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Erba HP, Kantarjian HM, Claxton DF, Arellano M, Lyons RM, Kovacsovics TJ, Gabrilove J, Eckert S, Faderl S. Updated remission duration and survival results of single-agent clofarabine in previously untreated older adult patients with acute myelogenous leukemia (AML) unlikely to benefit from standard induction chemotherapy due to unfavorable baseline risk factor(s). J Clin Oncol 2009. [DOI: 10.1200/jco.2009.27.15_suppl.7062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
7062 Background: The CLASSIC II trial has previously reported an independently confirmed overall remission rate of 46% (38% CR and 8% CRp) and 30- and 60-day mortality rates of 9.8% and 16.1%, respectively (Blood 112: 558, 2008). We now report updated duration of remission (DOR), disease-free survival (DFS), and overall survival (OS). Methods: Single arm, multi-center, phase II, open-label, 2-stage study of patients with untreated AML, ≥60 years old, and at least one adverse prognostic factor: age ≥70 years, antecedent hematologic disorder (AHD), PS = 2, and/or intermediate/unfavorable risk karyotype. Clofarabine (CLO) administered days 1–5 at 30 mg/m2 during induction and 20 mg/m2 during re-induction/consolidation for maximum 6 cycles. Patients were followed for at least 6 months past remission (CR/CRp). Results: 116 patients enrolled and 112 in full analysis set. Median age 71 years. Median DOR (censored at alternative therapy) for CR/CRp was 56 weeks (95% CI, 33 weeks - not yet estimable [n/e]) and for CR 65 weeks (95% CI, 41 weeks - n/e). Median DFS (not censored at alternative therapy) for CR/CRp was 34 weeks (95% CI, 24 - 65 weeks). Median OS was 41 weeks (95% CI 28 - 53 weeks), for CR/CRp 59 weeks (95% CI, 50 weeks - n/e ), and for CR was 72 weeks (95% CI, 53 weeks - n/e) after median follow-up of 36 weeks (range, 1 - 85 weeks). Thirty-day mortality was 9.8% for all patients with 4.7% and 13% for age <70 and age ≥70 years, respectively. Conclusions: These data expand on the previously reported efficacy and safety data of single agent CLO in adult AML. Complete remissions appear durable (median >1 yr), and DFS and OS compare favorably to historical experience, particularly in patients with these adverse prognostic factors. These results suggest that single agent CLO is an effective and tolerable treatment option for older adult patients with untreated AML and 1 or more unfavorable baseline prognostic factor(s). [Table: see text]
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Affiliation(s)
- H. P. Erba
- University of Michigan Health System, Ann Arbor, MI; M. D. Anderson Cancer Center, Houston, TX; Penn State Milton S. Hershey Medical Center, Hershey, PA; Emory University, Atlanta, GA; Cancer Care Centers South Texas/US Oncology, San Antonio, TX; Center for Hematological Malignancies OHSU, Portland, OR; Mount Sinai School of Medicine, New York, NY; Genzyme, San Antonio, TX
| | - H. M. Kantarjian
- University of Michigan Health System, Ann Arbor, MI; M. D. Anderson Cancer Center, Houston, TX; Penn State Milton S. Hershey Medical Center, Hershey, PA; Emory University, Atlanta, GA; Cancer Care Centers South Texas/US Oncology, San Antonio, TX; Center for Hematological Malignancies OHSU, Portland, OR; Mount Sinai School of Medicine, New York, NY; Genzyme, San Antonio, TX
| | - D. F. Claxton
- University of Michigan Health System, Ann Arbor, MI; M. D. Anderson Cancer Center, Houston, TX; Penn State Milton S. Hershey Medical Center, Hershey, PA; Emory University, Atlanta, GA; Cancer Care Centers South Texas/US Oncology, San Antonio, TX; Center for Hematological Malignancies OHSU, Portland, OR; Mount Sinai School of Medicine, New York, NY; Genzyme, San Antonio, TX
| | - M. Arellano
