The Pan-PIM Kinase Inhibitor LGB321 Affects Apoptotic Pathways and Microenvironmental Interactions in CLL

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4370-4370 ◽  
Author(s):  
Sarah Decker ◽  
Sandra Kissel ◽  
Konrad Aumann ◽  
Thorsten Zenz ◽  
Katja Zirlik ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Treatment Strategies ◽  
Protective Effects ◽  
Effective Treatment Option ◽  
Pim Kinases ◽  
Cxcr4 Receptor ◽  
Nog Mice

Abstract Introduction The emergence of kinase inhibitors like Ibrutinib has drastically altered treatment strategies and improved outcomes in CLL patients, but lack of cure and resistance to therapy still remain serious problems. The three PIM kinases are involved in various important disease mechanisms in CLL, with PIM1 regulating CXCR4 surface expression impacting its interaction with the microenvironment, and PIM2/3 affecting the apoptotic machinery by regulating BAD. The Pan-PIM kinase inhibitor LGB321 (Novartis) targets all three PIM kinases and therefore affects both, CLL apoposis and its interaction with the microenvironment. Results In the study presented here, we investigated the effect of the Pan-PIM kinase inhibitor LGB321 on CLL in vitro and in vivo. LGB321 was highly effective in inducing apoptosis in primary human CLL cells, independent of risk factors or the mutation status. Apoptosis induction correlated with reduced pBAD and BAD levels. LGB321 was also effective in the presence of protective stromal cells and could completely overcome the stroma protective effects. Furthermore, we found that Pan-PIM inhibitor treatment blocked the CXCR4/CXCL12 axis by dephosphorylating the CXCR4 receptor on Ser339, by reducing total CXCR4 protein levels, and by blocking the externalization of the CXCR4 receptor. Concordantly, LGB321 blocked CXCR4 functions like migration towards a CXCL12 gradient (P<.0001), and reduced homing of LGB321-pretreated primary CLL cells towards the bone marrow (P=.0001) of NOG mice. In vivo experiments comfirmed the efficacy of LGB321 in 4 different CLL xenograft studies. Transplantation of primary human CLL cells into NOG mice and treatment with LGB321 for 2 weeks strongly reduced WBC counts, spleen size and spleen infiltration with human CLL cells (P=.0295) in all four CLL cases, and blocked BAD as well as CXCR4 phosphorylation also in vivo. Conclusion Our results demonstrate, that the Pan-PIM kinase inhibitor LGB321 might be an effective treatment option for CLL patients by impairing PIM2/3 mediated CLL-cell survival, and by blocking the PIM1/CXCR4-mediated interaction of CLL cells with their protective microenvironment in vitro and in vivo. Future clinical trials should be performed to validate its efficacy in human CLL. Disclosures Claus: Roche: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria, Other: Travel Funding.

scholarly journals The Pan-PIM Kinase Inhibitor LGB321 Strongly Increases Ibrutinib Effects in CLL, By Blocking Anti-Apoptotic Pathways and Microenvironmental Interactions

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1840-1840 ◽  
Author(s):  
Sarah Decker ◽  
Shifa Saleem ◽  
Sandra Kissel ◽  
Anabel Zwick ◽  
Konrad Aumann ◽  
...  
Keyword(s):  
Kinase Inhibitor ◽  
Conflicts Of Interest ◽  
Single Treatment ◽  
Effective Treatment Option ◽  
Protein Levels ◽  
Cxcr4 Receptor ◽  
Nog Mice ◽  
Ibrutinib Resistance

