Transmembrane Tyrosine Kinase Receptor Research Articles

GASTRIC GASTROINTESTINAL STROMAL TUMOR WITH SUCCINATE DEHYDROGENASE B DEFICIENCY: CLINICAL CASE

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors found in the gastrointestinal tract, constituting a diverse group of c-Kit positive mesenchymal (stromal or connective tissue) tumors. Their development is primarily associated with mutations in the c-Kit proto-oncogene, leading to structural alterations in the type III transmembrane tyrosine kinase receptor (Kit). This receptor is crucial for regulating mitotic activity and cell differentiation. The activation of the Kit-receptor in tumor cells is identified through the expression of the immunohistochemical marker CD 117 (tyrosine kinase receptor protein), with approximately 80-90% of GISTs testing positive for CD 117. The objective of our study is to improve the diagnosis and treatment of gastrointestinal stromal tumors. The clinical case underscores the challenge of diagnosing gastrointestinal stromal tumors (GISTs) due to the absence of specific and definitive symptoms. In this instance, only radical surgical intervention facilitated an accurate diagnosis. Given the location of the tumor in the pyloric part of the gastric submucosal layer, a reliable biopsy during video esophagogastroduodenoscopy was unfeasible, as the gastric mucosa above the tumor appeared unaffected. Consequently, surgery with complete tumor excision and subsequent pathohistological and immunohistochemical analysis emerged as the primary diagnostic and therapeutic approach. These investigations confirmed the presence of a gastrointestinal stromal tumor of the stomach with succinate dehydrogenase B deficiency. In approximately 80% of GIST cases, succinate dehydrogenase deficiency plays a pivotal role. The absence of succinate dehydrogenase disrupts the Krebs cycle, leading to an accumulation of succinate, an oncometabolite that fuels carcinogenesis. Such tumors exhibit distinctive clinical characteristics, prognostic outcomes, and responsiveness to targeted therapies. Succinate dehydrogenase deficiency can arise from mutations or epigenomic alterations affecting gene expression. Notably, mutations or epigenomic disruptions in any succinate dehydrogenase subunit inevitably result in the loss of subunit B expression.

Targeting of C-ROS-1 Activity Using a Controlled Release Carrier to Treat Craniosynostosis in a Preclinical Model of Saethre-Chotzen Syndrome

Saethre-Chotzen syndrome (SCS) is one of the most prevalent craniosynostosis, caused by a loss-of-function mutation in the TWIST-1 gene, with current treatment options relying on major invasive transcranial surgery. TWIST-1 haploinsufficient osteogenic progenitor cells exhibit increased osteogenic differentiation potential due to an upregulation of the transmembrane tyrosine kinase receptor, C-ROS-1, a TWIST-1 target gene known to promote bone formation. The present study assessed the efficacy of suppressing C-ROS-1 activity using a known chemical inhibitor to C-ROS-1, crizotinib, to halt premature coronal suture fusion in a preclinical mouse model of SCS. Crizotinib (1 μM, 2 μM, or 4 μM) was administered locally over the calvaria of Twist‐1del/+ heterozygous mice prior to coronal suture fusion using either a nonresorbable collagen sponge (quick drug release) or a resorbable sodium carboxymethylcellulose microdisk (slow sustained release). Coronal suture fusion rates and bone parameters were determined by μCT imaging and histomorphometric analysis of calvaria postcoronal suture fusion. Results demonstrated a dose-dependent increase in the efficacy of crizotinib to maintain coronal suture patency, with no adverse effects to brain, kidney, liver, and spleen tissue, or blood cell parameters. Moreover, crizotinib delivered on microdisks resulted in a greater efficacy at a lower concentration to reduce bone formation at the coronal suture sites compared to sponges. However, the bone inhibitory effects were found to be diminished by over time following cessation of treatment. Our findings lay the foundation for the development of a pharmacological nonsurgical, targeted approach to temporarily maintain open coronal sutures in SCS patients. This study could potentially be used to develop similar therapeutic strategies to treat different syndromic craniosynostosis conditions caused by known genetic mutations.

Targeting epidermal growth factor receptor and its downstream signaling pathways by natural products: A mechanistic insight.

The epidermal growth factor receptor (EGFR) is a transmembrane receptor tyrosine kinase (RTK) that maintains normal tissues and cell signaling pathways. EGFR is overactivated and overexpressed in many malignancies, including breast, lung, pancreatic, and kidney. Further, the EGFR gene mutations and protein overexpression activate downstream signaling pathways in cancerous cells, stimulating the growth, survival, resistance to apoptosis, and progression of tumors. Anti-EGFR therapy is the potential approach for treating malignancies and has demonstrated clinical success in treating specific cancers. The recent report suggests most of the clinically used EGFR tyrosine kinase inhibitors developed resistance to the cancer cells. This perspective provides a brief overview of EGFR and its implications in cancer. We have summarized natural products-derived anticancer compounds with the mechanistic basis of tumor inhibition via the EGFR pathway. We propose that developing natural lead molecules into new anticancer agents has a bright future after clinical investigation.

