pci-32765 and Leukemia--Myeloid--Acute

The treatment of older, unfit patients with acute myeloid leukemia (AML) is challenging. Based on preclinical data of Bruton tyrosine kinase expression/phosphorylation and ibrutinib cytotoxicity in AML blasts, we conducted a randomized phase 2 multicenter study to assess the tolerability and efficacy of the addition of ibrutinib to 10-day decitabine in unfit (ie, Hematopoietic Cell Transplantation Comorbidity Index ≥3) AML patients and higher risk myelodysplasia patients (HOVON135/SAKK30/15 trial). In total, 144 eligible patients were randomly (1:1) assigned to either 10-day decitabine combined with ibrutinib (560 mg; sequentially given, starting the day after the last dose of decitabine) (n = 72) or to 10-day decitabine (n = 72). The addition of ibrutinib was well tolerated, and the number of adverse events was comparable for both arms. In the decitabine plus ibrutinib arm, 41% reached complete remission/complete remission with incomplete hematologic recovery (CR/CRi), the median overall survival (OS) was 11 months, and 2-year OS was 27%; these findings compared with 50% CR/CRi, median OS of 11.5 months, and 2-year OS of 21% for the decitabine group (not significant). Extensive molecular profiling at diagnosis revealed that patients with STAG2, IDH2, and ASXL1 mutations had significantly lower CR/CRi rates, whereas patients with mutations in TP53 had significantly higher CR/CRi rates. Furthermore, multicolor flow cytometry revealed that after 3 cycles of treatment, 28 (49%) of 57 patients with available bone marrow samples had no measurable residual disease. In this limited number of cases, measurable residual disease revealed no apparent impact on event-free survival and OS. In conclusion, the addition of ibrutinib does not improve the therapeutic efficacy of decitabine. This trial was registered at the Netherlands Trial Register (NL5751 [NTR6017]) and has EudraCT number 2015-002855-85.

Topics: Adenine; Decitabine; Humans; Leukemia, Myeloid, Acute; Myelodysplastic Syndromes; Netherlands; Piperidines

Preclinical studies have suggested a role for Bruton tyrosine kinase (BTK) as a potential therapeutic target in acute myeloid leukemia (AML), and anti-AML activity in vivo has been demonstrated with BTK inhibitors.. In this open-label phase 2a study, patients with AML were treated with ibrutinib 560 mg per day alone (cohort 1; n = 7), or ibrutinib in combination with either cytarabine 20 mg administered subcutaneously twice daily for 10 days of a 28-day cycle (cohort 2; n = 21) or azacitidine 75 mg/m. A total of 36 patients were enrolled and received treatment; median duration of ibrutinib treatment was 5.4 weeks, and median time on study was 16 months. Of 24 patients evaluable for response, 1 partial remission (cohort 3) and 1 complete remission (cohort 2) were observed; the remaining responses were treatment failures. Median overall survival was 4.0 months in cohort 1, 2.2 months in cohort 2, 2.8 months in cohort 3, and 2.4 months for the overall population. No unexpected safety signals were identified. Grade 3 or higher adverse events that occurred in ≥ 10% of patients included AML progression, febrile neutropenia, pneumonia, anemia, thrombocytopenia, fatigue, asthenia, and respiratory failure.. Ibrutinib alone or in combination with cytarabine or azacitidine demonstrated an acceptable safety profile. However, limited efficacy with ibrutinib was observed in patients with AML.

Topics: Adenine; Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Azacitidine; Cohort Studies; Cytarabine; Female; Follow-Up Studies; Humans; Leukemia, Myeloid, Acute; Male; Middle Aged; Non-Randomized Controlled Trials as Topic; Piperidines; Prognosis; Pyrazoles; Pyrimidines; Remission Induction; Survival Rate

