scholarly journals Inhibitory Effects of Midostaurin and Blu-285 on Myeloid Progenitor Cells Derived from Patients with Multi-Mutated KIT D816V+ Advanced Systemic Mastocytosis

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1964-1964 ◽  
Author(s):  
Mohamad Jawhar ◽  
Nicole Naumann ◽  
Sebastian Kluger ◽  
Juliana Schwaab ◽  
Georgia Metzgeroth ◽  
...  
Keyword(s):  
Mast Cell ◽  
Progenitor Cells ◽  
Kinase Inhibitor ◽  
Systemic Mastocytosis ◽  
Relative Reduction ◽  
Inhibitory Effects ◽  
Dose Dependent ◽  
Kit D816v

Abstract Recent data have highlighted that the molecular pathogenesis of advanced systemic mastocytosis (advSM) is complex. In addition to the phenotypically most important mutations in KIT, e.g. KIT D816V in 80-90% of patients, one or more additional mutations, e.g. in SRSF2, ASXL1, RUNX1, CBL, JAK2 and others, are present in 60-70% of patients (Jawhar et al., Leukemia 30, 2016). In individual patients, a complex mutational profile is detected not only in mature mast cells (MCs) but also in myeloid progenitors derived from granulocyte-macrophage colony-forming progenitor cells (CFU-GM), indicating multi-lineage involvement of all identified mutations in the vast majority of patients (Jawhar et al., Leukemia 29, 2015). Midostaurin, a multi-targeted kinase inhibitor, has demonstrated an overall response rate of 60% in advSM patients (Gotlib et al., NEJM 374, 2016). BLU-285 is a highly selective KIT D816V kinase inhibitor which has demonstrated biochemical activity on the mutated KIT enzyme (KIT D816V IC50 = 0.27 nM). In the current study, we sought to a) investigate the inhibitory effects of midostaurin and BLU-285 on single-cell-derived CFU-GM from bone marrow mononuclear cells derived from multi-mutated KIT D816V+ advSM patients and b) correlate the midostaurin CFU-GM data with clinical and various response parameters in midostaurin-treated advSM patients. The mutational status of CFU-GM colonies (median colonies per patient, n=20; range 10-30) was analyzed for KIT D816V and additional mutations by PCR followed by Sanger Sequencing. In 10 multi-mutated advSM patients (aggressive SM [n=8] or mast cell leukemia [n=2] with an associated hematological neoplasm), CFU-GM colonies were screened prior to midostaurin (month 0, n=10) and, if available, at month 6 on midostaurin (n=8). At month 0, a median of 90% (range, 40-100) CFU-GM colonies were KIT D816V+, while at month 6 a median of 70% (range, 5-100) CFU-GM colonies were KIT D816V+. A significant relative reduction (≥50%) in the proportion of KIT D816V+ colonies at month 6 was observed in 4/8 (50%) patients. Midostaurin-naïve CFU-GM were incubated with midostaurin at concentrations up to 1000 nM and showed a dose-dependent significant reduction (≥50%) of KIT D816V+ colonies in 1/7 (14%) patients. Overall, the in vitro effects correlated with the in vivo effects of midostaurin on CFU-GM and established IWG-MRT-ECNM response criteria (e.g. mast cell infiltration in BM, serum tryptase level) and KIT D816V allele burden in peripheral blood. Midostaurin-naïve CFU-GM from 7/10 (70%) patients were also incubated with different concentrations of BLU-285 ranging from 0 to 75 nM. A dose-dependent, significant relative reduction (≥50%) of KIT D816V+ CFU-GM colonies was observed at concentrations between 45 and 75nM in 5/7 (71%) patients. Of interest, 3/5 (60%) in vitro responders to BLU-285 were resistant to midostaurin (in vivo and in vitro) while CFU-GM colonies from 2 patients resistant to BLU-285 were also resistant to midostaurin. In addition to KIT D816V, recurrent molecular aberrations (median 2/patient, range 1-3) were identified in all patients, most frequently in SRSF2 (n=9), TET2 (n=7) and ASXL1 (n=4). Neither drug had an effect on the relative frequency of additional mutations in CFU-GM colonies. In summary, we conclude that a) the relative reduction of KIT D816V+ CFU-GM colonies between month 0 and month 6 on midostaurin correlates with clinical response, b) the CFU-GM colony assays may provide useful information for prediction of response to midostaurin, c) the highly selective KIT D816V inhibitor BLU-285 has significant activity against KIT D816V, even in cases which are resistant to midostaurin, and d) neither drug had an effect on the prognostically relevant additional mutations. Disclosures Evans: Blueprint Medicines: Employment, Equity Ownership. Gardino:Blueprint Medicines Corporation: Employment. Lengauer:Blueprint Medicines Corporation: Employment.

