Polyfluoroalkyl Tag Decoration Enables Significantly Enhanced Tumor Penetration Ability of a PTK7 Targeting Aptamer.

Aptamers are widely used molecular recognition tools in targeted therapy, but their ability to effectively penetrate deep into solid tumors remains a significant challenge, leading to suboptimal treatment efficacy. Here, we developed a polyfluoroalkyl (PFA) decoration strategy to enhance aptamer recognition, cell internalization, and solid tumor penetration. Our results indicate that PFA with around 11 fluorine atoms significantly improves aptamer internalization both in vitro and in vivo settings. However, we also observed that the use of PFA tags containing 19 and 23 fluorine atoms on aptamers resulted in nonspecific cell anchoring in control cell lines, affecting the specificity of aptamers. Overall, we found that using a chemical modification strategy could enhance the deep tumor penetration ability of aptamers and validate their effectiveness in vivo. This approach has significant practical applications in targeted drug delivery for cancer treatment.

Dabrafenib mitigates the neuroinflammation caused by ferroptosis in experimental autoimmune encephalomyelitis by up regulating Axl receptor.

Multiple sclerosis is an autoimmune disease that causes inflammatory damage to the central nervous system. At present, the pathogenesis of the disease is unknown. There is a lack of few effective therapy medications available. Therefore, it is necessary to further explore the pathogenesis of this illness and develop potential therapeutic drugs. Dabrafenib is potential therapeutic medicine for nervous system disease. In this study, we preliminarily studied the possible mechanism of dabrafenib in the treatment of multiple sclerosis from the perspective of ferroptosis. First, we observed that dabrafenib significantly improved symptoms of gait abnormalities, limb weakness or paralysis, and down-regulated levels of spinal cord inflammation in an experimental autoimmune encephalitis (EAE) model. Meanwhile, we also observed that dabrafenib could inhibit the proteins of ferroptosis in spinal cord tissue of EAE mice by Western blot. The results of immunohistochemical analysis showed that the effect of dabrafenib on ferroptosis mainly occurred in microglia. Second, dabrafenib was demonstrated to be able to inhibit the S phase of the cell cycle, reduce ROS levels, and reinstate mitochondrial activity in the LPS-induced BV2 inflammatory cell model. Futhermore, we found that dabrafenib inhibits P-JAK2 and P-STAT3 activation by acting Axl receptor, which in turn prevents neurogenic inflammation in microglia. The co-stimulated BV2 cell model with LPS and Erastin also verified these findings. Ultimately, the Axl knockout mice used to construct the EAE model allowed for the confirmation that dabrafenib prevented ferroptosis in microglia by up-regulating Axl receptor, which reduced the inflammatory demyelination associated with EAE. In summary, our research demonstrates the advantages of dabrafenib in multiple sclerosis treatment, which can prevent ferroptosis in microglia in multiple sclerosis through up-regulating Axl receptor, thus halting the progression of multiple sclerosis.

Exploratory drug discovery in breast cancer patients: A multimodal deep learning approach to identify novel drug candidates targeting RTK signaling.

Breast cancer, a highly formidable and diverse malignancy predominantly affecting women globally, poses a significant threat due to its intricate genetic variability, rendering it challenging to diagnose accurately. Various therapies such as immunotherapy, radiotherapy, and diverse chemotherapy approaches like drug repurposing and combination therapy are widely used depending on cancer subtype and metastasis severity. Our study revolves around an innovative drug discovery strategy targeting potential drug candidates specific to RTK signalling, a prominently targeted receptor class in cancer. To accomplish this, we have developed a multimodal deep neural network (MM-DNN) based QSAR model integrating omics datasets to elucidate genomic, proteomic expression data, and drug responses, validated rigorously. The results showcase an R2 value of 0.917 and an RMSE value of 0.312, affirming the model's commendable predictive capabilities. Structural analogs of drug molecules specific to RTK signalling were sourced from the PubChem database, followed by meticulous screening to eliminate dissimilar compounds. Leveraging the MM-DNN-based QSAR model, we predicted the biological activity of these molecules, subsequently clustering them into three distinct groups. Feature importance analysis was performed. Consequently, we successfully identified prime drug candidates tailored for each potential downstream regulatory protein within the RTK signalling pathway. This method makes the early stages of drug development faster by removing inactive compounds, providing a hopeful path in combating breast cancer.