Patients with refractory or relapsed haematological malignancies have few treatment options and short survival times. Identification of effective therapies with genomic-based precision medicine is hampered by intratumour heterogeneity and incomplete understanding of the contribution of various mutations within specific cancer phenotypes. Ex-vivo drug-response profiling in patient biopsies might aid effective treatment identification; however, proof of its clinical utility is limited.. We investigated the feasibility and clinical impact of multiparametric, single-cell, drug-response profiling in patient biopsies by immunofluorescence, automated microscopy, and image analysis, an approach we call pharmacoscopy. First, the ability of pharmacoscopy to separate responders from non-responders was evaluated retrospectively for a cohort of 20 newly diagnosed and previously untreated patients with acute myeloid leukaemia. Next, 48 patients with aggressive haematological malignancies were prospectively evaluated for pharmacoscopy-guided treatment, of whom 17 could receive the treatment. The primary endpoint was progression-free survival in pharmacoscopy-treated patients, as compared with their own progression-free survival for the most recent regimen on which they had progressive disease. This trial is ongoing and registered with ClinicalTrials.gov, number NCT03096821.. Pharmacoscopy retrospectively predicted the clinical response of 20 acute myeloid leukaemia patients to initial therapy with 88·1% accuracy. In this interim analysis, 15 (88%) of 17 patients receiving pharmacoscopy-guided treatment had an overall response compared with four (24%) of 17 patients with their most recent regimen (odds ratio 24·38 [95% CI 3·99-125·4], p=0·0013). 12 (71%) of 17 patients had a progression-free survival ratio of 1·3 or higher, and median progression-free survival increased by four times, from 5·7 (95% CI 4·1-12·1) weeks to 22·6 (7·4-34·0) weeks (hazard ratio 3·14 [95% CI 1·37-7·22], p=0·0075).. Routine clinical integration of pharmacoscopy for treatment selection is technically feasible, and led to improved treatment of patients with aggressive refractory haematological malignancies in an initial patient cohort, warranting further investigation.. Austrian Academy of Sciences; European Research Council; Austrian Science Fund; Austrian Federal Ministry of Science, Research and Economy; National Foundation for Research, Technology and Development; Anniversary Fund of the Austrian National Bank; MPN Research Foundation; European Molecular Biology Organization; and Swiss National Science Foundation.

Topics: Adenine; Adult; Aged; Antineoplastic Agents; Area Under Curve; Bone Marrow; Bortezomib; Cladribine; Disease-Free Survival; Female; Hematologic Neoplasms; Humans; Kaplan-Meier Estimate; Leukemia, Myeloid, Acute; Male; Microscopy, Fluorescence; Middle Aged; Odds Ratio; Pilot Projects; Piperidines; Positron Emission Tomography Computed Tomography; Pyrazoles; Pyrimidines; Remission Induction; ROC Curve; Young Adult

This study uses personalized chronic lymphoblastic leukemia (CLL) cybrid cells to test various drugs/agents designed to improve mitochondrial function and cell longevity. Age-matched control (NL) and CLL cybrids were created. The NL and CLL cybrids were treated with ibrutinib (Ibr-10 μM), mitochondrial-targeted nutraceuticals such as alpha lipoic acid (ALA-1 mM), amla (Aml-300 μg), melatonin (Mel-1 mM), resveratrol (Res-100 μM) alone, or a combination of ibrutinib with nutraceuticals (Ibr + ALA, Ibr + Aml, Ibr + Mel, or Ibr + Res) for 48 h. MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazoliumbromide), H2DCFDA(2',7' Dichlorodihydrofluorescein diacetate), and JC1 assays were used to measure the cellular metabolism, intracellular ROS levels, and mitochondrial membrane potential (∆ψm), respectively. The expression levels of genes associated with antioxidant enzymes (

Topics: Antioxidants; Dietary Supplements; Drug Resistance, Neoplasm; Gene Expression; Humans; Hybrid Cells; Leukemia, Lymphocytic, Chronic, B-Cell; Leukemia, Myeloid, Acute; Membrane Potential, Mitochondrial; Mitochondria; Reactive Oxygen Species

Acute myeloid leukemia (AML) results from the enhanced proliferation and impaired differentiation of hematopoietic stem and progenitor cells. Using an ex vivo functional screening assay, we identified that the combination of the BTK inhibitor ibrutinib and BCL2 inhibitor venetoclax (IBR + VEN), currently in clinical trials for chronic lymphocytic leukemia (CLL), demonstrated enhanced efficacy on primary AML patient specimens, AML cell lines, and in a mouse xenograft model of AML. Expanded analyses among a large cohort of hematologic malignancies (n = 651 patients) revealed that IBR + VEN sensitivity associated with selected genetic and phenotypic features in both CLL and AML specimens. Among AML samples, 11q23 MLL rearrangements were highly sensitive to IBR + VEN. Analysis of differentially expressed genes with respect to IBR + VEN sensitivity indicated pathways preferentially enriched in patient samples with reduced ex vivo sensitivity, including IL-10 signaling. These findings suggest that IBR + VEN may represent an effective therapeutic option for patients with AML.