Abstract 4365: Mechanistic effects of N361 glycosylation in epidermal growth factor receptor protein

Abstract Glycosylation is a tightly regulated post-translational modification where structured sugar groups are added to protein amino acid backbones, most commonly on asparagine for N-glycosylation. The glycosylation-regulating metabolic enzyme uridine diphosphate-glucose pyrophosphorylase 2 (UGP2) is required in oncogene-transformed cancer cells, but not in normal cells. UGP2 heavily regulates glycosylation of epidermal growth factor receptor (EGFR) at asparagine 361 (N361), a key site near the ligand binding domain. EGFR is a transmembrane tyrosine kinase receptor that promotes cell proliferation via growth cascades. Mutations and amplifications in EGFR account for a significant fraction of non-small cell lung carcinomas and breast adenocarcinoma, with L858R being the most common oncogenic hotspot. Other glycosylation sites on EGFR have been implicated in ligand binding, dimerization, and phosphorylation of downstream targets. Molecular dynamic simulations suggested that N361 may be important for dimerization or ligand binding. However, the functional relevance of how glycosylation of EGFR at N361 impacts EGFR protein and cellular behaviors remains unclear. To determine the functional relevance of glycosylation at N361, we created glycosylation-defective EGFR N361A mutant, with or without an additional oncogenic EGFR L858R mutant. We expressed these constructs in MCF10A and 293T cells, which do not have pre-existing activation of this pathway. Immunofluorescence and flow cytometry showed that the mutants were each well expressed at the cell membrane. Proximity ligation assays measuring dimerization of EGFR in cells showed that EGFR N361A greatly increased dimerization relative to wildtype controls. Loss of glycosylation of EGFR N361 impacted cell viability when grown in dose courses of its high affinity ligand EGF or lower affinity ligand amphiregulin. Furthermore, EGFR N361A desensitized cells expressing the oncogenic EGFR L858R to inhibitors targeting the extracellular domain, possibly because the mutation alters the antibody binding interface. N361A sensitized EGFR L858R to inhibitors targeting the cytoplasmic domain of EGFR. These findings help us understand the intricate relationship between EGFR and N-glycosylation, reinforcing the critical functional relevance of post-translational modifications on oncogenes. Citation Format: Dennis Lam, Ariel N. Liberchuk, Brandon Arroyo, Andrew L. Wolfe. Mechanistic effects of N361 glycosylation in epidermal growth factor receptor protein [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4365.

Abstract 3755: Impact of antigen retrieval and other parameters on detection of FGFR2b in various solid tumors on a BenchMark ULTRA automated staining platform: Development of a new IHC assay for FGFR2b

Abstract Background: Fibroblast growth factor receptor 2b (FGFR2b) is part of the FGFR transmembrane tyrosine kinase receptor family. This protein has gained more attention in recent years as a tumor progression biomarker in numerous solid tumors. The detection of FGFR2b by immunohistochemistry (IHC) has been used recently in immunotherapy clinical trials with multiple tumor types. During IHC assay development on formalin-fixed paraffin embedded tissue, a thorough study of antigen retrieval through cell conditioning or enzyme incubation, primary antibody incubation, and detection parameters is critical to evaluate staining performance. Design: A study of an investigational anti-FGFR2b (FPR2-D) assay developed on a BenchMark ULTRA automated staining platform explored the effect of antigen retrieval and detection parameters on staining performance. VENTANA System Software was used to modify steps in the IHC staining protocol resulting in 42 permutations. Ten different solid tumors were stained with these modifications to the assay and subsequently evaluated for FGFR2b expression. Result:s The results demonstrate that the staining clarity, intensity, and dynamic range within tissue cases of FGFR2b staining can vary widely between different solid tumor types. While most permutations of the initial assay parameters had minimal impact on the staining performance and readability by a pathologist, the order of the enzyme treatment and the cell conditioning steps (in addition to increased incubation time of primary antibody) had a significant impact when comparing across different solid tumors. Detection of FGFR2b seemed to have a greater susceptibility by tumor type to the antigen retrieval process than has traditionally been observed in other biomarkers. Conclusion: The overall results of this investigation show the importance of an extensive parameter screening approach when evaluating new antibody targets and indication combinations in IHC to ensure optimal staining performance. This is critical to downstream testing and the potential use of new assays in the context of in vitro diagnostics. Citation Format: Autumn Sky Watson, Catherine Le, Anne M. Wertheimer, Spencer Escobedo, Lisa So, Bhavani Bagevalu Siddegowda, John D. Palting, Susan Marion, Steven P. Stratton, Birte Aggeler. Impact of antigen retrieval and other parameters on detection of FGFR2b in various solid tumors on a BenchMark ULTRA automated staining platform: Development of a new IHC assay for FGFR2b [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3755.