scholarly journals CD117 As an Immunotherapeutic Target in Advanced Forms of Mastocytosis

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2538-2538
Author(s):  
Anne Kaiser ◽  
Renier Myburgh ◽  
Laura Volta ◽  
Christian Edoardo Pellegrino ◽  
Markus G Manz
Keyword(s):  
T Cells ◽  
Mast Cell ◽  
Mast Cells ◽  
Systemic Mastocytosis ◽  
Car T Cells ◽  
Car T ◽  
University Of Zurich ◽  
Kit D816v

Abstract Mastocytosis is a malignant disease resulting from oncogenic transformed mast cells. Up to 80% of malignant cells harbor a D816V mutation in the KIT-receptor (CD117), leading to constitutive kinase activation and proliferation and survival of mast cells. Advanced forms of mastocytosis (aggressive systemic mastocytosis: ASM, systemic mastocytosis with associated hematological disease: SM-AHN, mast cell leukemia: MCL) present as a therapeutic challenge. Although the recently approved poly tyrosine kinase inhibitor Midostaurin provides some improvement, the median overall survival ranges from 3.5 years (ASM) to less than six months (MCL). The reduced life expectancy is frequently due to mast cell infiltration resulting in multi organ failure. Additionally, there are patients who do not benefit from the treatment with Midostaurin (overall response 60%) or suffer from side effects, which lead to reduction or termination of therapy. Currently, the only available curative approach is conditioning poly-chemotherapy followed by allogenic stem cell transplantation (allo-HSCT). However, allo-HSCT is associated with substantial side-effects and, also due to high rates of relapse, only leads to an overall survival of 43% for ASM and 17% for MCL after three years. Thus, better therapeutic options are needed. Recently, we demonstrated that CD117 (KIT-receptor) positive human AML can be efficiently eradicated by anti-CD117 CAR T-cells in vitro and in vivo (Myburgh et al., Leukemia 2020). As mast cells, and also transformed mast cells, highly express CD117, we here tested if anti-CD117 CAR T-cells would equally efficiently eliminate this malignant cell population. We thus co-cultured various established mast cell lines (partly harboring the oncogenic driver mutation KIT D816V) with anti-CD117-CAR T-cells in a 1:1 effector to target ratio in vitro. After 24 hours of co-culturing, the tumor cells were effectively killed, and this was still observed despite increasing the effector to target ratio to 1:4. Also, within 28 days of co-culture, the longest time followed in vitro, tumor cells were controlled and did not outgrow. Increased proliferation of anti-CD117-CAR T-cells in the presence of mast cells was observed and tracked throughout the 28-day experiment. In conclusion, we demonstrate that the human mast cell lines HMC-1.1 KIT V560G, HMC-1.2 KIT V560G, KIT D816V, ROSA KIT WT, ROSA KIT D816V, LAD2 and MCPV-1 can be efficiently targeted and killed in vitro by allogeneic anti-CD117-CAR T-cells. Given that CD117 is expressed on healthy hematopoietic stem and progenitor cells (HSPCs) on a substantially lower level, there might be a therapeutic window for anti-CD117 immunotherapy in advanced forms of mastocytosis. However, as CAR T-cells are highly efficient, collateral damage on healthy HSPCs will likely need to be compensated by subsequent HSC transplantation. We are currently translating these promising in vitro immunotherapeutic settings into surrogate xenogeneic in vivo models. Disclosures Myburgh: University of Zurich: Patents & Royalties: CD117xCD3 TEA. Manz: CDR-Life Inc: Consultancy, Current holder of stock options in a privately-held company; University of Zurich: Patents & Royalties: CD117xCD3 TEA.

