0000000000249454
AUTHOR
Daniel B. Lipka
showing 19 related works from this author
Wild-type JAK2 secondary acute erythroleukemia developing after JAK2-V617F-mutated primary myelofibrosis.
2009
A 54-year-old female patient developed acute erythroleukemia after an 8-year course of primary myelofibrosis. The latter harbors the JAK2-V617F mutation and was treated with hydroxyurea and anagrelide. A bone marrow trephine biopsy disclosed 2 morphologically distinct areas of chronic primary myelofibrosis and acute erythroleukemia. Microdissection and a separate molecular pathological analysis was performed. Although the activating JAK2-V617F mutation was not maintained in blasts of acute erythroleukemia, it was detectable in the chronic phase of primary myelofibrosis, indicating that this mutation did not play a role in the leukemic transformation of erythroid cells.
Novel pathway in Bcr-Abl signal transduction involves Akt-independent, PLC-γ1-driven activation of mTOR/p70S6-kinase pathway
2009
In chronic myeloid leukemia, activation of the phosphoinositide 3-kinase (PI3K)/Akt pathway is crucial for survival and proliferation of leukemic cells. Essential downstream molecules involve mammalian target of rapamycin (mTOR) and S6-kinase. Here, we present a comprehensive analysis of the molecular events involved in activation of these key signaling pathways. We provide evidence for a previously unrecognized phospholipase C-gamma1 (PLC-gamma1)-controlled mechanism of mTOR/p70S6-kinase activation, which operates in parallel to the classical Akt-dependent machinery. Short-term imatinib treatment of Bcr-Abl-positive cells caused dephosphorylation of p70S6-K and S6-protein without inactivat…
Bis(1H-indol-2-yl)methanones are effective inhibitors of FLT3-ITD tyrosine kinase and partially overcome resistance to PKC412A in vitro.
2009
Inhibition of the mutated fms-like tyrosine kinase 3 (FLT3) receptor tyrosine kinase is a promising therapeutic strategy in acute myeloid leukaemia (AML). However, development of resistance to FLT3 tyrosine kinase inhibitors (TKI), such as PKC412A, has been described recently. This observation may have an increasing impact on the duration of response and relapse rates in upcoming clinical trials employing FLT3-TKI. Herein we investigated two representatives of a novel class of FLT3-TKI: Bis(1H-indol-2-yl)methanones. Both compounds effectively induced apoptosis in FLT3-internal tandem duplicate (ITD)-transfected murine myeloid cells and in primary FLT3-ITD positive blasts. Combination of bot…
The JAK2 Kinase Inhibitor LS104 Induces Growth-Arrest and Apoptosis in JAK2V617F Positive Cells.
2007
Abstract The JAK2V617F-mutation (V617F) is a novel, highly prevalent molecular marker in Ph-negative myeloproliferative disease (MPD). In vitro, the V617F mutation confers cytokine independent growth of Ba/F3 cells expressing erythropoietin receptor (EpoR) and constitutive activation of the JAK2 kinase and of the JAK-STAT pathway. In a murine bone-marrow transplant model the V617F-mutation alone is sufficient to induce a polycythemia vera-like phenotype. Therefore, mutant JAK2 kinase is a promising target for kinase inhibitor development. In this report, we characterize the small molecule LS104 (previously CR4; Grunberger et al., Blood 2003) as a novel non-ATP-competitive JAK2V617F kinase i…
Comprehensive Genomic and Transcriptomic Analysis for Guiding Therapeutic Decisions in Patients with Rare Cancers
2021
Abstract The clinical relevance of comprehensive molecular analysis in rare cancers is not established. We analyzed the molecular profiles and clinical outcomes of 1,310 patients (rare cancers, 75.5%) enrolled in a prospective observational study by the German Cancer Consortium that applies whole-genome/exome and RNA sequencing to inform the care of adults with incurable cancers. On the basis of 472 single and six composite biomarkers, a cross-institutional molecular tumor board provided evidence-based management recommendations, including diagnostic reevaluation, genetic counseling, and experimental treatment, in 88% of cases. Recommended therapies were administered in 362 of 1,138 patient…
Entwicklung von Tyrosinkinase-Inhibitoren bei hämatologischen Neoplasien. FLT3 und JAK2 als therapeutischeTargets
2008
Tyrosinkinase-Inhibitoren stellen einen wichtigen Beitrag zur Weiterentwicklung und Verbesserung der Therapie von hamatologischen Neoplasien dar. Zahlreiche Inhibitoren befinden sich bereits in fortgeschrittener klinischer Testung. Wahrend bei einem Teil der Erkrankungen (CML) die Inhibitor-Therapie bereits als Standard etabliert ist, befinden sich die “small molecules” bei Akuter Myeloischer Leukamie und chronisch-myeloproliferativen Syndromen noch in der Etablierungsphase. Die Entwicklung von neuen zielgerichteten Substanzen zahlt zu den grosen praklinischen und klinischen Herausforderungen der nachsten Jahre.