Abstract 2761: Activating RET mutations promotes osteoblastic bone metastasis by inhibiting osteoclastogenesis and stimulating osteoblast activity via regulation of osteoprotegerin

Abstract Bone metastases (BM) are a source of increased mortality and significant morbidity in patients with medullary thyroid cancer (MTC), with ~50% survival at five years post-diagnosis. MTC causes osteoblastic, osteolytic, or mixed lesions, yet the underlying mechanisms are unknown. The RET proto-oncogene encodes a transmembrane tyrosine kinase receptor and is the driver oncogene in ~60% of MTC cases where a germline or somatic activating mutation results in ligand-independent constitutive activation of the receptor. However, the role of RET mutations in the genesis of bone metastasis lesions is unknown. We show that activating RET mutations promotes an osteoblastic phenotype in mice implanted with patient-derived MTC cells by increasing bone formation and decreasing bone resorption. We found that the radiographic appearance of osteoblastic lesions differed between the types of RET mutations (C634W and M918T). MTC cells with RETC634W mutation showed a four-fold increase in bone mineral density, trabecular bone volume, number, and thickness with a decreased number of osteoblasts compared to the non-tumor-bearing femur. TRAP staining revealed that osteoclast numbers per long bone were reduced in the injected femur compared to the control. In contrast, the MTC-RETM918T mutation showed an increased cortical thickness and porosity with reduced medullary area and increased bone formation rate compared to the non-tumor bearing femur. MTC cells formed tumors with extensive mineralized tissue, composed of bone matrix surrounded by osteoblast-like cells and osteoid. The knockdown of RET in the MTC-RETM918T model significantly reduced cortical thickness and increased the number of osteoclasts per bone surface. We observed increased osteoprotegerin (OPG) expression in MTC-bearing femurs compared to controls, suggesting decreased bone resorption. The factors secreted by MTC cells, including OPG, inhibited osteoclast formation from primary bone marrow cells and Raw264 cells. In addition, RET knockdown by shRNA in MTC cells decreased OPG expression. Moreover, the MTC-conditioned media (CM) increased osteoblast differentiation and mineralization of the primary culture of pre-osteoblasts isolated from calvarial bone, long bones, and MC3T3 cells. The conditioned media of RET-depleted cells inhibits osteoblast differentiation and mineralization. The expression of alkaline phosphatase, osteocalcin, OPG, and osterix increased in pre-osteoblast incubated with MTC-CM. Compared to primary non-metastatic tumors, the OPG expression increases in tissues of sporadic MTC bone metastases harboring RETM918T mutation. These results suggest that MTC with RET-activating mutations induces osteoblastic bone metastasis due to decreased bone resorption and increased bone formation. Citation Format: Rozita Bagheri-Yarmand, Joseph L. Kidd, Gabriel M. Pagnotti, Trupti Trivedi, Leah Guerra, Xinhai Wan, Jian Song, Sue-Hwa Lin, Theresa A Guise. Activating RET mutations promotes osteoblastic bone metastasis by inhibiting osteoclastogenesis and stimulating osteoblast activity via regulation of osteoprotegerin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2761.

Deplete and repeat: microglial CSF1R inhibition and traumatic brain injury.

Traumatic brain injury (TBI) is a public health burden affecting millions of people. Sustained neuroinflammation after TBI is often associated with poor outcome. As a result, increased attention has been placed on the role of immune cells in post-injury recovery. Microglia are highly dynamic after TBI and play a key role in the post-injury neuroinflammatory response. Therefore, microglia represent a malleable post-injury target that could substantially influence long-term outcome after TBI. This review highlights the cell specific role of microglia in TBI pathophysiology. Microglia have been manipulated via genetic deletion, drug inhibition, and pharmacological depletion in various pre-clinical TBI models. Notably, colony stimulating factor 1 (CSF1) and its receptor (CSF1R) have gained much traction in recent years as a pharmacological target on microglia. CSF1R is a transmembrane tyrosine kinase receptor that is essential for microglia proliferation, differentiation, and survival. Small molecule inhibitors targeting CSF1R result in a swift and effective depletion of microglia in rodents. Moreover, discontinuation of the inhibitors is sufficient for microglia repopulation. Attention is placed on summarizing studies that incorporate CSF1R inhibition of microglia. Indeed, microglia depletion affects multiple aspects of TBI pathophysiology, including neuroinflammation, oxidative stress, and functional recovery with measurable influence on astrocytes, peripheral immune cells, and neurons. Taken together, the data highlight an important role for microglia in sustaining neuroinflammation and increasing risk of oxidative stress, which lends to neuronal damage and behavioral deficits chronically after TBI. Ultimately, the insights gained from CSF1R depletion of microglia are critical for understanding the temporospatial role that microglia develop in mediating TBI pathophysiology and recovery.