scholarly journals Targeting USP47 overcomes tyrosine kinase inhibitor resistance and eradicates leukemia stem/progenitor cells in chronic myelogenous leukemia

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hu Lei ◽  
Han-Zhang Xu ◽  
Hui-Zhuang Shan ◽  
Meng Liu ◽  
Ying Lu ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Progenitor Cells ◽  
Chronic Myelogenous Leukemia ◽  
Drug Targets ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Myelogenous Leukemia ◽  
Tki Resistance

AbstractIdentifying novel drug targets to overcome resistance to tyrosine kinase inhibitors (TKIs) and eradicating leukemia stem/progenitor cells are required for the treatment of chronic myelogenous leukemia (CML). Here, we show that ubiquitin-specific peptidase 47 (USP47) is a potential target to overcome TKI resistance. Functional analysis shows that USP47 knockdown represses proliferation of CML cells sensitive or resistant to imatinib in vitro and in vivo. The knockout of Usp47 significantly inhibits BCR-ABL and BCR-ABLT315I-induced CML in mice with the reduction of Lin−Sca1+c-Kit+ CML stem/progenitor cells. Mechanistic studies show that stabilizing Y-box binding protein 1 contributes to USP47-mediated DNA damage repair in CML cells. Inhibiting USP47 by P22077 exerts cytotoxicity to CML cells with or without TKI resistance in vitro and in vivo. Moreover, P22077 eliminates leukemia stem/progenitor cells in CML mice. Together, targeting USP47 is a promising strategy to overcome TKI resistance and eradicate leukemia stem/progenitor cells in CML.

Tyrosine kinase-deficient Wvc-kit induces mast cell adhesion and chemotaxis

1998 ◽  
Vol 275 (5) ◽  
pp. C1291-C1299 ◽  
Author(s):  
Jaroslaw Dastych ◽  
Dennis Taub ◽  
Mary C. Hardison ◽  
Dean D. Metcalfe
Keyword(s):  
Mast Cell ◽  
Cell Adhesion ◽  
Mast Cells ◽  
Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Mouse Bone Marrow ◽  
Intact Cells ◽  
Protein Kinase C Inhibitors

W/Wvmice are deficient in tissue mast cells, and mast cells cultured from these mice do not proliferate in response to the c-kit ligand, stem cell factor (SCF). In this paper, we report that mouse bone marrow cultured mast cells derived from W/Wvmice do adhere to fibronectin in the presence of SCF and exhibit chemotaxis to SCF, and we explore this model for the understanding of c-kit-mediated signaling pathways. Both in vitro and in vivo (in intact cells) phosphorylation experiments demonstrated a low residual level of W/Wvc-kit protein phosphorylation. SCF-induced responses in W/Wvmast cells were abolished by the tyrosine kinase inhibitor herbimycin A and by the phospatidylinositol 3-kinase (PI 3-kinase) inhibitor wortmannin but were not affected by protein kinase C inhibitors. These observations are consistent with the conclusions that Wvc-kit initiates a signaling process that is PI 3-kinase dependent and that mutated Wvc-kit retains the ability to initiate mast cell adhesion and migration.

Combined Targeting of BCR-ABL and JAK2 with ABL and JAK2 Inhibitors Is Effective Against CML Patients' Leukemic Stem/Progenitor Cells.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3404-3404
Author(s):  
Donna DeGeer ◽  
Paolo Gallipoli ◽  
Min Chen ◽  
Ivan Sloma ◽  
Heather Jorgensen ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Kinase Inhibitor ◽  
Conflicts Of Interest ◽  
Integration Site ◽  
Single Agent ◽  
K562 Cells ◽  
High Rate ◽  
Jak2 Inhibitors

