Gastric Cancer Xenograft Model Research Articles

87P - Preclinical pharmacokinetic/pharmacodynamic (PK/PD) relationship of ABN401, a highly selective met inhibitor, in gastric and non-small cell lung cancer models

BackgroundABN401 is a highly selective best-in-class Met inhibitor that is targeting MET-driven cancers. Met which is also known as a hepatocyte growth factor (HGF) receptor is encoded by the MET gene. MET alterations, including amplification and mutation, and Met overexpression are well known for tumorigenic transformation, tumor growth, angiogenesis, invasion, and metastasis in several cancer types, including gastric and non-small-cell lung cancer (NSCLC). ABN401 shows significant MET signaling inhibition in in vitro and in vivo preclinical studies, especially for cell lines, xenograft, and PDx models which have high MET amplification and/or MET exon 14 deletion. MethodsIn this study, to confirm the pharmacokinetic and pharmocodynamic correlation of ABN401, gastric cancer and NSCLC xenograft models were used. SNU-5, a gastric cancer cell line and EBC-1, a NSCLC cell line both of which has high MET amplification, were used for the xenograft model and dosed at 10mg/kg and 30mg/kg of ABN401 by oral administration. Pharmacokinetic parameters were analyzed in both plasma and tumor tissue samples. Pharmacodynamic biomarkers including Met and phospho-Met (T1234/1235) and downstream signaling were analyzed by immunoblotting. In addition, an expression of Met and phospho-Met were analyzed by immunohistochemistry. ResultsThe PK results demonstrated that in both gastric and NSCLC xenograft models ABN401 drug was readily distributed to tumor tissues. According to both PD studies, ABN401 showed inhibitory effects of Met and downstream signaling in a time dependent manner for both cancer types. There was also correlated between the PK parameters in plasma and tumor samples and pharmacodynamics studies. ConclusionsThis preclinical PK/PD correlation study of ABN401 provides evidence for human dose predictions and dosing strategy for clinical studies. Legal entity responsible for the studyThe authors. FundingAbion Inc. DisclosureAll authors have declared no conflicts of interest.

Piperlongumine potentiates the antitumor efficacy of oxaliplatin through ROS induction in gastric cancer cells.

Oxaliplatin is one of the most commonly used chemotherapeutic agents in the treatment of various cancers, including gastric cancer. It has, however, a narrow therapeutic index due to its toxicity and the occurrence of drug resistance. Therefore, there is a pressing need to develop novel therapies to potentiate the efficacy and reduce the toxicity of oxaliplatin. Piperlongumine (PL), an alkaloid isolated from Piper longum L., has recently been identified as a potent agent against cancer cells in vitro and in vivo. In the present study, we investigated whether PL can potentiate the antitumor effect of oxaliplatin in gastric cancer cells. Cellular apoptosis and ROS levels were analyzed by flow cytometry. Thioredoxin reductase 1 (TrxR1) activity in gastric cancer cells or tumor tissues was determined using an endpoint insulin reduction assay. Western blotting was used to analyze the expression levels of the indicated proteins. Nude mice xenograft models were used to test the effects of PL and oxaliplatin combinations on gastric cancer cell growth in vivo. We found that PL significantly enhanced oxaliplatin-induced growth inhibition in both gastric and colon cancer cells. Moreover, we found that PL potentiated the antitumor effect of oxaliplatin by inhibiting TrxR1 activity. PL combined with oxaliplatin markedly suppressed the activity of TrxR1, resulting in the accumulation of ROS and, thereby, DNA damage induction and p38 and JNK signaling pathway activation. Pretreatment with antioxidant N-acetyl-L-cysteine (NAC) significantly abrogated the combined treatment-induced ROS generation, DNA damage and apoptosis. Importantly, we found that activation of the p38 and JNK signaling pathways prompted by PL and oxaliplatin was also reversed by NAC pretreatment. In vivo, we found that PL combined with oxaliplatin significantly suppressed tumor growth in a gastric cancer xenograft model, and effectively reduced the activity of TrxR1 in tumor tissues. Remarkably, we found that PL attenuated body weight loss evoked by oxaliplatin treatment. Our data support a synergistic effect of PL and oxaliplatin and suggest that application of its combination may be more effective for the treatment of gastric cancer than oxaliplatin alone.

Abstract 4817: Preclinical evaluation of a new, non-agonist ADC targeting MET-amplified tumors with a peptide-linked maytansinoid