Design, synthesis and evaluate of indazolylaminoquinazoline derivatives as potent Tropomyosin receptor kinase (TRK) inhibitors

Tropomyosin receptor kinases (TRKs), the superfamily of transmembrane receptor tyrosine kinases, have recently become an attractive method for precision anticancer therapies since the approval of Larotrectinib and Entrectinib by FDA. Herein, we reported the discovery of a series of novel indazolylaminoquinazoline and indazolylaminoindazole as TRK inhibitors. The representative compound 30f exhibited good inhibitory activity against TRKWT, TRKG595R and TRKG667C with IC50 values of 0.55 nM, 25.1 nM and 5.4 nM, respectively. The compound also demonstrated potent superior to Larotrectinib antiproliferative activity against a panel of Ba/F3 cell lines transformed with both NTRK wild type and mutant fusions (IC50 = 10–200 nM). In addition, compound 30f exhibited good in vitro metabolic stability (T1/2 = 73.0 min), indicating that the quinazoline derivatives may have better metabolic stability. Finally, the binding mode of compound 30f predicted by molecular docking well explained the good enzyme inhibitory activity of indazolylaminoquinazoline compounds as TRK inhibitor. Thus, compound 30f can be used as a promising lead molecule for further structural optimization.

Investigating the activity of Quinazoline derivatives against T790 mutant EGFR receptors employing computer-aided drug design

The uncontrolled growth of cancer cells is caused by their innate tendency to multiply without limits. In addition to colonizing adjacent tissues, they are capable of forming aggregates in isolated anatomical sites, thereby significantly increasing their invasiveness. Over time, malignant tumors that progressively destroy essential tissues and organs are ultimately lethal. It is well known that growth factor-driven signaling influence malignancy. The transmembrane receptor tyrosine kinases of growth factors influence the survival, differentiation, and proliferation of cells. To expedite cell division, neurotransmitters and proteins resembling epidermal growth factor (EGF) stimulate EGF receptor (EGFR) family members including HER2-4 and EGFR. The development and growth of numerous varieties of human cancer cells, as well as the morphogenesis of numerous animal species (nematodes to humans), are influenced by this signaling module, which is remarkably conserved. The EGFR family, consisting of over thirty ligands and four receptors, forms a complex and advanced human signal transduction network. The T790M mutation in the EGFR kinase enhances treatment resistance by increasing the affinity for ATP. This work used a molecular design tool to evaluate quinazoline derivatives with the highest IC50 values against EGFR and analyze the molecular interactions in the binding site. The goal was to uncover novel compounds with promising potential.

SAM domain variants of EPHB4 associated with aberrant signaling are linked to lymphatic-related fetal hydrops and facial dysmorphology.

Variants in EPHB4 (Ephrin type B receptor 4), a transmembrane tyrosine kinase receptor, have been identified in individuals with various vascular anomalies including Capillary Malformation-Arteriovenous Malformation syndrome 2 and lymphatic-related (non-immune) fetal hydrops (LRHF). Here, we identify two novel variants in EPHB4 that disrupt the SAM domain in two unrelated individuals. Proband 1 presented within the LRHF phenotypic spectrum with hydrops, and proband 2 presented with large nuchal translucency prenatally that spontaneously resolved in addition to dysmorphic features on exam postnatally. These are the first disease associated variants identified that do not disrupt EPHB4 protein expression or tyrosine-kinase activity. We identify that EPHB4 SAM domain disruptions can lead to aberrant downstream signaling, with a loss of the SAM domain resulting in elevated MAPK signaling in proband 1, and a missense variant within the SAM domain resulting in increased cell proliferation in proband 2. This data highlights that a functional SAM domain is required for proper EPHB4 function and vascular development.

Fibroblast growth factor receptor-4 mediates activation of Nuclear Factor Erythroid 2-Related Factor-2 in gastric tumorigenesis

Helicobacter pylori (H. pylori) is the leading risk factor for gastric carcinogenesis. Fibroblast growth factor receptor 4 (FGFR4) is a member of transmembrane tyrosine kinase receptors that are activated in cancer. We investigated the role of FGFR4 in regulating the cellular response to H. pylori infection in gastric cancer. High levels of oxidative stress signature and FGFR4 expression were detected in gastric cancer samples. Gene set enrichment analysis (GSEA) demonstrated enrichment of NRF2 signature in samples with high FGFR4 levels. H. pylori infection induced reactive oxygen species (ROS) with a cellular response manifested by an increase in FGFR4 with accumulation and nuclear localization NRF2. Knocking down FGFR4 significantly reduced NRF2 protein and transcription activity levels, leading to higher levels of ROS and DNA damage following H. pylori infection. We confirmed the induction of FGFR4 and NRF2 levels using mouse models following infection with a mouse-adapted H. pyloristrain. Pharmacologic inhibition of FGFR4 using H3B-6527, or its knockdown, remarkably reduced the level of NRF2 with a reduction in the size and number of gastric cancer spheroids. Mechanistically, we detected binding between FGFR4 and P62 proteins, competing with NRF2-KEAP1 interaction, allowing NRF2 to escape KEAP1-dependent degradation with subsequent accumulation and translocation to the nucleus. These findings demonstrate a novel functional role of FGFR4 in cellular homeostasis via regulating the NRF2 levels in response to H. pylori infection in gastric carcinogenesis, calling for testing the therapeutic efficacy of FGFR4 inhibitors in gastric cancer models.

