Effects of Tulp4 deficiency on murine embryonic development and adult phenotype.

Genetically engineered mouse models have the potential to unravel fundamental biological processes and provide mechanistic insights into the pathogenesis of human diseases. We have previously observed that germline genetic variation at the TULP4 locus influences clinical characteristics in patients with myeloproliferative neoplasms. To elucidate the role of TULP4 in pathological and physiological processes in vivo, we generated a Tulp4 knockout mouse model.

Phenotypic characterization of disease-initiating stem cells in JAK2- or CALR-mutated myeloproliferative neoplasms.

Myeloproliferative neoplasms (MPN) are characterized by uncontrolled expansion of myeloid cells, disease-related mutations in certain driver-genes including JAK2, CALR, and MPL, and a substantial risk to progress to secondary acute myeloid leukemia (sAML). Although behaving as stem cell neoplasms, little is known about disease-initiating stem cells in MPN. We established the phenotype of putative CD34 /CD38 stem cells and CD34 /CD38 progenitor cells in MPN.

Secreted mutant calreticulins as rogue cytokines in myeloproliferative neoplasms.

Mutant calreticulin (CALR) proteins resulting from a -1/+2 frameshifting mutation of the CALR exon 9 carry a novel C-terminal amino acid sequence and drive the development of myeloproliferative neoplasms (MPNs). Mutant CALRs were shown to interact with and activate the thrombopoietin receptor (TpoR/MPL) in the same cell. We report that mutant CALR proteins are secreted and can be found in patient plasma at levels up to 160 ng/mL, with a mean of 25.

PD-L1 overexpression correlates with JAK2-V617F mutational burden and is associated with 9p uniparental disomy in myeloproliferative neoplasms.

Myeloproliferative neoplasms (MPN) are chronic stem cell disorders characterized by enhanced proliferation of myeloid cells, immune deregulation, and drug resistance. JAK2 somatic mutations drive the disease in 50-60% and CALR mutations in 25-30% of cases. Published data suggest that JAK2-V617F-mutated MPN cells express the resistance-related checkpoint PD-L1.

High-throughput drug screening identifies the ATR-CHK1 pathway as a therapeutic vulnerability of CALR mutated hematopoietic cells.

Mutations of calreticulin (CALR) are the second most prevalent driver mutations in essential thrombocythemia and primary myelofibrosis. To identify potential targeted therapies for CALR mutated myeloproliferative neoplasms, we searched for small molecules that selectively inhibit the growth of CALR mutated cells using high-throughput drug screening. We investigated 89 172 compounds using isogenic cell lines carrying CALR mutations and identified synthetic lethality with compounds targeting the ATR-CHK1 pathway.

Hematopoietic expression of a chimeric murine-human CALR oncoprotein allows the assessment of anti-CALR antibody immunotherapies in vivo.

Myeloproliferative neoplasms (MPNs) are characterized by a pathologic expansion of myeloid lineages. Mutations in JAK2, CALR and MPL genes are known to be three prominent MPN disease drivers. Mutant CALR (mutCALR) is an oncoprotein that interacts with and activates the thrombopoietin receptor (MPL) and represents an attractive target for targeted therapy of CALR mutated MPN.

Multimodality imaging beyond CLEM: Showcases of combined in-vivo preclinical imaging and ex-vivo microscopy to detect murine mural vascular lesions.

In imaging, penetration depth comes at the expense of lateral resolution, which restricts the scope of 3D in-vivo imaging of small animals at micrometer resolution. Bioimaging will need to expand beyond correlative light and electron microscopy (CLEM) approaches to combine insights about in-vivo dynamics in a physiologically relevant 3D environment with ex-vivo information at micrometer resolution (or beyond) within the spatial, structural and biochemical contexts. Our report demonstrates the immense potential for biomedical discovery and diagnosis made available by bridging preclinical in-vivo imaging with ex-vivo biological microscopy to zoom in from the whole organism to individual structures and by adding localized spectroscopic information to structural and functional information.

Precision Medicine in Hematology 2021: Definitions, Tools, Perspectives, and Open Questions.

During the past few years, our understanding of molecular mechanisms and cellular interactions relevant to malignant blood cell disorders has improved substantially. New insights include a detailed knowledge about disease-initiating exogenous factors, endogenous (genetic, somatic, epigenetic) elicitors or facilitators of disease evolution, and drug actions and interactions that underlie efficacy and adverse event profiles in defined cohorts of patients. As a result, precision medicine and personalized medicine are rapidly growing new disciplines that support the clinician in making the correct diagnosis, in predicting outcomes, and in optimally selecting patients for interventional therapies.