Abstract With cancer among the leading causes of death worldwide, the search for better, personalized treatments is imperative. Novel techniques such as next generation sequencing have identified many assayable genetic biomarkers associated with cancer in patient samples. The tyrosine kinase receptor cMet is one such biomarker that is upregulated in various solid tumors and associated with poor prognosis, disease progression and metastasis. While most patients with elevated cMet show increased levels through protein upregulation, a small population harbors gene amplification. These patients face worse outcomes which could be improved with therapies specifically targeting MET-amplification. Antibody-drug conjugates (ADCs) are a modality designed to selectively deliver highly potent cytotoxic agents to tumors. cMet is an attractive target for ADCs which may address the unmet treatment need for patients with tumors harboring MET amplification. Since dimerization of cMet receptors by ligand HGF leads to agonistic proliferative events, a carefully selected antibody should be chosen to avoid triggering activation. As previously described, we identified and humanized an antibody with minimal agonism. Introducing an additional disulfide in the hinge region while maintaining the IgG1 isotype further reduced agonism as measured in vitro in both cell proliferation and phosphorylation signaling assays, while retaining high affinity to human and cynomolgus cMet, and acceptable expression and biophysical properties. To assess potential toxicity due to normal tissue expression, we measured binding of our antibody to normal hepatocytes from humans and cynos. Here we found very low expression and binding versus tumor cell lines. Next, we demonstrated that the cytotoxic activity of disulfide-cleavable maytansinoid ADCs prepared from the hinge-variant cMet antibody were equivalent to the parental form in in vivo models. In a MET-amplified xenograft model of gastric cancer, Hs746T, both parental and modified hucMet-sSPDB-DM4 ADCs demonstrated tumor eradication and comparable plasma clearance at 5 mg/kg. Similar results were found in the MET-amplified NSCLC model EBC-1 at 2.5 mg/kg. Conjugation to the newly-described dipeptide-linked maytansinoid DM21 further improved anti-tumor activity in both Hs746T and EBC-1 models, with a 2-fold decrease in minimally-efficacious dose. The activity of hucMet27Gv1.3Hinge-L-DM21 was durable, with a single dose yielding full regressions and tumor-free survivors in both models (EBC-1, 1.25 mg/kg dose, 6/6 TFS d49; Hs746T, 2.5 mg/kg dose, 8/8 TFS d55). Taken together, these data demonstrate compelling cMet-targeted activity of hucMet27Gv1.3Hinge-L-DM21 in MET-amplified models of NSCLC and gastric cancer with a wide margin of safety. These data merit further exploration of this ADC as a novel treatment option for patients with MET-amplified tumors. Citation Format: Katharine C. Lai, Min Li, Kathryn Selvitelli, Surina Sikka, Steven Boulé, L Cristina Gavrilescu, Stuart W. Hicks, Kerry Donahue. Preclinical evaluation of a new, non-agonist ADC targeting MET-amplified tumors with a peptide-linked maytansinoid [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4817.

Abstract 4815: Novel Globo H targeting antibody-drug conjugate with binding specificity and anti-tumor efficacy in multiple cancer types

Abstract Background: Globo H, a hexasaccharide, has been reported to be highly expressed in multiple cancers types, but not express or, if at all, express to a lesser extent in normal tissue. Therefore, Globo H may be a potential target for cancer immunotherapy. OBI-999 is an antibody-drug conjugate (ADC) which consists of a Globo H-specific monoclonal antibody OBI-888, conjugated with monomethyl auristatin E (MMAE), a synthetic antineoplastic agent. The present study investigates antigen specificity, drug internalization, anti-tumor efficacy, and pharmacokinetics profiles of OBI-999. Methods: Globo H expression was surveyed in various human cancer cell lines. The binding specificity and internalization of OBI-999 were determined by flow cytometry and confocal microscopy, respectively. In vivo anti-tumor efficacy was studied in conventional xenograft and patient-derived xenograft models. Pharmacokinetic parameters were evaluated in normal and tumor bearing xenograft mice. Results: We confirmed positive Globo H expression on the cell surface of multiple cancer cell lines ranging from breast, gastric, lung, to pancreatic cancer. From flow cytometry, OBI-999 showed binding selectivity to the aforementioned Globo H expressing cell lines. In contrast, OBI-999 did not bind to non-Globo H expressing cell lines. When bound to the antigen, OBI-999 was internalized and trafficked to endosome and lysosome within 2.5 to 5 hours, suggesting that the drug payload, MMAE, was cleaved in a lysosome dependent manner. OBI-999 showed significant tumor inhibition in breast, gastric, lung, and pancreatic cancer xenograft and PDX models in dose-dependent manner. At 1 mg/kg of OBI-999, tumor growth inhibition in breast, gastric, and lung cancer model were 77%, 89%, and 68% respectively. At 10 mg/kg of OBI-999, complete tumor growth inhibition in pancreatic cancer model was observed. In vitro serum stability studies revealed that OBI-999 has comparable stabilities to Adcetris® in mouse, rat, monkey, and human sera. Tissue distribution study revealed that OBI-999 is accumulated gradually at the tumor site while the level of OBI-999 showed a time dependent decrease in blood-rich organs. Accumulation of OBI-999 at the tumor site reached its maximum level at 168 hour post treatment. Level of MMAE in tumor mass was approximately 25 folds higher than that in other organs and 250 folds higher than that in serum, suggesting that OBI-999 targets and releases its payload at tumor region. Conclusion: The preclinical studies of OBI-999 demonstrated its targeting specificity and anti-tumor efficacy in multiple Globo H positive cancer models. OBI-999 also demonstrated a longer retention at tumor site. The preclinical results provided the fundamental basis for OBI-999’s clinical application as targeted cytotoxicity therapy for solid tumors. Citation Format: Ming-Chen Yang, Yu-Jung Chen, Chi-Sheng Shia, Hui-Wen Chang, Wan-Fen Li, Cheng-Der Tony Yu, I-Ju Chen. Novel Globo H targeting antibody-drug conjugate with binding specificity and anti-tumor efficacy in multiple cancer types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4815.