Ex Vivo Drug Sensitivity Evaluation of a ZMYM2::FGFR1 Fusion-Positive 8p11 Myeloproliferative Syndrome (EMS) Leukemia

Introduction : Fibroblast growth factor receptors (FGFRs) are conserved single transmembrane receptor tyrosine kinases (RTKs) with an extracellular ligand-binding domain and a cytoplasmic tyrosine kinase domain. They play vital roles in cellular proliferation, survival, development, fetal organogenesis, metabolism, and tissue repair. 8p11 myeloproliferative syndrome (EMS) is a hematologic malignancy caused by a translocation of the fibroblast growth factor receptor 1 (FGFR1) gene on chromosome 8p11-12. The most common fusion partner of FGFR1 is the zinc-finger domain ZNF198 (also known as ZMYM2) on chromosome 13q12. Pemigatinib is approved for FGFR fusion positive myeloid/lymphoid neoplasms (MLNs), and other FGFR inhibitors are being tested in clinical trials. However, EMS patients still face a poor prognosis and drug resistance, necessitating further research to overcome these challenges. This study evaluated ex vivo drug screening assay data generated from ZMYM2::FGFR1 positive primary leukemia samples throughout the course of an EMS patient's clinical response and validated these findings on a ZMYM2::FGFR1 positive cell line. Methods : Ex vivo and drug screening experiments were performed on freshly isolated primary patient samples and a ZMYM2::FGFR1-expressing cell line. The fusion was confirmed using FISH, and additional clinical specimens were collected with informed patient consent. Ex vivo drug sensitivity assays were conducted on patient mononuclear cells isolated from blood and bone marrow. IL-3 dependent BaF3 cells were infected with retrovirus containing a ZMYM2::FGFR1-V5 construct. ZMYM2::FGFR1 transformed BaF3 cells were evaluated with single agent and drug combination panels. Sanger sequencing of the FGFR portion of the fusion was performed on patient samples to confirm the breakpoint and identify potential mutations affecting sensitivity to Ponatinib throughout the course of treatment. Results : Sample were obtained with informed consent from a 36-year-old man diagnosed with 8p11 myeloproliferative syndrome and a ZMYM2::FGFR1 fusion along with a RUNX1 R201Q mutation. Ex vivo drug screens performed on isolated mononuclear cells demonstrated sensitivity to Ponatinib and Pemigatinib. He underwent treatment with HyperCVAD plus Ponatinib and subsequently HyperCVAD with Ponatinib and Velcade (Bortezomib) to CR1, FISH for FGFR1 rearrangement was undetected. He was scheduled to proceed with hematopoietic stem cell transplant (HSCT), however his pre-transplant bone marrow biopsy showed return of his FGFR1 translocation by FISH. Ex vivo drug screening assays confirmed resistance to Ponatinib, but continued sensitivity to Pemigatinib. He was transitioned to treatment with single agent Pemigatinib and was able to re-clear his FGFR1 fusion by FISH, and has since undergone hematopoietic stem cell transplantation. He remains in remission on post-transplant Pemigatinib maintenance therapy. Sanger sequencing performed at the time of progression on Ponatinib identified a nucleotide alteration resulting in an amino acid substitution (FGFR1 F686L; ZMYM2::FGFR1 F1171L) within the kinase domain that could contribute to decreased Ponatinib sensitivity. Bortezomib and Axitinib exhibited high efficacy on the patient's sample. Ex vivo drug assays performed on ZMYM2::FGFR1 transformed BaF3 cells confirmed the efficacy of Pemigatinib and Ponatinib. Other FGFR inhibitors, including Olverematinib, AZD4547, Axitinib, Cediranib, Dovitinib, and Lenvatinib, also demonstrated exquisite sensitivity. Despite extensive screening, no other single agents or drug combinations exhibited increased effectiveness in the ZMYM2::FGFR1 transformed BaF3 cells except for Trametinib, a MEK inhibitor, and the combination of Belvarafenib (RAF inhibitor) and Gilteritinib (FLT3 inhibitor). Conclusions : Ex vivo drug sensitivity assays demonstrated the highly selective efficacy of FGFR inhibitors in ZMYM2::FGFR1 fusion-positive leukemia cells and a fusion-expressing BaF3 cell line. Mutations in the FGFR1 kinase domain (ZMYM2::FGFR1 F1171L) could contribute to Ponatinib insensitivity. These ex vivo drug screening results provide further support for ongoing clinical trials which are investigating the use of single agent Pemigatinib and other FGFR1 inhibitors for the treatment of patients with FGFR1-fusion positive leukemias.

The leukemia inhibitory factor regulates fibroblast growth factor receptor 4 transcription in gastric cancer.