A review on potential heterocycles for the treatment of glioblastoma targeting receptor tyrosine kinases.

Glioblastoma, the most aggressive form of brain tumor, poses significant challenges in terms of treatment success and patient survival. Current treatment modalities for glioblastoma include radiation therapy, surgical intervention, and chemotherapy. Unfortunately, the median survival rate remains dishearteningly low at 12-15 months. One of the major obstacles in treating glioblastoma is the recurrence of tumors, making chemotherapy the primary approach for secondary glioma patients. However, the efficacy of drugs is hampered by the presence of the blood-brain barrier and multidrug resistance mechanisms. Consequently, considerable research efforts have been directed toward understanding the underlying signaling pathways involved in glioma and developing targeted drugs. To tackle glioma, numerous studies have examined kinase-downstream signaling pathways such as RAS-RAF-MEK-ERK-MPAK. By targeting specific signaling pathways, heterocyclic compounds have demonstrated efficacy in glioma therapeutics. Additionally, key kinases including phosphatidylinositol 3-kinase (PI3K), serine/threonine kinase, cytoplasmic tyrosine kinase (CTK), receptor tyrosine kinase (RTK) and lipid kinase (LK) have been considered for investigation. These pathways play crucial roles in drug effectiveness in glioma treatment. Heterocyclic compounds, encompassing pyrimidine, thiazole, quinazoline, imidazole, indole, acridone, triazine, and other derivatives, have shown promising results in targeting these pathways. As part of this review, we propose exploring novel structures with low toxicity and high potency for glioma treatment. The development of these compounds should strive to overcome multidrug resistance mechanisms and efficiently penetrate the blood-brain barrier. By optimizing the chemical properties and designing compounds with enhanced drug-like characteristics, we can maximize their therapeutic value and minimize adverse effects. Considering the complex nature of glioblastoma, these novel structures should be rigorously tested and evaluated for their efficacy and safety profiles.

CSF1R inhibitors are emerging immunotherapeutic drugs for cancer treatment.

Colony-Stimulating Factor-1 Receptor (CSF1R) is a receptor tyrosine kinase that controls the differentiation and maintenance of most tissue-resident macrophages and bone-resorbing osteoclasts. Mutations of CSF1R have been implicated in neurodegeneration, skeletal anomalies, and cancers. Activation of CSF1R by endogenous cytokine ligation to the ectodomain triggers the autophosphorylation of the intracellular tyrosine kinase domain, and thereafter, activation of several downstream pro-survival kinase cascades, including PI3K, ERK1/2, and JNK. The immunological role of CSF1R in regulating tumor-associate macrophages (TAMs) have been well-documented. TAMs harboring activated CSF1R release tumorigenic cytokines, which further deconditioning tumor microenvironment to a protumoral phenotype. Pharmacological inhibition of CSF1R has emerged as a promising antitumor strategy, with PLX3397 (pexidartinib) been approved by the FDA for the treatment of tenosynovial giant cell tumor in 2019. Research around developing novel small-molecule CSF1R inhibitors, as well as expanding their potential indications, have drawn numerous attentions thenceforward. Herein, we've comprehensively reviewed the latest progression of CSF1R inhibitors under clinical and preclinical studies. Key findings of CSF1R targeted therapies either as monotherapy or combinatorial therapy have also been discussed.

Discoidin domain receptor inhibitors as anticancer agents: A systematic review on recent development of DDRs inhibitors, their resistance and structure activity relationship.

Discoidin domain receptors (DDRs) are one of the less explored targets for the treatment of cancer which belong to receptor tyrosine kinases family. Discoidin domain receptors (DDRs) are a collagen-activated receptor tyrosine kinase and essential for controlling cellular functions like proliferation, morphogenesis, adhesion, differentiation, invasion, matrix remodeling, and migration. Although there are many targets and their inhibitors are reported which treat cancer. But most of drugs were amalgamated with moderate to severe side effects. This results in untreated cancerous cells. One of the reasons that cancer is considered challenging to treat because the targets were mutating rapidly and the inhibitor become less potent. The target identification is a tedious task for the researchers from the early 1990 s till date. When it comes to cancer, there has not been any magical stick to treat it undisputedly. Therefore, need for discovery of new receptor may helpful to overcome these difficulties. The development of DDR inhibitors has received a lot of attention ever since the target was discovered. In this review we have reported the development of most promising DDR1 and DDR2 small molecule inhibitors from the perspective of medicinal chemistry. We have also discussed about the clinical trials, recent patents, selectivity biological activity, and structure-activity relationship (SAR) of DDR1 and DDR2 inhibitors.