Topics: Adenine; Animals; Antineoplastic Combined Chemotherapy Protocols; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Humans; Leukemia, Myeloid, Acute; Mice; Piperidines; Proto-Oncogene Proteins c-bcl-2; Pyrazoles; Pyrimidines; Sulfonamides; Xenograft Model Antitumor Assays

Granulocyte-colony stimulating factor receptor (G-CSFR) controls myeloid progenitor proliferation and differentiation to neutrophils. Mutations in CSF3R (encoding G-CSFR) have been reported in patients with chronic neutrophilic leukemia (CNL) and acute myeloid leukemia (AML); however, despite years of research, the malignant downstream signaling of the mutated G-CSFRs is not well understood. Here, we used a quantitative phospho-tyrosine analysis to generate a comprehensive signaling map of G-CSF induced tyrosine phosphorylation in the normal versus mutated (proximal: T618I and truncated: Q741x) G-CSFRs. Unbiased clustering and kinase enrichment analysis identified rapid induction of phospho-proteins associated with endocytosis by the wild type G-CSFR only; while G-CSFR mutants showed abnormal kinetics of canonical Stat3, Stat5, and Mapk phosphorylation, and aberrant activation of Bruton's Tyrosine Kinase (Btk). Mutant-G-CSFR-expressing cells displayed enhanced sensitivity (3-5-fold lower IC50) for ibrutinib-based chemical inhibition of Btk. Primary murine progenitor cells from G-CSFR-Q741x knock-in mice validated activation of Btk by the mutant receptor and retrovirally transduced human CD34

Topics: Adenine; Agammaglobulinaemia Tyrosine Kinase; Animals; Cell Proliferation; Cell Transformation, Neoplastic; Cells, Cultured; Humans; Leukemia, Myeloid, Acute; Leukemia, Neutrophilic, Chronic; Mice; Mutation; Phosphoproteins; Phosphorylation; Piperidines; Precursor Cells, B-Lymphoid; Protein-Tyrosine Kinases; Proteome; Pyrazoles; Pyrimidines; Receptors, Granulocyte Colony-Stimulating Factor

Kinase inhibitors are important cancer therapeutics. Polypharmacology is commonly observed, requiring thorough target deconvolution to understand drug mechanism of action. Using chemical proteomics, we analyzed the target spectrum of 243 clinically evaluated kinase drugs. The data revealed previously unknown targets for established drugs, offered a perspective on the "druggable" kinome, highlighted (non)kinase off-targets, and suggested potential therapeutic applications. Integration of phosphoproteomic data refined drug-affected pathways, identified response markers, and strengthened rationale for combination treatments. We exemplify translational value by discovering SIK2 (salt-inducible kinase 2) inhibitors that modulate cytokine production in primary cells, by identifying drugs against the lung cancer survival marker MELK (maternal embryonic leucine zipper kinase), and by repurposing cabozantinib to treat FLT3-ITD-positive acute myeloid leukemia. This resource, available via the ProteomicsDB database, should facilitate basic, clinical, and drug discovery research and aid clinical decision-making.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cytokines; Drug Discovery; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Lung Neoplasms; Mice; Molecular Targeted Therapy; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases; Proteomics; Xenograft Model Antitumor Assays

Topics: ADAMTS13 Protein; Adenine; Antibodies, Monoclonal; Antineoplastic Agents; Central Venous Catheters; fms-Like Tyrosine Kinase 3; Genetic Therapy; Graft vs Host Disease; Hematologic Diseases; Hemophilia B; Humans; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukemia, Myeloid, Acute; Multiple Myeloma; Mutation; Piperidines; Protein Kinase Inhibitors; Purpura, Thrombotic Thrombocytopenic; Pyrazoles; Pyrimidines; Recombinant Proteins; Societies, Medical; Thrombosis

