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Olaparib, a potent PARP inhibitor, has been shown to have great anti-tumor effects in some tumor types. Although biliary tract cancer (BTC) is a good candidate for DNA damage response (DDR)-targeted agents, targeted DDR inhibitors, including olaparib, are currently rarely evaluated in BTC. In our project, a total of ten BTC cell lines were used to assess the efficacy of olaparib. Olaparib alone showed moderate anti-proliferative effects in BTC cells and increased p-ATR and PD-L1 expression levels. In combination with an ATR inhibitor (AZD6738, ceralasertib) showed synergistic anti-proliferative effects and increased DNA strand breaks in vitro. PD-L1 induced by olaparib was also downregulated by ceralasertib through p-STAT-3 and YAP reduction with or without human primary peripheral blood mononuclear cells. In SNU478-xenograft models, the combination treatment significantly suppressed tumor growth. PD-L1 and YAP were strongly downregulated, similar to in vitro conditions, and expression of CXCR2 and CXCR4 was further reduced. In the current ongoing clinical trial (NCT04298021), BTC patients treated with olaparib and ceralasertib combination have shown tumor response. In conclusion, co-targeting of PARP and ATR might be a potential therapeutic approach for patients with BTC.

To date, many efforts have been made to understand the resistance mechanism of trastuzumab in human epidermal growth factor receptor 2 (HER2)-positive breast and gastric cancer. However, there is still a huge unmet medical need for patients with trastuzumab resistance. In our study, we generated four trastuzumab-resistant (HR) cancer cell lines from ERBB2-amplified gastric and biliary tract cancer cell lines (SNU-216, NCI-N87, SNU-2670, and SNU-2773). Here, we found higher PD-L1 expression in trastuzumab-resistant (HR) HER2-positive cancer cells than in parental cells, and blocking PD-L1 reversed the resistance to trastuzumab in HR cells. Trastuzumab upregulated PD-L1 expression via NF-κB activation in both parental and HR cells, however, led to DNA damage only in parental cells. The WEE1 inhibitor adavosertib, which downregulates PD-L1 expression, enhanced trastuzumab efficacy by blocking BRCA1-CMTM6-PD-L1 signals and the HER2-CDCP-1-SRC axis. Additionally, the levels of galectin-9, CD163, FoxP3, and CTLA-4 were diminished by blocking WEE1 in the presence of human PBMCs in vitro. Taken together, the strategy of co-targeting HER2 and WEE1 could overcome resistance to trastuzumab in HER2-positive cancers, supporting further clinical development in HER2-positive cancer patients.

BACKGROUND This study aimed to evaluate the association between soluble TGF-β (sTGF-β) and soluble PD-L1 (sPDL1), the dynamics of sTGF-β during treatment and its prognostic role in biliary tract cancer (BTC). METHODS The study population consisted of 90 BTC patients with first-line chemotherapy (cohort 1) and 35 BTC patients with second- or third-line chemotherapy (cohort 2). Plasma sTGF-β and sPDL1 levels were measured using an enzyme-linked immunosorbent assay. RESULTS In both groups, sTGF-β was positive correlated with sPDL1 for baseline and change values after treatment. sTGF-β was elevated at disease progression compared to baseline in cohort 1 (P

PurposeCurrently, the DNA damage response (DDR) pathway represents a key target for new cancer drug development. Advanced biliary tract cancer (BTC) has a poor prognosis because of the lack of efficacious treatment options. Although DNA repair pathway alterations have been reported in many patients with BTC, little is known regarding the effects of DDR-targeted agents against BTC.Materials and MethodsIn this study, nine BTC cell lines were exposed to the WEE1 inhibitor (AZD1775). In vitro, MTT assay, colony-forming assay, cell cycle analysis, phospho-histone H3 staining assay, Transwell migration assay, and western blot were performed. Then, to enhance the antitumor effect of AZD1775, the combination treatment of WEE1 inhibitor and ataxia telangiectasia mutated and Rad3 related (ATR) inhibitor (AZD6738) was conducted using MTT assay and comet assay. Finally, HuCCT-1 and SNU2670 xenograft models were established to confirm the anti-tumor effect of AZD1775 alone. Furthermore, the combination treatment was also evaluated in SNU2670 xenograft models.ResultsAZD1775 blocked the phosphorylation of CDC2 and CDC25C in all cell lines, but significantly increased apoptosis and S phase arrest in sensitive cells. However, increased p-ATR and phosphorylated ataxia telangiectasia mutated levels were observed in less sensitive cells. In addition, in vitro and in vivo data illustrated that AZD1775 combined with AZD6738 exerted more potent anti-tumor effects than either drug alone. Although WEE1 inhibition has promising anti-tumor effects in some BTC cells, the addition of ATR inhibitors could enhance its efficacy.ConclusionTaken together, this study supports further clinical development of DDR-targeted strategies as monotherapy or combination regimens for BTC.