Discovery of 3-Aminopyrazole Derivatives as New Potent and Orally Bioavailable AXL Inhibitors.

The receptor tyrosine kinase AXL is a promising target for anticancer drug discovery. Herein, we describe the discovery of 3-aminopyrazole derivatives as new potent and selective AXL kinase inhibitors. One of the representative compounds, 6li, potently inhibited AXL enzymatic activity with an IC50 value of 1.6 nM, and tightly bound with AXL protein with a Kd value of 0.26 nM, while was obviously less potent against most of the 403 wild-type kinases evaluated. Cell-based assays demonstrated that compound 6li potently inhibited AXL signaling, suppressed Ba/F3-TEL-AXL cell proliferation, reversed TGF-ß1-induced epithelial-mesenchymal transition, and dose-dependently impeded cancer cell migration and invasion. Compound 6li also showed reasonable pharmacokinetic properties in rats and exhibited significant in vivo antitumor efficacy in a xenograft model of highly metastatic murine breast cancer 4T1 cells. Taken together, this study provides a new potent and selective AXL inhibitor for further anticancer drug discovery.

Endocytic trafficking of GAS6-AXL complexes is associated with sustained AKT activation.

AXL, a TAM receptor tyrosine kinase (RTK), and its ligand growth arrest-specific 6 (GAS6) are implicated in cancer metastasis and drug resistance, and cellular entry of viruses. Given this, AXL is an attractive therapeutic target, and its inhibitors are being tested in cancer and COVID-19 clinical trials. Still, astonishingly little is known about intracellular mechanisms that control its function. Here, we characterized endocytosis of AXL, a process known to regulate intracellular functions of RTKs. Consistent with the notion that AXL is a primary receptor for GAS6, its depletion was sufficient to block GAS6 internalization. We discovered that upon receptor ligation, GAS6-AXL complexes were rapidly internalized via several endocytic pathways including both clathrin-mediated and clathrin-independent routes, among the latter the CLIC/GEEC pathway and macropinocytosis. The internalization of AXL was strictly dependent on its kinase activity. In comparison to other RTKs, AXL was endocytosed faster and the majority of the internalized receptor was not degraded but rather recycled via SNX1-positive endosomes. This trafficking pattern coincided with sustained AKT activation upon GAS6 stimulation. Specifically, reduced internalization of GAS6-AXL upon the CLIC/GEEC downregulation intensified, whereas impaired recycling due to depletion of SNX1 and SNX2 attenuated AKT signaling. Altogether, our data uncover the coupling between AXL endocytic trafficking and AKT signaling upon GAS6 stimulation. Moreover, our study provides a rationale for pharmacological inhibition of AXL in antiviral therapy as viruses utilize GAS6-AXL-triggered endocytosis to enter cells.

The Efficacy and Safety of Anlotinib Alone and in Combination with Other Drugs in Advanced Lung Cancer: A Retrospective Cohort Study.

OBJECTIVE: Lung cancer is a disease associated with high levels of morbidity and mortality, with approximately 2.1 million new cases every year. Anlotinib is a new small-molecule multitarget tyrosine kinase inhibitor independently developed in China that can inhibit the formation of tumor blood vessels and has a therapeutic effect on various cancers. However, the application of anlotinib in lung cancer needs further investigation. METHODS: We collected the progress notes of 43 patients with advanced lung cancer treated at the Oncology Department of Guangzhou Chest Hospital from March 2019 to March 2021. Additionally, we assessed the differences between drug combination therapy and single-drug therapy among patients treated with anlotinib. RESULTS: Patients in both the anlotinib-combination and anlotinib-monotherapy groups experienced remission; however, the overall disease control rate in the anlotinib-combination group was higher than that in the anlotinib-monotherapy group. Reexamination via computed tomography showed that patients in the anlotinib-combination group had better recovery than those in the anlotinib-monotherapy group. Although the overall incidence of adverse reactions in the anlotinib-combination group was higher than that in the monotherapy group, most of the adverse reactions were I-II levels and improved after symptomatic treatment. CONCLUSION: Anlotinib combined with other therapies is better than anlotinib alone for the management of patients with advanced lung cancer.