- University of Michigan Health System, Ann Arbor, MI; M. D. Anderson Cancer Center, Houston, TX; Penn State Milton S. Hershey Medical Center, Hershey, PA; Emory University, Atlanta, GA; Cancer Care Centers South Texas/US Oncology, San Antonio, TX; Center for Hematological Malignancies OHSU, Portland, OR; Mount Sinai School of Medicine, New York, NY; Genzyme, San Antonio, TX
| | - R. M. Lyons
- University of Michigan Health System, Ann Arbor, MI; M. D. Anderson Cancer Center, Houston, TX; Penn State Milton S. Hershey Medical Center, Hershey, PA; Emory University, Atlanta, GA; Cancer Care Centers South Texas/US Oncology, San Antonio, TX; Center for Hematological Malignancies OHSU, Portland, OR; Mount Sinai School of Medicine, New York, NY; Genzyme, San Antonio, TX
| | - T. J. Kovacsovics
- University of Michigan Health System, Ann Arbor, MI; M. D. Anderson Cancer Center, Houston, TX; Penn State Milton S. Hershey Medical Center, Hershey, PA; Emory University, Atlanta, GA; Cancer Care Centers South Texas/US Oncology, San Antonio, TX; Center for Hematological Malignancies OHSU, Portland, OR; Mount Sinai School of Medicine, New York, NY; Genzyme, San Antonio, TX
| | - J. Gabrilove
- University of Michigan Health System, Ann Arbor, MI; M. D. Anderson Cancer Center, Houston, TX; Penn State Milton S. Hershey Medical Center, Hershey, PA; Emory University, Atlanta, GA; Cancer Care Centers South Texas/US Oncology, San Antonio, TX; Center for Hematological Malignancies OHSU, Portland, OR; Mount Sinai School of Medicine, New York, NY; Genzyme, San Antonio, TX
| | - S. Eckert
- University of Michigan Health System, Ann Arbor, MI; M. D. Anderson Cancer Center, Houston, TX; Penn State Milton S. Hershey Medical Center, Hershey, PA; Emory University, Atlanta, GA; Cancer Care Centers South Texas/US Oncology, San Antonio, TX; Center for Hematological Malignancies OHSU, Portland, OR; Mount Sinai School of Medicine, New York, NY; Genzyme, San Antonio, TX
| | - S. Faderl
- University of Michigan Health System, Ann Arbor, MI; M. D. Anderson Cancer Center, Houston, TX; Penn State Milton S. Hershey Medical Center, Hershey, PA; Emory University, Atlanta, GA; Cancer Care Centers South Texas/US Oncology, San Antonio, TX; Center for Hematological Malignancies OHSU, Portland, OR; Mount Sinai School of Medicine, New York, NY; Genzyme, San Antonio, TX
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Kovacsovics TJ, Hartwig JH. Thrombin-induced GPIb-IX centralization on the platelet surface requires actin assembly and myosin II activation. Blood 1996; 87:618-29. [PMID: 8555484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In resting platelets, the GPIb-IX complex, the receptor for the von Willebrand factor (vWF), is linked to underlying actin filaments by actin-binding protein (ABP-280). Thrombin stimulation of human platelets leads to a decrease in the surface expression of the GPIb-IX complex, which is redistributed from the platelet surface into the open canalicular system (OCS). Because the centralization of GPIb-IX is inhibited by cytochalasin, it is believed to be linked to actin cytoskeletal rearrangements that take place during platelet activation. We have further characterized the mechanism of GPIb-IX centralization in platelets in suspension. Following thrombin stimulation, GPIb-IX shifts from the membrane skeleton of the resting cell to the cytoskeleton of the activated cell in a reaction sensitive to cytochalasin B. The cytoskeletal association of GPIb-IX involves ABP-280, as it correlates with the incorporation of ABP-280 into the activated cytoskeleton and because no dissociation of the ABP-280/GPIb-IX complexes is detected after thrombin activation. However, the incorporation of GPIb-IX into the cytoskeleton