Ju-Hee Bang

Soluble programmed death-ligand 1 (sPDL1) and neutrophil-to-lymphocyte ratio (NLR) predicts survival in advanced biliary tract cancer patients treated with palliative chemotherapy.

Programmed death-ligand 1 (PD-L1) expression in tumor tissue is under investigation as a candidate biomarker in immuno-oncology dug development. The soluble form of PD-L1 (sPDL1) is suggested to have immunosuppressive activity. In this study, we measured the serum level of sPDL1 and evaluated its prognostic implication in biliary tract cancer (BTC). Blood was collected from 158 advanced BTC patients (68 intrahepatic cholangiocarcinoma, 56 gallbladder cancer, 22 extrahepatic cholangiocarcinoma and 12 ampulla of vater cancer) before initiation of palliative chemotherapy. Serum sPDL1 was measured using an enzyme-linked immunosorbent assay. Clinical data included neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic immune-inflammation index (SII, neutrophil × platelet/lymphocyte). The patients were assigned to two cohorts (training and validation cohort) using a simple random sampling method to validate the cut-off value of each marker. Validation was performed using a twofold cross-validation method. Overall survival (OS) of all patients was 9.07 months (95% CI: 8.20-11.33). Median sPDL1 was 1.20 ng/mL (range 0.03-7.28, mean 1.50, SD 1.22). Median NLR, PLR and SII were 2.60, 142.85 and 584.93, respectively. Patients with high sPDL1 (≥0.94 ng/mL) showed worse OS than patients with low sPDL1 (7.93 vs. 14.10 months, HR 1.891 (1.35-2.65), p<0.001). In multivariate analysis, high sPDL1 and NLR were independent poor prognostic factors. In conclusion, serum sPDL1 can be measured and has significant role on the prognosis of advanced BTC patients treated with palliative chemotherapy.

Resistance Mechanism against Trastuzumab in HER2-Positive Cancer Cells and Its Negation by Src Inhibition

Trastuzumab in combination with chemotherapy is the standard of care for patients with human epidermal growth factor receptor 2 (HER2)-positive breast and gastric cancers. Several resistance mechanisms against anti-HER2 therapy have been proposed. Src activation has been suggested to be responsible for the resistance of HER2-positive breast cancer. In our study, we generated four trastuzumab-resistant (HR) cancer cell lines from HER2-amplified gastric and biliary tract cancer cell lines (SNU-216, NCI-N87, SNU-2670, and SNU-2773). Elevated Src phosphorylation was detected in SNU2670HR and NCI-N87HR cell lines, but not in SNU216HR or SNU2773HR cell lines. In SNU216HR and SNU2773HR cell lines, phospho-FAK (focal adhesion kinase) was elevated. Bosutinib as a Src inhibitor suppressed growth, cell-cycle progression, and migration in both parental and HR cell lines. Specifically, Src interacted with FAK to affect downstream molecules such as AKT, ERK, and STAT3. Bosutinib showed more potent antitumor effects in Src-activated HR cell lines than parental cell lines. Taken together, this study suggests that Src inhibition may be an effective measure to overcome trastuzumab resistance in HER2-positive cancer. Mol Cancer Ther; 16(6); 1145–54. ©2017 AACR.

Therapeutic implication of HER2 in advanced biliary tract cancer

Currently, there is no validated therapeutic target for biliary tract cancer (BTC). This study aimed to investigate the pre-clinical and clinical implication of HER2 as a therapeutic target in BTC. We established two novel HER2-amplified BTC cell lines, SNU-2670 and SNU-2773, from gallbladder cancer patients. SNU-2670 and SNU-2773 cells were sensitive to trastuzumab, dacomitinib, and afatinib compared with nine HER2-negative BTC cell lines. Dacomitinib and afatinib led to G1 cell cycle arrest in SNU-2773 cells and apoptosis in SNU-2670 cells. Furthermore, dacomitinib, afatinib, and trastuzumab showed synergistic cytotoxicity when combined with some cytotoxic drugs including gemcitabine, cisplatin, paclitaxel, and 5-fluorouracil. In a SNU-2670 mouse xenograft model, trastuzumab demonstrated a good anti-tumor effect as a monotherapy and in combination with gemcitabine increasing apoptosis. In our clinical data, 13.0% of patients with advanced BTC were defined as HER2-positive. Of these, three patients completed HER2-targeted chemotherapy. Two of them demonstrated a partial response, and the other one showed stable disease for 18 weeks. In summary, these pre-clinical and clinical data suggest that HER2 could be a therapeutic target, and that a HER2-targeting strategy should be developed further in patients with HER2-positive advanced BTC.

