred C57BL; Molecular Sequence Data; Mutation; Myeloproliferative Disorders; Protein Kinase Inhibitors; Pyrimidines; Receptors, Thrombopoietin; Sequence Analysis, RNA; Signal Transduction; Xenograft Model Antitumor Assays

The BCR-ABL-negative myeloproliferative neoplasms (MPNs) include essential thrombocythemia, polycythemia vera, and primary myelofibrosis. Historically, complex biochemical alterations defining these heterogeneously distinct malignancies have remained elusive and constrained available therapy options. The discovery of Janus kinase (JAK) mutations collectively present in BCR-ABL-negative MPNs has led to a resurgence of medical interest in JAK-STAT targeted treatment modalities, as well as provided a unique platform for inhibiting symptom-directing proinflammatory cytokines. INCB018424, CYT387, SB1518, and TG101348 are among the most propitious JAK2 inhibitors under investigation, providing substantial improvement in constitutional symptoms, transfusion-dependent cytopenias, and reduction in spleen size. Despite their attributes, evidence of complete or partial remission has yet to be observed with therapy. Many uncertainties surrounding the full clinical potential of JAK2 inhibitors persist. Treatment guidelines addressing optimal stages for drug implementation, ideal dosing parameters and criteria for medication continuation/withdrawal may effectively resolve these ongoing concerns and provide advancements in the morbidity and mortality of these multifaceted disease processes.

Topics: Animals; Benzamides; Bridged-Ring Compounds; Carbazoles; Furans; Humans; Janus Kinase 2; Myeloproliferative Disorders; Nitriles; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines; Pyrrolidines; Sulfonamides

Activating alleles of Janus kinase 2 (JAK2) such as JAK2(V617F) are central to the pathogenesis of myeloproliferative neoplasms (MPN), suggesting that small molecule inhibitors targeting JAK2 may be therapeutically useful. We have identified an aminopyrimidine derivative (CYT387), which inhibits JAK1, JAK2, and tyrosine kinase 2 (TYK2) at low nanomolar concentrations, with few additional targets. Between 0.5 and 1.5muM CYT387 caused growth suppression and apoptosis in JAK2-dependent hematopoietic cell lines, while nonhematopoietic cell lines were unaffected. In a murine MPN model, CYT387 normalized white cell counts, hematocrit, spleen size, and restored physiologic levels of inflammatory cytokines. Despite the hematologic responses and reduction of the JAK2(V617F) allele burden, JAK2(V617F) cells persisted and MPN recurred upon cessation of treatment, suggesting that JAK2 inhibitors may be unable to eliminate JAK2(V617F) cells, consistent with preliminary results from clinical trials of JAK2 inhibitors in myelofibrosis. While the clinical benefit of JAK2 inhibitors may be substantial, not the least due to reduction of inflammatory cytokines and symptomatic improvement, our data add to increasing evidence that kinase inhibitor monotherapy of malignant disease is not curative, suggesting a need for drug combinations to optimally target the malignant cells.

Topics: Animals; Apoptosis; Benzamides; Cell Line, Tumor; Cytokines; Disease Models, Animal; Drug Screening Assays, Antitumor; Hematologic Neoplasms; Hematopoiesis; Janus Kinase 1; Janus Kinase 2; Mice; Mice, Inbred BALB C; Mutation, Missense; Myeloproliferative Disorders; Protein Kinase Inhibitors; Pyrimidines