is complete within 1 minute, whereas GPIb-IX centralization requires 5 to 10 minutes for completion. The movement of GPIb-IX to the cytoskeleton of activated platelets is therefore necessary, but not sufficient for GPIb-IX centralization. Blockage of cytosolic calcium increases induced by thrombin by loading with the cell permeant calcium chelator Quin-2 AM inhibited GPIb-IX centralization by 70%, but did not prevent its association with the activated cytoskeleton. Quin-2 loading did, however, decrease the incorporation of myosin II into the activated cytoskeleton. The role of myosin II was further probed using the myosin light chain kinase (MLCK) inhibitor wortmannin. Wortmannin prevents myosin II association to the activated cytoskeleton and inhibits GPIb-IX centralization by 50%, without affecting actin assembly or the association of GPIb-IX to the cytoskeleton. Only micromolar concentrations of wortmannin, high enough to inhibit MLCK, prevent GPIb-IX centralization. These results indicate that thrombin-induced GPIb-IX centralization requires a minimum of two steps, one associating GPIb-IX to the activated cytoskeleton and the second requiring myosin II activation. The involvement of myosin II implies that GPIb-IX/ABP-280 complexes, linked to actin filaments, are pulled into the cell center, and that platelets may exert contractile tension on vWF bound to its receptor.
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Affiliation(s)
- T J Kovacsovics
- Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
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Toker A, Bachelot C, Chen CS, Falck JR, Hartwig JH, Cantley LC, Kovacsovics TJ. Phosphorylation of the platelet p47 phosphoprotein is mediated by the lipid products of phosphoinositide 3-kinase. J Biol Chem 1995; 270:29525-31. [PMID: 7493994 DOI: 10.1074/jbc.270.49.29525] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Platelet stimulation by thrombin or the thrombin receptor activating peptide (TRAP) results in the activation of phosphoinositide 3-kinase and the production of the novel polyphosphoinositides phosphatidylinositol 3,4-bisphosphate (PtdIns-3,4-P2) and phosphatidylinositol 3,4,5-trisphosphate (PtdIns-3,4,5-P3). We have shown previously that these lipids activate calcium-independent protein kinase C (PKC) isoforms in vitro (Toker, A., Meyer, M., Reddy, K. K., Falck, J. R., Aneja, R., Aneja, S., Parra, A., Burns, D. J., Ballas, L. M. and Cantley, L. C. (1994) J. Biol. Chem. 269, 32358-32367). Activation of platelet PKC in response to TRAP is detected by the phosphorylation of the major PKC substrate in platelets, the p47 phosphoprotein, also known as pleckstrin. Here we provide evidence for two phases of pleckstrin phosphorylation in response to TRAP. A rapid phase of pleckstrin phosphorylation (< 1 min) precedes the peak of PtdIns-3,4-P2 production and is unaffected by concentrations of wortmannin (10-100 nM) that block production of this lipid. However prolonged phosphorylation of pleckstrin (> 2 min) is inhibited by wortmannin concentrations that block PtdIns-3,4-P2 production. Phorbol ester-mediated pleckstrin phosphorylation was not affected by wortmannin and wortmannin had no effect on purified platelet PKC activity. Phosphorylation of pleckstrin could be induced using permeabilized platelets supplied with exogenous gamma-32P[ATP] and synthetic dipalmitoyl PtdIns-3,4,5-P3 and dipalmitoyl PtdIns-3,4-P2 micelles, but not with dipalmitoyl phosphatidylinositol 3-phosphate or phosphatidylinositol 4,5-bisphosphate. These results suggest two modes of stimulating pleckstrin phosphorylation: a rapid activation of PKC (via diacylglycerol and calcium) followed by a slower activation of calcium-independent PKCs via PtdIns-3,4-P2.