Ursolic Acid Inhibits Epithelial-Mesenchymal Transition through the Axl/NF-κB Pathway in Gastric Cancer Cells.

Background Ursolic acid (UA) is an antitumor component derived from Chinese herbal medicine; this study is to observe the effects of UA on epithelial-mesenchymal transition (EMT) in gastric cancer. Methods (1) In vitro experiments: 25μmol/L and 50μmol/L UA were applied to BGC-823, AGS, MGC-803, and HGC-27 cells; MTT staining, Transwell assay, and flow cytometry were used to assess cell proliferation, cell migration, and apoptosis, respectively. Western blot was performed to detect the expressions of N-Cadherin, Vimentin, Snail, Twist, Axl, p-Axl, IKK, p-IKK, NF-κB, and p-NF-κB. (2) In vivo experiments: Ten BALB/c-nu mice were used to establish gastric cancer xenograft model. Five were orally given UA for 4 weeks and five were given normal saline. Expressions of N-Cadherin and Snail were examined by immunohistochemical assay; expressions of N-Cadherin, Snail, Twist, Axl, p-Axl, IKK, and p-IKK were detected by Western blot. Results (1) UA inhibited cell proliferation in BGC-823 and HGC-27 cells in dose-dependent manners. (2) UA inhibited cell migration in BGC-823, AGS, and MGC-803 cells while inducing apoptosis in BGC-823 cells. (3) UA significantly decreased the expressions of N-Cadherin, Vimentin, Snail, Twist p-Axl, p-IKKα/β, and p-NF-κB in BGC-823 and MGC-803 cells. (4) UA distinctly decreased the expressions of N-Cadherin, Snail, p-Axl, and p-IKKα/β in gastric cancer xenograft model rats. Conclusion UA can effectively inhibit the proliferation and migration and induce apoptosis of gastric cancer cells. The antitumor effect of UA is conducted by EMT inhibition, which may be associated with the regulation of Axl/NF-κB signaling pathway.

Cancer extracellular vesicles contribute to stromal heterogeneity by inducing chemokines in cancer-associated fibroblasts

Cancer-associated fibroblasts (CAFs), one of the major components of a tumour microenvironment, comprise heterogeneous populations involved in tumour progression. However, it remains obscure how CAF heterogeneity is governed by cancer cells. Here, we show that cancer extracellular vesicles (EVs) induce a series of chemokines in activated fibroblasts and contribute to the formation of the heterogeneity. In a xenograft model of diffuse-type gastric cancer, we showed two distinct fibroblast subpopulations with alpha-smooth muscle actin (α-SMA) expression or chemokine expression. MicroRNAs (miRNAs) profiling of the EVs and the transfection experiment suggested that several miRNAs played a role in the induction of chemokines such as CXCL1 and CXCL8 in fibroblasts, but not for the myofibroblastic differentiation. Clinically, aberrant activation of CXCL1 and CXCL8 in CAFs correlated with poorer survival in gastric cancer patients. Thus, this link between chemokine expression in CAFs and tumour progression may provide novel targets for anticancer therapy.

Curcuminoid WZ35 synergize with cisplatin by inducing ROS production and inhibiting TrxR1 activity in gastric cancer cells

BackgroundCisplatin is one of the most widely used chemotherapeutic agents, but its efficacy is limited by its side effects. Hence, it is of great significance to develop novel agents to synergize with cisplatin and decrease side effects. In our previous study, we demonstrated that WZ35, a novel curcumin analogue, exhibited potent anti-cancer effects in vitro and in vivo. Here, we investigated whether WZ35 synergize to potentiate cisplatin activity in gastric cancer cells.MethodsCell apoptosis and cellular ROS levels were analyzed by flow cytometry. TrxR1 activity in gastric cells or tumor tissues was determined by the endpoint insulin reduction assay. Western blot was used to analyze the levels of indicated molecules. Nude mice xenograft model was used to test the effects of WZ35 and cisplatin combination on gastric cancer cell growth in vivo.ResultsWe found that WZ35 significantly enhanced cisplatin-induced cell growth inhibition and apoptosis in gastric cancer cells. Further mechanism study showed that WZ35 synergized the anti-tumor effects of cisplatin by inhibiting TrxR1 activity. By inhibiting TrxR1 activity, WZ35 combined with cisplatin markedly induced the production of ROS, activated p38 and JNK signaling pathways, and eventually induced apoptosis of gastric cancer cells. In vivo, WZ35 combined with cisplatin significantly suppressed tumor growth in a gastric cancer xenograft model, and effectively reduced the activity of TrxR1 in tumor tissues. Remarkably, WZ35 attenuated the body weight loss evoked by cisplatin treatment.ConclusionThis study elucidated the underlying mechanisms of synergistic effect of WZ35 and cisplatin, and suggest that such a combinational treatment might potentially become a more effective regimen in gastric cancer therapy.