Abstract Despite remarkable anti-tumor activity of ibrutinib in CLL, some patients develop resistance due to acquired mutations. By adding drugs which target survival pathways and the CLL protective microenvironmental interactions, we aim to increase ibrutinib efficacy and to prevent ibrutinib resistance. The three PIM kinases are involved in important disease mechanisms in CLL, with PIM1 regulating CXCR4 surface expression impacting the interaction with the protective microenvironment, and PIM2/3 affecting the apoptotic machinery by regulating BAD. Here, we investigated the effect of the Pan-PIM kinase inhibitor LGB321 in CLL in vitro and in vivo and its cooperative effect with ibrutinib. LGB321 was highly effective in inducing apoptosis in primary CLL cells, independent of prognostic factors or microenvironmental interactions, and reduced pBAD and total BAD protein levels in CLL. In vitro combination of ibrutinib and LGB321 demonstrated strong additive effects with doubled apoptosis rates compared to single treatment. Further, LGB321 treatment blocked the CXCR4/CXCL12 axis by dephosphorylating the CXCR4 receptor on Ser339, by reducing total CXCR4 protein levels, and by blocking the externalization of the CXCR4 receptor. Concordantly, LGB321 blocked CXCR4 functions regarding migration towards a CXCL12 gradient and homing of LGB321-pretreated primary CLL cells towards the bone marrow of NOG mice. In vivo experiments confirmed the efficacy of LGB321 in 5 different CLL xenograft studies. Transplantation of primary CLL cells into NOG mice and treatment with LGB321 for 2 weeks strongly reduced WBC counts, spleen size and spleen infiltration with human CLL cells in all 5 CLL cases, and blocked BAD as well as CXCR4 phosphorylation also in vivo. Xenograft studies combining ibrutinib with LGB321 demonstrated much faster reduction of WBC counts than ibrutinib single treatment and strongly reduced disease burden in the double treated mice, confirming the cooperative effects of those two inhibitors also in vivo. Our results demonstrate that LGB321 might be an effective treatment option for CLL patients by impairing PIM2/3 mediated CLL-cell survival, and by blocking the PIM1/CXCR4-mediated interaction of CLL cells with the protective microenvironment. Furthermore, LGB321 enhances ibrutinib treatment effects and might help to increase its efficacy and to avoid the development of ibrutinib resistance. Disclosures No relevant conflicts of interest to declare.

PIM Kinase Inhibitors Interfere with the Protective CLL Microenvironment by Blocking CXCR4 Surface Expression and Function

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3867-3867
Author(s):  
Sarah Decker ◽  
Johannes Finter ◽  
Katja Zirlik ◽  
Hendrik Veelken ◽  
Christine Dierks
Keyword(s):  
Bone Marrow ◽  
Stromal Cells ◽  
Kinase Inhibitors ◽  
Conflicts Of Interest ◽  
Surface Expression ◽  
Hematologic Malignancies ◽  
Effective Treatment Option ◽  
Pim Kinases ◽  
Cxcr4 Receptor

Abstract Abstract 3867 Introduction: CXCR4 surface expression is strongly elevated on CLL cells and is important for CLL cell survival and homing to the bone marrow. PIM kinases are overexpressed and mutated in various hematologic malignancies including B-cell lymphomas. Recent findings in AML suggest a direct link in between PIM1 kinase expression and the surface expression level of the CXCR4 receptor and Ser339 phosphorylation in CXCR4. Therefore the aim of the presented study was to investigate the role of PIM kinases in regulating the CXCR4-CXCL12 pathway in CLL. Results: By using a phospho-CXCR4 Ser339 antibody for both, western blot analysis of CLL cells from the peripheral blood (n=11) and IHC staining of bone marrow from CLL patients (n=30), we can show that in contrast to normal B-cells the majority of CLL cells have a hyperphosphorylated CXCR4 receptor. Furthermore high phosphorylation levels of the CXCR4 receptor in the bone marrow correlated with poor prognosis in CLL. Besides increased phosphorylation of the CXCR4 receptor, also the 3 PIM kinases, especially PIM1 (P=.0060) and PIM2 (P=.0404) are strongly overexpressed in CLL compared to normal B-lymphocytes on mRNA- and protein level. Transcript levels of PIM1 (P=.0020), PIM2 (P=.0006) and PIM3 (P=.0206) positively correlated with the median CXCR4 surface expression. Furthermore PIM1 protein expression demonstrated a positive correlation with the CXCR4 phosphorylation on Ser339. PIM kinase inhibition with 3 different PIM kinase inhibitors (K00135, K00486 and CMV-05–144–01) resulted in a dose-dependent induction of apoptosis in primary human CLL cells independent of the presence of stromal cells, indicating that pathways activated by stromal cells are directly targeted by PIM kinase inhibitors. Additionally, inhibition of PIM with the inhibitor K00135 induced dephosphorylation of the CXCR4 receptor on Ser339 and resulted in enhanced ligand-dependent CXCR4 internalization and reduced reexternalization after withdrawal of CXCL12. Furthermore PIM inhibition induced degradation of internalized CXCR4 receptor and blocked CXCR4 function regarding survival, ERK-phosphorylation and migration towards a CXCL12 gradient. We could further demonstrate that pretreatment of primary CLL cells with PIM kinase inhibitors and resulting down regulation of the CXCR4 receptor strongly reduced homing of CLL cells towards the bone marrow (P=.0293) and the spleen (P=.0104) of Rag2−/−γc−/− mice in vivo. Conclusion: Our results demonstrate, that PIM kinase inhibitors are an effective treatment option for CLL by directly inducing pro-apoptotic pathways in CLL cells, but also by blocking the CXCR4 pathway which is important for the interaction of CLL cells with their protective microenvironment. Disclosures: No relevant conflicts of interest to declare.