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Affiliation(s)
- A Toker
- Department of Medicine, Beth Israel Hospital, Boston Massachusetts 02115, USA
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Kovacsovics TJ, Bachelot C, Toker A, Vlahos CJ, Duckworth B, Cantley LC, Hartwig JH. Phosphoinositide 3-kinase inhibition spares actin assembly in activating platelets but reverses platelet aggregation. J Biol Chem 1995; 270:11358-66. [PMID: 7744773 DOI: 10.1074/jbc.270.19.11358] [Citation(s) in RCA: 159] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Platelet stimulation by thrombin leads to the activation of phosphoinositide 3-kinase (PI 3K) and to the production of the D3 phosphoinositides, phosphatidylinositol 3,4-bisphosphate (PdtIns-3,4P2) and 3,4,5-trisphosphate (PdtIns-3,4,5-P3). Because changes in the levels of these phosphoinositides correlate with the kinetics of actin assembly, they have been proposed to mediate actin assembly, causing cell shape changes. Wortmannin and LY294002, two unrelated inhibitors of PI 3-K, were used to investigate the role of PI 3-K in platelet actin assembly and aggregation. Both PI 3-K inhibitors abrogated the production of PdtIns-3,4-P2 and PdtIns-3,4,5-P3 in thrombin receptor-activating peptide (TRAP)-stimulated cells. However, neither wortmannin nor LY294002 altered the kinetics of actin assembly or the exposure of nucleation sites in TRAP-stimulated cells. In contrast, PI 3-K inhibitors showed a specific inhibitory pattern of cell aggregation, characterized by a primary phase of aggregation followed by progressive disaggregation. Flow cytometry analysis with the PAC1 monoclonal antibody or with FITC-labeled fibrinogen indicated that wortmannin inhibited the maintenance of the platelet integrin GPIIb-IIIa in its active state. Wortmannin also inhibited, in a dose-dependent manner, platelet aggregation induced by the binding of the monoclonal antibodies P256 and LIBS-6 to GPIIb-IIIa. LIBS Fab-induced aggregation also led to the production of PdtIns-3,4-P2. Platelet secretion, as evidenced by the release of preloaded 14C-5-hydroxy-tryptamine secretion or P-selectin up-regulation, was not affected by PI 3-K inhibition. These results demonstrate that the generation of D3 phosphoinositides is not required for actin assembly in TRAP-activated platelets. However, PI 3-K stimulation is necessary for prolonged GPIIb-IIIa activation and irreversible platelet aggregation. PI 3-K stimulation downstream of GPIIb-IIIa engagement may provide positive feedback required to sustain active GPIIb-IIIa.
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Affiliation(s)
- T J Kovacsovics
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
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Peitsch MC, Kovacsovics TJ, Tschopp J, Isliker H. Antibody-independent activation of C1. II. Evidence for two classes of nonimmune activators of the classical pathway of complement. J Immunol 1987; 138:1871-6. [PMID: 3029223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Nonimmune activation of the first component of complement (C1) by cardiolipin (CL) vesicles present specific features which were not demonstrated on immune complexes. CL vesicles which activate C1 in the presence of C1-inhibitor (C1-INH) were found to bind C1s in the absence of C1r, and to induce a specific C1r-independent cleavage of C1q-bound C1s. Therefore, several known natural nonimmune activators were analyzed by comparing their ability to activate C1 in the presence of C1-INH and to mediate a C1r-independent cleavage of C1s. Freshly isolated human heart mitochondria (HHM) activated C1 only in the absence of C1-INH. However, mitoplasts derived from HHM (HHMP) activated C1 regardless of the presence of C1-INH, and induced a specific cleavage of C1q-bound C1s. The same pattern was observed in the case of smooth E. coli and a semi-rough E. coli strain. DNA, known to activate C1 only in the absence of C1-INH, does not induce C1s cleavage in the absence of C1r. Thus, nonimmune activators can be classified into two distinct categories. "Strong" activators, such as CL vesicles, HHMP, or the semi-rough E. coli strain J5 can activate C1 in the presence of C1-INH. By using C1qs2 as a probe, they exhibit a specific, C1r-independent cleavage of C1s. C1s-binding to C1q is a critical factor for the activation process in this group. In the case of "weak" activators, such as E. coli smooth strains, DNA, or HHM, no C1s-binding to activator-bound C1q was detected, and C1r-independent C1s cleavage and C1 activation in the presence of C1-INH were not observed. As in the case of immune complexes, C1r activation appears to play a key role in the C1 activation by "weak" activators.
