Preclinical efficacy of CDK7 inhibitor-based combinations against myeloproliferative neoplasms transformed to AML.

Rising blast-percentage or secondary (s) AML transformation (sAML) in MPNs leads to JAK inhibitor (JAKi) therapy-resistance and poor survival. Here, we demonstrate that the CDK7 inhibitor (CDK7i) SY-5609 treatment depletes phenotypically-characterized post-MPN-sAML stem/progenitor cells. In the cultured post-MPN sAML SET2 and HEL as well as patient-derived (PD) post-MPN-sAML cells, SY-5609 treatment inhibited growth and induced lethality, while sparing normal cells.

Safety and efficacy of zinpentraxin alfa as monotherapy or in combination with ruxolitinib in myelofibrosis: stage I of a phase II trial.

Pentraxin 2 (PTX-2; serum amyloid P component), a circulating endogenous regulator of the inflammatory response to tissue injury and fibrosis, is reduced in patients with myelofibrosis (MF). Zinpentraxin alfa (RO7490677, PRM-151) is a recombinant form of PTX-2 that has shown preclinical antifibrotic activity and no dose-limiting toxicities in phase I trials. We report results from stage 1 of a phase II trial of zinpentraxin alfa in patients with intermediate-1/2 or high-risk MF.

GLI1 activates pro-fibrotic pathways in myelofibrosis fibrocytes.

Bone marrow (BM) fibrosis was thought to be induced exclusively by mesenchymal stromal cells (MSCs). However, we and others found that neoplastic fibrocytes induce BM fibrosis in myelofibrosis (MF). Because glioma-associated oncogene-1 (GLI1), an effector of the Hedgehog pathway, plays a role in the induction of BM fibrosis, we wondered whether GLI1 affects fibrocyte-induced BM fibrosis in MF.

STAT3 Activates the Pentraxin 3 Gene in Chronic Lymphocytic Leukemia Cells.

Pentraxin-related protein 3 (PTX3), commonly produced by myeloid and endothelial cells, is a humoral pattern recognition protein of the innate immune system. Because PTX3 plasma levels of patients with chronic lymphocytic leukemia (CLL) are high and most circulating cells in patients with CLL are CLL cells, we reasoned that CLL cells produce PTX3. Western immunoblotting revealed that low-density cells from seven of seven patients with CLL produce high levels of PTX3, flow cytometry analysis revealed that the PTX3-producing cells are B lymphocytes coexpressing CD19 and CD5, and confocal microscopy showed that PTX3 is present in the cytoplasm of CLL cells.

Superior efficacy of co-targeting GFI1/KDM1A and BRD4 against AML and post-MPN secondary AML cells.

There is an unmet need to overcome nongenetic therapy-resistance to improve outcomes in AML, especially post-myeloproliferative neoplasm (MPN) secondary (s) AML. Studies presented describe effects of genetic knockout, degradation or small molecule targeted-inhibition of GFI1/LSD1 on active enhancers, altering gene-expressions and inducing differentiation and lethality in AML and (MPN) sAML cells. A protein domain-focused CRISPR screen in LSD1 (KDM1A) inhibitor (i) treated AML cells, identified BRD4, MOZ, HDAC3 and DOT1L among the codependencies.

Altered T-cell subset repertoire affects treatment outcome of patients with myelofibrosis.

Phenotypic characterization of T cells in myelofibrosis (MF) is intriguing owing to increased inflammation, markedly elevated pro-inflammatory cytokines, and altered distribution of T-cell subsets. Constitutive activation of Janus kinase-2 (JAK2) in the majority of MF patients contributes to the expression of the programmed cell death protein-1 (PD1) and T-cell exhaustion. We wondered whether T-cell activation affects treatment outcome of patients with MF and sought to determine whether the JAK1/2 inhibitor ruxolitinib affects the activation of T-cell subsets.

Mechanistic basis and efficacy of targeting the β-catenin-TCF7L2-JMJD6-c-Myc axis to overcome resistance to BET inhibitors.

The promising activity of BET protein inhibitors (BETi's) is compromised by adaptive or innate resistance in acute myeloid leukemia (AML). Here, modeling of BETi-persister/resistance (BETi-P/R) in human postmyeloproliferative neoplasm (post-MPN) secondary AML (sAML) cells demonstrated accessible and active chromatin in specific superenhancers/enhancers, which was associated with increased levels of nuclear β-catenin, TCF7L2, JMJD6, and c-Myc in BETi-P/R sAML cells. Following BETi treatment, c-Myc levels were rapidly restored in BETi-P/R sAML cells.

miR-543 regulates the epigenetic landscape of myelofibrosis by targeting TET1 and TET2.

Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by cytopenia and extramedullary hematopoiesis, resulting in splenomegaly. Multiple pathological mechanisms (e.g.

Primary myelofibrosis marrow-derived CD14+/CD34- monocytes induce myelofibrosis-like phenotype in immunodeficient mice and give rise to megakaryocytes.

To confirm that neoplastic monocyte-derived collagen- and fibronectin-producing fibrocytes induce bone marrow (BM) fibrosis in primary myelofibrosis (PMF), we injected PMF BM-derived fibrocyte-precursor CD14+/CD34- monocytes into the tail vein of NOD-SCID-γ (NSG) mice. PMF BM-derived CD14+/CD34- monocytes engrafted and induced a PMF-like phenotype with splenomegaly, myeloid hyperplasia with clusters of atypical megakaryocytes, persistence of the JAK2V617F mutation, and BM and spleen fibrosis. As control we used normal human BM-derived CD14+/CD34- monocytes.

