Bruton’s tyrosine kinase: an emerging targeted therapy in myeloid cells within the tumor microenvironment

Btk Inhibitors

AbstractBruton’s tyrosine kinase (BTK) is a non-receptor kinase belonging to the Tec family of kinases. The role of BTK in B cell receptor signaling is well defined and is known to play a key role in the proliferation and survival of malignant B cells. Moreover, BTK has been found to be expressed in cells of the myeloid lineage. BTK has been shown to contribute to a variety of cellular pathways in myeloid cells including signaling in the NLRP3 inflammasome, receptor activation of nuclear factor-κβ and inflammation, chemokine receptor activation affecting migration, and phagocytosis. Myeloid cells are crucial components of the tumor microenvironment and suppressive myeloid cells contribute to cancer progression, highlighting a potential role for BTK inhibition in the treatment of malignancy. The increased interest in BTK inhibition in cancer has resulted in many preclinical studies that are testing the efficacy of using single-agent BTK inhibitors. Moreover, the ability of tumor cells to develop resistance to single-agent checkpoint inhibitors has resulted in clinical studies utilizing BTK inhibitors in combination with these agents to improve clinical responses. Furthermore, BTK regulates the immune response in microbial and viral infections through B cells and myeloid cells such as monocytes and macrophages. In this review, we describe the role that BTK plays in supporting suppressive myeloid cells, including myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAM), while also discussing the anticancer effects of BTK inhibition and briefly describe the role of BTK signaling and BTK inhibition in microbial and viral infections.

Bruton’s Tyrosine Kinase-Mediated Signaling in Myeloid Cells Is Required for Protective Innate Immunity During Pneumococcal Pneumonia

Frontiers in Immunology ◽

10.3389/fimmu.2021.723967 ◽

2021 ◽

Vol 12 ◽

Author(s):

Alexander P. de Porto ◽

Zhe Liu ◽

Regina de Beer ◽

Sandrine Florquin ◽

Joris J. T. H. Roelofs ◽

...

Keyword(s):

B Cells ◽

Tyrosine Kinase ◽

B Cell ◽

Host Defense ◽

Pneumococcal Pneumonia ◽

Myeloid Cells ◽

Natural Antibody ◽

Bruton’s tyrosine kinase (Btk) is a cytoplasmic kinase expressed in B cells and myeloid cells. It is essential for B cell development and natural antibody-mediated host defense against bacteria in humans and mice, but little is known about the role of Btk in innate host defense in vivo. Previous studies have indicated that lack of (natural) antibodies is paramount for impaired host defense against Streptococcus (S.) pneumoniae in patients and mice with a deficiency in functional Btk. In the present study, we re-examined the role of Btk in B cells and myeloid cells during pneumococcal pneumonia and sepsis in mice. The antibacterial defense of Btk-/- mice was severely impaired during pneumococcal pneumosepsis and restoration of natural antibody production in Btk-/- mice by transgenic expression of Btk specifically in B cells did not suffice to protect against infection. Btk-/- mice with reinforced Btk expression in MhcII+ cells, including B cells, dendritic cells and macrophages, showed improved antibacterial defense as compared to Btk-/- mice. Bacterial outgrowth in Lysmcre-Btkfl/Y mice was unaltered despite a reduced capacity of Btk-deficient alveolar macrophages to respond to pneumococci. Mrp8cre-Btkfl/Y mice with a neutrophil specific paucity in Btk expression, however, demonstrated impaired antibacterial defense. Neutrophils of Mrp8cre-Btkfl/Y mice displayed reduced release of granule content after pulmonary installation of lipoteichoic acid, a gram-positive bacterial cell wall component relevant for pneumococci. Moreover, Btk deficient neutrophils showed impaired degranulation and phagocytosis upon incubation with pneumococci ex vivo. Taken together, the results of our study indicate that besides regulating B cell-mediated immunity, Btk is critical for regulation of myeloid cell-mediated, and particularly neutrophil-mediated, innate host defense against S. pneumoniae in vivo.