Abstract Abstract 3404 Imatinib mesylate (IM) is a tyrosine kinase inhibitor (TKI) that induces clinical responses in most chronic myeloid leukemia (CML) patients. Nevertheless, early relapses and later emergence of IM-resistant disease pose serious concerns for many. The inadequacies of IM therapy are due, at least in part, to the unique properties of CML stem/progenitor cells that make them generally less responsive to IM and, indeed, other TKIs, and also confer on them a genetic instability that leads to a high rate of formation of BCR-ABL mutants. Improved treatment approaches to prevent the development of resistant subclones by targeting other key molecular elements active in CML stem/progenitor cells are thus clearly needed. One candidate is a complex that forms in CML stem/progenitor cells between the oncoproteins encoded by AHI-1 (Abelson helper integration site 1), BCR-ABL and the JAK2 kinase. This complex contributes to the transforming activity of BCR-ABL both in vitro and in vivo and also plays a role in the IM response/resistance of primary CML stem/progenitor cells. We now describe the results of experiments designed to test the ability of ABL and JAK2 inhibitors to block the activity of this protein complex in CML cells. K562 cells engineered to stably overexpress AHI-1 showed a significantly reduced sensitivity to both IM (at 1 and 5 μM) and TG101209, a JAK2 inhibitor, (at 0.5 and 1 μM), as determined by assays for cell viability, apopotosis, and colony-forming activity. K562 cells engineered to suppression AHI-1 showed an opposite effect, with a heightened sensitivity to IM at concentrations as low as 1 μM. In addition, IM together with TG101209 was more effective at killing AHI-1-overexpressing K562 cells, IM-resistant K562 cells and IM-resistant T315I-mutant cells than either treatment alone. Western blot and co-IP experiments demonstrated a significant reduction of p-BCR-ABL, p-JAK2 and p-STAT5 in cells treated with IM plus TG101209 compared to cells treated with IM or TG101209 alone. Importantly, treatment with 5 μM IM, 150 nM dasatinib (DA) or 5 μM nilotinib (NL) in combination with 100 nM TG101209 caused a significantly greater reduction in the viability of primary CD34+CD38− and CD34+CD38+ CML cells when these responses were compared to any of the TKIs or TG101209 alone (~2-4 fold, n=3). Apoptotic cells at 72 hours were also significantly increased for all drug combinations compared to single agent treatments (40%-52% for the combinations vs 15%-18% for the single agents). CFSE tracking analysis of cell division in these cells further demonstrated additive anti-proliferative activity from the TKI plus TG101219 combinations, although some rare undivided cells were not eliminated. Nevertheless, exposure of CD34+ CML cells from IM-nonresponders (n=4) to TG101209 plus IM or DA did cause a greater inhibition (81% and 85%) of patients' colony-forming cells as compared to the same cells treated with the combination of IM plus DA only, or IM or DA only (60%, 41% and 50% inhibition, p<0.05). Long-term culture-initiating cell assays were undertaken to compare the effect of these combination treatments versus the effects of TKIs or TG101209 alone on very primitive CML cells. The results again showed a more significant reduction of these cells treated with the combination (n=3). Intracellular staining revealed a greater reduction in the levels of p-CrKL and p-STAT5 in CD34+ CML cells treated for 24 hours with the combination of TKIs plus TG101219 as compared to single TKI-treated cells (~44% vs 65% for p-CrKL and 36% vs 57% for p-STAT5, n=3). Strikingly, the combination treatment produced an even greater inhibition of both p-CrKL and p-STAT5 after 72 hours while p-CrKL was almost fully reactivated with TKIs alone (~29% vs 89% for p-CrKL and 23% vs 50% for p-STAT5). These results point to the possibility of achieving improved therapeutic outcomes in CML patients by simultaneously targeting both BCR-ABL and JAK2 activities in the critical TKI-insensitive CML stem/progenitor reservoir. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Aurora kinase inhibitor tozasertib suppresses mast cell activation in vitro and in vivo

2020 ◽  
Vol 177 (12) ◽  
pp. 2848-2859
Author(s):  
Li‐Na Zhang ◽  
Kunmei Ji ◽  
Yue‐Tong Sun ◽  
Yi‐Bo Hou ◽  
Jia‐Jie Chen
Keyword(s):  
Mast Cell ◽  
Cell Activation ◽  
Kinase Inhibitor ◽  
Aurora Kinase ◽  
Mast Cell Activation ◽  
Aurora Kinase Inhibitor

scholarly journals Suppressive effects in vivo of purified recombinant human H-subunit (acidic) ferritin on murine myelopoiesis