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.

scholarly journals Identification of Hsp90 inhibitors as potential drugs for the treatment of TSC1/TSC2 deficient cancer

2021 ◽  
Author(s):  
Evelyn M. Mrozek ◽  
Vineeta Bajaj ◽  
Yanan Guo ◽  
Izabela Malinowska ◽  
Jianming Zhang ◽  
...  
Keyword(s):  
Cell Lines ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Xenograft Model ◽  
Growth Delay ◽  
Hsp90 Inhibitors ◽  
Null Cell ◽  
Standard Dosage

Inactivating mutations in either TSC1 or TSC2 cause Tuberous Sclerosis Complex, an autosomal dominant disorder, characterized by multi-system tumor and hamartoma development. Mutation and loss of function of TSC1 and/or TSC2 also occur in a variety of sporadic cancers, and rapamycin and related drugs show highly variable treatment benefit in patients with such cancers. The TSC1 and TSC2 proteins function in a complex that inhibits mTORC1, a key regulator of cell growth, which acts to enhance anabolic biosynthetic pathways. In this study, we identified and validated five cancer cell lines with TSC1 or TSC2 mutations and performed a kinase inhibitor drug screen with 197 compounds. The five cell lines were sensitive to several mTOR inhibitors, and cell cycle kinase and HSP90 kinase inhibitors. The IC50 for Torin1 and INK128, both mTOR kinase inhibitors, was significantly increased in three TSC2 null cell lines in which TSC2 expression was restored.  Rapamycin was significantly more effective than either INK128 or ganetespib (an HSP90 inhibitor) in reducing the growth of TSC2 null SNU-398 cells in a xenograft model. Combination ganetespib-rapamycin showed no significant enhancement of growth suppression over rapamycin. Hence, although HSP90 inhibitors show strong inhibition of TSC1/TSC2 null cell line growth in vitro, ganetespib showed little benefit at standard dosage in vivo. In contrast, rapamycin which showed very modest growth inhibition in vitro was the best agent for in vivo treatment, but did not cause tumor regression, only growth delay.