Purpose Up to 20% of patients with biliary tract cancer (BTC) have alterations in DNA damage response (DDR) genes, including homologous recombination (HR) genes. Therefore, the DDR pathway could be a promising target for new drug development in BTC. We aim to investigate the anti-tumor effects using poly(ADP-ribose) polymerase (PARP) and WEE1 inhibitors in BTC.Materials and Methods We used 10 BTC cell lines to evaluate an anti-tumor effect of olaparib (a PARP inhibitor) and AZD1775 (a WEE1 inhibitor) in in vitro. Additionally, we established SNU869 xenograft model for in vivo experiments.Results In this study, we observed a modest anti-proliferative effect of olaparib. DNA double-strand break (DSB) and apoptosis were increased by olaparib in BTC cells. However, olaparib-induced DNA DSB was repaired through the HR pathway, and G2 arrest was induced to secure the time for repair. As AZD1775 typically regulates the G2/M checkpoint, we combined olaparib with AZD1775 to abrogate G2 arrest. We observed that AZD1775 downregulated p-CDK1, a G2/M cell cycle checkpoint protein, and induced early mitotic entry. AZD1775 also decreased CtIP and RAD51 expression and disrupted HR repair. In xenograft model, olaparib plus AZD1775 treatment reduced tumor growth more potently than did monotherapy with either drug.Conclusion This is the first study to suggest that olaparib combined with AZD1775 can induce synergistic anti-tumor effects against BTC. Combination therapy that blocks dual PARP and WEE1 has the potential to be further clinically developed for BTC patients.

Purpose The soluble form programmed death-ligand 1 (sPDL1) has immunosuppressive properties and is being studied as a candidate biomarker for immuno-oncology drug development. We measured the serum sPDL1 at pre-and post-chemotherapy and evaluated its prognostic implication and dynamics during chemotherapy in advanced gastric cancer (GC).Materials and Methods We prospectively enrolled 68 GC patients who were candidates for palliative standard first-line chemotherapy, and serially collected blood at baseline and after one cycle of chemotherapy, at the best response and after disease progression. sPDL1 was measured using an enzyme-linked immunosorbent assay. Response to chemotherapy, overall survival (OS), progressionfree survival (PFS) and other prognostic factors including neutrophil-lymphocyte ratio (NLR) were obtained. The cut-off value of sPDL1 levels for survival analysis was found using C-statistics.Results The median baseline sPDL1 was 0.8 ng/mL (range, 0.06 to 6.06 ng/mL). The median OS and PFS were 14.9 months and 8.0 months, respectively. sPDL1 and NLR showed a weak positive correlation (Spearman’s rho=0.301, p=0.013). Patients with low levels of sPDL1 at diagnosis (< 1.92 ng/mL) showed a better OS and PFS than patients with a high sPDL1. The baseline sPDL1 before treatment was higher in the progressive disease group than in the stable disease and partial response groups. Patients whose sPDL1 increased after the first cycle of chemotherapy showed worse PFS and OS. Following disease progression, sPDL1 increased compared with the baseline.Conclusion sPDL1 at prechemotherapy confers a prognostic value for PFS and OS in GC patients under palliative first-line chemotherapy. Dynamics of sPDL1 during chemotherapy correlates with disease progression.