The gastric adenocarcinoma (GC) represents the third cause of cancer-related mortality worldwide, and available therapeutic options remain sub-optimal. The Fibroblast growth factor receptors (FGFRs) are oncogenic transmembrane tyrosine kinase receptors. FGFR inhibitors have been approved for the treatment of various cancers and a STAT3-dependent regulation of FGFR4 has been documented in the H.pylori infected intestinal GC. Therefore, the modulation of FGFR4 might be useful for the treatment of GC. To investigate wich factors could modulate FGFR4 signalling in GC, we employed RNA-seq analysis on GC patients biopsies, human patients derived organoids (PDOs) and cancer cell lines. We report that FGFR4 expression/function is regulated by the leukemia inhibitory factor (LIF) an IL-6 related oncogenic cytokine, in JAK1/STAT3 dependent manner. The transcriptomic analysis revealed a direct correlation between the expression of LIFR and FGFR4 in the tissue of an exploratory cohort of 31 GC and confirmed these findings by two external validation cohorts of GC. A LIFR inhibitor (LIR-201) abrogates STAT3 phosphorylation induced by LIF as well as recruitment of pSTAT3 to the promoter of FGFR4. Furthermore, inhibition of FGFR4 by roblitinib or siRNA abrogates STAT3 phosphorylation and oncogentic effects of LIF in GC cells, indicating that FGFR4 is a downstream target of LIF/LIFR complex. Treating cells with LIR-201 abrogates oncogenic potential of FGF19, the physiological ligand of FGFR4. Together these data unreveal a previously unregnized regulatory mechanism of FGFR4 by LIF/LIFR and demonstrate that LIF and FGF19 converge on the regulation of oncogenic STAT3 in GC cells.

Targeting isoforms of RON kinase (MST1R) drives antitumor efficacy.

Recepteur d'origine nantais (RON, MST1R) is a single-span transmembrane receptor tyrosine kinase (RTK) aberrantly expressed in numerous cancers, including various solid tumors. How naturally occurring splicing isoforms of RON, especially those which are constitutively activated, affect tumorigenesis and therapeutic response, is largely unknown. Here, we identified that presence of activated RON could be a possible factor for the development of resistance against anti-EGFR (cetuximab) therapy in colorectal cancer patient tissues. Also, we elucidated the roles of three splicing variants of RON, RON Δ155, Δ160, and Δ165 as tumor drivers in cancer cell lines. Subsequently, we designed an inhibitor of RON, WM-S1-030, to suppress phosphorylation thereby inhibiting the activation of the three RON variants as well as the wild type. Specifically, WM-S1-030 treatment led to potent regression of tumor growth in solid tumors expressing the RON variants Δ155, Δ160, and Δ165. Two mechanisms for the RON oncogenic activity depending on KRAS genotype was evaluated in our study which include activation of EGFR and Src, in a trimeric complex, and stabilization of the beta-catenin. In terms of the immunotherapy, WM-S1-030 elicited notable antitumor immunity in anti-PD-1 resistant cell derived mouse model, likely via repression of M1/M2 polarization of macrophages. These findings suggest that WM-S1-030 could be developed as a new treatment option for cancer patients expressing these three RON variants.

Molecular docking and molecular dynamics simulations reveal the clinical resistance of the gatekeeper mutation V564F of FGFR2 against Infigratinib

Fibroblast growth factor receptor 2 (FGFR2), as a transmembrane receptor tyrosine kinase, is implicated in a plethora of human cancers, including intrahepatic cholangiocarcinomas, breast cancers, and non-small cell lung cancer. The clinically relevant V564F gatekeeper mutation conferred resistance to current FGFR2 drug − Infigratinib. In this study, the protein − ligand interactions between FGFR2 kinase domain (wild-type and V564F) and Infigratinib were compared through an integrated computational method. The multiple, large-scale molecular dynamics (MD) simulations, together with dynamic cross-correlation analysis and binding free energy calculations suggested that the resistant mutation may not trigger the conformational changes of the FGFR2 kinase domain. The simulation results also indicated that the driving force to decrease the binding affinity of Infigratinib to the FGFR2 V564F variant derived from the difference in the protein − ligand hydrogen bonding interactions. Moreover, the per-residue free energy decomposition analysis revealed that the reduced contributions from several residues in the ATP-binding site of FGFR2, especially Glu565 and Ala567 located at the kinase hinge domain, were the key residues responsible for the loss of binding affinity of Infigratinib to the V564F variant. This study may offer useful information for the design of novel selective kinase inhibitors targeting FGFR2.

Preclinical Pharmacokinetics and in vitro Metabolism of FHND5071, a Novel Selective RET Kinase Inhibitor.