A novel ent-kaurane diterpenoid analog, DN3, selectively kills human gastric cancer cells via acting directly on mitochondria

Targeting mitochondria using proper pharmacological agents is considered an attractive strategy for cancer control and management. Herein, we report a newly synthetic triazole analog of Jaridonin, DN3, which exhibits more potent antitumor activity via acting directly on mitochondria. DN3 potently reduced viabilities of gastric cancer cell lines HGC-27 and MGC-803 through inducing apoptosis and cell cycle arrest. But, normal human gastric epithelial cell line GES-1 is more resistant to the growth inhibition by DN3 compared with gastric cancer cells. DN3 induced mitochondrial membrane potential (MMP) decrease and cytochrome c release in intact gastric cancer cell lines. Meanwhile, the DN3 treatment also caused the release of cytochrome c from mitochondria isolated from cancer cell lines in a mitochondrial permeability transition pore complex (PTPC) mediated manner, but not from mitochondria isolated from normal gastric epithelial cell. The induction of mitochondrial PTPC proteins voltage-dependent anion channel (VDAC) and cyclophilin D (CypD) were also observed in DN3-treated cells. More interestingly, DN3 mediated MMP decrease, release of cytochrome c, the expression of VDAC and CypD and apoptosis were blocked by the pretreatment of VDAC1 inhibitor (4, 4′-diisothiocyanatostilbene-2,2′-disulfonic acid, DIDS) and CypD inhibitor (cyclosporine A, CsA). In a mouse xenograft model of human gastric cancer, the treatment of 5 mg/kg DN3 led to significant tumor regression without affecting body weight. In conclusion, our findings indicate that DN3 is a potential agent for the treatment of gastric cancer through acting directly on mitochondria, and would be useful for us to design more and better anti-cancer compounds.

LPS-induced CXCR7 expression promotes gastric Cancer proliferation and migration via the TLR4/MD-2 pathway

BackgroundLipopolysaccharide (LPS) from Helicobacter pylori (HP) plays an important role in gastric cancer occurrence and development. Toll-like receptor 4 (TLR4) and myeloid differential protein-2 (MD-2) are also reported to be involved in gastric cancer cell proliferation and invasion. CXC chemokine receptor 7 (CXCR7), a second receptor for CXCL12, has been detected in multiple types of tumor tissues. Nevertheless, the biological function and regulation of CXCR7 and its relationship with TLR4 and MD-2 in gastric cancer are not completely understood and therefore warrant further study.MethodsCXCR7 expression was examined in 150 gastric cancer tissues using immunohistochemistry (IHC). RT-PCR and western blotting were used to detect CXCR7 expression in several gastric cancer cell lines (SGC7901, AGS, MGC-803, MKN-45 and BGC823). shRNAs were designed using a pGPU6/GFP/Neo vector. A CCK-8 assay was used to assess cell proliferation, and transwell assays were performed to assess cell migration. In addition, a gastric cancer xenograft model was generated.ResultsThe LPS-TLR4-MD-2 pathway elevates CXCR7 expression in SGC7901 cells, and TLR4/MD-2-mediated increases in CXCR7 levels modulate the proliferation and migration of tumor cells. Knockdown of TLR4 and MD-2 demonstrated that both are essential for LPS-induced CXCR7 expression, which in turn is responsible for LPS-induced SGC7901 cell proliferation and migration. Moreover, higher TLR4, MD-2 and CXCR7 expression was detected in gastric cancer tissues than in paracancerous normal control tissues. The expression levels of TLR4, MD-2 and CXCR7 were closely related to gastric cancer TNM stage and lymph node metastasis. In an animal model, significant differences in CXCR7 expression in tumor masses were observed between the control group and experimental group.ConclusionsThe results of this study indicate that CXCR7 plays an important role in gastric cancer progression via inflammatory mechanisms, suggesting that CXCR7 could provide a basis for the development and clinical application of a targeted drug for gastric cancer.

GLI1 overexpression promotes gastric cancer cell proliferation and migration and induces drug resistance by combining with the AKT-mTOR pathway

Hedgehog (HH) pathway significantly affected the pathogenesis of Gastric cancer (GC), but the multiple uncanonical HH pathways that are mediated by Zinc Finger protein GLI1 (GLI1) are still unclear. In the present work, we evaluated GLI1 and p-AKT expression in GC using immunohistochemistry (IHC) analysis. GLI1 and AKT specific shRNA was transfected into GC cell lines to investigate the cross-regulation between HH pathway and AKT-mTOR pathway. The effect of GLI1 and p-AKT on proliferation, migration, and drug resistance were examined. Moreover, a mouse xenograft model of GC was established to verify the role of GLI1 and p-AKT in promoting drug sensitivity in vivo. Our results suggested the clinicopathological factors and prognosis by the differential expression of GLI1 and p-AKT in GC patients. GLI1 was activated by the AKT-mTOR pathway. Co-expression of GLI1 and p-AKT was associated with cell viability, migration, and drug resistance and indicated a poor prognosis in GC patients. Agents targeted against both GLI1 and p-AKT may reverse drug-resistance and achieve better inhibition than agents targeted against a single molecule. There was a significant correlation between the high expression of GLI1 and p-AKT in GC. Additionally, our study confirmed the activity of the AKT-mTOR-GLI1 axis, which provided a new viable field for GC treatment.