Acute myeloid leukemia (AML) is a highly heterogeneous disease and internal tandem duplication mutation in FMS-like tyrosine-kinase-3 (FLT3-ITD) has a negative impact on outcome. Finding effective treatment regimens is desperately needed. In this study, we explored the inhibitory effect and mechanism of homoharringtonine (HHT) in combination with ibrutinib on FLT3-ITD mutant AML cells. Consequently, we observed a synergistic inhibitory effect when ibrutinib was combined with HHT to inhibit cell proliferation, induce apoptosis and arrest cell cycle at G0/G1 phase in MV4-11 and MOLM-13 leukemia cells. Our results indicate that the mechanisms of the combination effect are mainly via regulating the STAT5/Pim-2/C-Myc pathway, AKT pathway and Bcl-2 family, activating p21WAF1/CIP1 and inhibiting CCND/CDK complex protein. Interestingly, synergistic cytotoxicity of ibrutinib and HHT was dependent on both FLT3 and BTK. Here we provide a novel effective therapeutic approach for the treatment of AML patients with FLT3-ITD mutation.

Topics: Adenine; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Blotting, Western; Cell Line, Tumor; Cell Proliferation; Drug Synergism; fms-Like Tyrosine Kinase 3; Gene Knockdown Techniques; Harringtonines; Homoharringtonine; Humans; Leukemia, Myeloid, Acute; Mutation; Piperidines; Polymerase Chain Reaction; Pyrazoles; Pyrimidines

Topics: Adenine; Agammaglobulinaemia Tyrosine Kinase; Antineoplastic Agents; Apoptosis; Benzamides; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; fms-Like Tyrosine Kinase 3; G1 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Leukemic; Humans; Leukemia, Myeloid, Acute; Molecular Targeted Therapy; Organ Specificity; Phosphorylation; Piperidines; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Proto-Oncogene Proteins c-akt; Pyrazoles; Pyrimidines; Signal Transduction; STAT5 Transcription Factor

Targeting Bruton's tyrosine kinase (BTK) with the small molecule BTK inhibitor ibrutinib has significantly improved patient outcomes in several B-cell malignancies, with minimal toxicity. Given the reported expression and constitutive activation of BTK in acute myeloid leukemia (AML) cells, there has been recent interest in investigating the anti-AML activity of ibrutinib. We noted that ibrutinib had limited single-agent toxicity in a panel of AML cell lines and primary AML samples, and therefore sought to identify ibrutinib-sensitizing drugs. Using a high-throughput combination chemical screen, we identified that the poly(ADP-ribose) glycohydrolase (PARG) inhibitor ethacridine lactate synergized with ibrutinib in TEX and OCI-AML2 leukemia cell lines. The combination of ibrutinib and ethacridine induced a synergistic increase in reactive oxygen species that was functionally important to explain the observed cell death. Interestingly, synergistic cytotoxicity of ibrutinib and ethacridine was independent of the inhibitory effect of ibrutinib against BTK, as knockdown of BTK did not sensitize TEX and OCI-AML2 cells to ethacridine treatment. Thus, our findings indicate that ibrutinib may have a BTK-independent role in AML and that PARG inhibitors may have utility as part of a combination therapy for this disease.

Topics: Adenine; Agammaglobulinaemia Tyrosine Kinase; Animals; Apoptosis; Cell Line, Tumor; Drug Synergism; Drug Therapy, Combination; Ethacridine; Glycoside Hydrolases; Humans; Hydrolyzable Tannins; Jurkat Cells; Leukemia, Myeloid, Acute; Mice; Mice, SCID; Piperidines; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Reactive Oxygen Species; RNA Interference; RNA, Small Interfering

Topics: Adenine; Cytarabine; Daunorubicin; Leukemia, Myeloid, Acute; Piperidines; Pyrazoles; Pyrimidines

FLT3-ITD mutant has been observed in about 30% of AML patients and extensively studied as a drug discovery target. On the basis of the structure of PCI-32765 (ibrutinib), a BTK kinase inhibitor that was recently reported to bear FLT3 kinase activity through a structure-guided drug design approach, we have discovered compound 18 (CHMFL-FLT3-122), which displayed an IC50 of 40 nM against FLT3 kinase and achieved selectivity over BTK kinase (over 10-fold). It significantly inhibited the proliferation of FLT3-ITD positive AML cancer cell lines MV4-11 (GI50 = 22 nM), MOLM13/14 (GI50 = 21 nM/42 nM). More importantly, 18 demonstrated 170-fold selectivity between FLT3 kinase and c-KIT kinase (GI50 = 11 nM versus 1900 nM) in the TEL-fusion isogenic BaF3 cells indicating a potential to avoid the FLT3/c-KIT dual inhibition induced myelosuppression toxicity. In the cellular context it strongly affected FLT3-ITD mediated signaling pathways and induced apoptosis by arresting the cell cycle into the G0/G1 phase. In the in vivo studies 18 demonstrated a good bioavailability (30%) and significantly suppressed the tumor growth in MV4-11 cell inoculated xenograft model (50 mg/kg) without exhibiting obvious toxicity. Compound 18 might be a potential drug candidate for FLT3-ITD positive AML.

