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Christen L Andersen,
Mary F McMullin,
Elisabeth Ejerblad,
Sonja Zweegman,
Claire Harrison,
Savio Fernandes,
David Bareford, Steven Knapper,
Jan Samuelsson,
Eva Löfvenberg,
Olle Linder,
Bjørn Andreasson,
Erik Ahlstrand,
Morten K Jensen,
Ole W Bjerrum,
Hanne Vestergaard,
Herdis Larsen,
Tobias W Klausen,
Torben Mourits-Andersen,
Hans C Hasselbalch
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ABSTRACT: Inhibition of histone deacetylases may be an important target in patients with myeloproliferative neoplasms. This investigator-initiated, non-randomized, open-label phase II multi-centre study included 63 patients (19 essential thrombocythaemia, 44 polycythaemia vera) from 15 centres. The primary objective was to evaluate if vorinostat was followed by a decline in clonal myeloproliferation as defined by European Leukaemia Net. Thirty patients (48%) completed the intervention period (24 weeks of therapy). An intention-to-treat response rate of 35% was identified. Pruritus was resolved [19% to 0% (P = 0·06)] and the prevalence of splenomegaly was lowered from 50% to 27% (P = 0·03). Sixty-five per cent of the patients experienced a decrease in JAK2 V617F allele burden (P = 0·006). Thirty-three patients (52% of patients) discontinued study drug before end of intervention due to adverse events (28 patients) or lack of response (5 patients). In conclusion, vorinostat showed effectiveness by normalizing elevated leucocyte and platelet counts, resolving pruritus and significantly reducing splenomegaly. However, vorinostat was associated with significant side effects resulting in a high discontinuation rate. A lower dose of vorinostat in combination with conventional and/or novel targeted therapies may be warranted in future studies.
British Journal of Haematology 06/2013; · 4.94 Impact Factor
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ABSTRACT: Heat shock protein 90 (HSP90; HSP90AA1) is a molecular chaperone involved in signalling pathways for cell proliferation, survival, and cellular adaptation. Inhibitors of HSP90 are being examined as anti-cancer agents, but the critical molecular mechanism(s) of their activity remains unresolved. HSP90 inhibition potentially facilitates the simultaneous targeting of multiple molecules within tumour cells and represents an attractive therapeutic proposition. Here, we investigated HSP90 as a molecular target for acute myeloid leukaemia (AML) using the novel HSP90 inhibitor NVP-AUY922-AG. NVP-AUY922-AG induced dose-dependent killing in myeloid cell lines and primary AML blasts. In primary blasts, cell death in response to NVP-AUY922-AG was seen at concentrations almost 2 logs lower than cytarabine (Ara-C) (50% lethal dose = 0·12 μ mol/l ± 0·28). NVP-AUY922-AG was significantly less toxic to normal bone marrow (P = 0·02). In vitro response to NVP-AUY922-AG did not correlate with response to Ara-C (r(2) = 0·0006). NVP-AUY922-AG was highly synergistic with Ara-C in cell lines and in 20/25 of the primary samples tested. NVP-AUY922-AG induced increases in HSP70 expression and depletion of total AKT, IKKα and IKKβ in cell lines and primary blasts. This study shows that the novel HSP90 inhibitor NVP-AUY922-AG has significant single agent activity in AML cells and is synergistic with Ara-C.
British Journal of Haematology 01/2013; · 4.94 Impact Factor
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Steven Knapper
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ABSTRACT: INTRODUCTION: Activating mutations of the FMS-like tyrosine kinase 3 (FLT3) gene occur at high frequency in acute myeloid leukemia (AML), being detected in > 30% of patients at diagnosis and carrying a profound negative prognostic impact. The development of effective small molecule inhibitors of FLT3 has been the focus of an intensive international research effort in recent years. AREAS COVERED: The published results of the first decade of clinical trials of FLT3-targeted tyrosine kinase inhibitors are critically reviewed. Over this period, a first generation of compounds has followed an orderly progression from monotherapy studies through combination with chemotherapy and into advanced stage international trials in both relapsed and newly-diagnosed AML. Correlative laboratory studies performed alongside several of these studies have been highly illuminating, demonstrating close correlations between clinical activity and effective inhibition of FLT3, and highlighting potential drug resistance mechanisms. EXPERT OPINION: Clinical responses to several of the early multi-targeted agents were hindered by unfavorable pharmacokinetics and lack of potency. Newer, more potent FLT3 inhibitors such as sorafenib and AC220 possess the ability to achieve more sustained in vivo inhibition of FLT3 and have shown highly promising activity in early clinical studies. As these agents enter advanced stage trials, they carry the potential to make a major clinical impact in this disease. In future, FLT3 inhibitors may be effectively used in combination with other molecularly targeted agents.