TEL/PDGFβR Induces Hematologic Malignancies in Mice That Respond to a Specific Tyrosine Kinase Inhibitor

Blood ◽  
1999 ◽  
Vol 93 (5) ◽  
pp. 1707-1714 ◽  
Author(s):  
Michael H. Tomasson ◽  
Ifor R. Williams ◽  
Robert Hasserjian ◽  
Chirayu Udomsakdi ◽  
Shannon M. McGrath ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitor ◽  
Tyrosine Kinases ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Transgenic Animals ◽  
Myeloid Lineage ◽  
Protein Tyrosine

Abstract The TEL/PDGFβR fusion protein is expressed as the consequence of a recurring t(5;12) translocation associated with chronic myelomonocytic leukemia (CMML). Unlike other activated protein tyrosine kinases associated with hematopoietic malignancies, TEL/PDGFβR is invariably associated with a myeloid leukemia phenotype in humans. To test the transforming properties of TEL/PDGFβR in vivo, and to analyze the basis for myeloid lineage specificity in humans, we constructed transgenic mice with TEL/PDGFβR expression driven by a lymphoid-specific immunoglobulin enhancer-promoter cassette. These mice developed lymphoblastic lymphomas of both T and B lineage, demonstrating that TEL/PDGFβR is a transforming protein in vivo, and that the transforming ability of this fusion is not inherently restricted to the myeloid lineage. Treatment of TEL/PDGFβR transgenic animals with a protein tyrosine kinase inhibitor with in vitro activity against PDGFβR (CGP57148) resulted in suppression of disease and a prolongation of survival. A therapeutic benefit was apparent both in animals treated before the development of overt clonal disease and in animals transplanted with clonal tumor cells. These results suggest that small-molecule tyrosine kinase inhibitors may be effective treatment for activated tyrosine kinase–mediated malignancies both early in the course of disease and after the development of additional transforming mutations.

scholarly journals Colorectal Cancer Growth Retardation through Induction of Apoptosis, Using an Optimized Synergistic Cocktail of Axitinib, Erlotinib, and Dasatinib

Cancers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1878 ◽  
Author(s):  
Robert H. Berndsen ◽  
Nathalie Swier ◽  
Judy R. van Beijnum ◽  
Patrycja Nowak-Sliwinska
Keyword(s):  
Colorectal Cancer ◽  
Cell Lines ◽  
Kinase Inhibitors ◽  
Expression Profiles ◽  
Chorioallantoic Membrane ◽  
Treatment Strategies ◽  
Tumor Growth Inhibition ◽  
Clinical Implementation

Patients with advanced colorectal cancer (CRC) still depend on chemotherapy regimens that are associated with significant limitations, including resistance and toxicity. The contribution of tyrosine kinase inhibitors (TKIs) to the prolongation of survival in these patients is limited, hampering clinical implementation. It is suggested that an optimal combination of appropriate TKIs can outperform treatment strategies that contain chemotherapy. We have previously identified a strongly synergistic drug combination (SDC), consisting of axitinib, erlotinib, and dasatinib that is active in renal cell carcinoma cells. In this study, we investigated the activity of this SDC in different CRC cell lines (SW620, HT29, and DLD-1) in more detail. SDC treatment significantly and synergistically decreased cell metabolic activity and induced apoptosis. The translation of the in-vitro-based results to in vivo conditions revealed significant CRC tumor growth inhibition, as evaluated in the chicken chorioallantoic membrane (CAM) model. Phosphoproteomics analysis of the tested cell lines revealed expression profiles that explained the observed activity. In conclusion, we demonstrate promising activity of an optimized mixture of axitinib, erlotinib, and dasatinib in CRC cells, and suggest further translational development of this drug mixture.

Acquired Extramedullary Resistance to Dasatinib Due to Selection of Philadelphia-Positive Lymphoblast Clone Harboring a T315I BCR-ABL Gene Mutation: Reversal by Dose Escalation and Hydroxyurea.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4579-4579
Author(s):  
Tuija Lundan ◽  
Franz Gruber ◽  
Martin Hoglund ◽  
Bengt Simonsson ◽  
Sakari Knuutila ◽  
...  
Keyword(s):  
Dose Escalation ◽  
Low Dose ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Mutant Cell ◽  
Skin Lesions ◽  
Fish Analysis ◽  
Imatinib Resistance