Anti-tumor effects of NVP-BKM120 alone or in combination with MEK162 in biliary tract cancer.

There are currently no clinically validated therapeutic targets for biliary tract cancer (BTC). Despite promising results in other cancers, compounds targeting the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, alone or in combination with Ras/Raf/MEK pathway inhibitors, have not been evaluated in BTC. Here, we examined the effects of a pan-PI3K inhibitor (BKM120) with or without a MEK inhibitor (MEK162), on eight human BTC cell lines carrying mutations in K-Ras and/or the PI3K catalytic subunit, PI3KCA. BKM120 inhibited the colony-forming ability and migration of BTC cells carrying wild-type (WT) PI3KCA and either mutant (MT) or WT K-Ras, but not of cells carrying mutations in both genes. In K-Ras-WT cells, BKM120 decreased the phosphorylation of Akt, its downstream effector kinase p70S6K, and the translational repressor 4E-BP1. Interestingly, BKM120 did not induce cell cycle arrest or suppress PI3K signaling via restoration of p-4E-BP1 in cells with PIK3CA and K-Ras double mutations. Notably, the resistance of dual K-Ras/PI3KCA-mutant cells to BKM120 was overcome by treatment with a combination of BKM120 and MEK162. Our findings thus support the clinical development of BKM120 monotherapy or BKM120/MEK162 combination therapy for the treatment of BTC.

Src as a Therapeutic Target in Biliary Tract Cancer

Src, a nonreceptor tyrosine kinase, is involved in a number of cancer-related signaling pathways and aberrantly activated in biliary tract cancer (BTC). This study aimed to elucidate the potential role of Src as a therapeutic target in BTC. We tested bosutinib, an orally active c-Src/Abl kinase inhibitor, alone or in combination with cytotoxic agents using 9 human BTC cell lines: SNU-245, SNU-308, SNU-478, SNU-869, SNU-1079, SNU-1196, HuCCT1, TFK-1, and EGI-1. Of these, SNU-308 and SNU-478 were relatively sensitive to bosutinib. Bosutinib abrogated phosphorylation of Src and its downstream molecules, and significantly increased G1 cell-cycle arrest and apoptosis. Bosutinib significantly inhibited cell migration and invasion and decreased epithelial–mesenchymal transition markers. Bosutinib combined with gemcitabine or cisplatin showed synergistic antiproliferative and antimigratory effects. In addition, this combination further inhibited phosphorylation of Src and its downstream molecules and decreased epithelial–mesenchymal transition marker expression compared with bosutinib alone. We established a SNU-478 xenograft model for in vivo experiments, because SNU-478 was more tumorigenic than SNU-308. Bosutinib combined with gemcitabine or cisplatin showed significantly more potent antitumor effects than bosutinib alone. Bosutinib combined with gemcitabine further decreased Ki-67 expression and Src phosphorylation, and further increased TUNEL expression. Our data suggest that Src might be a potential therapeutic target in BTC. Bosutinib demonstrated promising antitumor activity alone or in combination with gemcitabine or cisplatin in BTC cells, which supports further clinical development in patients with advanced BTC. Mol Cancer Ther; 15(7); 1515–24. ©2016 AACR.

Dynamics of Soluble Programmed Death-Ligand 1 (sPDL1) during Chemotherapy and its Prognostic Implications in Cancer Patients: Biomarker Development in Immuno-Oncology