Expert Opinion on Investigational Drugs 10/2011; 20(10):1377-95. · 5.27 Impact Factor
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Eva Szegezdi,
Carlos R. Reis,
Almer M. van der Sloot,
Alessandro Natoni,
Aoife O’Reilly,
Janice Reeve,
Robbert H. Cool,
Michael O’Dwyer, Steven Knapper,
Luis Serrano,
Wim J. Quax,
Afshin Samali
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ABSTRACT: Despite progress in the treatment of acute myelogenous leukaemia (AML) the outcome often remains poor. Tumour necrosis factor related apoptosis-inducing ligand (TRAIL) is a promising therapeutic agent in many different types of tumours, but AML cells are relatively insensitive to TRAIL-induced apoptosis. Here we show that TRAIL-induced apoptosis in AML cells is predominantly mediated by death receptor 4 (DR4) and not DR5. Therefore, we constructed a variant of TRAIL (rhTRAIL-C3) that is a strong inducer of DR4-mediated apoptosis. TRAIL-C3 demonstrated much stronger pro-apoptotic activity than wild-type (WT) TRAIL in a panel of AML cell lines as well as in primary AML blasts. The higher pro-apoptotic potential was further enhanced when the TRAIL mutant was used in combination with BMS-345541, a selective inhibitor of inhibitor-κB kinases. It illustrates that combination of this TRAIL variant with chemotherapeutics or other targeted agents can kill AML with high efficacy. This may represent a major advantage over the currently used therapies that have serious toxic side effects. The high efficacy of rhTRAIL-C3 containing therapies may enable the use of lower drug doses to reduce the toxic side effects and improve patient outcome. Our findings suggest that the rational design of TRAIL variants that target DR4 potentiate the death-inducing activity of TRAIL and offer a novel therapeutic strategy for the treatment of AML.
Journal of Cellular and Molecular Medicine 09/2011; 15(10):2216 - 2231. · 4.13 Impact Factor
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ABSTRACT: We examined in vivo FLT3 inhibition in acute myeloid leukemia patients treated with chemotherapy followed by the FLT3 inhibitor lestaurtinib, comparing newly diagnosed acute myeloid leukemia patients with relapsed patients. Because we noted that in vivo FLT3 inhibition by lestaurtinib was less effective in the relapsed patients compared with the newly diagnosed patients, we investigated whether plasma FLT3 ligand (FL) levels could influence the efficacy of FLT3 inhibition in these patients. After intensive chemotherapy, FL levels rose to a mean of 488 pg/mL on day 15 of induction therapy for newly diagnosed patients, whereas they rose to a mean of 1148 pg/mL in the relapsed patients. FL levels rose even higher with successive courses of chemotherapy, to a mean of 3251 pg/mL after the fourth course. In vitro, exogenous FL at concentrations similar to those observed in patients mitigated FLT3 inhibition and cytotoxicity for each of 5 different FLT3 inhibitors (lestaurtinib, midostaurin, sorafenib, KW-2449, and AC220). The dramatic increase in FL level after chemotherapy represents a possible obstacle to inhibiting FLT3 in this clinical setting. These findings could have important implications regarding the design and outcome of trials of FLT3 inhibitors and furthermore suggest a rationale for targeting FL as a therapeutic strategy.