5-Arylidene-2-(4-hydroxyphenyl)aminothiazol-4(5H)-ones with selective inhibitory activity against some leukemia cell lines.

The data on the pharmacology of 4-thiazolidinones showed that 5-ene-2-(imino)amino-4-thiazolidinones are likely to comprise one of the most promising groups of compounds possessing anticancer properties. A series of 5-arylidene-2-(4-hydroxyphenyl)aminothiazol-4(5H)-ones was designed, synthesized, and studied against 10 leukemia cell lines, including the HL-60, Jurkat, K-562, Dami, KBM-7, and some Ba/F3 cell lines. The structure-activity relationship analysis shows that almost all tested 5-arylidene-2-(4-hydroxyphenyl)aminothiazol-4(5H)-ones were characterized by ІС values lower or comparable to that of the control drug chlorambucil.

Hematoxylin binds to mutant calreticulin and disrupts its abnormal interaction with thrombopoietin receptor.

Somatic mutations of calreticulin (CALR) have been identified as a main disease driver of myeloproliferative neoplasms, suggesting that development of drugs targeting mutant CALR is of great significance. Site-directed mutagenesis in the N-glycan binding domain (GBD) abolishes the ability of mutant CALR to oncogenically activate the thrombopoietin receptor (MPL). We therefore hypothesized that a small molecule targeting the GBD might inhibit the oncogenicity of the mutant CALR.

Myelomonocytic Skewing In Vitro Discriminates Subgroups of Patients with Myelofibrosis with A Different Phenotype, A Different Mutational Profile and Different Prognosis.

Normal hematopoietic function is maintained by a well-controlled balance of myelomonocytic, megaerythroid and lymphoid progenitor cell populations which may be skewed during pathologic conditions. Using semisolid in vitro cultures supporting the growth of myelomonocytic (CFU-GM) and erythroid (BFU-E) colonies, we investigated skewed differentiation towards the myelomonocytic over erythroid commitment in 81 patients with myelofibrosis (MF). MF patients had significantly increased numbers of circulating CFU-GM and BFU-E.

Germline genetic factors influence the outcome of interferon-α therapy in polycythemia vera.

Interferon-α (IFN-α)-based treatments can induce hematologic and molecular responses (HRs and MRs, respectively) in polycythemia vera (PV); however, patients do not respond equally. Germline genetic factors have been implicated in differential drug responses. We addressed the effect of common germline polymorphisms on HR and MR after treatment of PV in the PROUD-PV and CONTINUATION-PV studies in a total of 122 patients who received ropeginterferon alfa-2b.

STAT5 is Expressed in CD34/CD38 Stem Cells and Serves as a Potential Molecular Target in Ph-Negative Myeloproliferative Neoplasms.

Janus kinase 2 (JAK2) and signal transducer and activator of transcription-5 (STAT5) play a key role in the pathogenesis of myeloproliferative neoplasms (MPN). In most patients, V617F or mutations are found and lead to activation of various downstream signaling cascades and molecules, including STAT5. We examined the presence and distribution of phosphorylated (p) STAT5 in neoplastic cells in patients with MPN, including polycythemia vera (PV, = 10), essential thrombocythemia (ET, = 15) and primary myelofibrosis (PMF, = 9), and in the V617F-positive cell lines HEL and SET-2.

Ropeginterferon alfa-2b versus standard therapy for polycythaemia vera (PROUD-PV and CONTINUATION-PV): a randomised, non-inferiority, phase 3 trial and its extension study.

Background: The PROUD-PV and CONTINUATION-PV trials aimed to compare the novel monopegylated interferon ropeginterferon alfa-2b with hydroxyurea, the standard therapy for patients with polycythaemia vera, over 3 years of treatment.

Methods: PROUD-PV and its extension study, CONTINUATION-PV, were phase 3, randomised, controlled, open-label, trials done in 48 clinics in Europe. Patients were eligible if 18 years or older with early stage polycythaemia vera (no history of cytoreductive treatment or less than 3 years of previous hydroxyurea treatment) diagnosed by WHO's 2008 criteria.

Progress in elucidation of molecular pathophysiology of myeloproliferative neoplasms and its application to therapeutic decisions.

Myeloproliferative neoplasms (MPNs) are hematological diseases that are driven by somatic mutations in hematopoietic stem and progenitor cells. These mutations include JAK2, CALR and MPL mutations as the main disease drivers, mutations driving clonal expansion, and mutations that contribute to progression of chronic MPNs to myelodysplasia and acute leukemia. JAK-STAT pathway has played a central role in the disease pathogenesis of MPNs.