Tumoragnosztikus célzott terápia ­ tropomiozin-receptor-tirozinkináz gátlása a gyakorlatban.

Tumor agnostic therapies target specific genomic alterations regardless of tumor localization and histological subtype. Neurotrophic tropomyosin receptor tyrosine kinase (NTRK) gene fusions are important driver gene targets in both pediatric and adult tumors. The first generation TRK inhibitors provide a rapid, effective, and long-lasting antitumor effect with a favorable side effect profile through selective inhibition of TRK fusion proteins. In the case report, we present a case of a young adult female patient with soft tissue sarcoma, in whom the multiple recurrent lower limb tumor disseminated after 3 years, but the systemic treatments used did not show a meaningful therapeutic response. Molecular diagnostic method confirmed the translocation of a very rare driver oncology target, the neurotrophic tropomyosin receptor tyrosine kinase 3 gene. We used convenient and safe inhibitor of tropomyosin receptor tyrosine kinase larotrectinib therapy with good efficacy and excellent quality of life. Larotrectinib was the first and only systemic therapy to which this metastatic soft tissue tumor responded.

Assisting Multitargeted Ligand Affinity Prediction of Receptor Tyrosine Kinases Associated Nonsmall Cell Lung Cancer Treatment with Multitasking Principal Neighborhood Aggregation.

A multitargeted therapeutic approach with hybrid drugs is a promising strategy to enhance anticancer efficiency and overcome drug resistance in nonsmall cell lung cancer (NSCLC) treatment. Estimating affinities of small molecules against targets of interest typically proceeds as a preliminary action for recent drug discovery in the pharmaceutical industry. In this investigation, we employed machine learning models to provide a computationally affordable means for computer-aided screening to accelerate the discovery of potential drug compounds. In particular, we introduced a quantitative structure-activity-relationship (QSAR)-based multitask learning model to facilitate an in silico screening system of multitargeted drug development. Our method combines a recently developed graph-based neural network architecture, principal neighborhood aggregation (PNA), with a descriptor-based deep neural network supporting synergistic utilization of molecular graph and fingerprint features. The model was generated by more than ten-thousands affinity-reported ligands of seven crucial receptor tyrosine kinases in NSCLC from two public data sources. As a result, our multitask model demonstrated better performance than all other benchmark models, as well as achieving satisfying predictive ability regarding applicable QSAR criteria for most tasks within the model's applicability. Since our model could potentially be a screening tool for practical use, we have provided a model implementation platform with a tutorial that is freely accessible hence, advising the first move in a long journey of cancer drug development.

The expanding family of c-Met inhibitors in solid tumors: a comparative analysis of their pharmacologic and clinical differences.

c-Met inhibitors are a class of drugs that include nonselective and selective molecules. These drugs can differ in terms of pharmacodynamic and pharmacokinetic properties that may be clinically relevant. c-Met inhibitors with high potency and selectivity may allow achieving optimal c-Met inhibition in c-Met-driven tumors while reducing unwanted off-target toxicities due to activation of multiple kinases. Nonselective drugs can instead be considered in tumors that also recognize other drivers (e.g., ALK, ROS, VEGF). Improved understanding of the clinical pharmacokinetics of c-Met inhibitors can help avoid drug-drug interactions and optimize schedules for continuous in vivo inhibition of c-Met phosphorylation. The current review article provides a detailed overview of the clinical pharmacology of molecules used in c-Met-driven tumors.

CIC-Mediated Modulation of MAPK Signaling Opposes Receptor Tyrosine Kinase Inhibitor Response in Kinase-Addicted Sarcoma.