Bruton's tyrosine kinase inhibition in the treatment of preclinical models and multiple sclerosis

Current Pharmaceutical Design ◽

10.2174/1381612827666210701152934 ◽

2021 ◽

Vol 27 ◽

Author(s):

Anja Steinmaurer ◽

Isabella Wimmer ◽

Thomas Berger ◽

Paulus Stefan Rommer ◽

Johann Sellner

Keyword(s):

Multiple Sclerosis ◽

B Cells ◽

Tyrosine Kinase ◽

B Cell ◽

Cumulative Number ◽

Phase 2 ◽

Relapsing Remitting

: Significant progress has been made in understanding the immunopathogenesis of multiple sclerosis (MS) over recent years. Successful clinical trials with CD20-depleting monoclonal antibodies have corroborated the fundamental role of B cells in the pathogenesis of MS and reinforced the notion that cells of the B cell lineage are an attractive treatment target. Therapeutic inhibition of Bruton's tyrosine kinase (BTK), an enzyme involved in B cell and myeloid cell activation and function, is regarded as a next-generation approach that aims to attenuate both errant innate and adaptive immune functions. Moreover, brain-penetrant BTK inhibitors may impact compartmentalized inflammation and neurodegeneration within the central nervous system by targeting brain-resident B cells and microglia, respectively. Preclinical studies in animal models of MS corroborated an impact of BTK inhibition on meningeal inflammation and cortical demyelination. Notably, BTK inhibition attenuated the antigen-presenting capacity of B cells and the generation of encephalitogenic T cells. Evobrutinib, a selective oral BTK inhibitor, has been tested recently in a phase 2 study of patients with relapsing-remitting MS. The study met the primary endpoint of a significantly reduced cumulative number of Gadolinium-enhancing lesions under treatment with evobrutinib compared to placebo treatment. Thus, the results of ongoing phase 2 and 3 studies with evobrutinib, fenobrutinib, and tolebrutinib in relapsing-remitting and progressive MS are eagerly awaited. This review article introduces the physiological role of BTK, summarizes the pre-clinical and trial evidence, and addresses the potential beneficial effects of BTK inhibition in MS.

Receptor Tyrosine Kinase AXL: A Potential Strategy to Counter Immune Suppression and Dormancy in Multiple Myeloma

Blood ◽

10.1182/blood-2019-126834 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4335-4335

Author(s):

Kim De Veirman ◽

Siyang Yan ◽

Ken Maes ◽

Nathan De Beule ◽

Sylvia Faict ◽

...

Keyword(s):