Purpose The soluble programmed death-ligand 1 (sPDL1) has immunosuppressive activity and is a candidate biomarker for immuno-oncology drug development. In this study, we measured sPDL1 at pre- and post-chemotherapy and at disease progression to uncover the dynamics of sPDL1 during treatment in biliary tract cancer (BTC) patients. Materials and Methods From 90 BTC patients (training cohort, 53; validation cohort, 37) who were candidates for palliative first-line chemotherapy, blood was collected at pre- and post-chemotherapy (at the time of best response) and at disease progression. The sPDL1 levels were measured using an enzyme-linked immunosorbent assay. Responses to chemotherapy, overall survival (OS), and other prognostic factors including the neutrophil-lymphocyte ratio (NLR) were analyzed. Results The OS of all patients was 11.5 months (confidence interval [CI], 9.7 to 16.2). The best response was complete response in seven (7.8%), partial response in 20 (22.2%), stable disease in 52 (57.8%), and disease progression (PD) in 11 patients (12.2%). Patients with high pre-chemotherapy sPDL1 (≥ 1.30 ng/mL) showed worse OS than patients with low prechemotherapy sPDL1 (9.1 months vs. 12.5 months, p=0.003). In multivariate analyses, high pre-chemotherapy sPDL1 (hazard ratio [HR], 1.96; 95% CI, 1.2 to 3.9; p=0.011) and high pre-chemotherapy NLR (HR, 1.82; 95% CI, 1.1 to 3.0; p=0.020) were independent poor prognostic factors for OS. At the time of PD, sPDL1 was increased significantly compared with pre-chemotherapy sPDL1 (1.59 ng/mL vs. 0.72 ng/mL, p=0.003). Conclusion The sPDL1 at pre-chemotherapy confers the prognostic value for OS in BTC patients under palliative chemotherapy. The dynamics of sPDL1 during chemotherapy correlate with disease burden and have prognostic value.

Jab1 Silencing Inhibits Proliferation and Sensitizes to Cisplatin in Biliary Tract Cancer

Purpose Jab1 is a coactivator of c-Jun that enhances the transcriptional function of c-Jun. Jab1 is frequently overexpressed in various cancers and is associatedwith poor prognosis of cancer patients. Thus, Jab1 could be a potential therapeutic target in cancer. However, the role of Jab1 in biliary tract cancer (BTC) has not been studied. Materials and Methods We performed in vitro and in vivo experiments to evaluate the therapeutic potential ofJab1 inhibition in BTC. Results Among 8 BTC cell lines, many showed higher Jab1 expression levels. In addition, Jab1 silencing by siRNA increased p27 expression levels. SNU478 and HuCCT-1 cells exhibited profound Jab1 knockdown and increased p27 expression by Jab1-specific siRNA transfection. Jab1 silencing induced anti-proliferative and anti-migratory effects and resulted in G1 cell cycle arrest in SNU478 and HuCCT-1 cells. In addition, Jab1 silencing potentiated the anti-proliferative and anti-migratory effects of cisplatin by increasing DNA damage. Interestingly,Jab1 knockdown increased PTEN protein half-life, resulting in increased PTEN expression. In the HuCCT-1 mouse xenograft model, stable knockdown of Jab1 by shRNA also showed anti-proliferative effects in vivo, with decreased Ki-67 expression and AKT phosphorylation and increased Terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling and p27 expression. Conclusion Jab1 knockdown demonstrated anti-proliferative and anti-migratory effects in BTC cells by increasing DNA damage and stabilizing PTEN, resulting in G1 cell cycle arrest. In addition, Jab1 silencing potentiated the anti-proliferative effects of cisplatin. Our data suggest that Jab1 may be a potential therapeutic target in BTC that is worthy of further investigations.

Effect of combined consideration of distinct signatures of VEGF and soluble VEGFR2 on prognostic implication in gastric cancer.

56 Background: Anti-angiogenic strategy in gastric cancer (GC) has been highlighted again due to the recent success of ramucirumab and apatinib. Therefore, the comprehensive network of VEGF, soluble VEGF receptor-2 (sVEGFR2) and cytokines and other angiogenic factors (CAF) in GC and their prognostic impact would be of importance, although they have been poorly understood. We aimed to find out the CAF signature associated with VEGF and sVEGFR2, and to explore their prognostic implication in GC. Methods: We measured pretreatment serum levels of 52 CAFs, including VEGF and sVEGFR2, using multiplex bead immunoassays and ELISA, in 70 patients who were diagnosed with GC in Seoul National University Hospital, and treated with palliative chemotherapy. Linear regression analysis for correlating CAFs with VEGF and sVEGFR2, and survival analysis by log rank test and Cox regression analysis were performed. Results: The VEGF signature was shown to be associated with seven CAFs (interluekin [IL]-7, IL-12p70, IL-2Ra, IL...