Analysis of Differentially Activated Signaling Pathways in Myeloproliferative Disease Using Kinomics Chip Profiling
2008
Abstract In a multitude of cases, oncogenic mutations are gain of function mutations that confer a constitutively activated gene product. Currently, evidence from a large body of experimental studies suggests that oncogenic transformation induced by activating kinase mutations is not sufficiently explained by constitutive kinase activation alone but is a result of aberrantly activated signaling pathways in affected cells. The JAK2V617F-mutation is a highly prevalent molecular marker in Ph-negative myeloproliferative disease (MPD). In vitro, Ba/F3-cells expressing both erythropoietin receptor (EpoR) and the JAK2V617F-mutation show constitutive activation of the JAK-STAT pathway and cytokine …
LS104, a non-ATP-competitive small-molecule inhibitor of JAK2, is potently inducing apoptosis in JAK2V617F-positive cells
2008
Abstract The activating JAK2V617F mutation has been described in the majority of patients with BCR-ABL-negative myeloproliferative disorders (MPD). In this report, we characterize the small-molecule LS104 as a novel non-ATP-competitive JAK2 inhibitor: Treatment of JAK2V617F-positive cells with LS104 resulted in dose-dependent induction of apoptosis and inhibition of JAK2 autophosphorylation and of downstream targets. Activation of these targets by JAK2 was confirmed in experiments using small interfering RNA. LS104 inhibited JAK2 kinase activity in vitro. This effect was not reversible using elevated ATP concentrations, whereas variation of the kinase substrate peptide led to modulation of …
Clinical resistance to the kinase inhibitor PKC412 in acute myeloid leukemia by mutation of Asn-676 in the FLT3 tyrosine kinase domain.
2005
Activating mutations in the FLT3 tyrosine kinase (TK) occur in approximately 35% of patients with acute myeloid leukemia (AML). Therefore, targeting mutated FLT3 is an attractive therapeutic strategy, and early clinical trials testing FLT3 TK inhibitors (TKI) showed measurable clinical responses. Most of these responses were transient; however, in a subset of patients blast recurrence was preceded by an interval of prolonged remission. The etiology of clinical resistance to FLT3-TKI in AML is unclear but is of major significance for the development of future therapeutic strategies. We searched for mechanisms of resistance in 6 patients with AML who had relapses upon PKC412 treatment. In an …
FLT3 as a therapeutic target in AML: still challenging after all these years
2010
Abstract Mutations within the FMS-like tyrosine kinase 3 (FLT3) gene on chromosome 13q12 have been detected in up to 35% of acute myeloid leukemia (AML) patients and represent one of the most frequently identified genetic alterations in AML. Over the last years, FLT3 has emerged as a promising molecular target in therapy of AML. Here, we review results of clinical trials and of correlative laboratory studies using small molecule FLT3 tyrosine kinase inhibitors (TKIs) in AML patients. We also review mechanisms of primary and secondary drug resistance to FLT3-TKI, and from the data currently available we summarize lessons learned from FLT3-TKI monotherapy. Finally, for using FLT3 as a molecul…
A phase 1b, dose-finding study of ruxolitinib plus panobinostat in patients with myelofibrosis.
2014
7022^ Background: Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by dysregulation of the Janus kinase (JAK) pathway resulting in bone marrow fibrosis, splenomegaly, and debilitat...
The kinase inhibitor LS104 induces apoptosis, enhances cytotoxic effects of chemotherapeutic drugs and is targeting the receptor tyrosine kinase FLT3…
2008
Activating mutations of FLT3 are found in approximately one-third of acute myeloid leukemia (AML)-cases and are considered to represent an attractive therapeutic target. In this study, we report that the hydroxystyryl-acrylonitrile compound LS104 inhibits proliferation and induces potent cytotoxic effects in FLT3 expressing leukemic cells in vitro. Immunoblot and phosphoprotein-FACS analysis demonstrated inhibiton of phosphorylation of FLT3-ITD and of its downstream targets. In pharmacokinetic studies, a rapid and dose dependent cellular uptake of LS104 lasting up to 11h could be demonstrated. Combination of LS104 with chemotherapeutic agents markedly enhanced cytotoxic effects. Recently, a…
Efficacy, Safety, and Confirmation of the Recommended Phase 2 Starting Dose of the Combination of Ruxolitinib (RUX) and Panobinostat (PAN) in Patient…
2015
Abstract BACKGROUND: MF is a myeloproliferative neoplasm characterized by bone marrow (BM) fibrosis, splenomegaly, and debilitating constitutional symptoms. RUX is a potent JAK1/JAK2 inhibitor that has demonstrated superiority in spleen volume reduction, symptom improvement, and survival in the phase 3 COMFORT studies compared with placebo and best available therapy. PAN, a potent pan-deacetylase inhibitor, inhibits JAK signaling by disrupting the interaction between JAK2 and heat shock protein 90, a protein chaperone. PAN has demonstrated reductions in splenomegaly and improvement of BM fibrosis in phase 1/2 studies. The combination of RUX and PAN demonstrated synergistic activity in precl…
LS104, a Novel Kinase Inhibitor, Induces Apoptosis, Synergizes with Cytostatic Drugs and Is Targeting the Receptor Tyrosine Kinase FLT3.