Background: DNA damage response (DDR) pathway is essential for maintaining genomic stability, cell survival, and tumorigenesis. However, the roles of DDR pathway in HER2-positive tumors remain unclear. This study aims to discover the function of DDR in trastuzumab-resistant (TR) cells to better understand HER2-biology and to suggest novel treatment strategy using DDR-targeting agents in HER2-positive TR tumors. Methods: Four HER2-positive TR cell lines (NCI-N87TR, SNU-216TR, SNU-2670TR, and SNU-2773TR) and their corresponding parental cells (NCI-N87, SNU-216, SNU-2670, and SNU-2773) were subject to immunoblotting to identify expression profiles of DDR proteins. Proteasome inhibitor MG-132 and cycloheximide chase assay were used for understanding PARP1 dynamics in TR cells. MTT assay and colony-forming assay were performed to evaluate antiproliferative effect of PARP inhibitor (PARPi, olaparib), ATM inhibitor (ATMi, AZD0156) and ATR inhibitor (ATRi, Ceralasertib). DNA damage and homologous recombination repair (HRR) efficiency were measured by comet assay and immunofluorescence respectively. Cell cycle analysis using flow cytometry was performed to assess drug-induced apoptosis. Results: Increase of PARP1 expression was observed in all four TR cells. Decreased proteasomal degradation of PARP1 was found in TR cells compared to parental cells. Olaparib showed better anti-proliferative effect in TR cells compared to parental cells. After treating with olaparib, there was a defect in formation of Rad51 foci, instead, there was induction of phosphorylation of ATM and ATR in TR cells, which might attenuate the effects of olaparib in TR cells. Combination of olaparib with AZD0156 showed stronger anti-tumor effect than olaparib monotherapy in TR cells. Moreover, synthetic lethal interaction was observed by olaparib/AZD0156 combination in TR cells. Interestingly, this synthetic lethal interaction was exclusively occurred in TR cells not in parental cells. Even though olaparib and ceralasertib combination showed better anti-tumor effect than each single drug in some TR cells, synthetic lethal interaction was not observed by olaparib/ceralasertib combination in TR cells. Conclusion: Dual inhibition of PARP1 and ATM could be a good strategy to overcome the resistance to trastuzumab in HER2-positive cancers using its synthetic lethal interaction. Citation Format: Kyoung-Seok Oh, Ah-Rong Nam, Ju-Hee Bang, Hye-Rim Seo, Jae-Min Kim, Jeesun Yoon, Tae-Yong Kim, Do-Youn Oh. A synthetic lethal strategy using PARP and ATM inhibition for overcoming trastuzumab-resistance in HER2-positive cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1079.

Background: Targeting DNA damage response (DDR) has potential anti-tumor effects in diverse cancer types. Homologous-recombination DDR gene mutations are found in 28.9% of biliary tract cancer (BTC). We aimed to evaluate the anti-tumor effects of olaparib (PARP inhibitor) with or without ceralasertib (ATR inhibitor) in BTC.Methods: Ten BTC cell lines (SNU245, SNU308, SNU478, SNU869, SNU1079, SNU1196, HuCCT-1, TFK-1, SNU2670, and SNU2773) were tested to evaluate the anti-tumor effects of olaparib alone and in combination with ceralasertib. MTT assay, colony formation assay, cell cycle analysis, western blot, comet assay and co-culture with human PBMC were used as experimental methods. Tumor xenograft model was established to test olaparib with or without ceralasertib in vivo.Results: Olaparib alone showed moderate anti-proliferative effects in all BTC cells and increased p-ATR and PD-L1 expression. Olaparib plus ceralasertib showed synergistic anti-proliferative effects and led to DNA damage breaks in vitro. Ceralasertib also downregulated PD-L1 level through p-STAT3 and YAP pathway with or without human PBMC conditions. In SNU478-xenograft models, Olaparib plus ceralasertib combination significantly suppressed tumor growth and downregulated PD-L1 and YAP, compared with monotherapy. It also effectively reduced CXCR2 and CXCR4 expression. Conclusion: Combination of olaparib plus ceralasertib showed potent anti-tumor effects in BTC cells. This study could provide the preclinical evidence of development of PARP and ATR dual inhibition in BTC patients. Clinical trial using olaparib and ceralasertib combination in advanced BTC is ongoing (ClinicalTrials.gov Identifier: NCT04298021). Citation Format: Ah Rong Nam, Mei Hua Jin, Kyoung-Seok Oh, Hye Rim Seo, Jae-Min Kim, Ju-Hee Bang, Jeesun Yoon, Tae-Yong Kim, Do-Youn Oh. Co-Targeting PARP and ATR in biliary tract cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2073.