Novel ginsenoside-based multifunctional liposomal delivery system for combination therapy of gastric cancer.

The clinical treatment of gastric cancer (GC) is hampered by the development of anticancer drug resistance and the unfavorable pharmacokinetics, off-target toxicity, and inadequate intratumoral accumulation of the current chemotherapy treatments. Ginsenosides combined with paclitaxel (PTX) have been shown to exert synergistic inhibition of human GC cell proliferation. In the present study, we developed a novel multifunctional liposome system, in which ginsenosides functioned as the chemotherapy adjuvant and membrane stabilizer. These had long blood circulation times and active targeting abilities, thus creating multifunctionality of the liposomes and facilitating drug administration to the GC cells.Methods: Three ginsenosides with different structures were used to formulate the unique nanocarrier, which was prepared using the thin-film hydration method. The stability of the ginsenoside liposomes was determined by particle size analysis using dynamic light scattering. The long circulation time of ginsenoside liposomes was compared with that of conventional liposome and polyethylene glycosylated liposomes in vivo. The active targeting effect of ginsenoside liposomes was examined with a GC xenograft model using an in vivo imaging system. To examine the antitumor activity of ginsenoside liposomes against GC, MTT, cell cycle, and apoptosis assays were performed on BGC-823 cells in vitro and PTX-loaded ginsenoside liposomes were prepared to evaluate the therapeutic efficacy on GC in vivo.Results: The ginsenosides stabilized the liposomes in a manner similar to cholesterol. We confirmed the successful delivery of the bioactive combination drugs and internalization into GC cells via analysis of the glucose-related transporter recognition and longer blood circulation time. PTX was encapsulated in different liposomal formulations for use as a combination therapy, in which ginsenosides were found to exert their inherent anticancer activity, as well as act synergistically with PTX. The combination therapy using these targeted liposomes significantly suppressed GC tumor growth and outperformed most reported PTX formulations, including Lipusu® and Abraxane®.Conclusion: We established novel ginsenoside-based liposomes as a tumor-targeting therapy, in which ginsenoside functioned not only as a chemotherapy adjuvant, but also as a functional membrane material. Ginsenoside-based liposomes offer a novel platform for anticancer drug delivery and may lead to a new era of nanocarrier treatments for cancer.

Targeting HER2-positive gastric cancer with a novel 18F-labeled ZHER2:342 probe.

To realize the diagnosis of HER2-positive gastric cancer via PET imaging, herein, a new kind of 18F-labeled HER2 affibody probe was created; the bifunctional maleimide derivative 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA-MAL) was first coupled to a polypeptide, and the resulting compound was subsequently labeled with the 18FAl complex. The binding characteristics of the probe were assessed using both in vitro studies and in vivo microPET imaging and biodistribution experiments. Immunohistochemical staining was performed to confirm the expression level of HER2 in the studied cell lines and tumors. The probe was successfully produced with the radiochemical purity of more than 95%. The NCI N87 cell-associated radioactivity was 19.31 ± 1.01% AD, and it decreased to 0.83 ± 0.04% AD per 106 cells after blocking HER2 as early as 15 minutes post-incubation (p < 0.05). A competition binding assay between radiolabeled and non-radioactive affibody molecules with NCI N87 indicated that the IC50 was 8.10 nM. The microPET imaging and biodistribution of human gastric cancer xenografts demonstrated that the probe could specifically accumulate in tumors at early time points. Protein detection confirmed a strong HER2 expression in NCIN87 and a weak HER2 expression in SGC7901. In conclusion, 18FAl-NOTA-MAL-Cys-GGGRDN(M0)-ZHER2:342 was successfully prepared via a one-step method. The favorable preclinical data showed specific and effective tumor targeting capacity of the proposed probe; this revealed that the probe proposed herein might have potential application in gastric cancer imaging.

Silencing of &lt;i&gt;circRACGAP1&lt;/i&gt; Sensitizes Gastric Cancer Cells to Apatinib via Modulating Autophagy by Targeting &lt;i&gt;miR-3657&lt;/i&gt; and &lt;i&gt;ATG7&lt;/i&gt;