Multiple Myeloma ◽

Overall Survival ◽

Tyrosine Kinase ◽

Cell Lines ◽

Receptor Tyrosine Kinase ◽

Single Agent ◽

Myeloid Cells ◽

Myeloma Cell ◽

Myeloma Cells

Introduction The AXL receptor tyrosine kinase (AXL) has emerged as a promising therapeutic target for cancer therapy. Recent studies revealed a crucial role of AXL signaling in proliferation, survival, dormancy and therapy resistance in different cancers including lung cancer, hepatocellular cancer and AML. In this study, we aimed to investigate the role of AXL in Multiple Myeloma (MM), focusing on myeloma cell dormancy and AXL expression in different cellular components of the bone marrow microenvironment. Material & Methods To investigate dormancy, we used the syngeneic murine 5TGM1 MM model. 5TGM1-GFP+cells were DiD-labeled and injected intravenously in naïve C57BL/KaLwRij mice. At end-stage, GFP+DiD+('dormant', non-proliferating) and GFP+DiD-('proliferating') MM cells were analyzed by flow cytometry for AXL expression. In addition, AXL expression was also analyzed in CD11b+ myeloid cells and in in vitrogenerated macrophages from the 5TMM model. The effects of AXL inhibition by R428 (BGB324|Bemcentinib, Sigma-Aldrich), a highly potent and AXL-specific small molecular inhibitor, on viability and induced apoptosis of MM cells was determined by Cell Titer Glo and AnnexinV/7AAD staining respectively. AXL expression in human myeloma cell lines (HMCL) (JJN3, U266 and LP-1) and murine 5TGM1 cells was analyzed by qRT-PCR and cytospin stainings. Patient cohorts (TT2/TT3) were used to correlate AXL expression and overall survival. Plasma of healthy donors and MM patients was analyzed by ELISA (R&D). Results Using the in vivo5TGM1 dormancy model, we demonstrated an increased expression of AXL (4x higher) in dormant MM cells compared to proliferating MM cells (n=3, p<0,05). Myeloma cell lines (JJN3, U266, 5TGM1) had a very low AXL expression, however, treatment with melphalan induced a more than twofold increase in AXL expression (n=3, p<0.05). The combination of melphalan and R428 significantly increased apoptosis of JJN3 (>10%), U266 (>20%) and LP-1 (>10%) cells compared to single agent therapy (n=6) (p<0.01). Using patient cohorts, we observed that AXL expression correlated with a good overall survival (p=0.006). In addition, plasma samples of patients (n=31) showed a decreased expression of AXL compared to samples of healthy controls (n=9) (p<0.001). This confirms our hypothesis that AXL is associated with dormancy and therefore correlates with a better overall survival. In a second part, we investigated AXL expression in 5TMM-derived myeloid cells and macrophages (n=3). We observed a high expression of AXL in myeloid derived suppressor cells and tumor associated macrophages compared to myeloma cells. In addition, we observed that myeloid cells were much more sensitive to R428 compared to MM cells (n=5, p>0.01). Conclusion We observed that AXL is highly expressed in dormant MM cells and environmental myeloid cells. Despite its association with a good prognosis in MM, AXL serves as an interesting target to eradicate dormant myeloma cells as AXL inhibitors affect viability and induce apoptosis of myeloma cells, especially in combination with melphalan. Therefore, AXL can be considered as a new therapeutic strategy, to target both the immunosuppressive myeloid cells and the residual cancer cells in MM patients. Disclosures No relevant conflicts of interest to declare.

50 Potential Role of Bruton’s Tyrosine Kinase in Toll-like Receptor 9 Mediated Cytokine Production from B Cells

Cytokine ◽

10.1016/j.cyto.2007.07.055 ◽

2007 ◽

Vol 39 (1) ◽

pp. 14

Author(s):

Maroof Hasan ◽

Gabriela Lopez-Herrera ◽

Emelie M. Blomberg ◽

Anna Berglof ◽

C.I. Edvard Smith ◽

...

Keyword(s):

B Cells ◽

Tyrosine Kinase ◽

Potential Role ◽

Cytokine Production ◽

Toll Like Receptor ◽

Role of Bruton’s tyrosine kinase in B cells and malignancies

Molecular Cancer ◽

10.1186/s12943-018-0779-z ◽

2018 ◽

Vol 17 (1) ◽

Cited By ~ 101

Author(s):

Simar Pal Singh ◽

Floris Dammeijer ◽

Rudi W. Hendriks

Keyword(s):

B Cells ◽

Tyrosine Kinase ◽

Targeting Bruton’s Tyrosine Kinase in Inflammatory and Autoimmune Pathologies

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.668131 ◽

2021 ◽

Vol 9 ◽

Author(s):

Stefan F. H. Neys ◽

Rudi W. Hendriks ◽

Odilia B. J. Corneth

Keyword(s):