Myelofibrosis osteoclasts are clonal and functionally impaired.

Bone marrow (BM) sclerosis is commonly found in patients with late-stage myelofibrosis (MF). Because osteoclasts (OCs) and osteoblasts play a key role in bone remodeling, and MF monocytes, the OC precursors, are derived from the neoplastic clone, we wondered whether decreased OC numbers or impairment in their osteolytic function affects the development of osteosclerosis. Analysis of BM biopsies from 50 MF patients showed increased numbers of multinucleated tartrate-resistant acid phosphatase (TRAP)/cathepsin K OCs expressing phosphorylated Janus kinase 2 (JAK2).

Targeting nuclear β-catenin as therapy for post-myeloproliferative neoplasm secondary AML.

Transformation of post-myeloproliferative neoplasms into secondary (s) AML exhibit poor clinical outcome. In addition to increased JAK-STAT and PI3K-AKT signaling, post-MPN sAML blast progenitor cells (BPCs) demonstrate increased nuclear β-catenin levels and TCF7L2 (TCF4) transcriptional activity. Knockdown of β-catenin or treatment with BC2059 that disrupts binding of β-catenin to TBL1X (TBL1) depleted nuclear β-catenin levels.

Therapy-related myelofibrosis does not appear to exist.

There is no evidence to support the existence of therapy-related myelofibrosis.Therapy for previous malignancy has no impact on myelofibrosis prognosis.

JAK2 detection and allele burden measurement in saliva vs. peripheral blood in patients with myelofibrosis.

We previously demonstrated that peripheral blood (PB) is a reliable source for testing JAK2 mutation in patients with myelofibrosis (MF); saliva has also been tested to detect such mutation, however its diagnostic accuracy as compared to PB has not been validated. In this study, we prospectively tested 167 patients with MF for JAK2 mutation, using both saliva and PB collected at the same time from each patient. The concordance between the 2 sources was 96%, with a sensitivity of 100% and a specificity of 90%.

Clonal evolution and outcomes in myelofibrosis after ruxolitinib discontinuation.

Despite significant improvements in the signs and symptoms of myelofibrosis (MF), and possible prolongation of patients' survival, some have disease that is refractory to ruxolitinib and many lose their response over time. Furthermore, patients with ≥3 mutations are less likely to respond to ruxolitinib. Here we describe outcomes after ruxolitinib discontinuation in MF patients enrolled in a phase 1/2 study at our center.

Patients with post-essential thrombocythemia and post-polycythemia vera differ from patients with primary myelofibrosis.

Prognostic scoring systems for primary myelofibrosis (PMF) are not accurate in patients with post-essential thrombocythemia and post-polycythemia vera myelofibrosis (PET-MF; PPV-MF). Given the paucity of data describing the clinical characteristics, disease course and outcomes of these patients, we sought to describe and compare the clinical characteristics and outcomes of 755 patients with PMF, 181 with PPV-MF, and 163 with PET-MF referred to our institution between 1984 and 2013. The median follow-up was 31 months, and 56% (n=616) patients had died.

Novel BET protein proteolysis-targeting chimera exerts superior lethal activity than bromodomain inhibitor (BETi) against post-myeloproliferative neoplasm secondary (s) AML cells.

The PROTAC (proteolysis-targeting chimera) ARV-825 recruits bromodomain and extraterminal (BET) proteins to the E3 ubiquitin ligase cereblon, leading to degradation of BET proteins, including BRD4. Although the BET-protein inhibitor (BETi) OTX015 caused accumulation of BRD4, treatment with equimolar concentrations of ARV-825 caused sustained and profound depletion (>90%) of BRD4 and induced significantly more apoptosis in cultured and patient-derived (PD) CD34+ post-MPN sAML cells, while relatively sparing the CD34+ normal hematopoietic progenitor cells. RNA-Seq, Reverse Phase Protein Array and mass cytometry 'CyTOF' analyses demonstrated that ARV-825 caused greater perturbations in messenger RNA (mRNA) and protein expressions than OTX015 in sAML cells.

BET protein bromodomain inhibitor-based combinations are highly active against post-myeloproliferative neoplasm secondary AML cells.

Myeloproliferative neoplasms with myelofibrosis (MPN-MF) demonstrate constitutive activation of Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling that responds to treatment with the JAK1 and 2 kinase inhibitor (JAKi) ruxolitinib. However, MPN-MF often progresses (~20%) to secondary acute myeloid leukemia (sAML), where standard induction chemotherapy or ruxolitinib is relatively ineffective, necessitating the development of novel therapeutic approaches. In the present studies, we demonstrate that treatment with BET (bromodomain and extraterminal) protein inhibitor (BETi), for example, JQ1, inhibits growth and induces apoptosis of cultured and primary, patient-derived (PD), post-MPN sAML blast progenitor cells.

An accurate, simple prognostic model consisting of age, JAK2, CALR, and MPL mutation status for patients with primary myelofibrosis.

In most patients with primary myelofibrosis, one of three mutually exclusive somatic mutations is detected. In approximately 60% of patients, the Janus kinase 2 gene is mutated, in 20%, the calreticulin gene is mutated, and in 5%, the myeloproliferative leukemia virus gene is mutated. Although patients with mutated calreticulin or myeloproliferative leukemia genes have a favorable outcome, and those with none of these mutations have an unfavorable outcome, prognostication based on mutation status is challenging due to the heterogeneous survival of patients with mutated Janus kinase 2.