Blood ◽  
1989 ◽  
Vol 73 (1) ◽  
pp. 74-79 ◽  
Author(s):  
HE Broxmeyer ◽  
DE Williams ◽  
K Geissler ◽  
G Hangoc ◽  
S Cooper ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Progenitor Cell ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor Cell ◽  
Hematopoietic Progenitor ◽  
Virus Complex ◽  
Progenitor Cell Proliferation ◽  
Dose Dependent

Purified recombinant human heavy-chain (acidic) ferritin (rHF) was assessed in vivo in mice for effects on the proliferation (percentage of cells in S-phase) and absolute numbers of granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells in the femur and spleen and on the nucleated cells in the marrow, spleen, and blood. rHF significantly decreased cycling rates and absolute numbers of marrow and splenic hematopoietic progenitors and marrow and blood nucleated cellularity. These effects were apparent in BDF1, C3H/Hej and DBA/2 mice and were dose dependent, time related, and reversible. Suppressive effects were noted within three hours for progenitor cell cycling, within 24 hours for progenitor cell numbers, and within 48 hours for circulating neutrophils. Additionally, hematopoietic progenitor cells in DBA/2 mice infected with the polycythemia-inducing strain of the Friend virus complex (FVC-P) were insensitive to the in vivo administration of rHF. These studies demonstrate activity of rHF in vivo on myelopoiesis of normal but not FVC-P-infected mice. Since rHF suppresses hematopoietic progenitor cell proliferation from normal donors in vitro and from normal mice in vitro and in vivo but does not suppress progenitor cells from patients with leukemia in vitro or from mice with FVC-P-infection in vitro or in vivo, rHF may be useful as a candidate adjunct molecule for the protection of normal hematopoietic progenitor cells during chemotherapy.

scholarly journals Modulation of Leukotriene Signaling Affecting Cell Growth in Chronic Myeloid Leukemia: A Key Pathway to Cure?

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 5137-5137
Author(s):  
Elham Yektaei ◽  
Anders Nilsson ◽  
Barbro Näsman-Glaser ◽  
Marja Ekblom ◽  
Hong Qian ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Receptor Antagonist ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Kinase Inhibitor ◽  
Conflicts Of Interest ◽  
K562 Cells ◽  
Inhibitory Effects ◽  
Dose Dependent

Abstract Background: Recent data suggest that tyrosine kinase inhibitor (TKI)-insensitive leukemic stem cells often prevail in chronic myeloid leukemia (CML) patients subjected to long-term TKI treatment. To achieve cure additional aberrant pathways in these patients, such as leukotriene (LT) signaling, may need to be targeted. We have previously shown that human CML cells have an increased capacity to produce LT and that LT can stimulate normal myelopoiesis (Tornhamre ExpHem 2003). Chen later noted a striking up-regulation of ALOX5/5LO (catalyzing an initial step in LT formation) in CML mice, and that inhibition of this enzyme improved survival of these animals by a magnitude similar to that induced by imatinib (Chen NatureGen 2009). Here wexve assessed the effect of LT modulating agents on the growth of human CML cells in vitro. Materials and methods: Human CML cells, derived from the three cell lines K562, Kcl22 and KU812, were grown in microtitre plate cultures, in the presence of RPMI 1640. The MTT technique was used to evaluate the number of viable cells at 72 hours. Protein expression was assessed by Western blot and immunocytochemistry. Results: Several specific modulators of LT-signaling were capable of inducing dose-dependent growth inhibitory effects on CML cells. Thus, the cysteinyl-LT receptor antagonist montelukast, a drug with approved clinical use in human asthma, was shown to reduce the growth of all three tested CML cell lines. In Fig. 1 this is examplified by K562 cells, where also additive effects between montelukast and imatinib are indicated. All cell lines expressed the cysLT1-receptor. Furthermore, the LTB4 receptor antagonist etalocib, as well as the 5-LO activating protein (FLAP) inhibitors licofelone and Bay-X-1005, also executed inhibitory effects at concentrations considered as physiological. As expected, addition of the TKIs imatinib, nilotinib or dasatinib to the cultures also generated dose-dependent inhibitory effects on the growth of all tested CML cell lines. An LD50 of approximately 0.5 µM, 10 nM and 0.1 nM was noted for imatinib, nilotinib and dasatinib, respectively, for K562 cells at 72 hours. Conclusions: We demonstrate that several compounds, known to specifically inhibit leukotriene signaling by different mechanisms, were at clinically relevant concentrations capable of significantly suppressing the growth of human CML cells. Some of these compounds are already in clinical practice for non-hematological disorders. They could provide an additional therapeutic possibility in the quest to cure CML. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals Nintedanib Targets KIT D816V Neoplastic Cells Derived from Induced Pluripotent Stem cells of Systemic Mastocytosis