Background: The positive results of the apatinib phase III trial have cast new light on treatment for patients with advanced gastric cancer (GC). However, in terms of safety, apatinib toxicities may lead to a dose modification or treatment interruption. Therefore, properly intervene is urgently needed to reduce toxicities and help patients benefit from apatinib treatment. Methods: The in vitro and in vivo assays were conducted to investigate the mechanisms of apatinib in GC. Autophagy functional assays were performed. MicroRNA sequencing and circular RNA sequencing of the GC tumor xenografts from the control and apatinib groups were performed to further study the mechanism. Results: In this study, we found that apatinib inhibited the growth of GC cells and xenograft tumors. Apatinib promoted autophagy activation via upregulation of ATG7 expression, and autophagy inhibition enhanced apatinib-induced apoptosis. With microRNA and circular RNA sequencing analyses of GC xenograft models, we demonstrated that circRACGAP1 functioned as an endogenous sponge for miR-3657 to inhibit its activity and further upregulate ATG7 expression. Silencing of circRACGAP1 inhibited apatinib-induced autophagy, which was rescued by miR-3657. Moreover, knockdown of circRACGAP1 sensitized GC cells to apatinib via autophagy inhibition in vitro and in vivo. Conclusions: These findings provided the first evidence that the circRACGAP1-miR-3657-ATG7 axis mediates a novel regulatory pathway critical for the regulation of autophagy and apatinib sensitivity in GC cells and xenografts. Thus, specific blockage of circRACGAP1 may be a potential therapeutic strategy to reduce the toxicities of apatinib and enhance its therapeutic effect in human GC. Funding Statement: This study was supported by grants from the National Natural Science Foundation of China (No. 81672896 and No. 81520108027), the National Key Research and Development Program: the key technology of palliative care and nursing for cancer patients (ZDZX2017ZL-01), the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) (JX10231802), and Jiangsu Provincial Key Research and Development Special Fund (BE2015666). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: All experiments were carried out according to the National Institutes of Health Guidelines for the Care and Use of Laboratory Animals (NIH Publication No. 80-23) revised in 1996. The animal studies were reviewed and approved by the Ethics Committee for Animal Studies at Nanjing Medical University.

A novel tetravalent bispecific antibody targeting programmed death 1 and tyrosine-protein kinase Met for treatment of gastric cancer.

Background Redirecting T cells to tumor cells using bispecific antibodies (BsAbs) is emerging as a potent cancer therapy. The main concept of this strategy is to cross-link tumor cells and T cells by simultaneously binding to cell surface tumor-associated antigen (TAA) and the CD3ƹ chain. However, immune checkpoint programmed cell death ligand-1 (PD-L1) on tumor cells or other myeloid cells upreglulated remarkablely after the treatment of CD3-binding BsAbs, leads to the generation of suppressed microenvironment for immune evasion and tumor progression. Although this resistance could be partially reversed by anti-PD-L1 treatment, targeting two pathways through one antibody-based molecule may provide a strategic advantage over the combination of BsAbs and immune checkpoint inhibitors. Methods We developed two novel BsAbs PD-1/c-Met DVD-Ig and IgG-scFv both targeting PD-1 to restore the immune effector function of T cells and engaging them to tumor cells via binding to cellular-mesenchymal to epithelial transition factor (c-Met). Binding activities, T cell activation and proliferation were analyzed by flow cytometry. Cell Cytotoxicity and cytokine release were measured using LDH release assay and ELISA, respectively. Anti-tumor response in vivo was evaluated by generate xenograft models in NOD-SCID mice. Results These bispecific antibodies exhibited effective antitumor activity against high- and low- c-Met-expressing gastric cancer cell lines in vitro and mediated strong tumor growth inhibition in human gastric cancer xenograft models. Conclusion The engagement of the PD-1/PD-L1 blockade to c-Met-overexpressing cancer cells is a promising strategy for the treatment of gastric cancer and potentially other malignancies.

Perilaldehyde activates AMP-activated protein kinase to suppress the growth of gastric cancer via induction of autophagy.

Perillaldehyde (PAH), one of the major oil components in Perilla frutescens, is very critical to health maintenance, for a wide range of human chronic diseases, including cancers. AMP-activated protein kinase (AMPK) has been implicated in the activation of autophagy in distinct tissues. This study was designed to explore whether PAH prevents gastric cancer growth and to investigate the molecular mechanism. In cultured mouse gastric cancer cell line MFCs and human gastric cancer cell lines GC9811-P, PAH activated AMPK by increasing the Thr172 phosphorylation and activity in a time-/concentration-dependent manner. Furthermore, incubation of MFCs with PAH also increased autophagy as determined by monodansylcadaverine (MDC) staining, which was reversed by AMPK inhibitor compound C. PAH further decreased MFCs cell survival, which was abolished by compound C or autophagy inhibitor 3-Methyladenine (3-MA). In vivo studies indicated that 4-week administration of PAH (100 mg/kg/day) suppressed the growth of gastric cancer and increased the levels of autophagy-related proteins, including beclin-1, LC3-II, cathepsin, caspase-3, p53, and cathepsin in tumors isolated from the xenograft model of gastric cancer in mice. Moreover, these anticancer effects produced by PAH were abolished by coadministration of compound C or 3-MA in vivo. PAH increases AMPK phosphorylation and activity to induce gastric cancer cell autophagy to inhibit the growth of gastric cancer. In perspective, therapy of PAH should be applied to treat patients with gastric cancer.