TPS4153 Background: Olaparib (PARP inhibitor) leads to DNA damage and cell death. In phase III study (GOLD), olaparib plus paclitaxel did not improve overall survival (OS) compared with paclitaxel in second-line gastric cancer (GC) patients with statistical significance, even though there was absolute increase of OS (Lancet Oncol 2017). This highlights the importance of biomarker-based patient selection. The changes of tumor microenvironment by paclitaxel/olaparib have not been explored. Besides DNA damage, olaparib induces positive or negative immune modulation by recruiting T cells, promoting type I interferon and upregulating PD-L1, which suggests anti-PD (L1) inhibitor plus olaparib could enhance anti-tumor immunity. Combination of Anti-PD-1 agents with chemotherapy showed a good clinical efficacy in first-line of GC compared with chemotherapy alone (Checkmate 649). Based on these findings, the combination of paclitaxel/olaparib/anti-PD(L1)1 inhibitor, with different mode of actions, might enhance antitumor activity. This is phase II study of paclitaxel/olaparib/durvalumab combination in second-line GC patients, to find out immune modulation effects by paclitaxel/olaparib combination, and to see the efficacy, safety, optimal biomarkers for this combination. Methods: All patients with histologically confirmed unresectable GC have failed to prior one chemotherapy and measurable lesion. Prior exposure to anti-PD(L1)1, PARP inhibitor is excluded. At 1st cycle, paclitaxel (80 mg/m2) on D1, 8 and 15 and olaparib (150 mg bid) on D1-28 is administered. Pre-treatment biopsy and after first cycle biopsy is done. From second cycle, durvalumab 1500 mg on D1 every 4 weeks is added. At the time of disease progression, tumor biopsy is mandatory. Blood samples for biomarkers should be obtained every cycles. Response evaluation is performed after first 3 cycles and repeated every 2 cycles. Primary endpoint is the disease control rate (the percentage of patients who have achieved complete or partial remission, stable disease based on RECIST v1). Key secondary endpoints are overall response rate, progression-free survival, OS, quality of life and safety. Clinical trial information: NCT03579784.

TPS4166 Background: Ceralasertib (AZD6738) is a selective ATR inhibitor that causes stalled replication forks to collapse, leading to accumulation of double-strand DNA breaks, which is expected to have synergistic anti-tumor effects with immune checkpoint inhibitors (ICI) or PARP inhibitors. First, accumulation of DNA damage by ceralasertib induces tumor cell death, leads to the release of tumor-specific antigen, changing the tumor microenvironment to promote antigen presentation and enhances the anti-tumor effect of ICI. Second, by simultaneously inhibiting two DNA-damage response (DDR) pathways downstream of PARP and ATR, cancer cells are unable to repair damaged DNA, leading to cell death. Ceralasertib has demonstrated promising anti-tumor activity and manageable toxicity in combination with durvalumab or olaparib in solid tumors in a phase 1 study (NCT02264678). In preclinical studies, ceralasertib has shown potent anti-tumor effects in biliary tract cancer (BTC) as a monotherapy and in combination with chemotherapy (Nam, et al, 2019). Methods: This is an open-label, phase 2 umbrella study assessing the efficacy of ceralasertib in combination with durvalumab or olaparib in patients with advanced BTC. Eligible patients have histologically confirmed BTC (including intrahepatic or extrahepatic cholangiocarcinoma, gallbladder cancer, or ampullary cancer), have failed at least one chemotherapy and have ECOG performance status of 0-1. Patients who have received prior ICI, ATR or PARP inhibitor are excluded. Each cycle consists of 4 weeks. In ceralasertib /durvalumab cohort, 37 patients will receive durvalumab 1.5g on day 1 and ceralasertib 240mg twice daily on days 15-28. In ceralasertib /olaparib cohort, 37 patients receive ceralasertib 160mg once daily on days 1-7 and olaparib 300mg twice daily on days 1-28. The primary endpoint is disease control rate, with key secondary endpoints including overall response rate, progression-free survival, overall survival, and safety. Tissue and blood samples are being collected for translational biomarker studies. Clinical trial information: NCT04298021.

4034 Background: The soluble form Programmed Death-Ligand 1(sPDL1) is suggested to have immunosuppressive activity and under investigation as candidate biomarker for immuno-oncology drug development. In this study, we measured the serum sPDL1 at pre-and post-chemotherapy and evaluated its prognostic implication and dynamics during chemotherapy in advanced gastric cancer (GC). Methods: We prospectively enrolled 68 GC patients who were candidates for palliative standard 1st-line chemotherapy, and blood was serially collected at pre-and post-one cycle of chemotherapy, at best response and disease progression. sPDL1 was measured using an enzyme-linked immunosorbent assay. Response to chemotherapy, overall survival (OS), progression-free survival (PFS) and other prognostic factors including neutrophil-lymphocyte ratio (NLR) were obtained. The cut-off values of sPDL1 levels and changes for survivals were found using C-statistics. Results: The median baseline sPDL1 was 0.8ng/mL(range, 0.06 - 6.06ng/mL). The median OS and PFS were 14.9 months (95% CI: 7.33-22.47) and 8.0 months (95% CI: 5.96-10.0), respectively. sPDL1 and NLR showed a positive correlation. Patients with low levels of sPD-L1 at diagnosis ( < 1.92 ng/mL) showed a better OS and PFS than the patients with a high sPDL1 (OS: 18.3 vs. 95 months, P = 0.057, PFS: 8.9 vs. 6.0 months, P = 0.04). The baseline sPDL1 before treatment were higher in the PD group than in the SD and PR groups (mean:2.91, 1.17, 1.19, P = 0.019). Patients whose sPDL1 increased after 1st cycle of chemotherapy showed the tendency of worse PFS and OS. When disease progressed, sPDL1 increased compared with baseline (mean:1.31, 1.45, P = 0.029). Conclusions: sPDL1 at pre-chemotherapy confers the prognostic value for PFS and OS in GC patients under palliative 1st-line chemotherapy. The dynamics of sPDL1 during chemotherapy correlates with disease courses.