Blood 01/2011; 117(12):3286-93. · 9.90 Impact Factor
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ABSTRACT: Topoisomerase II is essential for the maintenance of DNA integrity and the survival of proliferating cells. Topoisomerase II poisons, including etoposide and doxorubicin, inhibit enzyme-mediated DNA ligation causing the accumulation of double-stranded breaks and have been front-line drugs for the treatment of leukemia for many years. Voreloxin is a first-in-class anti-cancer quinolone derivative that intercalates DNA and inhibits topoisomerase II. The efficacy and mechanisms of action of voreloxin in acute myeloid leukaemia were addressed in this study.
Primary acute myeloid leukemia blasts (n = 88) and myeloid cell lines were used in vitro to study voreloxin through viability assays to assess cell killing and synergy with other drugs. Apoptosis and cell cycling were assessed by flow cytometry. DNA relaxation assays were utilized to determine that voreloxin was active on topoisomerase II.
The mean lethal dose 50% (LD(50)) (± standard deviation) of voreloxin for primary acute myeloid leukemia blasts was 2.30 μM (± 1.87). Synergy experiments between voreloxin and cytarabine identified synergism in 22 of 25 primary acute myeloid leukemia samples tested, with a mean combination index of 0.79. Apoptosis was shown to increase in a dose-dependent manner. Furthermore, voreloxin was active in the p53-null K562 cell line suggesting that the action of voreloxin is not affected by p53 status. The action of voreloxin on topoisomerase II was confirmed using a DNA relaxation assay.
Voreloxin may provide an interesting addition to the cache of drugs available for the treatment of acute myeloid leukemia, a disease with a poor long-term survival. In addition to its potent action as a single agent in dividing cells, the synergy we demonstrated between voreloxin and cytarabine recommends further investigation of this topoisomerase II inhibitor.
Haematologica 12/2010; 96(3):393-9. · 6.42 Impact Factor
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Eva Szegezdi,
Carlos R Reis,
Almer M van der Sloot,
Alessandro Natoni,
Aoife O'Reilly,
Janice Reeve,
Robbert H Cool,
Michael O'Dwyer, Steven Knapper,
Luis Serrano,
Wim J Quax,
Afshin Samali
[show abstract]
[hide abstract]
ABSTRACT: Despite progress in the treatment of acute myelogenous leukaemia (AML) the outcome often remains poor. Tumour necrosis factor related apoptosis-inducing ligand (TRAIL) is a promising therapeutic agent in many different types of tumours, but AML cells are relatively insensitive to TRAIL-induced apoptosis. Here we show that TRAIL-induced apoptosis in AML cells is predominantly mediated by death receptor 4 (DR4) and not DR5. Therefore, we constructed a variant of TRAIL (rhTRAIL-C3) that is a strong inducer of DR4-mediated apoptosis. TRAIL-C3 demonstrated much stronger pro-apoptotic activity than wild-type (WT) TRAIL in a panel of AML cell lines as well as in primary AML blasts. The higher pro-apoptotic potential was further enhanced when the TRAIL mutant was used in combination with BMS-345541, a selective inhibitor of inhibitor-κB kinases. It illustrates that combination of this TRAIL variant with chemotherapeutics or other targeted agents can kill AML with high efficacy. This may represent a major advantage over the currently used therapies that have serious toxic side effects. The high efficacy of rhTRAIL-C3 containing therapies may enable the use of lower drug doses to reduce the toxic side effects and improve patient outcome. Our findings suggest that the rational design of TRAIL variants that target DR4 potentiate the death-inducing activity of TRAIL and offer a novel therapeutic strategy for the treatment of AML.
Journal of Cellular and Molecular Medicine 11/2010; 15(10):2216-31. · 4.13 Impact Factor
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ABSTRACT: As IgM multiple myeloma is a rare poorly characterised disease entity; there is only limited published data on its clinical, microscopic and immunophenotypic features. We report a 72-year-old man misdiagnosed as Waldenström's macroglobulinemia. Also the diagnosis was further complicated by coexisting chronic lymphocytic leukaemia. Following confirmation of IgM myeloma, in view of the patient's deteriorating clinical condition; he was entered into the UK Medical Research Council Myeloma IX trial where he had partial response to chemotherapy. This case highlights the value of detailed immunophenotypic evaluation when clinical and morphological markers are equivocal.
