Combined Treatment with Acalabrutinib and Rapamycin Inhibits Glioma Stem Cells and Promotes Vascular Normalization by Downregulating BTK/mTOR/VEGF Signaling

Medicinal chemistry breakthroughs on ATM, ATR, and DNA-PK inhibitors as prospective cancer therapeutics

This review discusses the critical roles of Ataxia Telangiectasia Mutated Kinase (ATM), ATM and Rad3-related Kinase (ATR), and DNA-dependent protein kinase (DNA-PK) in the DNA damage response (DDR) and their implications in cancer. Emphasis is placed on the intricate interplay between these kinases, highlighting their collaborative and distinct roles in maintaining genomic integrity and promoting tumour development under dysregulated conditions. Furthermore, the review covers ongoing clinical trials, patent literature, and medicinal chemistry campaigns on ATM/ATR/DNA-PK inhibitors as antitumor agents. Notably, the medicinal chemistry campaigns employed robust drug design strategies and aimed at assembling new structural templates with amplified DDR kinase inhibitory ability, as well as outwitting the pharmacokinetic liabilities of the existing DDR kinase inhibitors. Given the success attained through such endeavours, the clinical pipeline of DNA repair kinase inhibitors is anticipated to be supplemented by a reasonable number of tractable entries (DDR kinase inhibitors) soon.

Reversible posterior leukoencephalopathy syndrome (RPLS) in a patient with chronic lymphocytic leukemia (CLL) treated with Acalabrutinib, a Bruton's tyrosine kinase (BTK) inhibitor: a case report

RPLS is a rare neuroradiologic syndrome characterized by headache, visual disturbances, focal deficits and confusion. There are several underlying mechanisms causing RPLS, including arterial hypertension and renal failure, but also treatments with immunosuppressive therapy, chemotherapy or targeted therapy (such as small molecule inhibitors). Acalabrutinib is a novel second-generation BTK inhibitor, frequently used as treatment for B-cell malignancies. Here, we present a case of RPLS in a CLL patient treated with Acalabrutinib, for 18 months. A 76-year-old male, with a history of arterial hypertension and kidney disease, experienced throbbing headache and visual disturbances and was diagnosed with RPLS based on the typical high parietal subcortical hyperintensities on FLAIR MRI. Due to the effective management of his aggravated hypertension, the new MRI lesions were resolved at the follow-up scan after one month. We conclude that, in patients treated with a BTK inhibitor like Acalabrutinib, clinicians should pay special attention to the development of a new or worsened hypertension or the development of a new headache, visual disturbances or other symptoms that may indicate RPLS.

Inhibiting Bruton's Tyrosine Kinase to Counteract Chemoresistance and Stem Cell-Like Properties in Osteosarcoma

Osteosarcoma, a highly aggressive bone cancer, often develops resistance to conventional chemotherapeutics, leading to poor prognosis and survival rates. The malignancy and chemoresistance of osteosarcoma pose significant challenges in its treatment, highlighting the critical need for novel therapeutic approaches. Bruton's tyrosine kinase (BTK) plays a pivotal role in B-cell development and has been linked to various cancers, including breast, lung, and oral cancers, where it contributes to tumor growth and chemoresistance. Despite its established importance in these malignancies, the impact of BTK on osteosarcoma remains unexplored. Our study delves into the expression levels of BTK in osteosarcoma tissues by data from the GEO and TCGA database, revealing a marked increase in BTK expression compared with primary osteoblasts and a potential correlation with primary site progression. Through our investigations, we identified a subset of osteosarcoma cells, named cis-HOS, which exhibited resistance to cisplatin. These cells displayed characteristics of cancer stem cells (CSCs), demonstrated a higher angiogenesis effect, and had an increased migration ability. Notably, an upregulation of BTK was observed in these cisplatin-resistant cells. The application of ibrutinib, a BTK inhibitor, significantly mitigated these aggressive traits. Our study demonstrates that BTK plays a crucial role in conferring chemoresistance in osteosarcoma. The upregulation of BTK in cisplatin-resistant cells was effectively countered by ibrutinib. These findings underscore the potential of targeting BTK as an effective strategy to overcome chemoresistance in osteosarcoma treatment.

Bruton's tyrosine kinase inhibition suppresses pathological retinal angiogenesis

BACKGROUND AND PURPOSE

Pathological retinal angiogenesis is a typical manifestation of vision-threatening ocular diseases. Many patients exhibit poor response or resistance to anti-vascular endothelial growth factor (VEGF) agents. Bruton's tyrosine kinase (BTK) controls the proliferation and function of immune cells. Therefore, we examined the anti-inflammatory and anti-angiogenic effects of BTK inhibition on retinal angiogenesis.