2005
Abstract Fms-like tyrosine kinase 3 (FLT3), a member of the class III tyrosine kinase receptor family, is expressed in up to 90% of acute myeloid leukemia (AML). Activating mutations like internal tandem duplication (ITD) of the juxtamembrane domain and kinase domain point mutations are found in approximately 35% of AML-cases and are considered to represent an attractive therapeutic target. In this study, we report that the novel hydroxystyryl-acrylonitrile compound LS104 induces potent cytotoxic effects in FLT3 ITD-positive leukemic cells. As a cellular model to investigate FLT3-ITD specific effects we used 32D myeloid cells stably transfected with FLT3-ITD and wt-FLT3, respectively. In MT…
Addition of rituximab to standard therapy improves response rate and progression-free survival in relapsed or refractory thrombotic thrombocytopenic …
2007
SummaryTreatment of relapsed or refractory autoimmune mediated haemolytic syndromes, such as autoimmune haemolytic anaemia (AIHA) and thrombotic thrombocytopenic purpura (TTP), represents a therapeutic challenge. Here we report on our experience with the monoclonal anti-CD20 antibody rituximab (R) compared to standard treatment in these diseases. Patients with non-familialTTP orAIHA and no underlying malignancy were included in our analysis. Safety and efficacy of R-treatment were compared to results obtained in standard treatment approaches. Altogether, 27 patients were analyzed, comprising 15 patients withTTP and 12 patients with AIHA. The patients’ average age at the time of diagnosis wa…
Efficacy, Safety, and Confirmation of the Recommended Phase 2 Dose of Ruxolitinib Plus Panobinostat in Patients with Intermediate or High-Risk Myelof…
2014
Abstract Background: Myelofibrosis (MF) is a clonal neoplastic disease resulting in bone marrow fibrosis, splenomegaly, and debilitating constitutional symptoms. The Janus kinase (JAK) pathway is often dysregulated in MF, and agents targeting this pathway have demonstrated efficacy in this disease. Ruxolitinib (RUX), a potent JAK1/JAK2 inhibitor, demonstrated superiority in spleen volume reduction, symptom improvement, and survival compared with the control arm in the phase III COMFORT-I and COMFORT-II studies. Panobinostat (PAN), a potent pan-deacetylase inhibitor (pan-DACi), inhibits JAK signaling through disruption of the interaction of JAK2 with the protein chaperone heat shock protein …
3,4-Diarylmaleimides Effectively Inhibit Proliferation of FLT3-ITD-Positive Leukemic Cells, Induce Apoptosis and Show Additive Effects in Combination…
2007
Abstract Internal tandem duplication (ITD) mutations of FLT3 are present in leukemic blasts of approximately 30% of AML patients. ITD-mutations of FLT3 confer a worse prognosis and decreased overall survival. Therefore, FLT3-tyrosine kinase is considered an attractive drug target in AML and several FLT3-tyrosine kinase inhibitors (TKIs) are currently being tested in clinical trials (CEP701, MLN518, Sorafenib, PKC412). However, using these drugs as monotherapy, against the setting of remarkable efficacy has emerged the problem of short duration of remission indicating rapid development of secondary resistance. In addition, up to 30% of patients may show primary resistance to currently availa…
Intracellular retention of ABL kinase inhibitors determines commitment to apoptosis in CML cells
2012
PLoS one 7(7), e40853 (2012). doi:10.1371/journal.pone.0040853
Different FLT3-ITD Integration Sites Are Associated with Differential Sensitivity to Tyrosine Kinase Inhibitors (TKI) In Vitro.
2010
Abstract Abstract 1709 Introduction: Currently, small molecule FLT3 tyrosine kinase inhibitors (TKIs) are promising therapeutic approaches to overcome the dismal prognosis of AML patients harbouring FLT3-ITD mutations. However, up to 30% of these patients show primary resistance to FLT3-TKIs. Recently, we uncovered a novel mechanism of primary resistance to FLT3 TKIs in a patient displaying an atypical integration site of ITD within the beta2-sheet (ITD_A627E). The data suggested that atypical integration sites of ITDs within the tyrosine kinase domain-1 (TKD1) of FLT3 (beta1-sheet, nucleotide binding loop and beta2-sheet) are associated with rewired signaling and differential responsivenes…