Human equilibrative nucleoside transporter 1 expression predicts survival of advanced cholangiocarcinoma patients treated with gemcitabine-based adjuvant chemotherapy after surgical resection

Equilibrative nucleotide transporter ENT3 (SLC29A3): A unique transporter for inherited disorders and cancers

As a crucial gene associated with diseases, the SLC29A3 gene encodes the equilibrative nucleoside transporter 3 (ENT3). ENT3 plays an essential regulatory role in transporting intracellular hydrophilic nucleosides, nucleotides, hydrophilic anticancer and antiviral nucleoside drugs, energy metabolism, subcellular localization, protein stability, and signal transduction. The mutation and inactivation of SLC29A3 are intimately linked to the occurrence, development, and prognosis of various human tumors. Moreover, many hereditary human diseases, such as H syndrome, pigmentary hypertrichosis and non-autoimmune insulin-dependent diabetes mellitus (PHID) syndrome, Faisalabad histiocytosis (FHC), are related to SLC29A3 mutations. This review explores the mechanisms of SLC29A3 mutations and expression alterations in inherited disorders and cancers. Additionally, we compile studies on the inhibition of ENT3, which may serve as an effective strategy to potentiate the anticancer activity of chemotherapy. Thus, the synopsis of genetics, permeant function and drug therapy of ENT3 provides a new theoretical and empirical foundation for the diagnosis, prognosis of evaluation and treatment of various related diseases.

Clinical efficacy of adjuvant treatments for patients with resected biliary tract cancer: a systematic review and network meta-analysis

OBJECTIVE

This study aimed to determine the benefits of adjuvant therapy in patients with resected biliary tract cancer (BTC) and identify the optimal adjuvant treatment scheme.

DESIGN

Systematic review and network meta-analysis.

DATA SOURCES

Studies comparing different adjuvant therapies in patients with BTC were searched in PubMed, Embase, CINAHL, Cochrane Central Register of Controlled Trials and ClinicalTrials.gov databases from inception to December 2021. Additionally, the references were manually searched for the related literature.

MATERIALS AND METHODS

Eligible studies were identified, and data were extracted independently by two authors. A random-effects network meta-analysis was performed using R software. The pooled outcomes of overall survival (OS) and disease-free survival (DFS) were measured using the combined HRs with 95% CIs.

RESULTS

Nineteen eligible studies reporting three types of adjuvant therapies were included in our network meta-analysis. Adjuvant radiotherapy (ART, HR 0.62; 95% CI 0.42 to 0.93), adjuvant chemoradiotherapy (ACRT; HR 0.71; 95% CI 0.54 to 0.83) and adjuvant chemotherapy (ACT; HR 0.84; 95% CI 0.68 to 0.98) were more effective in prolonging OS than that of observation, with no significant difference between the three adjuvant therapies. Moreover, the improvement in DFS was also found in ACRT and ACT compared with that of observation (HR 0.60; 95% CI 0.45 to 0.75; HR 0.82; 95% CI 0.68 to 0.97, respectively). Furthermore, ACRT obtained a slightly better DFS benefit compared with that of ACT (HR 0.73; 95% CI 0.53 to 0.95).

CONCLUSIONS

Our primary results demonstrated that, compared with that of observation, ACRT and ACT after radical resection could provide better OS and DFS benefits in patients with BTC. However, ART only showed improvement in OS, but not in DFS. Due to the lack of head-to-head studies of ACT, ACRT and ART, the above results need to be further verified by prospective randomised controlled trials.

Predictive and Prognostic Properties of Human Equilibrative Nucleoside Transporter 1 Expression in Gemcitabine-Treated Pancreatobiliary Cancer: A Meta-Analysis

Purpose

Gemcitabine, the primary drug for the treatment of pancreatobiliary cancer (PBC), requires human equilibrative nucleoside transporter 1 (hENT1) to enter cells. High tumoral hENT1 expression has been linked with improved survival among patients with PBC treated with gemcitabine; however, this finding has been inconsistent, and studies used different expression assays.

Methods

Databases were reviewed for studies that examined hENT1 and clinical outcome in PBC. Of 307 publications, 34 studies were found that used immunohistochemistry (IHC) with one of eight anti–hENT1 antibody assays. Five studies were excluded for redundancy, and 29 studies underwent detailed review.