EXPERIMENTAL APPROACH

Retinal neovascularisation and vascular leakage in oxygen-induced retinopathy in C57/BL6J mice were assessed by whole-mount retinal immunofluorescence. PLX5622 was used to deplete microglia and Rag1-knockout mice were used to test the contribution of lymphocytes to the effects of BTK inhibition. The cytokines, activation markers, inflammatory and immune-regulatory activities of retinal microglia/macrophages were detected using qRT-PCR and immunofluorescence. NLRP3 was detected by western blotting, and the effects of BTK inhibition on the co-culture of microglia and human retinal microvascular endothelial cells (HRMECs) were examined.

KEY RESULTS

BTK inhibition suppressed pathological angiogenesis and vascular leakage, and significantly reduced retinal inflammation, which involved microglia/macrophages but not lymphocytes. BTK inhibition increased anti-inflammatory factors and reduced pro-inflammatory cytokines that resulted from NLRP3 inflammasome activation. BTK inhibition suppressed the inflammatory activity of microglia/macrophages, and acted synergistically with anti-VEGF without retinal toxicity. Moreover, the supernatant of microglia incubated with BTK-inhibitor reduced the proliferation, tube formation and sprouting of HRMECs.

CONCLUSION AND IMPLICATIONS

BTK inhibition suppressed retinal neovascularisation and vascular leakage by modulating the inflammatory activity of microglia and macrophages. Our study suggests BTK inhibition as a novel and promising approach for alleviating pathological retinal angiogenesis.

BTK Expression Level Prediction and the High-Grade Glioma Prognosis Using Radiomic Machine Learning Models

We aimed to study whether the Bruton's tyrosine kinase (BTK) expression is correlated with the prognosis of patients with high-grade gliomas (HGGs) and predict its expression level prior to surgery, by constructing radiomic models. Clinical and gene expression data of 310 patients from The Cancer Genome Atlas (TCGA) were included for gene-based prognostic analysis. Among them, contrast-enhanced T1-weighted imaging (T1WI + C) from The Cancer Imaging Archive (TCIA) with genomic data was selected from 82 patients for radiomic models, including support vector machine (SVM) and logistic regression (LR) models. Furthermore, the nomogram incorporating radiomic signatures was constructed to evaluate its clinical efficacy. BTK was identified as an independent risk factor for HGGs through univariate and multivariate Cox regression analyses. Three radiomic features were selected to construct the SVM and LR models, and the validation set showed area under curve (AUCs) values of 0.711 (95% CI, 0.598-0.824) and 0.736 (95% CI, 0.627-0.844), respectively. The median survival times of the high Rad_score and low-Rad_score groups based on LR model were 15.53 and 23.03 months, respectively. In addition, the total risk score of each patient was used to construct a predictive nomogram, and the AUCs calculated from the corresponding time-dependent ROC curves were 0.533, 0.659, and 0.767 for 1, 3, and 5 years, respectively. BTK is an independent risk factor associated with poor prognosis in patients, and the radiomic model constructed in this study can effectively and non-invasively predict preoperative BTK expression levels and patient prognosis based on T1WI + C.

FGF19 promotes nasopharyngeal carcinoma progression by inducing angiogenesis via inhibiting TRIM21-mediated ANXA2 ubiquitination

PURPOSE

Nasopharyngeal carcinoma (NPC) has characteristics of high invasion and early metastasis. Most NPC patients present with locoregionally advanced illness when first diagnosed. Therefore, it is urgent to discover NPC biomarkers. Fibroblast growth Factor 19 (FGF19) plays a role in various physiological or pathological processes, including cancer. In this research, we discovered the importance of FGF19 in NPC, and clarified its role in tumour angiogenesis.

METHODS

Western blotting, immunohistochemistry and ELISA were used to investigate FGF19 expression in NPC. Then we took CCK8, colony formation, Transwell and wound healing assays to identify the influence of FGF19 on NPC malignant behaviours. The proliferative and metastatic capacity of FGF19 were evaluated in nude mice and zebrafish. The role of FGF19 in angiogenesis was investigated by tube formation and Matrigel plug angiogenesis assays. We then evaluated the variation in Annexin A2(ANXA2) levels with the treatment of FGF19. Lastly, co-immunoprecipitation and ubiquitination assays were performed to identify the mechanisms involved.

RESULTS

FGF19 levels were elevated in tissues and serum of NPC patients and were associated with poor clinical stages. High expression of FGF19 promoted NPC malignant behaviours. In particular, FGF19 expression was correlated with microvessel density in tissues and NPC-derived FGF19 could accelerate angiogenesis in vitro and in vivo. Mechanistically, FGF19 influenced ANXA2 expression to promote angiogenesis. Moreover, tripartite motif-containing 21(TRIM21) interacted with ANXA2 and was responsible for ANXA2 ubiquitination.