Abstract 1714: The role and mechanism of JAB1 as a therapeutic target in biliary tract cancer

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Background: JAB1 (c-Jun activation domain binding protein-1) is a c-Jun coactivator, also known as COP9 signalosome subunit 5 (CSN5). Jab1 has an important role in cell proliferation and apoptosis. Overexpression of Jab1 is correlated with poor prognosis in various cancers. Biliary tract cancer (BTC) has a poor prognosis with a huge unmet medical need. The role of Jab1 has not been studied in BTC. We investigated the role and mechanism of Jab1 as a potential therapeutic target in BTC. Methods: We used 8 kinds of BTC cells and designed Jab1 siRNA. MTT assay and colony formation assay were done to determine growth inhibitory effect of Jab1 knockdown. Cell cycle analysis was done by FACS Calibur flow cytometer and cell migration was evaluated by wound healing assay. We used cycloheximide chase assay for measuring of protein half-life. Results: BTC cell lines showed high level of Jab1 expression. Among them, SNU478, SNU869 and SNU 1196 were indicated with especially higher level of Jab1 expression. Cell growth and proliferation of BTC cells were decreased by Jab1 knockdown. Depletion of Jab1 induced G1 arrest, as well as decreased CyclinD/CyclinA and increased p27. Cell migration was also inhibited by Jab1 knockdown. Inhibition of Jab1 showed the decrease of pSrc, pAkt. Interestingly, depletion of Jab1 led to the elevation of PTEN protein levels without change of PTEN mRNA levels. PTEN half-life was longer in Jab1 siRNA-transfected cells. Suppression of Jab1 increased the sensitivity of BTC cells to the cytotoxic chemotherapeutic agent. Conclusion: Suppression of Jab1 shows antitumor effects in BTC cells by inhibiting cell proliferation, migration, cell cycle and increase of chemosensitivity. Taken together, Jab1 might be a potential therapeutic target in BTC. Citation Format: Ah-Rong Nam, Kyo Hwa Kang, Ji Eun Park, Ju-Hee Bang, Ling Jin, Mei Hua Jin, Tae Yong Kim, Sae-Won Han, Sang-Hyun Song, Seock-Ah Im, Tae-You Kim, Do-Youn Oh, Yung-Jue Bang. The role and mechanism of JAB1 as a therapeutic target in biliary tract cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1714. doi:10.1158/1538-7445.AM2015-1714

Abstract 3599: Resistance mechanisms to HER2-targeting treatment in HER2-positive gastric cancer

Background: HER2 is the first validated therapeutic target in advanced gastric cancer (GC). Trastuzumab in combination with chemotherapy is used as a first-line treatment of GC. The resistance mechanisms to trastuzumab have not been widely known in GC. We investigated the resistance mechanisms to HER2-targeting agents in HER2-positive gastric cancer cells. Methods: SNU216 and NCI-N87 are HER2 amplified gastric cancer cells. Using these cells, we established trastuzumab-resistant cells (SNU216-HR, N87-HR) and dacomitinib (panHER inhibitor)-resistant cells (SNU216-PR). Acquired resistance of the established cell lines was verified by MTT assay and western blotting. We compared various receptor tyrosine kinase activities and protein expression levels between parental and resistant cells by RTK arrays and western blotting. We used many targeted agents (HER family inhibitor, PI3K inhibitor, mTOR inhibitor, MEK inhibitor, Src inhibitor, HSP90 inhibitor, etc) to overcome the resistance. Results: Resistant cells displayed more rapid growth rate and different morphology compared with parent cells. Resistant cells showed increased levels of pEGFR, pHER2, pHER3, pMET, pIGF1R, pAXL, pSTAT3, pAKT, pFAK, and TS compared with the parental cells in western blot. With the treatment of trastuzumab, HR cells showed elevated levels of EGFR, pHER2, AXL, pAXL, pMEK, pSRC, pSTAT3, pAKT, pERK and TS compared with the parental cells. With the treatment of dacominitib, PR cells showed elevated levels of pEGFR, pAXL, pIGF1R, pMEK, pSRC, pERK and TS compared with the parental cells in western blot. The RTK arrays also showed the similar findings. These resistant cells were more sensitive to Src inhibitor and PI3K inhibitor than parent cells. Conclusion: Resistance mechanisms to HER2-targeting strategy in gastric cancer include activation of HER, MET, FAK and Src pathway. Targeting these pathways is needed to overcome resistance. Citation Format: Kyo Hwa Kang, Ah-Rong Nam, Ji Eun Park, Ju-Hee Bang, Jin Ling, Mei Hua Jin, Tae Yong Kim, Sae-Won Han, Sang-Hyun Song, Seock-Ah Im, Tae-You Kim, Do-Youn Oh, Yung-Jue Bang. Resistance mechanisms to HER2-targeting treatment in HER2-positive gastric cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3599. doi:10.1158/1538-7445.AM2015-3599