Abstract Most patients with advanced Philadelphia-positive (Ph+) hematologic malignancies develop resistance to imatinib. Acquired resistance to imatinib is commonly a result of selection for subclones bearing point-mutations in the catalytic kinase domain of BCR-ABL. Dasatinib (BMS-354825), a dual-specific SRC/ABL kinase inhibitor, has shown activity in imatinib-resistant Ph+ diseases both in vitro and in vivo. Preliminary data also indicate efficacy in patients. Based on laboratory evidence, dasatinib appears to inhibit all known BCR-ABL mutant clones, with the exception of T315I, a gatekeeper mutation conferring resistance to several kinase inhibitors. Here we describe a Ph+ ALL patient, who initially developed imatinib resistance (hematologic) possibly due to BCR-ABL amplification (FISH). His disease relapsed as extensive extramedullary tumors bearing wild-type BCR-ABL. He received dasatinib 70 mg BID as part of the BMS CA180–015 study and achieved a very good partial remission. After 5 months of therapy, the disease relapsed as a solitary axillary tumor and several small palmar skin lesions. He also had blasts in the CSF indicative of neuroleukemia. Bone marrow remained in cytogenetic remission. FISH analysis of the tumor revealed 2–3 copies of BCR-ABL as previously. A highly sensitive, quantitative, mutation-specific PCR (Gruber F, ASH 2004) showed the presence of the T315I mutation, which was confirmed by sequencing. A very low level of T315I transcript was also detected in the blood. Dasatinib dose was escalated to 100 mg BID, and low-dose hydroxyurea 500 mg BID was initiated to putatively enhance the access of dasatinib in the CSF sanctuary. He also received two doses of i.t. therapy (methotrexate, cytarabine). Patient’s symptoms (confusion, headache) related to neuroleukemia resolved rapidly, skin lesions disappeared and axillary tumor decreased in size. He is currently symptom-free and has no signs of active ALL. The favorable response to dasatinib dose escalation and low-dose hydroxyurea was unexpected. Preclinical data on T315I mutant cell lines would argue against a significant concentration dependence in kinase inhibition by dasatinib. Putatively, targets other than BCR-ABL may be of importance in particular in Ph+ ALL (e.g. Src, Lyn), and this effect may account for the response. Similar off-target activity of hydroxyurea is utilized in clinical trials to overcome resistance to multidrug HIV therapy - a setting resembling current treatment of Ph+ malignancies with kinase inhibitors.

mTOR Kinase Inhibitors Enhance Efficacy of TKIs in Preclinical Models of Ph-like B-ALL

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2763-2763 ◽  
Author(s):  
Moran Gotesman ◽  
Thanh-Trang T Vo ◽  
Sharmila Mallya ◽  
Qi Zhang ◽  
Ce Shi ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Research Funding ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Inhibitor Therapy ◽  
Cellular Viability ◽  
Murine Bone Marrow ◽  
Pdx Models