B Cells ◽

Tyrosine Kinase ◽

B Cell ◽

Critical Role ◽

Myeloid Cells ◽

Systemic Autoimmune Disease ◽

Bruton’s tyrosine kinase (BTK) was discovered due to its importance in B cell development, and it has a critical role in signal transduction downstream of the B cell receptor (BCR). Targeting of BTK with small molecule inhibitors has proven to be efficacious in several B cell malignancies. Interestingly, recent studies reveal increased BTK protein expression in circulating resting B cells of patients with systemic autoimmune disease (AID) compared with healthy controls. Moreover, BTK phosphorylation following BCR stimulation in vitro was enhanced. In addition to its role in BCR signaling, BTK is involved in many other pathways, including pattern recognition, Fc, and chemokine receptor signaling in B cells and myeloid cells. This broad involvement in several immunological pathways provides a rationale for the targeting of BTK in the context of inflammatory and systemic AID. Accordingly, numerous in vitro and in vivo preclinical studies support the potential of BTK targeting in these conditions. Efficacy of BTK inhibitors in various inflammatory and AID has been demonstrated or is currently evaluated in clinical trials. In addition, very recent reports suggest that BTK inhibition may be effective as immunosuppressive therapy to diminish pulmonary hyperinflammation in coronavirus disease 2019 (COVID-19). Here, we review BTK’s function in key signaling pathways in B cells and myeloid cells. Further, we discuss recent advances in targeting BTK in inflammatory and autoimmune pathologies.

Bruton’s Tyrosine Kinase and Its Isoforms in Cancer

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.668996 ◽

2021 ◽

Vol 9 ◽

Author(s):

Xianhui Wang ◽

Leila Kokabee ◽

Mostafa Kokabee ◽

Douglas S. Conklin

Keyword(s):

B Cells ◽

Tyrosine Kinase ◽

B Cell ◽

B Cell Malignancies ◽

Epithelial Cancers ◽

And Migration ◽

Btk Inhibitors ◽

Novel Isoforms

Bruton’s tyrosine kinase (BTK) is a soluble tyrosine kinase with central roles in the development, maturation, and signaling of B cells. BTK has been found to regulate cell proliferation, survival, and migration in various B-cell malignancies. Targeting BTK with recently developed BTK inhibitors has been approved by the Food and Drug Administration (FDA) for the treatment of several hematological malignancies and has transformed the treatment of several B-cell malignancies. The roles that BTK plays in B cells have been appreciated for some time. Recent studies have established that BTK is expressed and plays pro-tumorigenic roles in several epithelial cancers. In this review, we focus on novel isoforms of the BTK protein expressed in epithelial cancers. We review recent work on the expression, function, and signaling of these isoforms and their value as potential therapeutic targets in epithelial tumors.

Bruton’s tyrosine kinase (BTK) regulates myeloid cell recruitment during acute inflammation

10.22541/au.162003905.59954600/v1 ◽

2021 ◽

Author(s):

Gareth Purvis ◽

Haidee Aranda ◽

Keith Channon ◽

David Greaves

Keyword(s):

Tyrosine Kinase ◽

Myeloid Cells ◽

Myeloid Cell ◽

Cell Recruitment ◽

Wide Range ◽

Monocyte Recruitment ◽

Monocytes And Macrophages

Bruton’s tyrosine kinase (BTK) is a non-receptor kinase best known for its role in B lymphocyte development that is critical for proliferation, and survival of leukaemia cells in B cell malignancies. However, BTK is expressed in myeloid cells, particularly monocytes and macrophages where its inhibition has been reported to exhibit anti-inflammatory properties. Therefore, we explored the role of BTK on the migration of myeloid cells in vitro and in vivo. Using the zymosan induced peritonitis model of sterile inflammation we demonstrated that acute (1 h prior to zymosan) inhibition of BTK using a wide range of FDA (Ibrutinib and Acalabrutinib) and non-FDA approved inhibitors (ONO-4059, CNX-774, Olumatinib and LFM-A13) reduced neutrophil and monocyte recruitment. XID mice, which have a point mutation in the Btk gene had reduced neutrophil and monocyte recruitment to the peritoneum following zymosan challenge. To better understand the role of BTK in myeloid cell recruitment we investigated both chemotaxis and chemokine production in monocytes and macrophages. Pharmacological or genetic inhibition of BTK signalling substantially reduced human monocyte and murine macrophage chemotaxis to a range of chemoattractants (complement C5a and CCL2). We also demonstrated that inhibition of BTK in tissue resident macrophages significantly decreases chemokine secretion by reducing NF-kB activity and Akt signalling. Our work has identified a new role of BTK in regulating myeloid cell recruitment via two mechanisms, 1) reducing monocyte/macrophages’ ability to undergo chemotaxis, and 2) reducing chemokine secretion, via reduced NF-kB activity in tissue resident macrophages.