Results

On average, 51% of tumor samples had high hENT1 expression (range, 7% to 92%). Among studies that examined hENT1 expression and overall survival (OS), 58% (15 of 26 studies) showed an association between high tumoral hENT1 and improved OS for gemcitabine-treated patients. Among 10D7G2 antibody studies, 88% (seven of eight studies) demonstrated this association. Studies with other antibodies—in particular, SP120 (two of nine studies)—were less consistent. The ability to detect an association between improved OS and high hENT1 was antibody dependent (χ2 P = .0237). An association between high tumoral hENT1 expression and improved disease-free/progression-free survival (DFS/PFS) was demonstrated in 71% of studies (15 of 21 studies). Pooled hazard ratio (HR) analyses of all antibody studies demonstrated a link between high hENT1 tumor expression and improved OS (HR, 0.674; 95% CI, 0.509 to 0.893; P = .006) and DFS/PFS (HR, 0.740; 95% CI, 0.517 to 0.1.059; P = .10). This signal was stronger among studies that used the 10D7G2 antibody in comparison to those in which another antibody was used, with HRs of 0.488 (95% CI, 0.396 to 0.602; P < .001) and 0.410 (95% CI, 0.280 to 0.599; P < .001), respectively.

Conclusion

High tumoral hENT1 expression on IHC with 10D7G2 is a strong and reproducible prognostic marker for improved outcome among gemcitabine-treated patients with PBC.

Nab-Paclitaxel and Gemcitabine as First-line Treatment of Advanced or Metastatic Cholangiocarcinoma: A Phase 2 Clinical Trial

Importance

Gemcitabine with platinum has limited efficacy for treatment of advanced cholangiocarcinoma, necessitating an evaluation of alternative drug combinations. Recent evidence suggests that paclitaxel may potentiate gemcitabine activity.

Objective

To evaluate whether gemcitabine plus nanoparticle albumin-bound (nab)-paclitaxel is safe and effective for treatment of advanced cholangiocarcinoma.

Design, Setting, and Participants

This single-arm, 2-stage, phase 2 clinical trial was conducted at 23 community and academic centers across the United States and Europe. Patients aged 18 years or older enrolled between September 2014 and March 2016 had confirmed advanced or metastatic cholangiocarcinoma without prior systemic therapy, and had an Eastern Cooperative Oncology Group Performance Status score of 0 to 1 and a Child-Pugh score less than 8. Previous surgery, radiation, or liver-directed therapies were permitted.

Interventions

Patients received intravenous nab-paclitaxel, 125 mg/m2, followed by gemcitabine, 1000 mg/m2, on days 1, 8, and 15 of each 28-day treatment cycle until disease progression or unacceptable toxic effects.

Main Outcomes and Measures

The primary outcome was improvement in 6-month progression-free survival (PFS) rate (null and alternative hypotheses of 55% and 70%, respectively) in the evaluable population. Secondary outcomes included median overall survival (OS), PFS, time to progression, best overall response rate, disease control rate, safety and toxicity, and association of change in carbohydrate antigen 19-9 with survival.

Results

Seventy-four patients with a median age of 62 (range, 36-87) years, including 44 women (60%), were enrolled. Patients received a median of 6 (range, 1-18) treatment cycles, and the median follow-up was 10.2 (range, 0.6-27.3) months. The observed 6-month PFS rate of 61% (95% CI, 48%-73%) did not favor the alternative hypothesis. Median PFS was 7.7 (95% CI, 5.4-13.1) months, median OS was 12.4 (95% CI, 9.2-15.9) months, and median time to progression was 7.7 (95% CI, 6.1-13.1) months. The confirmed best overall response rate and disease control rate were 30% and 66%, respectively. Hazard ratios for an association between a change in serum carbohydrate antigen 19-9 and median PFS as well as median OS were 2.02 (95% CI, 0.86-4.75) (P = .10) and 1.54 (95% CI, 0.64-3.71) (P = .34), respectively. The most common treatment-related hematologic and nonhematologic adverse events at grade 3 or higher were neutropenia (43%) and fatigue (14%), respectively.

Conclusions and Relevance

Although the trial did not meet its primary efficacy end point, the results indicate that a nab-paclitaxel plus gemcitabine regimen was well tolerated and may be an alternative option to current therapeutic approaches for advanced cholangiocarcinoma.

Trial Registration

ClinicalTrials.gov identifier: NCT02181634.

Orotate phosphoribosyltransferase as a predictor of benefit from S-1 adjuvant chemotherapy for cholangiocarcinoma patients

BACKGROUND AND AIM

To improve the prognosis of cholangiocarcinoma, we investigated potential biomarkers that may enable the selection of patients for whom postoperative adjuvant chemotherapy is likely effective.

METHODS

The cohort of this retrospective study included 170 surgically resected cholangiocarcinoma patients, 26 with gemcitabine adjuvant chemotherapy (GEM group), 36 with S-1 adjuvant chemotherapy (S-1 group), and 103 receiving no adjuvant chemotherapy (NC group). Propensity score matching was performed to adjust patient backgrounds; 36 patients from the NC group then were selected. Immunohistochemistry of orotate phosphoribosyltransferase (OPRT) and human equilibrative nucleoside transporter 1 (hENT1) was performed to determine the correlation between their expression and disease-free survival (DFS).

RESULTS

After matching, the backgrounds of these three groups were unbiased. No significant improvement of DFS by adjuvant chemotherapy was observed in the whole cohort. However, among the high-OPRT-expression patients, DFS of GEM, S-1, and NC groups at 5 years was 28.8%, 53.8%, and 25.5%, respectively. The DFS of the S-1 group was significantly longer than that of the NC group (P = 0.034). On the other hand, no significant differences in DFS were observed among the low OPRT expression patients. hENT1 expression was shown to have no predictive value. Multivariate analysis of the high-OPRT-expression patients demonstrated that S-1 adjuvant chemotherapy can reduce tumor recurrence (HR, 0.303; P = 0.013).

CONCLUSION

Cholangiocarcinoma patients with high OPRT expression would benefit from postoperative adjuvant S-1 therapy, which increases the DFS. Assessment of OPRT expression may contribute to the optimization of adjuvant chemotherapy for cholangiocarcinoma.

Adjuvant Therapy for Resected Biliary Tract Cancer: ASCO Clinical Practice Guideline

PURPOSE

To develop an evidence-based clinical practice guideline to assist in clinical decision making for patients with resected biliary tract cancer.

METHODS

ASCO convened an Expert Panel to conduct a systematic review of the literature on adjuvant therapy for resected biliary tract cancer and provide recommended care options for this patient population.

RESULTS

Three phase III randomized controlled trials, one phase II trial, and 16 retrospective studies met the inclusion criteria.

RECOMMENDATIONS

Based on evidence from a phase III randomized controlled trial, patients with resected biliary tract cancer should be offered adjuvant capecitabine chemotherapy for a duration of 6 months. The dosing used in this trial is described in the qualifying statements, while it should be noted that the dose of capecitabine may also be determined by institutional and regional practices. Patients with extrahepatic cholangiocarcinoma or gallbladder cancer and a microscopically positive surgical resection margin (R1 resection) may be offered chemoradiation therapy. A shared decision-making approach is recommended, considering the risk of harm and potential for benefit associated with radiation therapy for patients with extrahepatic cholangiocarcinoma or gallbladder cancer. Additional information is available at www.asco.org/gastrointestinal-cancer-guidelines .

Human equilibrative nucleoside transporter 1 (hENT1) expression as a predictive biomarker for gemcitabine chemotherapy in biliary tract cancer

Gemcitabine is a principal chemotherapeutic agent for biliary tract cancer (BTC). Expression of human equilibrative nucleoside transporter 1 (hENT1) is regarded as a potential predictive biomarker for a gemcitabine response in some cancers. This study was conducted to investigate the association between hENT1 expression and the effects of gemcitabine on BTC cell lines and on patients with advanced BTC receiving gemcitabine-based chemotherapy. A total of four BTC cell lines, HuCCT1, SNU-478, SNU-1079, and SNU-1196, were tested. mRNA and protein expression levels of hENT1 were measured by quantitative reverse-transcription polymerase chain reaction and western blotting, respectively. Cell viability after gemcitabine treatment was measured in a chemosensitivity assay. For clinical assessment, 40 patients with unresectable or recurrent BTC who were treated with gemcitabine (1000 mg/m²) and cisplatin (25 mg/m²) between June 2012 and May 2014 were enrolled. Among the four cell lines, SNU1196 showed the highest mRNA and protein levels of hENT1. Expression of hENT1 showed a linear correlation with the log value of the half-maximal inhibitory concentration of gemcitabine. During incubation with gemcitabine, pretreatment with hENT1-specific small interfering RNA (siRNA) resulted in higher cell viability than that in samples pretreated with control siRNA. In a clinical evaluation, the median progression-free survival was 24 and 11 weeks among patients with strong and weak intratumoral hENT1 immunohistochemical staining (P = 0.05), and the median overall survival was 52 and 26 weeks (P = 0.15), respectively. In conclusion, this study showed that increased hENT1 expression is associated with a stronger toxic effect of gemcitabine on BTC cell lines. The clinical outcomes in this study suggest that increased intratumoral hENT1 immunohistochemical staining is a possible biomarker predicting better therapeutic effects of gemcitabine on patients with advanced BTC. Further studies are needed to determine the precise role of hENT1 in BTC.

Outcomes of adjuvant treatments for resectable intrahepatic cholangiocarcinoma: Chemotherapy alone, sequential chemoradiotherapy, or concurrent chemoradiotherapy

BACKGROUND

Prospective randomized trials have not been used to evaluate the efficacy of adjuvant therapies after intrahepatic cholangiocarcinoma (ICC) resection.

METHODS

We analyzed data from the Taiwan Cancer Registry database of ICC patients receiving resection. To compare outcomes, patients with ICC were enrolled and categorized into the following adjuvant treatment modality groups: group 1, concurrent chemoradiotherapy (CCRT); group 2, sequential chemotherapy (CT) and radiotherapy (RT); and group 3, CT alone.

RESULTS

We enrolled 599 patients with resectable ICC who received surgery without distant metastasis. Of these patients, 174 received adjuvant CCRT (group 1), 146 received adjuvant sequential CT and RT (group 2), and 279 received adjuvant CT alone (group 3). Multivariate Cox regression analysis indicated that pathologic stage and positive margin were significantly poor independent predictors. After adjustment for confounders, adjusted hazard ratios (95% confidence intervals) for overall mortality at advanced pathologic stages III and IV were 0.55 (0.41-0.74) and 0.92 (0.70-1.33) in groups 1 and 2, respectively, compared with group 3.

CONCLUSIONS

Adjuvant CCRT improved survival in resected ICC with advanced pathologic stages or a positive margin in early pathologic stages compared with adjuvant CT alone or adjuvant sequential CT and RT.

Tumor-infiltrating mast cells predict prognosis and gemcitabine-based adjuvant chemotherapeutic benefit in biliary tract cancer patients

BACKGROUND

Recent studies have reported TIMs play an important role in tumors progression or regression, but the effect of TIMs in biliary tract cancer remains unclear. The aim of this study is to investigate the prognostic value of tumor infiltrating mast cells (TIMs) and its influence on gemcitabine-based adjuvant chemotherapy (ACT) benefits in biliary tract cancer patients after surgery.

METHODS

TIMs were evaluated by immunohistochemical staining of tryptase in 250 patients with resected gallbladder carcinoma (GBC) or extrahepatic bile duct carcinoma (EBDC) from Zhongshan Hospital. The relationships between TIMs and clinicopathological factors and postoperative prognosis were analyzed respectively.

RESULTS

High TIMs infiltration was significantly correlated with prolonged overall survival (OS). Furthermore, multivariate analysis indicated TNM stage and TIMs as independent prognostic factors for OS. Patients with high TIMs infiltration appeared to significantly benefit from Gemcitabine-based ACT in the discovery and validation cohorts. Spearman analysis identified that TIMs infiltration were positively correlated with anti-tumor CD8+ T cells.

CONCLUSION

TIMs infiltration is an independent favorable prognostic factor in GBC and EBDC patients, which could better stratify patients with different prognosis and predict benefit from gemcitabine-based ACT.

Role of drug-dependent transporter modulation on the chemosensitivity of cholangiocarcinoma

Cholangiocarcinoma (CCA) is a heterogeneous group of malignancies with limited therapeutic options. Curative therapy is limited to surgery whereas chemotherapy treatments are the election option for unresectable or metastatic cholangiocarcinoma. Cisplatin plus gemcitabine is the reference chemotherapy regimen, albeit the contribution to the median overall survival barely reaches one year. Drug transporters are undoubtedly a limiting step for drug bioavailability and have been clearly related to chemoresistance. Several members of the SoLute Carrier (SLC) superfamily involved in the uptake of anticancer drugs used to treat cholangiocarcinoma are downregulated in these tumors. This study shows the increase in the expression of specific drug transporters exerted by cisplatin treatment thereby enhancing their transport activity. Combination treatments of cisplatin with selected drugs as gemcitabine and sorafenib take in by these transporters at the desired combination schedule induced synergy. These data support the concept that proper administration pattern could favor treatment outcome.

Adjuvant chemotherapy for resected biliary tract cancers: a systematic review and meta-analysis

INTRODUCTION

The use of adjuvant treatment (AT) in resected biliary tract cancers (BTC) is still controversial. No efficacy comparison has been performed between chemotherapy (CT) and chemoradiotherapy (CTRT). A systematic review of the available evidence regarding adjuvant chemotherapy (AC) in resected BTC was performed.

METHODS

PubMed, EMBASE, Web of Science, SCOPUS and The Cochrane Library databases were searched for relevant articles published. Only studies including at least 50 patients affected by tumors of gallbladder, intrahepatic, perihilar, and distal bile ducts were considered. Data were pooled using a random-effects model. The primary endpoint of the study was overall survival (OS).

RESULTS

Thirty studies were analyzed with a total of 22,499 patients, 3967 of whom received AC. Eleven cohorts included Western patients and 19 were Asiatic. Surgeries were classified as R0 with negative margins, R1 with positive microscopic and R2 with positive macroscopic margins. Weighted mean OS difference among experimental (AC) and control arm was 4.3 months (95% CI 0.88-7.79, P = 0.014). AC reduced the risk of death by 41% (Hazard ratio [HR] = 0.59, 95% CI 0.49-0.71; P < 0.001).

CONCLUSIONS

AC administration gives an OS benefit in resected BTC. The results of prospective randomized studies are awaited in order to define the standard AT in BTC.

Expression and regulation of drug transporters in vertebrate neutrophils

There remains a need to identify novel pro-resolution drugs for treatment of inflammatory disease. To date, there are no neutrophil-specific anti-inflammatory treatments in clinical use, perhaps due to our lack of understanding of how drugs access this complex cell type. Here we present the first comprehensive description and expression of both major classes of drug transporters, SLC and ABC, in resting human blood neutrophils. Moreover, we have studied the expression of these carriers in the tractable model system, the zebrafish (Danio rerio), additionally examining the evolutionary relationship between drug transporters in zebrafish and humans. We anticipate that this will be a valuable resource to the field of inflammation biology and will be an important asset in future anti-inflammatory drug design.

DCK expression, a potential predictive biomarker in the adjuvant gemcitabine chemotherapy for biliary tract cancer after surgical resection: results from a phase II study

The role of adjuvant therapy following resection of biliary tract cancer (BTC) remains unclear. We therefore evaluated the feasibility and toxicity of adjuvant gemcitabine in patients with BTC. This clinical phase II trial was an open-label, single center, single-arm study. Within 8 weeks after gross complete resection of BTC, patients were started on intravenous infusions of gemcitabine 1000 mg/m² over 30 min on days 1, 8, and 15 of every 28-day cycle. Intratumoral expression of cytidine deaminase (CDA), human equilibrative transporter-1 (hENT1), deoxycytidine kinase (dCK) and ribonucleotide reductase subunit 1 (RRM1) was measured by immunohistochemistry. This study enrolled 72 patients with BTC (26 with gallbladder cancer, 33 with extrahepatic cholangiocarcinoma, and 13 with intrahepatic cholangiocarcinoma). The 2-year recurrence-free survival (RFS) rate was 43% (95% CI, 33–57%). Multivariable analysis showed that DCK expression, vascular invasion, and lymph node metastasis were significantly associated with RFS. Twenty-one (31.8%) were positive for DCK immunoreactivity. The median RFS was 34.95 months for DCK-positive patients, compared with 11.41 months for DCK-negative patients. Although the primary hypothesis of this study, defined as a 2-year RFS of 60%, was not met, intratumoral DCK expression was significantly associated with RFS in patients with resected BTC treated with postoperative gemcitabine chemotherapy. Future randomized controlled trials are warranted.

Adjuvant therapy in biliary tract and gall bladder carcinomas: a review

Biliary tract carcinomas are relatively rare, but are increasingly diagnosed. They comprise several anatomically contiguous sites, so are often grouped together, but they do appear to represent distinct diseases, in part because of anatomical and surgical considerations. Complete upfront surgical resection is generally difficult because these cancers are often diagnosed at relatively advanced stages of disease. Thus, adjuvant therapy is often considered. This paper will review the evidence underpinning current recommendations for adjuvant therapy in biliary carcinomas.

Enhancing Drug Efficacy and Therapeutic Index through Cheminformatics-Based Selection of Small Molecule Binary Weapons That Improve Transporter-Mediated Targeting: A Cytotoxicity System Based on Gemcitabine

The transport of drug molecules is mainly determined by the distribution of influx and efflux transporters for which they are substrates. To enable tissue targeting, we sought to develop the idea that we might affect the transporter-mediated disposition of small-molecule drugs via the addition of a second small molecule that of itself had no inhibitory pharmacological effect but that influenced the expression of transporters for the primary drug. We refer to this as a “binary weapon” strategy. The experimental system tested the ability of a molecule that on its own had no cytotoxic effect to increase the toxicity of the nucleoside analog gemcitabine to Panc1 pancreatic cancer cells. An initial phenotypic screen of a 500-member polar drug (fragment) library yielded three “hits.” The structures of 20 of the other 2,000 members of this library suite had a Tanimoto similarity greater than 0.7 to those of the initial hits, and each was itself a hit (the cheminformatics thus providing for a massive enrichment). We chose the top six representatives for further study. They fell into three clusters whose members bore reasonable structural similarities to each other (two were in fact isomers), lending strength to the self-consistency of both our conceptual and experimental strategies. Existing literature had suggested that indole-3-carbinol might play a similar role to that of our fragments, but in our hands it was without effect; nor was it structurally similar to any of our hits. As there was no evidence that the fragments could affect toxicity directly, we looked for effects on transporter transcript levels. In our hands, only the ENT1-3 uptake and ABCC2,3,4,5, and 10 efflux transporters displayed measurable transcripts in Panc1 cultures, along with a ribonucleoside reductase RRM1 known to affect gemcitabine toxicity. Very strikingly, the addition of gemcitabine alone increased the expression of the transcript for ABCC2 (MRP2) by more than 12-fold, and that of RRM1 by more than fourfold, and each of the fragment “hits” served to reverse this. However, an inhibitor of ABCC2 was without significant effect, implying that RRM1 was possibly the more significant player. These effects were somewhat selective for Panc cells. It seems, therefore, that while the effects we measured were here mediated more by efflux than influx transporters, and potentially by other means, the binary weapon idea is hereby fully confirmed: it is indeed possible to find molecules that manipulate the expression of transporters that are involved in the bioactivity of a pharmaceutical drug. This opens up an entirely new area, that of chemical genomics-based drug targeting.

The efficacy of fluoropyrimidine-based adjuvant chemotherapy on biliary tract cancer after R0 resection

Background

The optimal treatment strategy for biliary tract cancer (BTC) after curative-intent resection remains controversial. The purpose of this study was to evaluate the efficacy of fluoropyrimidine-based adjuvant chemotherapy for BTC patients undergoing microscopically margin-negative (R0) resection.

Methods

We retrospectively analyzed the clinical data of BTC patients who underwent curative-intent R0 resection. Patients were eligible if they received either fluoropyrimidine-based adjuvant chemotherapy or observation after R0 resection.

Results

A total of 153 patients were included. In the entire patient cohort, no significant differences were observed in 5-year overall survival (OS) rates (48.4% vs. 39.6%, P = 0.439) or 3-year recurrence-free survival (RFS) rates (49.1% vs. 39.5%, P = 0.299) between patients who received fluoropyrimidine-based adjuvant chemotherapy or observation. However, for patients with stages II and III BTC, chemotherapy significantly improved 5-year OS rate (52.4% vs. 35.6%, P = 0.002) and 3-year RFS rate (55.5% vs. 39.1%, P = 0.021) compared with observation.

Conclusion

Fluoropyrimidine-based adjuvant chemotherapy may prolong the survival of patients with stages II and III BTC after R0 resection.

Efflux transporter variants as predictors of drug toxicity in lung cancer patients: systematic review and meta-analysis

Chemotherapeutic drugs are underutilized in lung cancer management due in part to serious adverse drug reactions (ADRs).

AIM

With studies revealing an association between interindividual patient ADR variation and efflux transporter variants, we carried out a meta-analysis and systemic review, in order to highlight current knowledge regarding the strength of association between efflux transporter SNPs variants and chemotherapeutic-drug induced ADRs.

MATERIALS & METHODS

Papers were sourced from MEDLINE, Cochrane Library, CINHL, EMBASE, Web of Knowledge, Scopus. The Cochrane Collaboration Risk of Bias Tool v13 was used to evaluate six types of bias domains for each of the publications reviewed.

RESULTS

Twenty-five publications comprising three randomised control trials, two retrospective case-controls and 20 clinical observation studies, totalling 3578 patients, were deemed eligible for review. Of the known efflux drug transporters, we report findings on the ABC members ABCB1, ABCC1, ABCC2, ABCG2, ABCA1, ABCC4 and ABCC5. Meta-analysis showed an decreased risk of irinotecan-induced neutropenia in patients expressing ABCB1 2677G>T/G (odds ratio [OR]: 0.24; 95% CI: 0.1-0.59; p = 0.002) but increased risk for ABCC2 3972T>T (OR: 1.67; 95% CI: 1.01-2.74; p = 0.04). ABCG2 34G>A was associated with a threefold increased risk of irinotecan-induced diarrhea (95% CI: 1.00-6.24; p = 0.05).

CONCLUSION

The majority of studies have identified a role for variants in effluxdrug transporters in contributing to lung cancer treatment-associated ADRs. However, for implementation of use of these transporter genetic variants as prognostic markers for ADR risk, future studies must incorporate larger patient numbers.

Membrane Localization of Human Equilibrative Nucleoside Transporter 1 in Tumor Cells May Predict Response to Adjuvant Gemcitabine in Resected Cholangiocarcinoma Patients

BACKGROUND

The use of gemcitabine as an adjuvant modality for cholangiocarcinoma (CC) is increasing, but limited data are available on predictive biomarkers of response. Human equilibrative nucleoside transporter 1 (hENT-1) is the major transporter involved in gemcitabine intracellular uptake. This study investigated the putative predictive role of hENT-1 localization in tumor cells of CC patients undergoing treatment with adjuvant gemcitabine.

METHODS

Seventy-one consecutive patients with resected CC receiving adjuvant gemcitabine at our center were retrospectively analyzed by immunohistochemistry for hENT-1 localization in tumor cells. The main outcome measure was disease-free survival (DFS). Hazard ratios (HRs) of relapse and associated 95% confidence intervals (CIs) were obtained from proportional hazards regression models stratified on quintiles of propensity score.

RESULTS

Twenty-three (32.4%) cases were negative for hENT-1, 22 (31.0%) were positive in the cytoplasm only, and 26 (36.6%) showed concomitant cytoplasm/membrane staining. Patients with membrane hENT-1 had a longer DFS (HR 0.49, 95% CI 0.24-0.99, p = .046) than those who were negative or positive only in the cytoplasm of tumor cells. Notably, the association between DFS and membrane hENT-1 was dependent on the number of gemcitabine cycles (one to two cycles: HR 0.96, 95% CI 0.34-2.68; three to four cycles: HR 0.99, 95% CI 0.34-2.90; five to six cycles: HR 0.27, 95% CI 0.10-0.77).

CONCLUSION

hENT-1 localization on tumor cell membrane may predict response to adjuvant gemcitabine in CC patients receiving more than four cycles of chemotherapy. Further prospective randomized trials on larger populations are required to confirm these preliminary results, so that optimal gemcitabine-based chemotherapy may be tailored for CC patients in the adjuvant setting.

IMPLICATIONS FOR PRACTICE

Gemcitabine is becoming an increasingly used adjuvant modality in cholangiocarcinoma (CC), but limited data are available on predictive biomarkers of response. In this study, patients receiving more than four cycles of adjuvant gemcitabine and harboring Human equilibrative nucleoside transporter 1 (hENT-1, the major transporter involved in gemcitabine intracellular uptake) on tumor cell membrane had a longer disease-free survival compared with patients negative or positive for hENT-1 only in the cytoplasm of tumor cells. Overall these results may lay the basis for further prospective randomized trials based on a larger population of patients and may prove useful for tailoring appropriate gemcitabine-based chemotherapy for CC patients in the adjuvant setting.

Nucleoside transporter proteins as biomarkers of drug responsiveness and drug targets

Nucleoside and nucleobase analogs are currently used in the treatment of solid tumors, lymphoproliferative diseases, viral infections such as hepatitis and AIDS, and some inflammatory diseases such as Crohn. Two gene families are implicated in the uptake of nucleosides and nucleoside analogs into cells, SCL28 and SLC29. The former encodes hCNT1, hCNT2, and hCNT3 proteins. They translocate nucleosides in a Na⁺ coupled manner with high affinity and some substrate selectivity, being hCNT1 and hCNT2 pyrimidine- and purine-preferring, respectively, and hCNT3 a broad selectivity transporter. SLC29 genes encode four members, being hENT1 and hENT2 the only two which are unequivocally implicated in the translocation of nucleosides and nucleobases (the latter mostly via hENT2) at the cell plasma membrane. Some nucleoside-derived drugs can also interact with and be translocated by members of the SLC22 gene family, particularly hOCT and hOAT proteins. Inter-individual differences in transporter function and perhaps, more importantly, altered expression associated with the disease itself might modulate the transporter profile of target cells, thereby determining drug bioavailability and action. Drug transporter pharmacology has been periodically reviewed. Thus, with this contribution we aim at providing a state-of-the-art overview of the clinical evidence generated so far supporting the concept that these membrane proteins can indeed be biomarkers suitable for diagnosis and/or prognosis. Last but not least, some of these transporter proteins can also be envisaged as drug targets, as long as they can show “transceptor” functions, in some cases related to their role as modulators of extracellular adenosine levels, thereby providing a functional link between P1 receptors and transporters.