Topics: Administration, Oral; Animals; Antineoplastic Agents; Biological Availability; Cell Line, Tumor; Drug Screening Assays, Antitumor; Female; fms-Like Tyrosine Kinase 3; Heterografts; Humans; Leukemia, Myeloid, Acute; Male; Mice, Nude; Molecular Docking Simulation; Mutation; Neoplasm Transplantation; Pyrazoles; Pyrimidines; Rats, Sprague-Dawley; Stereoisomerism; Structure-Activity Relationship

Approximately 20% of patients with acute myeloid leukaemia (AML) have a mutation in FMS-like-tyrosine-kinase-3 (FLT3). FLT3 is a trans-membrane receptor with a tyrosine kinase domain which, when activated, initiates a cascade of phosphorylated proteins including the SRC family of kinases. Recently our group and others have shown that pharmacologic inhibition and genetic knockdown of Bruton's tyrosine kinase (BTK) blocks AML blast proliferation, leukaemic cell adhesion to bone marrow stromal cells as well as migration of AML blasts. The anti-proliferative effects of BTK inhibition in human AML are mediated via inhibition of downstream NF-κB pro-survival signalling however the upstream drivers of BTK activation in human AML have yet to be fully characterised. Here we place the FLT3-ITD upstream of BTK in AML and show that the BTK inhibitor ibrutinib inhibits the survival and proliferation of FLT3-ITD primary AML blasts and AML cell lines. Furthermore ibrutinib inhibits the activation of downstream kinases including MAPK, AKT and STAT5. In addition we show that BTK RNAi inhibits proliferation of FLT3-ITD AML cells. Finally we report that ibrutinib reverses the cyto-protective role of BMSC on FLT3-ITD AML survival. These results argue for the evaluation of ibrutinib in patients with FLT3-ITD mutated AML.

Topics: Adenine; Agammaglobulinaemia Tyrosine Kinase; Apoptosis; Blast Crisis; Cell Line, Tumor; Cell Survival; Daunorubicin; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Mutation; Piperidines; Protein Structure, Tertiary; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; RNA, Small Interfering; Signal Transduction

Roughly 80% of patients with acute myeloid leukaemia have high activity of Bruton's tyrosine-kinase (BTK) in their blast cells compared with normal haemopoietic cells, rendering the cells sensitive to the oral BTK inhibitor ibrutinib in vitro. We aimed to develop the biological understanding of the BTK pathway in acute myeloid leukaemia to identify clinically relevant diagnostic information that might define a subset of patients that should respond to ibrutinib treatment.. We obtained acute myeloid leukaemia blast cells from unselected patients attending our UK hospital between Feb 19, 2010, and Jan 20, 2014. We isolated primary acute myeloid leukaemia blast cells from heparinised blood and human peripheral blood mononuclear cells to establish the activity of BTK in response to CD117 activation. Furthermore, we investigated the effects of ibrutinib on CD117-induced BTK activation, downstream signalling, adhesion to primary bone-marrow mesenchymal stromal cells, and proliferation of primary acute myeloid leukaemia blast cells. We used the Mann-Whitney U test to compare results between groups.. We obtained acute myeloid leukaemia blast cells from 29 patients. Ibrutinib significantly inhibited CD117-mediated proliferation of primary acute myeloid leukaemia blast cells (p=0·028). CD117 activation increased BTK activity by inducing phosphorylated BTK in patients with CD117-positive acute myeloid leukaemia. Furthermore, ibrutinib inhibited CD117-induced activity of BTK and downstream kinases at a concentration of 100 nM or more. CD117-mediated adhesion of CD117-expressing blast cells to bone-marrow stromal cells was significantly inhibited by Ibrutinib at 500 nM (p=0·028) INTERPRETATION: As first-in-man clinical trials of ibrutinib in patients with acute myeloid leukaemia commence, the data suggest not all patients will respond. Our findings show that BTK has specific pro-tumoural biological actions downstream of surface CD117 activation, which are inhibited by ibrutinib. Accordingly, we propose that patients with acute myeloid leukaemia whose blast cells express CD117 should be considered for forthcoming clinical trials of ibrutinib.. Worldwide Cancer Research, The Big C, UK National Institutes for Health Research, the Humane Research Trust, the Department of Higher Education and Research of the Libyan Government, and Norwich Research Park.