Abstract Background and Rationale: B-lymphoblastic leukemia (B-ALL) is the most common cancer of childhood. While event-free survival (EFS) exceeds 85% for most patients treated with contemporary therapy, outcomes are very poor for children who relapse, highlighting a need for new treatments. In particular, children with Philadelphia chromosome-like (Ph-like) B-ALL (who lack BCR-ABL1 rearrangement) have high rates of relapse and mortality with conventional chemotherapy. Transcriptional profiling and genomic sequencing of Ph-like ALL specimens have identified a variety of alterations that activate oncogenic kinase signaling, including rearrangements (R) of CRLF2, ABL1, and PDGFRB. Addition of the tyrosine kinase inhibitor (TKI) imatinib to chemotherapy has dramatically improved EFS for patients with BCR-ABL1-rearranged (Ph+) B-ALL, and it is hypothesized that TKI addition to therapy will similarly improve outcomes for patients with Ph-like ALL. Our prior preclinical studies in Ph+ B-ALL demonstrated enhanced efficacy of combining TKIs (imatinib or dasatinib) with mTOR kinase inhibitors (TOR-KIs) (Janes et al., Nature Medicine 2010; Janes et al, Leukemia2013). In the current studies, we hypothesized that dual kinase inhibitor therapy would have superior anti-leukemia cytotoxicity in Ph-like ALL and thus investigated combined TKI and TOR-KI treatment using patient-derived xenograft (PDX) models of childhood Ph-like ALL. Methods: For in vitro studies, viably cryopreserved leukemia cells from established ABL1-R Ph-like ALL PDX models (2 ETV6-ABL1) were incubated with the TKI dasatinib, TOR-KIs, or both TKI + TOR-KI for 72 hours prior to flow cytometric assessment of cellular viability via Annexin V and propidium iodide staining. Two chemically distinct TOR-KIs (MLN0128 or AZD2014) were used to confirm on-target effects. Additional primary ABL1-R or PDGFRB-R Ph-like ALL specimens were plated in methylcellulose without or with inhibitors in colony-forming assays. Phosphoflow cytometry (PFC) analysis of ALL cells incubated with inhibitors was also performed to measure the ability of TKIs and TOR-KIs to inhibit intracellular ABL1 and PI3K/mTOR signaling pathways. For in vivo studies, Ph-like ALL PDX models were treated with dasatinib, the TOR-KI AZD8055, or both drugs via daily oral gavage for 8 days. Human CD19+ ALL was quantified in murine spleens and bone marrow at end of treatment with quantification of cycling cells by EdU incorporation. PFC analysis of murine bone marrow was also performed 2 hours after drugs were dosed, to measure in vivo inhibition of signaling proteins. Results: Combined in vitro treatment with dasatinib and MLN0128 or AZD2014 decreased cellular viability more than inhibitor monotherapy. Similarly, in a set of CRLF2-rearranged samples, mTOR inhibitors augmented killing by the JAK2 inhibitor BBT-594. Incubation of primary ABL1-R or PDGFRB-R ALL cells with both dasatinib and AZD2014 more robustly inhibited colony formation than did inhibitor monotherapy. In in vitro PFC analyses of ABL1-R samples, we observed expected dasatinib-induced inhibition of phosphorylated (p) STAT5. Inhibition of the mTOR substrate pS6 was observed with dasatinib, MLN0128, and AZD2014 with more complete inhibition achieved when dasatinib combined with either MLN0128 or AZD2014. Similarly, in vivo treatment of PDX models with dasatinib and AZD8055 reduced leukemia burden and pS6 signaling more completely than either inhibitor alone. Importantly, dual inhibition decreased the percentage of cycling human ALL cells in murine bone marrow, but preserved cycling in normal mouse bone marrow cells in the same animals. Our data thus provide additional compelling preclinical rationale for combined inhibitor therapy with TKIs and TOR-KIs in Ph-like ALL. Disclosures Weinstock: Novartis: Consultancy, Research Funding. Mullighan:Incyte: Membership on an entity's Board of Directors or advisory committees; Amgen: Speakers Bureau; Loxo Oncology: Research Funding. Konopleva:Reata Pharmaceuticals: Equity Ownership; Abbvie: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Stemline: Consultancy, Research Funding; Eli Lilly: Research Funding; Cellectis: Research Funding; Calithera: Research Funding.

scholarly journals Emerging role of kinase-targeted strategies in chronic lymphocytic leukemia

Hematology ◽  
2012 ◽  
Vol 2012 (1) ◽  
pp. 88-96 ◽  
Author(s):  
Adrian Wiestner
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Absolute Lymphocyte Count ◽  
Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Cell Trafficking