Kinase fusions have been identified in a growing subset of sarcomas, but a lack of preclinical models has impeded their functional analysis as therapeutic targets in the sarcoma setting. In this study, we generated models of sarcomas bearing kinase fusions and assessed their response to molecularly targeted therapy. Immortalized, untransformed human mesenchymal stem cells (HMSC), a putative cell of origin of sarcomas, were modified using CRISPR-Cas9 to harbor a RET chromosomal translocation (HMSC-RET). In parallel, patient-derived models of RET- and NTRK-rearranged sarcomas were generated. Expression of a RET fusion activated common proliferation and survival pathways and transformed HMSC cells. The HMSC-RET models displayed similar behavior and response to therapy as the patient-derived counterparts in vitro and in vivo. Capicua (CIC)-mediated suppression of negative MAPK pathway regulators was identified as a potential mechanism by which these sarcomas compensate for RET or NTRK inhibition. This CIC-mediated feedback reactivation was blocked by coinhibition of the MAPK pathway and RET or NTRK in the respective models. Importantly, the combination of RET and ERK inhibitors was more effective than single agents at blocking tumor growth in vivo. This work offers new tools and insights to improve targeted therapy approaches in kinase-addicted sarcomas and supports upfront combination therapy to prolong responses. SIGNIFICANCE: Novel models of kinase-rearranged sarcomas show that MAPK pathway feedback activation dampens responses to tyrosine kinase inhibitors, revealing the potential of combinatorial therapies to combat these tumors.

A phase III, randomized, open-label study (CONTACT-02) of cabozantinib plus atezolizumab versus second novel hormone therapy in patients with metastatic castration-resistant prostate cancer.

Cabozantinib inhibits multiple receptor tyrosine kinases, including the TAM kinase family, and may enhance response to immune checkpoint inhibitors. One cohort of the ongoing phase Ib COSMIC-021 study (NCT03170960) evaluating cabozantinib plus the PD-L1 inhibitor atezolizumab in men with metastatic castration-resistant prostate cancer (mCRPC) that has progressed in soft tissue on/after enzalutamide and/or abiraterone treatment for metastatic disease has shown promising efficacy. Here, we describe the rationale and design of a phase III trial of cabozantinib plus atezolizumab versus a second novel hormone therapy (NHT) in patients who have previously received an NHT for mCRPC, metastatic castration-sensitive PC or nonmetastatic CRPC and have measurable visceral disease and/or extrapelvic adenopathy - a population with a significant unmet need for treatment options. Trial Registration Clinical Trial Registration: NCT04446117 (ClinicalTrials.gov) Registered on 24 June 2020.

Identification of an AXL kinase inhibitor in triple-negative breast cancer by structure-based virtual screening and bioactivity test.

Breast cancer is a malignant tumor that occurs in the glandular epithelium of the breast, and more than 15% of the patients are triple-negative breast cancer (TNBC). Therefore, finding new targets and targeted therapeutic drugs for TNBC is urgent. Overexpression of the AXL is associated with motility and invasiveness of the TNBC cells, which is a potential target for breast cancer therapy. A compound Y041-5921 (IC50  = 6.069 µm for AXL kinase and IC50  = 4.1 µm for MDA-MB-231 cell line) was identified through structure-based virtual screening and bioassay test for the first time. The compound Y041-5921 could significantly inhibit the proliferation and invasion of the TNBC cells and the toxicity of Y041-5921 to normal immortalized breast epithelial cells was far lower than that of commonly used clinical chemotherapy drugs. Besides, it also had well inhibitory effect on the proliferation of many other malignant tumor cell lines (the IC50  value are 10.0 m, 7.1 m, 10.3 m, 11.4 m and 5.8 m for U251 cell, COLO cell, PC-9 cell, CAKI-1 cell and MG63 cell, respectively). The interaction mechanism between Y041-5921 and AXL was studied by molecular dynamics (MD) simulations and binding free energy calculation, and the key residues whose energy contribution mainly comes from non-polar solvation interaction (such as Ala565, Lys567, Met598, Leu620, Pro621, Met623, Lys624, Arg676, Asn677 and Met679) were identified. The small molecule inhibitors Y041-5921 targeting AXL reported in this work will lay a foundation and provide a theoretical basis for the development of the TNBC.

Identification of tyrosine kinase inhibitors from Panax bipinnatifidus and Panax pseudoginseng for RTK-HER2 and VEGFR2 receptors, by in silico approach.