CONCLUSION

FGF19 promoted NPC angiogenesis by inhibiting TRIM21-mediated ANXA2 ubiquitination. It may serve as a noninvasive biomarker for NPC and provides new insights for therapy.

mTOR signalling pathway in stem cell bioactivities and angiogenesis potential

The mammalian target of rapamycin (mTOR) is a protein kinase that responds to different stimuli such as stresses, starvation and hypoxic conditions. The modulation of this effector can lead to the alteration of cell dynamic growth, proliferation, basal metabolism and other bioactivities. Considering this fact, the mTOR pathway is believed to regulate the diverse functions in several cell lineages. Due to the pleiotropic effects of the mTOR, we here, hypothesize that this effector can also regulate the bioactivity of stem cells in response to external stimuli pathways under physiological and pathological conditions. As a correlation, we aimed to highlight the close relationship between the mTOR signalling axis and the regenerative potential of stem cells in a different milieu. The relevant publications were included in this study using electronic searches of the PubMed database from inception to February 2023. We noted that the mTOR signalling cascade can affect different stem cell bioactivities, especially angiogenesis under physiological and pathological conditions. Modulation of mTOR signalling pathways is thought of as an effective strategy to modulate the angiogenic properties of stem cells.

Unveiling Novel Avenues in mTOR-Targeted Therapeutics: Advancements in Glioblastoma Treatment

The mTOR signaling pathway plays a pivotal and intricate role in the pathogenesis of glioblastoma, driving tumorigenesis and proliferation. Mutations or deletions in the PTEN gene constitutively activate the mTOR pathway by expressing growth factors EGF and PDGF, which activate their respective receptor pathways (e.g., EGFR and PDGFR). The convergence of signaling pathways, such as the PI3K-AKT pathway, intensifies the effect of mTOR activity. The inhibition of mTOR has the potential to disrupt diverse oncogenic processes and improve patient outcomes. However, the complexity of the mTOR signaling, off-target effects, cytotoxicity, suboptimal pharmacokinetics, and drug resistance of the mTOR inhibitors pose ongoing challenges in effectively targeting glioblastoma. Identifying innovative treatment strategies to address these challenges is vital for advancing the field of glioblastoma therapeutics. This review discusses the potential targets of mTOR signaling and the strategies of target-specific mTOR inhibitor development, optimized drug delivery system, and the implementation of personalized treatment approaches to mitigate the complications of mTOR inhibitors. The exploration of precise mTOR-targeted therapies ultimately offers elevated therapeutic outcomes and the development of more effective strategies to combat the deadliest form of adult brain cancer and transform the landscape of glioblastoma therapy.

Multiple therapeutic approaches of glioblastoma multiforme: From terminal to therapy

Glioblastoma multiforme (GBM) is an aggressive brain cancer showing poor prognosis. Currently, treatment methods of GBM are limited with adverse outcomes and low survival rate. Thus, advancements in the treatment of GBM are of utmost importance, which can be achieved in recent decades. However, despite aggressive initial treatment, most patients develop recurrent diseases, and the overall survival rate of patients is impossible to achieve. Currently, researchers across the globe target signaling events along with tumor microenvironment (TME) through different drug molecules to inhibit the progression of GBM, but clinically they failed to demonstrate much success. Herein, we discuss the therapeutic targets and signaling cascades along with the role of the organoids model in GBM research. Moreover, we systematically review the traditional and emerging therapeutic strategies in GBM. In addition, we discuss the implications of nanotechnologies, AI, and combinatorial approach to enhance GBM therapeutics.

HZ-A-018, a novel inhibitor of Bruton tyrosine kinase, exerts anti-cancer activity and sensitizes 5-FU in gastric cancer cells

Gastric cancer is the third leading cause of cancer related death worldwide. Due to the complexity and heterogeneity of gastric cancer, the development of targeted drugs is somehow limited, but is urgently needed. Since the expression of Bruton tyrosine kinase (BTK) was significantly associated with the prognosis of gastric cancer patients, we aimed to determine the anti-cancer activity of HZ-A-018, which was a novel derivative of ACP-196, in gastric cancer cells. As a result, HZ-A-018 presented a stronger anti-proliferation activity than ACP-196 via the substantial suppression of AKT/S6 pathway. In addition, HZ-A-018, but not ACP-196, exerted the synergistic effects in combined treatment with 5-FU both in vitro and in vivo, without exacerbating the adverse effects of 5-FU. Mechanismly, the combination of HZ-A-018 and 5-FU remarkably reduced the expression of RRM2, which played an essential role in proliferation and drug sensitivity in gastric cancer cells. In summary, our work demonstrated the stronger anti-cancer activity of HZ-A-018 than ACP-196 in gastric cancer cells, and revealed synergistic effects of HZ-A-018 and 5-FU combination probably through the inhibition of RRM2 via AKT/S6 pathway, thereby providing a promising therapeutic strategy in gastric cancer.