Abstract Chronic lymphocytic leukemia (CLL) is a malignancy of mature B cells that depend on host factors in the tissue microenvironment for survival and proliferation. In vitro, CLL cells rapidly undergo apoptosis unless microenvironmental factors are provided that support their survival. Signaling pathways activated in the microenvironment in vivo include the B-cell receptor (BCR) and NF-κB pathways. Thus, CLL is a disease “addicted to the host” and is dependent on pathways that promote normal B-cell development, expansion, and survival; this is particularly true in the case of the BCR signaling cascade. Small-molecule inhibitors of kinases that are essential for BCR signal transduction abrogate the stimulating effects of the microenvironment on CLL cells. The orally administered tyrosine kinase inhibitors fostamatinib and ibrutinib and the phosphatidylinositol 3-kinase inhibitor GS-1101 have induced impressive responses in relapsed and refractory CLL patients, mostly with moderate side effects. Reductions in lymphadenopathy and splenomegaly are seen within weeks and are frequently accompanied by a transient rise in absolute lymphocyte count that is asymptomatic and probably the result of changes in CLL cell trafficking. This review discusses the biologic basis for kinase inhibitors as targeted therapy of CLL and summarizes the exciting early clinical experience with these agents.

In Vitro and In Vivo Activity of the Src/Abl Kinase Inhibitor AP23464 and Analogs Against Activation Loop Mutants of KIT.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 793-793 ◽  
Author(s):  
Amie S. Corbin ◽  
Shadmehr Demehri ◽  
Ian J. Griswold ◽  
Chester A. Metcalf ◽  
William C. Shakespeare ◽  
...  
Keyword(s):  
Cell Lines ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Myelogenous Leukemia ◽  
Activation Loop ◽  
Wild Type ◽  
Abl Kinase ◽  
Ic50 Values

Abstract Oncogenic mutations of the KIT receptor tyrosine kinase have been identified in several malignancies including gastrointestinal stromal tumors (GIST), systemic mastocytosis (SM), seminomas/dysgerminomas and acute myelogenous leukemia (AML). Mutations in the regulatory juxtamembrane domain are common in GIST, while mutations in the activation loop of the kinase (most commonly D816V) occur predominantly in SM and at low frequency in AML. Several ATP-competitive kinase inhibitors, including imatinib, are effective against juxtamembrane KIT mutants, however, the D816V mutant is largely resistant to inhibition. We analyzed the sensitivities of cell lines expressing wild type KIT, juxtamembrane mutant KIT (V560G) and activation loop mutant KIT (D816V,F,Y and murine D814Y) to a potent Src/Abl kinase inhibitor, AP23464, and analogs. IC50 values for inhibition of cellular KIT phosphorylation by AP23464 were 5–11 nM for activation loop mutants, 70 nM for the juxtamembrane mutant and 85 nM for wild type KIT. Consistent with this, IC50 values in cell proliferation assays were 3–20 nM for activation loop mutants and 100 nM for wild type KIT and the juxtmembrane mutant. In activation loop mutant-expressing cell lines, AP23464, at concentrations ≤50 nM, induced apoptosis, arrested the cell cycle in G0/G1 and down-regulated phosphorylation of Akt and STAT3, signaling pathways critical for the transforming capacity of mutant KIT. In contrast, 500 nM AP23464 was required to induce equivalent effects in wild-type KIT and juxtamembrane mutant-expressing cell lines. These data demonstrate that activation loop KIT mutants are considerably more sensitive to inhibition by AP23464 than wild type or juxtamembrane mutant KIT. Non-specific toxicity in parental cells occurred only at concentrations above 2 μM. Additionally, at concentrations below 100 nM, AP23464 did not inhibit formation of granulocyte/macrophage and erythrocyte colonies from normal bone marrow, suggesting that therapeutic drug levels would not impact normal hematopoiesis. We also examined in vivo target inhibition in a mouse model. Mice were subcutaneously injected with D814Y-expressing (D816V homologous) murine mastocytoma cells. Once tumors were established, compound was administered three-times daily by oral gavage. One hour post treatment we observed >90% inhibition of KIT phosphorylation in tumor tissue. Following a three-day treatment regimen, there was a statistically significant difference in tumor size compared to controls. Thus, AP23464 analogs effectively target D816-mutant KIT both in vitro and in vivo and inhibit activation loop KIT mutants more potently than the wild type protein. These data provide evidence that this class of kinase inhibitors may have therapeutic potential for D816V-expressing malignancies such as SM or AML.

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