Breast and stomach cancer is reported as a leading cause for human mortality across the world. The overexpression of receptor tyrosine kinase (RTK) proteins, namely the human epidermal growth factor receptor2 (HER2) and the vascular endothelial growth factor receptor2 (VEGFR2), is reported to be responsible for development and metastasis of breast and stomach cancer. Although several synthetic tyrosine kinase inhibitors (TKIs) as drug candidates targeting RTK-HER2 and VEGFR2 are currently available in the market, these are expensive with the reported side effects. This confers an opportunity for development of alternative novel tyrosine kinase inhibitors (TKIs) for RTK-HER2 and VEGFR2 receptors from the botanical sources. In the present study, we characterized 47 bioactive phytocompounds from the methanol extracts of the rhizomes of Asiatic traditional medicinal herbs-Panax bipinnatifidus and Panax pseudoginseng, of Indian Himalayan landraces using HPLC, GC-MS and high-sensitivity LC-MS tools. We performed molecular docking and molecular dynamics simulation analysis using Schrödinger suite 2020-3 to confirm the TKI phytocompounds showing the best binding affinity towards RTK-HER2 and VEGFR2 receptors. The results of molecular docking studies confirmed that the phytocompound (ligand) luteolin 7-O-glucoside (IHP15) showed the highest binding affinity towards receptor HER2 (PDB ID: 3PP0) with docking score and Glide g score (G-Score) of - 13.272, while chlorogenic acid (IHP12) showed the highest binding affinity towards receptor VEGFR2 (PDB ID: 4AGC) with docking score and Glide g score (G-Score) of - 10.673. Molecular dynamics (MD) simulation analysis carried out for 100 ns has confirmed strong binding interaction between the ligand and receptor complex [luteolin 7-O-glucoside (IHP15) and HER2 (PDB ID: 3PP0)] and is found to be stabilized within 40 to 100 ns of MD simulation, whereas ligand-receptor complex [chlorogenic acid (IPH12) and VEGFR2 (PDB ID: 4AGC)] also showed strong binding interaction and is found to be stabilized within 18-30 ns but slightly deviated during 100 ns of MD simulation. In silico ADME-Tox study using SwissADME revealed that the ligands luteolin 7-O-glucoside (IHP15) and chlorogenic acid (IHP12) have passed majority parameters of the common drug discovery rules. The present study has confirmed luteolin 7-O-glucoside (IHP15) and chlorogenic acid (IHP12) as potential tyrosine kinase inhibitors (TKIs) which were found to inhibit RTKs-HER2 and VEGFR2 receptor proteins, and thus paving the way for development of alternative potential TKIs (drug molecules) for treatment of HER2- and VEGFR2-positive breast and stomach cancer.

Bevacizumab and anexelekto inhibitor, TP-0903 inhibits TGF-ß1-induced epithelial-mesenchymal transition of colon cancer cells.

The incidence of colorectal cancer (CRC) is reported to be increasing nowadays, with a large proportion of newly diagnosed CRC patients being affected by metastasis. Epithelial-mesenchymal transition (EMT) is an important event in the development of metastasis of CRC. In this study, we investigated whether the anticancer drug bevacizumab and anexelekto inhibitor, TP-0903, regulate EMT of colon cancer cells induced by transforming growth factor-beta 1 (TGF-ß1). Using quantitative real-time PCR and western blot analysis, we found that bevacizumab and TP-0903 decreased the expression levels of fibronectin, alpha-smooth muscle actin, and vimentin, whereas they restored E-cadherin expression in TGF-ß1-exposed SW480 and HCT116 cells. In addition, we elucidated that bevacizumab and TP-0903 inhibited the migration and invasion of TGF-ß1-exposed colon cancer cells using scratched wound healing, transwell migration, and Matrigel-coated invasion assays. Finally, we discovered that bevacizumab and TP-0903 inactivated the Smad 2/3 signaling pathway in TGF-ß1-exposed SW480 and HCT116 cells. Therefore, we suggest that treatment of bevacizumab and TP-0903 inhibits TGF-ß1-induced EMT of colon cancer cells through inactivation of the Smad 2/3 signaling pathway.

Bemcentinib and Gilteritinib Inhibit Cell Growth and Impair the Endo-Lysosomal and Autophagy Systems in an AXL-Independent Manner.