International journal of hematology 11/2008; 88(4):424-7. · 1.17 Impact Factor
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Steven Knapper
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ABSTRACT: FMS-like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase that appears to play a significant role in leukaemogenesis. Activating mutations of FLT3 are present in approximately one-third of acute myeloid leukaemia patients and are associated with adverse clinical outcome, while many non-mutated cases also show evidence of FLT3 activation. FLT3 thus represents a potentially exciting molecular therapeutic target. A number of small-molecule tyrosine kinase inhibitors with anti-FLT3 activity have been developed and several of these compounds have entered early phase clinical trials where clinical anti-leukaemic activity has been demonstrated. The depth and duration of clinical responses to FLT3 inhibitor monotherapy have been modest, however, and a number of mechanisms by which blasts may acquire resistance have been proposed. Based on preclinical evidence of synergy with conventional chemotherapy, several combination trials are now underway. FLT3 inhibition may also be effective used in combination with other molecularly targeted agents, in postchemotherapy stem-cell-directed maintenance therapy and in MLL-rearranged infant acute lymphoblastic leukaemia.
British Journal of Haematology 10/2007; 138(6):687-99. · 4.94 Impact Factor
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ABSTRACT: The receptor tyrosine kinase FLT3 is a promising molecular therapeutic target in acute myeloid leukemia (AML). Activating mutations of FLT3 are present in approximately one-third of patients, while many nonmutants show evidence of FLT3 activation, which appears to play a significant role in leukemogenesis. We studied the effects of lestaurtinib (CEP701) and PKC412, 2 small molecule inhibitors of FLT3, on 65 diagnostic AML blast samples. Both agents induced concentration-dependent cytotoxicity in most cases, although responses to PKC412 required higher drug concentrations. Cytotoxic responses were highly heterogeneous and were only weakly associated with FLT3 mutation status and FLT3 expression. Importantly, lestaurtinib induced cytotoxicity in a synergistic fashion with cytarabine, particularly in FLT3 mutant samples. Both lestaurtinib and PKC412 caused inhibition of FLT3 phosphorylation in all samples. Translation of FLT3 inhibition into cytotoxicity was influenced by the degree of residual FLT3 phosphorylation remaining and correlated with deactivation of STAT5 and MAP kinase. FLT3 mutant and wild-type cases both varied considerably in their dependence on FLT3 signaling for survival. These findings support the continued clinical assessment of FLT3 inhibitors in combination with cytotoxic chemotherapy: Entry to future clinical trials should include FLT3 wild-type patients and should remain unrestricted by FLT3 expression level.
Blood 12/2006; 108(10):3494-503. · 9.90 Impact Factor
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ABSTRACT: Activating mutations of FMS-like tyrosine kinase 3 (FLT3) are present in approximately one third of patients with acute myeloid leukemia (AML) and are associated with adverse prognosis. The important role played by FLT3 in the survival and proliferation of blasts, and its overexpression in most patients with AML, make FLT3 an attractive therapeutic target. We undertook a phase 2 trial of the FLT3-selective tyrosine kinase inhibitor lestaurtinib (CEP701) used as monotherapy in untreated older patients with AML not considered fit for intensive chemotherapy, irrespective of FLT3 mutation status. Lestaurtinib was administered orally for 8 weeks, initially at a dose of 60 mg twice daily, escalating to 80 mg twice daily, and was generally well tolerated. Clinical activity, manifest as transient reductions in bone marrow and peripheral-blood blasts or longer periods of transfusion independence, was seen in 3 (60%) of 5 patients with mutated FLT3 and 5 (23%) of 22 evaluable wild-type FLT3 patients. Laboratory data demonstrated that clinical responses occurred where the presence of sustained FLT3-inhibitory drug levels were combined with in vitro cytotoxic sensitivity of blasts to lestaurtinib. Further evaluation of this compound, in combination with cytotoxic chemotherapy or other targeted agents, is warranted in both FLT3 mutant and wild-type patients.
Blood 12/2006; 108(10):3262-70. · 9.90 Impact Factor