4094 Background: We previously reported that soluble programmed death-Ligand 1 (sPD-L1) at pre-chemotherapy indicated the prognostic value for overall survival (OS) and the dynamics of sPD-L1 during palliative chemotherapy correlated with disease burden in biliary tract cancer (BTC). Transforming growth factor (TGF) -β attenuates tumor response to PD1/PD-L1 inhibitors. Strategy of dual targeting of PD1/PD-L1 and TGF-β is now under investigation. This study aimed to evaluate the association between soluble TGF-β (sTGF-β) and sPD-L1, dynamics during chemotherapy and its prognostic role in BTC. Methods: Study population consisted of 90 BTC patients treated with first line chemotherapy. Blood samples at pre-and post-chemotherapy and at disease progression (PD) were prospectively collected. Plasma sTGF-β and sPD-L1 levels were measured by using an enzyme-linked immunosorbent assay. Results: The median progression free survival (PFS) and OS of all patients was 6.9 months (m) (95% CI, 5.2-8.6) and 11.5 m (95% CI, 9.4-13.6). The best response was CR in 7 (7.8%), PR in 20 (22.2%), SD in 52 (57.8%), and PD in 11 patients (12.2%). The mean baseline sTGF-β and sPD-L1 were 16.4 ng/ml and 1.3 ng/ml. There was a positive association between sTGF-β and sPD-L1 in terms of baseline levels and changes after chemotherapy (at pre-chemo, Pearson correlation = 0.578, p < 0.001; change after chemotherapy, Pearson correlation = 0.542, p < 0.001). Patients with higher pre-chemotherapy sPD-L1 ( > 1.3 ng/ml) showed worse OS (9.2 vs 16.2 m, p < 0.001). Both sPD-L1 (1.8 vs 1.0 ng/ml, p < 0.001) and sTGF-β (20.5 vs 11.6 ng/ml, p < 0.001) were increased significantly at the time of PD compared with pre-chemotherapy. Regarding changes after chemotherapy, increased sTGF-β after chemotherapy (Δ > 3.2 ng/ml) had worse prognosis (PFS: 5.1 vs 7.3 m, p = 0.024; OS: 9.2 vs 12.3 m, p = 0.028). This prognostic value of change of sTGF-β after chemotherapy was also significant in multivariable analysis with other clinical factors (PFS: HR = 1.78, p = 0.022; OS: HR = 1.86, p = 0.018). Conclusions: In BTC, there is a positive association between sTGF-β and sPD-L1 value in terms of baseline levels and changes after chemotherapy. sTGF-β could be associated with the survival, particularly, increased value after chemotherapy indicates worse prognosis.

Blepharoplasty is one of the most common anti-aging operations. Although rare, complications such as ectropion may occur. Thus, we introduced an operative technique to prevent ectropion of the lower lid after blepharoplasty. From January 2012 to August 2013, we performed a nonincisional suspension suture (NISS) technique for 30 patients who visited our clinic for lower blepharoplasty. These patients had a distance of greater than 7 mm on the distraction test and were suspected of having horizontal lid laxity. We performed a slit incision 3 mm superior to the junction between the lateral epicanthus and the orbital bone during lower blepharoplasty. We passed a 7-0 nylon suture through the subcutaneous layer and the orbicularis oculi muscle. Then, we punctured the tarsal plate at the lateral limbus and fixed it to the lateral orbital rim by puncturing the periosteum. We tied a suspension knot through the slit incision. Thirty patients had satisfactory results without major complications, such as scleral exposure or ectropion. The NISS technique could be an effective method by which to prevent postoperative ectropion in cases with a mild to moderate degree lower lid laxity. The use of a NISS procedure is also a simple surgical technique, which saves time and is minimally invasive.