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Kovacsovics TJ, Peitsch MC, Kress A, Isliker H. Antibody-independent activation of C1. I. Differences in the mechanism of C1 activation by nonimmune activators and by immune complexes: C1r-independent activation of C1s by cardiolipin vesicles. The Journal of Immunology 1987. [DOI: 10.4049/jimmunol.138.6.1864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
C1 activation is controlled by the regulatory protein C1-inhibitor (C1-INH). In contrast to immune-complex-induced activation, which is insensitive to C1-INH, antibody-independent activation of C1 is modulated by C1-INH. The mechanisms regulating nonimmune activation were studied with two phospholipids varying in their capacity to activate C1 in the presence of C1-INH: cardiolipin (CL) and phosphatidylglycerol (PG). Whereas C1-INH consistently suppressed activation by PG vesicles, a dose-dependent increase in C1 activation was measured with CL vesicles above 40 mole %. A similar dose-response binding of C1s requiring C1q, but not C1r, was detected only on CL vesicles, but neither on PG vesicles nor on immune complexes. This binding was Ca2+-dependent, suggesting that dimeric C1s is involved and was inhibited by spermine. The C1q-bound C1s was specifically cleaved at 37 degrees C into its active 58 kDa and 28 kDa chains, in the absence of C1r. On the addition of anti-CL antibodies, the C1q-mediated cleavage of C1s by CL vesicles was specifically inhibited. The cleavage of C1r on CL vesicles was also determined. When macromolecular C1 was offered in the presence of C1-INH, C1r cleavage was detected; however, the presence of C1s was a critical factor for C1r activation, because it was required on CL vesicles, but not on immune complexes. These results show that nonimmune activation of C1 presents specific features which distinguish it from immune complex-induced activation. These characteristics varied with the capacity of antibody-independent activators to activate C1 in the presence of C1-INH.
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Peitsch MC, Kovacsovics TJ, Tschopp J, Isliker H. Antibody-independent activation of C1. II. Evidence for two classes of nonimmune activators of the classical pathway of complement. The Journal of Immunology 1987. [DOI: 10.4049/jimmunol.138.6.1871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Nonimmune activation of the first component of complement (C1) by cardiolipin (CL) vesicles present specific features which were not demonstrated on immune complexes. CL vesicles which activate C1 in the presence of C1-inhibitor (C1-INH) were found to bind C1s in the absence of C1r, and to induce a specific C1r-independent cleavage of C1q-bound C1s. Therefore, several known natural nonimmune activators were analyzed by comparing their ability to activate C1 in the presence of C1-INH and to mediate a C1r-independent cleavage of C1s. Freshly isolated human heart mitochondria (HHM) activated C1 only in the absence of C1-INH. However, mitoplasts derived from HHM (HHMP) activated C1 regardless of the presence of C1-INH, and induced a specific cleavage of C1q-bound C1s. The same pattern was observed in the case of smooth E. coli and a semi-rough E. coli strain. DNA, known to activate C1 only in the absence of C1-INH, does not induce C1s cleavage in the absence of C1r. Thus, nonimmune activators can be classified into two distinct categories. "Strong" activators, such as CL vesicles, HHMP, or the semi-rough E. coli strain J5 can activate C1 in the presence of C1-INH. By using C1qs2 as a probe, they exhibit a specific, C1r-independent cleavage of C1s. C1s-binding to C1q is a critical factor for the activation process in this group. In the case of "weak" activators, such as E. coli smooth strains, DNA, or HHM, no C1s-binding to activator-bound C1q was detected, and C1r-independent C1s cleavage and C1 activation in the presence of C1-INH were not observed. As in the case of immune complexes, C1r activation appears to play a key role in the C1 activation by "weak" activators.
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