Noninvasive assessment of characteristics of novel anti-HER2 antibodies by molecular imaging in a human gastric cancer xenograft-bearing mouse model

Human epidermal growth factor receptor 2 (HER2) overexpression occurs in various types of cancers. Regarding the anti-HER2 targeted therapies showed superior treatment outcomes in several (pre)clinical studies, we used multimodality image to rapidly select novel HER2-targeting antibodies for further therapeutics development. The four anti-HER2 antibodies (H32 IgG, 75 IgG, 61 IgG, and trastuzumab) labeled with either In-111 or a DyLight680 fluorescent dye were applied to perform cellular uptake, endocytosis, optical/microSPECT/CT imaging and biodistribution studies. In vitro and in vivo relative effectiveness of these antibodies were also compared in an N87 gastric cancer xenograft model. The internalized radioactivity of [111In]61 IgG in N87 cells increased from 33% at 12 hr to 56% at 48 hr after incubation, while the majority of other antibodies stayed on the cell membranes. Among these antibodies, 61 IgG showed the highest accumulation in tumors with the tumor-to-muscle ratio (T/M) of 131 ± 61.4 and 19.13 ± 3.42 conducted by IVIS and microSPECT/CT, respectively. We demonstrated that multimodality imaging is a reliable approach for selecting potential antibodies and found that 61 IgG manifested significant tumor accumulation with elevated internalization rate thus could be a suitable candidate for further development of new HER2-targeted therapies.

Anti-tumor efficacy of Selinexor (KPT-330) in gastric cancer is dependent on nuclear accumulation of p53 tumor suppressor

Exportin-1 (XPO1) controls the nucleo-cytoplasmic trafficking of several key growth regulatory and tumor suppressor proteins. Nuclear export blockade through XPO1 inhibition is a target for therapeutic inhibition in many cancers. Studies have suggested XPO1 upregulation as an indicator of poor prognosis in gastric cancer. In the current study, we investigated the anti-tumor efficacy of selective inhibitors of nuclear export (SINE) compounds KPT-185, KTP-276 and clinical stage selinexor (KPT-330) in gastric cancer. XPO1 was found to be overexpressed in gastric cancer as compared to adjacent normal tissues and was correlated with poor survival outcomes. Among the 3 SINE compounds, in vitro targeting of XPO1 with selinexor resulted in greatest potency with significant anti-proliferative effects at nano molar concentrations. XPO1 inhibition by selinexor resulted in nuclear accumulation of p53, causing cell cycle arrest and apoptosis. Also, inhibition of XPO1 lead to the cytoplasmic retention of p21 and suppression of survivin. Orally administered selienxor caused significant inhibition of tumor growth in xenograft models of gastric cancer. Furthermore, combination of selinexor with irinotecan exhibited greater anti-tumor effect compared to individual treatment. Taken together, our study underscores the therapeutic utility of XPO1 targeting in gastric cancer and suggests the potential benefits of XPO1 inhibition in-combination with chemotherapy.

Abstract 5788: Preclinical evaluation of HZB0071, a small molecule inhibitor of AKT

Abstract Objective: AKT is a component of the PI3K/AKT/mTOR (PAM) pathway, which plays an important part in cell proliferation, growth and survival, activated in many cancers and has been validated as a therapeutic target in the clinic. Inhibition of AKT activity can block the PAM pathway and proliferation of various types of tumor cells with loss of tumor suppressor PTEN, mutational activation of p110a catalytic subunit of PI3K and amplification of the gene encoding either AKT or PI3K. The purpose of this study is to investigate the in vitro and in vivo antitumor activity of HZB0071, a small molecule AKT kinase inhibitor, in preclinical models of solid cancer with AKT overexpression. Method: Kinase inhibiting activity of HZB0071 was determined with AKT1, 2, 3 kinase assays. Cellular anti-proliferative activity was evaluated with AKT overexpressed LNcap cell line and DU145 cell line without AKT overexpression. The antitumor activity of HZB0071 was evaluate in vivo and the synergistic effect combined with Paclitaxel in AKT highly expressed patient-derived mouse xenograft (PDX) models of Gastric Cancer ST-02-0013 and cell-derived mouse xenograft (CDX) models of Breast Cancer BT474. Result: HZB0071 displayed potent kinase inhibiting activity for AKT1, 2, 3 with IC50 1.3±0.41 nM, 50.3±13.4 nM and 90.4±5.84 nM, respectively. HZB0071 inhibited cell proliferation in AKT overexpressed LNcap cells with IC50 67±7 nM. In contrast, HZB0071 showed much weaker anti-proliferative activity in DU145 cells with IC50 &amp;gt;10,000 nM. HZB0071 showed antitumor efficacy in AKT highly expressed gastric cancer PDX model ST-02-0013 (TGI = 62% @30 mpk, QD as single agent; TGI = 61% @15 mpk + Paclitaxel @10 mpk, QD, in combination with Paclitaxel), as well as in the breast cancer BT474 CDX model (TGI = 88% @30 mpk + Paclitaxel @15 mpk, QD). Conclusion: We have identified a novel potent AKT inhibitor HZB0071. Preclinical studies shows antitumor efficacy of HZB0071 in AKT overexpressed solid cancer models. HZB0071 represents a promising clinical candidate for treating solid cancers with high AKT expression. Citation Format: Gang Li, Lihong Hu, Weifeng Mao, Dongfang Li, Charles Z. Ding, Shuhui Chen. Preclinical evaluation of HZB0071, a small molecule inhibitor of AKT [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5788.