AXL, a receptor tyrosine kinase from the TAM (TYRO3 AXL and MER) subfamily, and its ligand growth arrest-specific 6 (GAS6) are implicated in pathogenesis of a wide array of cancers, acquisition of resistance to diverse anticancer therapies and cellular entry of viruses. The continuous development of AXL inhibitors for treatment of patients with cancer and COVID-19 underscores the need to better characterize the cellular effects of AXL targeting.In the present study, we compared the cellular phenotypes of CRISPR-Cas9-induced depletion of AXL and its pharmacological inhibition with bemcentinib, LDC1267 and gilteritinib. Specifically, we evaluated GAS6-AXL signaling, cell viability and invasion, the endo-lysosomal system and autophagy in glioblastoma cells. We showed that depletion of AXL but not of TYRO3 inhibited GAS6-induced phosphorylation of downstream signaling effectors, AKT and ERK1/2, indicating that AXL is a primary receptor for GAS6. AXL was also specifically required for GAS6-dependent increase in cell viability but was dispensable for viability of cells grown without exogenous addition of GAS6. Furthermore, we revealed that LDC1267 is the most potent and specific inhibitor of AXL activation among the tested compounds. Finally, we found that, in contrast to AXL depletion and its inhibition with LDC1267, cell treatment with bemcentinib and gilteritinib impaired the endo-lysosomal and autophagy systems in an AXL-independent manner. IMPLICATIONS: Altogether, our findings are of high clinical importance as we discovered that two clinically advanced AXL inhibitors, bemcentinib and gilteritinib, may display AXL-independent cellular effects and toxicity.

Molecular targets of tyrosine kinase inhibitors in thyroid cancer.

Thyroid cancer (TC) is the eighth most frequently diagnosed cancer worldwide with a rising incidence in the past 20 years. Surgery is the primary strategy of therapy for patients with medullary TC (MTC) and differentiated TC (DTC). In DTC patients, radioactive iodine (RAI) is administered after thyroidectomy. Neck ultrasound, basal and thyroid-stimulating hormone-stimulated thyroglobulin are generally performed every three to six months for the first year, with subsequent intervals depending on initial risk assessment, for the detection of possible persistent/recurrent disease during the follow up. Distant metastases are present at the diagnosis in ∼5 % of DTC patients; up to 15 % of patients have recurrences during the follow up, with a survival reduction (70 %-50 %) at 10-year. During tumor progression, the iodide uptake capability of DTC cancer cells can be lost, making them refractory to RAI, with a negative impact on the prognosis. Significant advances have been done recently in our understanding of the molecular pathways implicated in the progression of TCs. Several drugs have been developed, which inhibit signaling kinases or oncogenic kinases (BRAFV600E, RET/PTC), such as those associated with Platelet-Derived Growth Factor Receptor and Vascular Endothelial Growth Factor Receptor. Tyrosine kinase receptors are involved in cancer cell proliferation, angiogenesis, and lymphangiogenesis. Several tyrosine kinase inhibitors (TKIs) are emerging as new treatments for DTC, MTC and anaplastic TC (ATC), and can induce a clinical response and stabilize the disease. Lenvatinib and sorafenib reached the approval for RAI-refractory DTC, whereas cabozantinib and vandetanib for MTC. These TKIs extend median progression-free survival, but do not increase the overall survival. Severe side effects and drug resistance can develop in TC patients treated with TKIs. Additional studies are needed to identify a potential effective targeted therapy for aggressive TCs, according to their molecular characterization.

Effects of tyrosine kinase inhibitors on thyroid function and thyroid hormone metabolism.

The increasing knowledge of the molecular mechanisms in the cell signaling pathways of malignant cells, has recently led to the discovery of several tyrosine kinases (TKs), mainly TK receptors (TKR), which play a major role in the pathogenesis of many types of cancer. These receptors, physiologically involved in cell growth and angiogenesis, may harbor mutations or be overexpressed in malignant cells, and represent a target for anticancer therapy. Indeed, several therapeutic agents targeting specific altered pathways such as RET, BRAF, RAS, EGFR and VEGFR, have been identified. Tyrosine kinase inhibitors (TKIs) affect TK dependent oncogenic pathways by competing with ATP binding sites of the TK domain, thus blocking the activity of the enzyme, and thereby inhibiting the growth and spread of several cancers. Although the therapeutic action may be very effective, these molecules, due to their mechanism of multitargeted inhibition, may produce adverse events involving several biological systems. Both hypothyroidism and thyrotoxicosis have been reported during treatment with TKI, as well as an effect on the activity of enzymes involved in thyroid hormone metabolism. The pathogenic mechanisms leading to thyroid dysfunction and changes in serum thyroid function tests occurring in patients on TKI are reviewed and discussed in this manuscript.