2020 ◽  
Author(s):  
Marcelo A. S. Toledo ◽  
Malrun Gatz ◽  
Stephanie Sontag ◽  
Karoline V. Gleixner ◽  
Gregor Eisenwort ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mast Cell ◽  
Progenitor Cells ◽  
Pluripotent Stem Cells ◽  
Systemic Mastocytosis ◽  
Hematopoietic Progenitor Cells ◽  
Patient Specific ◽  
Hematopoietic Progenitor ◽  
Induced Pluripotent ◽  
Kit D816v

AbstractThe KIT D816V mutation is found in more than 80% of patients with systemic mastocytosis (SM) and is key to neoplastic mast cell (MC) expansion and accumulation in affected organs. KIT D816V therefore represents a prime therapeutic target for SM. Here we generated a panel of patient-specific KIT D816V induced pluripotent stem cells (iPSCs) from patients with aggressive SM (ASM) and mast cell leukemia (MCL) to develop a patient-specific SM disease model for mechanistic and drug discovery studies. KIT D816V iPSCs differentiated into neoplastic hematopoietic progenitor cells and MCs with patient-specific phenotypic features, thereby reflecting the heterogeneity of the disease. CRISPR/Cas9n-engineered KIT D816V human embryonic stem cells (ESCs), when differentiated into hematopoietic cells, recapitulated the phenotype observed for KIT D816V iPSC hematopoiesis. KIT D816V causes constitutive activation of the KIT tyrosine kinase receptor and we exploited our iPSCs and ESCs to investigate new tyrosine kinase inhibitors targeting KIT D816V. Our study identified nintedanib as a novel KIT D816V inhibitor. Nintedanib selectively reduced the viability of iPSC-derived KIT D816V hematopoietic progenitor cells and MCs in the nanomolar range. Nintedanib was also active on primary samples of KIT D816V SM patients. Molecular docking studies show that nintedanib binds to the ATP binding pocket of inactive KIT D816V. Our results suggest nintedanib as a new drug candidate for KIT D816V targeted therapy of advanced SM.

scholarly journals Suppressive effects in vivo of purified recombinant human H-subunit (acidic) ferritin on murine myelopoiesis

Blood ◽  
1989 ◽  
Vol 73 (1) ◽  
pp. 74-79 ◽  
Author(s):  
HE Broxmeyer ◽  
DE Williams ◽  
K Geissler ◽  
G Hangoc ◽  
S Cooper ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Progenitor Cell ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor Cell ◽  
Hematopoietic Progenitor ◽  
Virus Complex ◽  
Progenitor Cell Proliferation ◽  
Dose Dependent

Abstract Purified recombinant human heavy-chain (acidic) ferritin (rHF) was assessed in vivo in mice for effects on the proliferation (percentage of cells in S-phase) and absolute numbers of granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells in the femur and spleen and on the nucleated cells in the marrow, spleen, and blood. rHF significantly decreased cycling rates and absolute numbers of marrow and splenic hematopoietic progenitors and marrow and blood nucleated cellularity. These effects were apparent in BDF1, C3H/Hej and DBA/2 mice and were dose dependent, time related, and reversible. Suppressive effects were noted within three hours for progenitor cell cycling, within 24 hours for progenitor cell numbers, and within 48 hours for circulating neutrophils. Additionally, hematopoietic progenitor cells in DBA/2 mice infected with the polycythemia-inducing strain of the Friend virus complex (FVC-P) were insensitive to the in vivo administration of rHF. These studies demonstrate activity of rHF in vivo on myelopoiesis of normal but not FVC-P-infected mice. Since rHF suppresses hematopoietic progenitor cell proliferation from normal donors in vitro and from normal mice in vitro and in vivo but does not suppress progenitor cells from patients with leukemia in vitro or from mice with FVC-P-infection in vitro or in vivo, rHF may be useful as a candidate adjunct molecule for the protection of normal hematopoietic progenitor cells during chemotherapy.