Topics: Adenine; Adult; Agammaglobulinaemia Tyrosine Kinase; Aged; Aged, 80 and over; B-Lymphocytes; Female; Humans; Leukemia, Myeloid, Acute; Leukocytes, Mononuclear; Male; Middle Aged; Piperidines; Protein-Tyrosine Kinases; Proto-Oncogene Proteins c-kit; Pyrazoles; Pyrimidines; Signal Transduction

Bruton's tyrosine kinase (BTK) is a cytoplasmic protein found in all hematopoietic cell lineages except for T cells. BTK mediates signaling downstream of a number of receptors. Pharmacologic targeting of BTK using ibrutinib (previously PCI-32765) has recently shown encouraging clinical activity in a range of lymphoid malignancies. This study reports for the first time that ibrutinib inhibits blast proliferation from human acute myeloid leukemia (AML) and that treatment with ibrutinib significantly augmented cytotoxic activities of standard AML chemotherapy cytarabine or daunorubicin. Here we describe that BTK is constitutively phosphorylated in the majority of AML samples tested, with BTK phosphorylation correlating highly with the cell's cytotoxic sensitivity toward ibrutinib. BTK-targeted RNAi knockdown reduced colony-forming capacity of primary AML blasts and proliferation of AML cell lines. We showed that ibrutinib binds at nanomolar range to BTK. Furthermore, we showed ibrutinib's antiproliferative effects in AML are mediated via an inhibitory effect on downstream nuclear factor-κB survival pathways. Moreover, ibrutinib inhibited AML cell adhesion to bone marrow stroma. Furthermore, these effects of ibrutinib in AML were seen at comparable concentrations efficacious in chronic lymphocytic leukemia. These results provide a biological rationale for clinical evaluation of BTK inhibition in AML patients.

Topics: Adenine; Adult; Agammaglobulinaemia Tyrosine Kinase; Aged; Aged, 80 and over; Apoptosis; Cell Adhesion; Cell Proliferation; Enzyme Activation; Female; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Leukemic; Humans; Leukemia, Myeloid, Acute; Male; Middle Aged; NF-kappa B; Phosphorylation; Piperidines; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Signal Transduction; Tumor Cells, Cultured

Topics: Adenine; Agammaglobulinaemia Tyrosine Kinase; Animals; Female; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Leukemia, Myeloid, Acute; Male; Piperidines; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines

Pharmacological targeting of BTK using ibrutinib has recently shown encouraging clinical activity in a range of lymphoid malignancies. Recently we reported that ibrutinib inhibits human acute myeloid leukemia (AML) blast proliferation and leukemic cell adhesion to the surrounding bone marrow stroma cells. Here we report that in human AML ibrutinib, in addition, functions to inhibit SDF1/CXCR4-mediated AML migration at concentrations achievable in vivo. It has previously been shown that SDF1/CXCR4-induced migration is dependent on activation of downstream BTK in chronic lymphocytic leukaemia (CLL) and multiple myeloma. Here we show that SDF-1 induces BTK phosphorylation and downstream MAPK signalling in primary AML blast. Furthermore, we show that ibrutinib can inhibit SDF1-induced AKT and MAPK activation. These results reported here provide a molecular mechanistic rationale for clinically evaluating BTK inhibition in AML patients and suggests that in some AML patients the blasts count may initially rise in response to ibrutinib therapy, analgous to similar clinical observations in CLL.

Topics: Adenine; Adult; Agammaglobulinaemia Tyrosine Kinase; Aged; Aged, 80 and over; Cell Line, Tumor; Cell Movement; Cell Proliferation; Chemokine CXCL12; Female; Gene Knockdown Techniques; Humans; Leukemia, Myeloid, Acute; Male; MAP Kinase Signaling System; Middle Aged; Piperidines; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines