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e16127 Background: There are different views on the scope of indications for surgical treatment of HCC worldwide. Unlike the Barcelona Clinic Liver Cancer, the European Association for Study of the Liver, and the American Association for the Study of Liver Diseases which recommend surgical resection as the first choice only for early HCC, it is also recommended as the first treatment for selected patients with intermediate or advanced HCC in China. However, in any case, postoperative recurrence is an important issue affecting the long-term survival of HCC patients, and to date, there is no globally recognized treatment algorithm for adjuvant therapy. We performed a survey to understand the patient characteristics and clinical status of hepatobiliary surgeons’ decision aids for adjuvant treatment. Methods: This survey was conducted among senior hepatobiliary surgeons who work at high-volume hospitals in China. Surgeons were asked to fill out an online questionnaire by scanning the QR code. Results: From September to November 2021, 511 surgeons from 55 cities responded. Among them, 70.3% worked in general hospitals, 26.8% in cancer hospitals, and 2.9% in integrative medicine hospitals. The majority of the institutions were tertiary hospitals (91.2 %). When determining whether a patient was suitable or not for adjuvant therapy, surgeons mainly considered tumor factors (chosen by 92.8% and 81.6%) and patient factors (chosen by 80.8% and 75.3%). The analysis showed that the patients whom surgeons considered for adjuvant therapy had one or more of the following characteristics: Tumor factors including China liver cancer (CNLC) stage Ia-IIIb (preoperative), R1 resection, Child-Pugh A or B liver function, well recovery from surgery, presence of ≥1 high-risk recurrence factors (i.e. microvascular invasion, macrovascular tumor thrombus, and hilar lymph node metastasis); Patient factors which were hepatocarcinoma-related medical history (e.g., HBV/HCV) and affordability. Most surgeons used targeted therapy (83.8%, mainly anti-angiogenic multi-kinase inhibitors), TACE (72.8%), or combination therapy (60.3%, mainly targeted drugs combined with immunotherapy or TACE) as adjuvant therapy. When asked to choose the two most related factors impacting treatment compliance, 52.1% chose patients' financial status, and 51.7% considered adverse reactions. Less adverse reactions (71.0% of surgeons), better efficacy (66.7%), and a higher reimbursement ratio (53.3%) were the top 3 unmet need for future adjuvant therapy. Conclusions: This survey presented a patient portrait that Chinese hepatobiliary surgeons considered for adjuvant therapy and the practice patterns in adjuvant therapy for HCC. However, the patient group that can benefit from adjuvant therapy remains to be explored and validated in prospective clinical studies.

4103 Background: Hepatocellular carcinoma (HCC) is one of the most common and lethal cancers worldwide, especially in Asian counties. Patients can be treated more effectively if detected earlier, however the current screening strategies with alpha-fetoprotein (AFP) or ultrasound it is largely suboptimal. We aimed to develop non-invasive and cost-effective assay to improve HCC early detection. Methods: HCC-specific DNA methylation markers were screened from tissue and plasma samples through a modified reduce representation bisulfite sequencing assaay,and optimized by a targeted methylation sequencing assay. The most informative markers were then integrated in a multi-locus qPCR assay, HepaQ. Results: Profiling DNA methylation pattern on 61 tissue samples (31 HCC tumor and 30 normal tissues) and 663 plasma samples (276 HCC and 393 control plasma samples) achieved an AUC of 0.99, which corresponds to 91% sensitivity at 94% specificity. The best-performance markers were further screened and analytically verified in additional tissues and plasmas after several rounds of marker selection. A multi-locus qPCR assay, designated as HepaQ, was then developed to incorporate the most effective markers. A cohort of 559 plasma samples including 293 HCC (84% of them at stage 0/A), 60 liver cirrhosis (LC), 36 chronic hepatitis B (CHB) and 170 healthy controls (CTRL), were used to train a classifier for HCC early detection. HepaQ classifier enables to detect 85.3% of HCC under a specificity of 88.3%, 91.7% and 92.4% in LC, CHB and CTRL, respectively. Finally, HepaQ classifier was validated in 374 plasma samples independently collected from multiple clinical centers to confirm its performance of 87.2% sensitivity in HCC and 86.8%,90.5% and 93.4% specificities in LC, CHB and CTRL respectively. Conclusions: We have developed and demonstrated a blood-based ctDNA methylation assay, HepaQ, that can detect early-stage HCC at high sensitivity and specificity. We proposed that HepaQ assay, a cost-effective qPCR assay, has the great potential to benefit the population at-risk for HCC early detection and screening.

e16182 Background: Hepatocellular carcinoma (HCC) is one of the most common malignancy with dismal outcomes. Recently, lenvatinib have been approved as the first-line therapy for unresectable HCC. However, the efficacy and safety of lenvatinib with the combination of other therapy such as transarterial chemoembolization (TACE) and immune checkpoint inhibitor (ICI) therapy was still unclear. Methods: A multicenter retrospective study was conducted and 158 HCC patients treated with lenvatinib from four medical centers were enrolled between November 2018 and December 2020. According to the treatment combined with lenvatinib, all patients were classified into four groups, including lenvatinib monotherapy (LEN) group, combined ICI (c-ICI) group, combined TACE (c-TACE) group and combined ICI and TACE (c-ICI-TACE) group. Objective response rate (ORR) and disease control rate (DCR) were assessed. Overall survival (OS) and time to progression (TTP) were calculated and compared among different groups. Results: All patients (n = 158) were classified into LEN group (n = 40), c-ICI group (n = 42), c-TACE group (n = 39) and c-TACE-ICI group (n = 37). In all patients, the ORR and DCR was 29.1% and 74.1%. The median OS and TTP were 21.8 and 6.2 months, respectively. Four groups showed significant differences in ORR and DCR rates. Specifically, c-ICI-TACE group have significantly higher ORR and DCR rate compared with LEN group (ORR: 12% vs. 38%, P = 0.002; DCR: 60% vs. 89%, P = 0.004). Kaplan-Meier analysis identified that LEN group, c-ICI group, c-TACE group and c-TACE-ICI group showed significantly different TTP (median TTP: 5.0 vs. 6.6 vs. 4.9 vs. 9.5 months; P = 0.021), but similar OS (median OS: 21.8 vs. 19.6 vs. 17.5 months vs. unreached; P = 0.180). Further investigation revealed lenvatinib combined with ICI could prolong TTP compare with lenvatinib without ICI (median TTP: 8.4 vs. 5.0 months; P = 0.019), but it had no significant impact on OS (median OS: unreached vs. 20.1 months; P = 0.300). c-ICI-TACE group showed both better TTP and improved OS compared with other three groups (median TTP: 9.5 vs. 5.2 months; P = 0.004; median OS: unreached vs. 20.1 months; P = 0.034). Univariate and multivariate analysis confirmed that c-ICI-TACE was an independent protective factor for OS (hazard ratio: 0.226; 95% confidence interval: 0.10-0.50; P < 0.001) and TTP (hazard ratio: 0.55; 95% confidence interval: 0.32-0.95; P = 0.032). Most patients (152/158, 96.2%) showed adverse events (AEs) during lenvatinib treatment and the grade 3 AE occurred in 45 patients (28.5%). No significant difference of AE (P = 0.569) and grade 3 AE (P = 0.572) was found among four groups. Conclusions: Lenvatinib was an effective treatment for patients with HCC. Lenvatinib combined ICI could prolong the TTP, while lenvatinib combined ICI and TACE could improve both TTP and OS. Combined therapy wouldn’t escalate the AE and grade 3 AE rates.

4094 Background: The outcome of advanced intrahepatic cholangiocarcinoma (ICC) remains poor with current gemcitabine-based chemotherapy. This study is to evaluate the safety and efficacy of anti-PD1 agent toripalimab, lenvatinib in combination with oxaliplatin and gemcitabine (Gemox) chemotherapy. Methods: Locally advanced or metastatic ICC patients (pts) were given 240 mg toripalimab Q3W via intravenous (IV) infusion, 8 mg lenvatinib QD orally, and 1g/m² gemcitabine on Day 1 and Day 8, and 85 mg/m² oxaliplatin Q3W by IV for 6 cycles. The primary outcome was objective response rate (ORR), which was evaluated according to RECIST v1.1. Secondary outcomes included safety, progression-free survival (PFS) and overall survival (OS). Treatment would be terminated by confirmed disease progression, unacceptable toxicity, or voluntary withdrawal. Whole exome sequencing was performed on available tumor tissues and PD-L1 expression was determined by immunohistochemistry staining. Results: From May 2019 to Oct 2019, 30 pathologically-confirmed advanced ICC pts with a mean age of 56.5 (range, 25-73) years, including 11 women (37%), were enrolled at Zhongshan Hospital, Fudan University (one pt withdrawn). At the end of last follow-up (February 1, 2021), the ORR was 80% (24/30; 95% CI: 61.4%-92.3%), and disease control rate (DCR) was 93.3% (28/30; 95% CI:77.9%-99.2%). Median follow-up was 16.6 months. One pt achieved complete response (CR). Three pts with locally advanced disease were down-staged and then underwent resection. They remained disease-free survival at the end of last follow-up. 23 pts experienced disease progression and 12 pts (including one pt withdrawn) have died. The median PFS was 10.0 months and median duration of response (DOR) was 9.8 months. The median OS have not been reached. 12-months OS rate was 73.3% (95% CI: 57.5%-89.2%). No grade 5 adverse event (AE) was observed in present study. Grade 3 or 4 neutropenia and thrombocytopenia observed in 3 (10%) and 1 (3.3%) patient, respectively. Non-hematological toxic effects were jaundice (10 %), rash (6.7 %), proteinuria (6.7 %), increased AST level (3.3%), vomiting (3.3%), upper gastrointestinal hemorrhage (3.3%), sepsis (3.3%), gastrointestinal fistula (3.3%), adrenocortical insufficiency (3.3%), interstitial pneumonia (3.3%), and hyponatremia (3.3%). High ORR was significantly associated with positive PD-L1 expression ( p= 0.048) and DNA damage repair (DDR)-related mutations ( p= 0.022) in tumor samples. Conclusions: Gemox chemotherapy in combination with Anti-PD1 antibody Toripalimab and Lenvatinib provided remarkable efficacy with reasonable tolerability in advanced ICC patients. These findings warrant further validation in a large randomized clinical trial. Clinical trial information: NCT03951597.

4099 Background: Lenvatinib monotherapy and lenvatinib plus PD-1 antibody have shown some clinical benefit for advanced intrahepatic cholangiocarcinoma (ICC) in the second-line setting. Our study assesses the role of lenvatinib plus toripalimab (PD-1 antibody) for advanced ICC patients as the first line therapy. Methods: Patients (pts) with locally advanced or metastatic ICC received 12 mg/day (Body Weight ≥60 kg) or 8 mg/day (Body Weight

e16163 Background: The prognosis of advanced intrahepatic cholangiocarcinoma (ICC) remains dismal with gemcitabine-based first-line chemotherapy. This study is to evaluate the safety and efficacy of lenvatinib in combination with gemcitabine and oxaliplatin (Gemox) chemotherapy in the advanced ICC. Methods: Locally advanced or metastatic ICC patients (pts) were given lenvatinib 12 mg/day (body weight ≥60 kg) or 8 mg/day (body weight

e16669 Background: Cofilin1 (CFL1) is an actin-binding protein that plays an essential role in cytoskeleton regulation. However, its function in hepatocellular carcinoma (HCC) is largely unknown. The aim of study was to investigate the role of CFL1 in HCC. Methods: We used qRT-PCR and western blot assays to detect CFL1 expression. The role of CFL1 in regulating HCC cell growth and invasion were assessed by forced expression and downregulation. A tissue microarray study containing 189 HCC cases was conducted to evaluate the clinical relevance and prognostic significance of CFL1. Results: The expression level of CFL1 in high metastasis cell lines was significantly higher than that in low metastasis lines ( P < 0.05). Knockdown of CFL1 reduced the proliferation and invasion activities of Huh7 and MHHC97H cells ( P < 0.05). Western blot revealed that the cytoplasmic level of the p65 subunit of NF-κB was significantly elevated along with reduced nuclear levels and NF-κB-targeted genes MMP9, BCL2, EZH2, COX2 and VCAM1 levels significantly inhibited n HCC cells silenced for CFL1. Immunohistochemistry in a primary tissue array revealed that CFL1 expression correlated with Tumor encapsulation and microvascular invasion ( P < 0.05). High CFL1 expression patients had significantly higher recurrence and deaths rates (recurrence: 72.9% vs. 42.9%, death: 20.8% vs. 51.1%) than low CFL1 expression patients ( P < 0.001). Conclusions: CFL1 regulate the proliferation and dissemination of HCC and TNF-α induced NF-κB nuclear translocation. CFL1 may serve as a prognostic marker in HCC and might be a promising therapeutic target for suppressing metastasis.

4600 Background: Hepatocellular carcinoma (HCC) represents the second most common cause of cancer deaths worldwide. □-fetoprotein (AFP) is the most common serological test used for screening and diagnosis of HCC. However, it is widely recognized that AFP has lower sensitivity with sub-optimal specificity. Tumor-originated circulating cell-free DNA (cfDNA) provides new opportunity for non-invasive detection of liver cancer. Methods: HCC-specific differentially methylated regions (DMRs) were identified by whole genome bisulfite sequencing (WGBS) in 44 pairs of HCC tissues and adjacent tissues. We then performed methylome profiling on cfDNA from HCC patients and healthy individuals by targeted bisulfite sequencing covering genome-wide CpG islands, shelves, and shores. We employed machine learning approaches to build diagnostic models based on cfDNA regional methylation level to classify the plasma of HCC (n = 140) from that of healthy individuals (n = 84). Further analyses were performed in the validation cohort, including 155 HCC patients, and a control group with 96 healthy individuals, 21 chronic hepatitis B infection (CHB)/liver cirrhosis (LC) patients and 34 patients with benign hepatic lesions (BHL). Area under the receiver operating characteristic curve (AUC-ROC) was used to evaluate diagnostic performance. Results: A random forest classifier achieved an AUC of 0.97 (sensitivity: 92.9%; specificity: 89.4%) with 10-fold cross-validation using a panel of 39 DMR markers. The AUC of the diagnostic panel was 0.93 (sensitivity: 81.3%; specificity: 90.7%) in validation cohort, and it performed equally well in detecting BCLC stage 0+A (AUC = 0.90; sensitivity: 74.7%) and AFP negative (AUC = 0.92; sensitivity: 79.4%) HCC, as well as differentiating HCC from CHB/LC and BHL. Based on these results, we have further developed a small targeted bisulfite sequencing panel covering 127 CpG sites for non-invasive diagnosis of HCC. The panel had similar performance in training and validation cohorts, an AUC of 0.96 (sensitivity: 90.7%, specificity: 88.2%) in the training set, and 0.91 (sensitivity: 80.0%, specificity: 88.7%) in the validation set. Conclusions: Our diagnostic panel with 39 DMR markers showed high sensitivity and specificity in HCC diagnosis as well as surveillance in high-risk populations for developing HCC. More importantly, simple diagnostic model show similar diagnostic performance for early HCC diagnosis, which was easily to transfer to clinical application in the future.

1557 Background: Cancers of the gastrointestinal (GI) system, including esophagus, stomach, pancreas, gallbladder, liver, bile duct, colon, and rectum are estimated to account for 38% of all cancer incidences and nearly 46% of cancer-related deaths in China. We conducted a multi-center study to evaluate the feasibility of using genetic and epigenetic abnormalities in plasma cfDNA to diagnose and locate GI cancers. Methods: We performed parallel genetic and epigenetic profiling of plasma cfDNA from hepatocellular carcinoma (HCC), colorectal cancer (CRC) and pancreatic cancer (PC) patients as well as age-matched healthy individuals by ultra-deep sequencing targeting cancer driver genes, and by targeted bisulfite sequencing covering genome-wide CpG islands, shelves, and shores. Results: Using a pre-specified mutation scoring system, we found that cfDNA mutation profiling achieved a sensitivity of 59.6%, 67.2%, and 46.8% for detecting HCC (n = 322), CRC (n = 244) and PC (n = 141) respectively, with a specificity of 95% in healthy controls (n = 207). For 901 plasma cfDNA samples that underwent methylome profiling, we first applied a machine learning approach to classify each cancer type versus healthy controls in the training cohort (HCC: n = 125; CRC: n = 105; PC: n = 97; healthy individuals: n = 84). Random Forest models with 10-fold cross validation achieved an AUC of 0.96±0.04,0.89±0.06, 0.91±0.07 for HCC, CRC, and PC, respectively. Further analyses were performed on the validation cohort, including 172 HCC patients, 162 CRC patients, 60 PC patients, and an independent cohort of healthy individuals (HCC validation: n = 63; HCC independent validation: n = 109; CRC validation: n = 104; CRC external validation: n = 58; PC validation: n = 60; healthy controls: n = 96). The trained model achieved a sensitivity of 83.1% (specificity = 95.8%), 89.5% (specificity = 95.8%), and 76.7% (specificity = 91.7%) for HCC, CRC, and PC, respectively. Using regional methylation markers from diagnostic models for individual cancer types, we built a tissue-of-origin classification model, which achieved a cross-validation accuracy of 83.3% in the training cohort and an accuracy of 80.1% in the validation cohort in assigning correct cancer types. Conclusions: Plasma cfDNA methylome profiling identified effective biomarkers for the detection and tissue-of-origin determination of GI cancers, and outperformed mutation-based detection approach. Therefore, a liquid biopsy test capable of detecting and locating GI cancers is feasible and may serve as a valuable tool for early detection and intervention.

e16649 Background: Circulating tumor cells (CTCs) play important role in tumor dissemination and is an independent survival predictor in Hepatocellular carcinoma (HCC) patients. The aim of this study was to investigate C5a/C5aR, an important axis in complement pathway, which causes the difference capacity of the dissemination of CTCs between HCC patients. The influence of C5a/C5aR axis on recurrence and HCC cell functions was also explored. Methods: Expression microarray analysis was carried out to identify key molecule that cause the difference of CTC enumeration. Clinical significance of the key gene C5aR was evaluated by immunohistochemistry in 187 resectable HCC patients with CTC detection from March 2011 to October 2014. The function of C5a/C5aR axis to enhance the dissemination capacity of CTCs was confirmed first in HCC cell line and than validated in a mouse model. CTCs isolated from the animal circulation were identified by immunostaining for human EpCAM and nuclear counterstaining of red blood cell-lysed blood. Results: Analysis of 187 HCC patients undergoing curative resection showed that C5aR high expression patients were prone to developing vascular invasion, suffering higher AFP level as well as higher percentage of recurrence and death. Further, C5aR expression was also positive correlated with CTC number in HCC patients. In vitro, we observed that cell migration, invasive, proliferation, anti-apoptosis ability and EMT could be greatly inhibited after C5aR knockdown. Opposite results could be observed when C5aR is overexpressed. Further exploration indicated that C5a/C5aR axis could upregulate the expression of INHBA/Activin, and induce phosphorylation of smad2/3 which maintains the mesenchymal phenotype in HCC. Inhibition of the C5a/C5aR signal pathway could decrease circulating capacities of tumor cells and inhibit their colonization to distal organs such as lung in mouse model. Conclusions: Our research elucidated a new C5a/C5aR targeted INHBA-p-smad2/3-EMT/MMP axis to regulate the dissemination of CTC in HCC patients. And these molecules could be novel therapeutic targets for inhibiting the metastasis of tumor cell in the futures.

514 Background: Adjuvant therapy for hepatocellular carcinoma (HCC) is an unmet need. Apatinib, a VEGFR2 inhibitor, showed antitumor activity and tolerable toxicity for advanced HCC in a phase 2 study. We were aiming to explore the safety and efficacy of apatinib in adjuvant settings after resection of HCC with portal vein tumor thrombosis (PVTT). Methods: This is a single-center single-arm phase 2 study. The key inclusion criteria were: (1) pathologically confirmed HCC; (2) underwent liver resection with curative intention within 4-6 wk before recruitment; (3) PVTT assessed by preoperative imaging or intraoperative findings. Eligible pts received apatinib at 500 mg/day for a maximum of 12 mo until unacceptable toxicity or tumor recurrence. The primary outcome was recurrence-free survival (RFS) defined as the interval between surgery and the diagnosis of tumor recurrence or death from any causes whichever comes first. The secondary outcome is overall survival (OS) and treatment safety. Results: From Aug 17, 2017 to Dec 18, 2018, 49 pts were screened, and 30 pts were recruited. PVTT were classified as Vp1 (n = 7), Vp2 (n = 11), and Vp3 (n = 12) according to the LCSGJ classification. As the data cutoff on Aug 22, 2019, 4 pts are still on treatment. The median follow-up was 14.3 mo (IQR 12.3-19.3). Median duration of treatment was 4.8 mo (IQR 2.0–8.8). 20 recurrence and 2 death occurred including one death without recurrence. The mRFS was 7.6 mo (95% CI, 3.7-11.5), and the 1-year RFS rate was 36.1%. The mOS was not reached, and 1-year OS rate was 93.3% (standard error, 4.6%). Treatment-related adverse events occurred in 29 pts (96.7%). Grade 3 or 4 adverse events were reported in 14 pts (46.7%) (Table). Dose modification due to adverse events was recorded in 23 pts (76.7%). Conclusions: Apatinib is tolerant in most pts after resection for HCC with PVTT. A controlled study is warranted to prove its efficacy on tumor recurrence. Clinical trial information: NCT03261791. [Table: see text]

e15641 Background: Patient-derived xenograft (PDX) models have been regarded as valuable preclinical models for oncology drug development and exploring underlying mechanism of drug resistance. As the standard treatment option for advanced hepatocellular carcinoma (HCC), the survival benefit of sorafenib is modest. Even among those who initially responded well to sorafenib treatment, most patients ultimately develop progressive disease owing to acquired drug resistance. Understanding how selective pressure from sorafenib directs the evolution of HCC and shapes its clonal architecture is a central biological question with important clinical implications to combat acquired drug resistance. Methods: Three sorafenib-resistant PDX models were generated by continuous sorafenib treament for more than six months. Whole exome sequencing (WES) and RNA sequencing were performed. The subclone of mutation, fusion genes, and the evolving landscape of tumor neoantigens were further explored. Finally, the antitumor efficacy of recombinant mouse PD-1 antibody was evaluated in sorafenib resistance syngeneic tumors model by immune-competent C57BL/6J mice with Hepa 1-6. Results: High spatiotemporal heterogeneity was observed in engraftment among pre- and post- sorafenib resistance in established acquired-resistance PDX models. Clonal selection on engraftment was observed in established acquired-resistance PDX models. There are many high expressed genes, which showed subclone expansion with the emergence of sorafenib resistance. There is vary difference of neoantigens between pre- and post-resistance engraftment as well as sampling points in same tissues. It was presented that a high burden of clonal neoantigens in sorafenib resistant tissues (P < 0.05), while there has no difference in tumor mutation burden. Moreover, the intra-tumor heterogeneity upon the neoantigen landscape was much bigger than that upon tumor mutation burden. We found that fusion subclone sizes were increased significantly after sorafenib resistance (P < 0.05). Finally, the antitumor efficacy of recombinant mouse PD-1 antibody was confirmed in sorafenib resistance syngeneic tumors mice model (P < 0.001). Conclusions: High spatiotemporal heterogeneity, clonal selection and neoantigen evolution was observed in acquired sorafenib-resistant PDX model of HCC. Immunotherapy such as immune checkpoint inhibitors might be a promising strategy for HCC patients with acquired sorafenib resistance. .

246 Background: The transcriptional heterogeneity and immune evasion mechanisms of CTCs during systemic circulation are not well defined. Methods: Blood was drawn from 4 different vascular sites, including hepatic vein (HV), peripheral artery (PA), peripheral vein (PV) and portal vein (PoV) of 10 localized HCC patients. Single CTCs were isolated by negative enrichment and robotic micromanipulator, followed by single-cell RNA-sequencing (sc-RNAseq). After filtering, 113 CTCs with qualified data remained were subjected to further bioinformatics analysis. The scRNA-seq results were further validated in three independent cohorts of HCC patients. Results: Our scRNA-seq data revealed remarkable intra- and inter-vascular heterogeneity among CTCs from four vascular sites. We determined CTC transcriptional dynamics during transportation through consecutive vascular compartments and revealed their adaptation mechanisms under biomechanical stress during circulation. We further classified CTCs from different vascular sites into two subsets, namely dormant CTCs and activated CTCs. Dormant CTCs were associated with a non-cycling state and upregulation of EMT/angiogenic signatures and showed stronger prognostic ability for early recurrence than activated CTCs did. Furthermore, we discovered an immune escape mechanism by which CTCs recruited regulatory T cells (Tregs) via expression of CCL5, consequently promoting the formation of an immunosuppressive microenvironment favorable for their survival in the bloodstream and seeding in secondary organs. We proved that MAX, activated through the p38 pathway, was the key transcriptional factor regulating CCL5 overexpression, which was validated by ChIP, luciferase reporter gene and in vitro/vivo knockdown assays. And we further determined that Tregs-derived TGF-β1 can heighten MAX expression, thus amplifying the CCL5 expression. Conclusions: Collectively, our results reveal a previously unappreciated spatial heterogeneity of CTCs and a CTC immune-escape mechanism, which may aid in designing new anti-metastasis therapeutic strategies in HCC.

e16144Background: CD13 is a novel marker for liver cancer stem cells (CSC) that is responsible for therapy resistance in hepatocellular carcinoma (HCC). However, functional characterization of CD13...

e22013 Background: Little is known on the biological variability and kinetics of CTCs in the patients with localized cancer. Herein, we investigated biological characteristics of CTCs at different ...

e15132 Background: Circulating tumor-initiating cells (CTICs) with stem cell-like properties play important roles in tumor metastasis and recurrence. Little is known about CTICs biology and their c...

e22133 Background: Our previous data showed that a preoperative CTC ≥2 was significantly related with relapse of hepatocellular carcinoma (HCC) after surgery. However, how CTCs managed to evade immune surveillance, invade into circulation and reseed in the original organ still remains largely unclear. In this study, we illustrated the pro-tumor effect of Treg infiltration in the context of CTC releasing and reseeding. Methods: Using CellSearch system, 115 HCC patients were tested for CTCs prior to resection. Foxp3+, CD8+ and Granzyme B-positive (GrB+) tumor -infiltrating lymphocytes were evaluated by immunohistochemistry (IHC) in tissue microarrays. For IHC markers, the cutoff for stratification subsets was the median value. The pro-invasiveness properties of Tregs were analyzed in both in vitro and vivo assays. Results: Twenty-two patients with high Tregs and low activated CTLs in tumoral tissues had increased number of CTCs compared to 22 patients with low Tregs and high activated CTLs (6.68 vs. 0.91, P

e22043 Background: CD24 expression has previously been reported in hepatocellular carcinoma (HCC), although little is known about its prognostic significance. The aim of this study is to evaluate the relation of CD24 expression and its prognostic significance in HCC. Methods: CD24 expression in stepwise metastatic HCC cell lines and tumor tissues from 50 HCC patients was investigated by quantitative real-time reverse transcription-PCR and Western blot analyses. The role of CD24 was investigated by depletion CD24 expression in HCC cells through small-interfering RNA. Tumor tissue microarrays of 314 HCC patients who underwent resection between 1997 and 2000 were used to detect the expressions of CD24, β-catenin and PCNA expression. The prognostic significance was assessed using Kaplan-Meier survival estimates and log-rank tests. Results: CD24 was overexpressed in the high metastatic HCC cell line and in tumor tissues of recurrent patients. Depletion of CD24 caused a notable decrease in cell proliferation, migration and invasiveness in vitro. CD24 was confirmed as an independent predictor for overall survival (p+ HCC patients (p=0.024), while there had no significant changes in CD24- patients (p=0.284). Conclusions: High expression levels of CD24 were related with high invasive and metastatic potential, high tumor proliferation status and activation of Wnt/β-catenin pathway. The expression of CD24 provides new prognostic information about HCC prognosis and targeted therapy to CD24+fraction in HCC may comprise a promising anti-recurrence strategy for HCC patients after surgery. No significant financial relationships to disclose.

10713 Background: There were no standard chemotherapy regimen to patients with advanced breast cancer who had been exposed to anthracyclines, vinorelbine and taxanes. The mitomycin-C and cisplatin combination was investigated in this subgroup of patients. Methods: Three-weekly regimen consisted of mitomycin, 6 mg/m2 administered intravenously on day 1, and cisplatin, 25 mg/m2 intravenously on day 1–3. Results: 38 patients aged 25–75 years (median: 46 years) were treated with an overall response rate of 31.6%. The median time to progression (TTP) was 4.0 months. Median TTP for 12 patients with a complete or partial response was 9.0 months, while stable disease and progression of disease 4.0 months, p = 0.002. Grade 3/4 side effects of neutropenia, thrombocytopenia and nausea/vomiting were documented in 4 (10.5%), 4 (10.5%) and 3 (7.9%) patients, respectively. The median overall survival was 13+ months. Conclusions: The mitomycin-C/cisplatin doublet showed antitumor activity for anthracycline-, vinorelbine-, and taxane-resistant breast cancer comparable to other regimens. This well-tolerated regimen provides an affordable option for patients in China. No significant financial relationships to disclose.