PO-071 Silencing of circRNA004582 sensitises gastric cancer cells to APATINIB via modulating autophagy by targeting miR-3657 and ATG7

IntroductionGastric cancer (GC) is the fourth most common cancer and the third-leading cause of cancer-related deaths worldwide. Despite certain advances in chemotherapy regimens and targeted therapies, the 5 year survival of patients with advanced GC is disappointing. The positive results of the apatinib phase III trial have cast new light on treatment for patients with advanced gastric cancer (GC) refractory to two or more lines of prior systemic chemotherapies. However, a dose reduction or treatment interruption is required to prevent apatinib toxicity such as hand-foot skin reaction (HFSR), proteinuria, and hypertension. In addition, suitable biomarkers are not accessible for identifying the patients who are most likely to benefit from apatinib. Therefore, predictive biomarkers are urgently needed to reduce toxicity and identify patients that will benefit from apatinib treatment.Material and methodsClonogenic assay, cytotoxicity assay, apoptosis assay, qRT-PCR, western blot were conducted in GC cells to evaluate the effectiveness of apatinib in vitro. Confocal microscopy assay was peformed to examine apatinib-induced autophagic flux in GC cells. Transmission electron microscopy assay was conducted to show the formation of autophagic vesicles. Xenograft models in mice were conducted and six tumour tissues were sent for miRNA-seq and circRNA-seq. Sanger sequencing was applied to determine the full length of the amplification products.Results and discussionsIn this study, we found that apatinib inhibited the growth of GC cells and xenograft tumours. Apatinib promoted autophagy activation via upregulation of ATG7 expression, and autophagy inhibition enhanced apatinib-induced apoptosis. With miRNA-seq and circRNA-seq analyses of GC xenograft models, we demonstrated that circRNA004582 functioned as an endogenous sponge for miR-3657 to inhibit its activity and further upregulate ATG7 expression. Silencing of circRNA004582 inhibited apatinib-induced autophagy, which was rescued by miR-3657. Moreover, knockdown of circRNA004582 promoted apatinib-induced apoptosis in GC cells. These findings provided the first evidence that the circRNA004582-miR-3657-ATG7 axis mediates a regulatory pathway critical for the regulation of autophagy and apatinib sensitivity in GC cells and xenografts.ConclusionIn conclusion, specific blockage of circRNA004582 may be a potential therapeutic target for autophagy inhibition in the context of apatinib treatment in human GC. Prospective clinical studies are warranted to examine these biomarkers.

PO-074 Metformin-induced apoptosis facilitates degradation of the C-FLIPL protein through a caspase-dependent pathway in human renal cell carcinoma A498 cells

IntroductionGastric cancer (GC) is the fourth most common cancer and the third-leading cause of cancer-related deaths worldwide. Despite certain advances in chemotherapy regimens and targeted therapies, the 5 year survival of patients with advanced GC is disappointing. The positive results of the apatinib phase III trial have cast new light on treatment for patients with advanced gastric cancer (GC) refractory to two or more lines of prior systemic chemotherapies. However, a dose reduction or treatment interruption is required to prevent apatinib toxicity such as hand-foot skin reaction (HFSR), proteinuria, and hypertension. In addition, suitable biomarkers are not accessible for identifying the patients who are most likely to benefit from apatinib. Therefore, predictive biomarkers are urgently needed to reduce toxicity and identify patients that will benefit from apatinib treatment.Material and methodsClonogenic assay, cytotoxicity assay, apoptosis assay, qRT-PCR, western blot were conducted in GC cells to evaluate the effectiveness of apatinib in vitro. Confocal microscopy assay was peformed to examine apatinib-induced autophagic flux in GC cells. Transmission electron microscopy assay was conducted to show the formation of autophagic vesicles. Xenograft models in mice were conducted and six tumour tissues were sent for miRNA-seq and circRNA-seq. Sanger sequencing was applied to determine the full length of the amplification products.Results and discussionsIn this study, we found that apatinib inhibited the growth of GC cells and xenograft tumours. Apatinib promoted autophagy activation via upregulation of ATG7 expression, and autophagy inhibition enhanced apatinib-induced apoptosis. With miRNA-seq and circRNA-seq analyses of GC xenograft models, we demonstrated that circRNA004582 functioned as an endogenous sponge for miR-3657 to inhibit its activity and further upregulate ATG7 expression. Silencing of circRNA004582 inhibited apatinib-induced autophagy, which was rescued by miR-3657. Moreover, knockdown of circRNA004582 promoted apatinib-induced apoptosis in GC cells. These findings provided the first evidence that the circRNA004582-miR-3657-ATG7 axis mediates a regulatory pathway critical for the regulation of autophagy and apatinib sensitivity in GC cells and xenografts.ConclusionIn conclusion, specific blockage of circRNA004582 may be a potential therapeutic target for autophagy inhibition in the context of apatinib treatment in human GC. Prospective clinical studies are warranted to examine these biomarkers.