Co-delivery of ibrutinib and hydroxychloroquine by albumin nanoparticles for enhanced chemotherapy of glioma

Ibrutinib (IBR) is an oral covalent inhibitor of Bruton's tyrosine kinase (BTK) that has been approved for the treatment of hematological malignancies. It was reported that IBR exhibited great therapeutic potential for glioma. However, the poor water solubility and high hepatic first-pass effect restrict its anti-glioma application. Meanwhile, IBR induces cytoprotective autophagy through Akt/mTOR signaling pathway, thus leading to a compromised antitumor effect. Herein, we aimed to develop a human serum albumin (HSA) based co-delivery system (IBR&HCQ HSA NPs) encapsulating IBR and hydroxychloroquine (HCQ). The bioavailability of IBR was largely improved, and enhanced sensitivity of glioma to IBR was achieved due to inhibition effect of HCQ on IBR-induced pro-survival autophagy. The physicochemical properties of IBR&HCQ HSA NPs were characterized to optimize the formulation. Biodistribution investigation revealed that HSA NPs (20 mg/kg, i.v.) dramatically increased the accumulation of IBR in glioma, which was 5.59 times higher than that of free IBR (100 mg/kg, i.g.). CCK-8 and apoptosis assays demonstrated that IBR&HCQ HSA NPs showed maximal cytotoxicity to C6 cells. In vivo studies indicated that the survival time was significantly prolonged in IBR&HCQ HSA NPs treated mice compared to those treated with IBR HSA NPs. Taken together, the HSA-based drug delivery system of IBR and HCQ opens a new avenue for efficient treatment of glioma.

BTK, the new kid on the (oncology) block?

In the last decade data piled up indicating that BTK – for twenty years considered as a “private matter” of bone marrow-derived cells – it is expressed and plays important and different roles also outside of the hematopoietic compartment and, most notably, in tumor cells. Initial evidence that BTK plays a critical role in B cell-derived malignancies prompted the chase for specific inhibitors, the forefather of which entered the clinic in a record time and paved the way for an ever increasing number of new molecules to be trialed. The growing interests in BTK also led to the discovery that, in solid tumors, two novel isoforms are mainly expressed and actionable liabilities for target therapy. Remarkably, the different isoforms appear to be involved in different signaling pathways which will have to be attentively specified in order to define the area of therapeutic intervention. In this perspective we briefly summarize the progress made in the last decade in studying BTK and its isoforms in cancer cells and define the open questions to be addressed in order to get the most benefits from its targeting for therapeutic purposes.

Glioblastoma: Current Status, Emerging Targets, and Recent Advances

Glioblastoma (GBM) is a highly malignant brain tumor characterized by a heterogeneous population of genetically unstable and highly infiltrative cells that are resistant to chemotherapy. Although substantial efforts have been invested in the field of anti-GBM drug discovery in the past decade, success has primarily been confined to the preclinical level, and clinical studies have often been hampered due to efficacy-, selectivity-, or physicochemical property-related issues. Thus, expansion of the list of molecular targets coupled with a pragmatic design of new small-molecule inhibitors with central nervous system (CNS)-penetrating ability is required to steer the wheels of anti-GBM drug discovery endeavors. This Perspective presents various aspects of drug discovery (challenges in GBM drug discovery and delivery, therapeutic targets, and agents under clinical investigation). The comprehensively covered sections include the recent medicinal chemistry campaigns embarked upon to validate the potential of numerous enzymes/proteins/receptors as therapeutic targets in GBM.

Switch Pocket Kinase: An Emerging Therapeutic Target for the Design of Anticancer Agents

Protein kinases are amongst the most focused enzymes in current century to design, synthesize and formulate drugs ought to be effective in the treatment of various disordered and diseased states involving either overexpression or deficiency situations. The ATP pocket on the kinases is the binding active site for most of the kinase inhibitors. However, the kinase mutations prevent the binding of kinase inhibitors to ATP pocket. The switch pocket site on this enzyme when occupied by switch pocket inhibitors, the enzyme become inactive even in the mutated state. This review comprises the detailed information on various classical protein kinases and switch pocket kinase inhibitors with their mechanism of action so that new molecules can be designed to encounter mutations in the kinase enzyme.