Rearranged during transfection (RET) is a transmembrane receptor tyrosine kinase that plays a crucial role in tumorigenesis. FHND5071, a potent and selective RET kinase inhibitor, could exert antitumor effects by inhibiting RET autophosphorylation. The present work aims to profile the pharmacokinetics of FHND5071 in in vivo and in vitro experiments as a ground work for further clinical research. The absorption, distribution, metabolism, and excretion properties of FHND5071 were examined, along with metabolite production and cytochrome P450 (CYP) phenotyping assay. Additionally, plasma protein binding and pharmacokinetics in mice were investigated. Microsomal stability assay corroborated moderate to high clearance of FHND5071, and the use of UPLC-Q-TOF-MS identified a total of six metabolites and suggested a possible metabolic pathway involving oxidation, demethylation, and N-dealkylation. Primary contributors to the CYP-mediated metabolism of FHND5071 were found to be CYP2C8 and CYP3A4, and FHND5071 displayed low permeability and acted as a substrate for the P-glycoprotein (P-gp). FHND5071 had a moderate to high binding in plasma and exhibited a moderate absorption degree (absolute bioavailability > 60%) The distribution of FHND5071 in mouse tissues was rapid (mostly peaking at 1-4 h) and wide (detectable in almost all tissues and organs), with the highest exposure in the spleen. A small fraction of FHND5071 was excreted via the urine and feces, and a presumed metabolic pathway involving 20 metabolites in mice is proposed. Pharmacokinetic characteristics of FHND5071 were systemically profiled, which may lay the foundation for further clinical development as a drug candidate.

Phase 1 trial of bemcentinib (BGB324), a first-in-class, selective AXL inhibitor, with docetaxel in patients with previously treated advanced non-small cell lung cancer

ObjectivesAXL, a transmembrane receptor tyrosine kinase, is highly expressed and associated with poor prognosis in non-small cell lung cancer (NSCLC). Bemcentinib (BGB324), a selective orally bioavailable small molecule AXL inhibitor, synergizes with docetaxel in preclinical models. We performed a phase I trial of bemcentinib plus docetaxel in previously treated advanced NSCLC. Materials and MethodsEscalation of two dose levels of bemcentinib (200 mg load × 3 days then 100 mg daily, or 400 mg load × 3 days then 200 mg daily) in combination with docetaxel (60 or 75 mg/m2 every 3 weeks) followed a 3+3 study design. Due to hematologic toxicity, prophylactic G-CSF was added. Bemcentinib monotherapy was administered for one week prior to docetaxel initiation to assess pharmacodynamic and pharmacokinetic effects alone and in combination. Plasma protein biomarker levels were measured. Results21 patients were enrolled (median age 62 years, 67% male). Median treatment duration was 2.8 months (range 0.7–10.9 months). The main treatment-related adverse events were neutropenia (86%, 76% ≥G3), diarrhea (57%, 0% ≥G3), fatigue (57%, 5% ≥G3), and nausea (52%, 0% ≥G3). Neutropenic fever occurred in 8 (38%) patients. The maximum tolerated dose was docetaxel 60 mg/m2 with prophylactic G-CSF support plus bemcentinib 400 mg load × 3 days followed by 200 mg daily thereafter. Bemcentinib and docetaxel pharmacokinetics resembled prior monotherapy data. Among 17 patients evaluable for radiographic response, 6 (35%) patients had partial response and 8 (47%) patients had stable disease as best response. Bemcentinib administration was associated with modulation of proteins involved in protein kinase B signaling, reactive oxygen species metabolism, and other processes. ConclusionBemcentinib plus docetaxel with G-CSF support demonstrates anti-tumor activity in previously treated, advanced NSCLC. The role of AXL inhibition in the treatment of NSCLC remains under investigation.

Enhancing Anticancer Efficacy of Chemotherapeutics Using Targeting Ligand-Functionalized Synthetic Antigen Receptor-Mesenchymal Stem Cells.

Mesenchymal stem cells (MSCs) have been studied for their potential in facilitating tumor-targeted delivery of chemotherapeutics due to their tumor-homing characteristics. We hypothesized that targeting effectiveness of MSCs can be further enhanced by incorporating tumor-targeting ligands on MSC surfaces that will allow for enhanced arrest and binding within the tumor tissue. We utilized a unique strategy of modifying MSCs with synthetic antigen receptors (SARs), targeting specific antigens overexpressed on cancer cells. MSCs were surface-functionalized by first incorporating recombinant protein G (PG) on the surface, followed by binding of the targeting antibody to the PG handle. We functionalized MSCs with antibodies targeting a tyrosine kinase transmembrane receptor protein, epidermal growth factor receptor (EGFR), overexpressed in non-small-cell lung cancer (NSCLC). The efficacy of MSCs functionalized with anti-EGFR antibodies (cetuximab and D8) was determined in murine models of NSCLC. Cetuximab-functionalized MSCs demonstrated improved binding to EGFR protein and to EGFR overexpressing A549 lung adenocarcinoma cells. Further, cetuximab-functionalized MSCs loaded with paclitaxel nanoparticles were efficient in slowing orthotopic A549 tumor growth and improving the overall survival relative to that of other controls. Biodistribution studies revealed a six-fold higher retention of EGFR-targeted MSCs than non-targeted MSCs. Based on these results, we conclude that targeting ligand functionalization could be used to enhance the concentration of therapeutic MSC constructs at the tumor tissue and to achieve improved antitumor response.