Systemic Mastocytosis with c-KITD816V Mutation Treated with Dasatinib.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4656-4656 ◽  
Author(s):  
Rudolf Benz ◽  
Juerg Boesiger ◽  
Jorg Fehr
Keyword(s):  
Mast Cell ◽  
Systemic Mastocytosis ◽  
Lumbar Pain ◽  
Common Mutation ◽  
Medical Council ◽  
Imatinib Resistance ◽  
Kit Mutation ◽  
Tyrosinkinase Inhibitor ◽  
Kit D816v

Abstract Objectives: Systemic mastocytosis (SM) is mainly a clonal disease with a variable clinical outcome. Prognosis is very much related to additional symptoms. If so called c-findings are present, survival is often limited to months. Until recently only Interferon and Cladribine could show some effect on the disease progression. With the introduction of Imatinib some hope grew to treat the disease by acting on c-KIT (CD 117; stem cell factor receptor). However, the substitution of valine for aspartic acid at position 816 in c-KIT (D816V) leads to prolonged mast cell survival and increased proliferation because of constitutive activation of the tyrosine kinase of c-KIT. Between 31% and 100% of patients with SM harbour the c-KIT D816V mutation which is invariably related to Imatinib resistance. Fortunately, the new tyrosinkinase inhibitor Dasatinib (BMS-354825) could show a much higher inhibition of the c-KIT D816V mutated receptor in vitro. Therefore we treated a patient with systemic mastocytosis with associated hematologic clonal non mast cell lineage disease (SM-AHNMD) and c-findings with Dasatinib. Case description: A 69 year old patient was diagnosed 5 years ago with cutaneous mastocytosis. Because of a markedly increased tryptase levels of 130μg/l he was referred to our clinic for further investigation. In a bone marrow biopsy, the classical signs of SM could be found together with a chronic myelomonocytic leukemia (CMML) without any cytogenetic alterations. During 2 years the patient remained clinically stable without any treatment. Subsequently the patient droped weight and got strong lumbar pain. A MRI scan revealed fractures of L2 and L4 without signs for osteoporosis. Additionally, splenomegaly and hepatomegaly have been noticed with enlarged lymph nodes in the retroperitoneal space together with profound thrombocytopenia. Even SM-AHNMD is by definition of the ‘year 2000 Working Conference on Mastocytosis’ a distinct entity, the occurring c-findings together with a rapid increase in tryptase levels have been associated with an aggressive disease course. A c-KIT mutation analysis showed a D816V mutation. We decided after approval from the medical council to start the patient on Dasatinib. We started with 50mg daily for 3 days. Because no signs of acute mastcell degranulation we increased the dose to 50mg BID and continued the treatment for 13 weeks. Due to non-hematologic toxicity (fatigue) Dasatinib had to be stopped. Hepatosplenomegaly remained stable, lumbar pain disappeared even after cessation of analgetic therapy and weight increased gradually. However, laboratory follow up (tryptase, soluble interleukin 2 receptor) showed inconsistent results. Conclusion: Our patient with SM-CMML had many signs of systemic aggressive mastocytosis which is a mostly fatal variant of SM. With the introduction of Imatinib, a potent c-kit inhibitor, a novel approach to inhibit mastcell-proliferation was described. However, the most common mutation in CD117 of mastcells (D816V mutation) turned out to be resistant to Imatinib. However, Dasatinib a recently introduced tyrosinkinase inhibitor showed significant efficacy in vitro. A phase II study of Dasatinib in patients with Philadelphia-negative myeloproliferative disorders, including SM has recently been presented by Verstovsek and colleagues showing an overall response rate of 42% in SM. However, these patients were c-KIT mutation negative. This case report shows first evidence of clinical activity of Dasatinib in a patient with systemic aggressive mastocytosis harbouring the c-KIT mutation D816V. Further clinical studies in this patient population are warranted.

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