Novel c.2654+1G>A mutation in the CSF1R gene in a family with CSF1R‐microglial encephalopathy

AbstractBackgroundThe colony‐stimulating factor‐1 receptor (CSF1R) is a transmembrane tyrosine kinase receptor that is mainly expressed in the brain‐resident microglia. Thus, microglial dysfunction due to CSF1R mutation may play a primary and pivotal role in the pathogenesis of CSF1R‐microglial encephalopathy. Neither the functional consequences of all known CSF1R mutations nor the full genetic spectrum of mutations causing CSF1R‐microglial encephalopathy have been fully elucidated. We aimed to describe a novel heterozygous splicing variant of the CSF1R gene that caused CSF1R‐microglial encephalopathy in a Han Chinese family.MethodThe demographic data, detailed medical history, and clinical manifestations were collected from a family with CSF1R‐microglial encephalopathy. Some family members also underwent neuropsychological evaluation, structural and functional magnetic resonance imaging (MRI), and whole‐exome sequence analyses.ResultFour generations of this family, including 27 members, presented with a medical history of a dominant hereditary pattern (Figure 1). Seven of these 27 individuals had died, while five presented with similar cognitive impairments clinically, including the proband, and his sister, father, uncle, and grandmother during their life. Brain MRI of the proband (Figure 2) and his sister (Figure 3) depicted symmetric confluent and diffuse deep white matter changes, atrophy of the frontoparietal lobes, and thinning of the corpus callosum. The brother of the proband remained asymptomatic, and the structural brain MRI only revealed minimal white matter changes; however, pseudo‐continuous arterial spin labeling (pCASL) demonstrated marked reduction in the cerebral blood flow (CBF) in the bilateral deep white matter and corpus callosum (Figure 4). Whole‐exome sequencing was performed for seven family members, which identified a novel splice‐site heterozygous mutation (c.2319+1C>A) in intron 20 of the CSF1R gene in four members (Figure 5).ConclusionWe identified a novel splicing mutation (c.2319+1C>A) in intron 20 of CSF1R as the cause of CSF1R‐microglial encephalopathy in a Han Chinese family, which broadens the genetic spectrum of CSF1R‐microglial encephalopathy. We opine that clinically feasible pCASL techniques may be more sensitive to the alterations in CBF of associated with microglial density and cellular changes. This study highlights the potential value of pCASL techniques to improve the clinical diagnostic accuracy of CSF1R‐microglial encephalopathy.

Quinacrine inhibits cMET-mediated metastasis and angiogenesis in breast cancer stem cells.

A trans-membrane receptor tyrosine kinase, cMET, belonging to the MET proto-oncogene family, is responsible for cancer metastasis and angiogenesis. But not much is known about the role of cMET in growth and progression of cancer stem cells (CSCs). Earlier studies have shown that Quinacrine (QC), a bioactive agent, has anti-CSCs activity. Here, the role of QC in deregulation of cMET-mediated metastasis and angiogenesis has been systematically evaluated in vitro in highly metastatic breast CSCs (mBCSCs), ex vivo in patient-derived breast cancer stem cells (PDBCSCs) and in vivo in xenograft mice model systems. Cell proliferation, migration, invasion and representative metastasis markers were upregulated in cMET-overexpressed cells and QC exposure inhibited these processes in both mBCSCs and PDBCSCs. Interestingly, metastasis was significantly inhibited by QC in cMET-overexpressed cells but comparatively lesser significant alteration of the process was noted in cMET-silenced cells. Increase in vascularization (in in ovo CAM assay), and cell-cell tube formation (in HUVECs), and enhanced MMP9 and MMP2 enzymatic activities (in gelatin zymography) were noted after cMET overexpression but these processes got reversed after cMET knockdown or QC treatment in cMET-overexpressed cells. QC inhibited angiogenesis significantly in cMET-overexpressed cells, but lesser significant change was observed in cMET-silenced cells. Reduction in tumor volume and decreased expression of metastatic and angiogenic markers were also noted in xenograft mice after QC treatment. Furthermore, QC inhibited cMET activity by dephosphorylation of its tyrosine residues (Y1234 and Y1356) and downregulation of its downstream cascade. Thus, QC inhibited the cMET-mediated metastasis and angiogenesis in in vitro, in ovo, in vivo and ex vivo model systems. Ligand (HGF) binding leads to receptor dimerization and phosphorylation of tyrosine kinase domain of cMET. This activates the cMET signaling cascade. The representative downstream metastasis and angiogenesis-related proteins get upregulated and induce the metastasis and angiogenesis process. But after the QC treatment, cMET get dephosphorylated and inactivated. As a result, the downstream signaling proteins of cMET along with the other representative metastatic and angiogenic factors get downregulated. These lead to inhibition of cMET-mediated metastasis and angiogenesis. (Created with BioRender.com).