Curative-intent surgery for hilar cholangiocarcinoma: prognostic factors for clinical decision making

BACKGROUND

The surgical approach for hilar cholangiocarcinoma (HC) has largely evolved, and increased resectability rates are reported. Large series of patients with resections for HC were published in the last years, and potential predictors for survival were explored. However, the usefulness of these predictors in clinical decision making is controversial.

PURPOSE

The aim of the present review is to explore the main prognostic factors after curative-intent surgery for HC, as emerged from the current literature. Furthermore, the impact of these predictors on clinical decision making is assessed.

CONCLUSION

An aggressive surgical approach has improved the survival rates in patients with HC and implies bile duct resection associated with liver resection and loco-regional lymph node dissection. The AJCC staging system remains the main tool to assess the prognosis after resection of HC. Margin-negative resections and absence of lymph node metastases are the main prognostic factor after curative-intent surgery for HC. Response to chemotherapy is also a prognostic factor. Markers of systemic inflammatory response might predict prognosis of patients with HC, but their usefulness in clinical decision making remains unclear.

Differences in immunohistochemical biomarkers between intra- and extrahepatic cholangiocarcinoma: a systematic review and meta-analysis

BACKGROUND AND AIM

Cholangiocarcinomas of different locations differ in growth patterns, symptoms, treatment response, and survival. Still, they are regarded in many studies as a uniform malignancy. Because intra- (iCCA) and extrahepatic (eCCA) cholangiocarcinoma display such differences, we performed a systematic review and meta-analysis to analyze differences in the immunohistochemical profile of these tumors.

METHODS

In February 2014, we searched the two main medical literature databases MEDLINE and EMBASE. We extracted risk ratios and 95% confidence intervals from the identified studies and performed random-effects model meta-analyses in accordance with PRISMA and REMARK guidelines.

RESULTS

A total of 54 cohort studies, including 4458 patients and studying 102 individual markers met the inclusion criteria. Of the 57 markers that were evaluated in more than 30 iCCA and eCCA patients, 18 showed a statistically significant difference in expression between iCCA and eCCA. Biomarkers expressed differently between iCCA and eCCA included potential targets of therapy: EGFR, c-erbB-2 and VEGF-A. Several markers showed no statistical difference but large 95% confidence intervals, suggesting insufficient sample size.

CONCLUSIONS

This systematic review shows differences in marker expression between iCCA and eCCA. Consequently, patients with iCCA and eCCA may benefit from different treatment strategies.

Cholangiocarcinoma cell line TK may be useful for the pharmacokinetic study of the chemotherapeutic agent gemcitabine

Cholangiocarcinoma is a disease with a poor prognosis. A human cholangiocarcinoma cell line, TK, was previously established to enable further understanding of the disease. We conducted this investigation to determine whether or not the TK line is useful for pharmacokinetic study of the chemotherapeutic agent gemcitabine (GEM). Along with the BXPC3 human pancreatic adenocarcinoma cell line, the sensitivity to and effects on the TK cell line of GEM were compared. The influence of deoxycytidine kinase (dCK) transduction was also comparatively investigated. The effects of GEM in terms of drug sensitivity of the TK cell line, cell cycle and levels of transcripts of key enzymes were comparable to the BXPC3 cell line. Responses to the drug were similar in both cell lines. In contrast to pancreatic carcinoma, cell lines for research on cholangiocarcinoma have been limited. This study suggests the application of the TK cell line to the pharmacokinetic study of the chemosensitization of therapeutic drugs, such as GEM.

Concurrent analysis of human equilibrative nucleoside transporter 1 and ribonucleotide reductase subunit 1 expression increases predictive value for prognosis in cholangiocarcinoma patients treated with adjuvant gemcitabine-based chemotherapy

BACKGROUND

The aim of this study was to investigate the predictive and prognostic values of intratumoural human equilibrative nucleoside transporter 1 (hENT1) and ribonucleotide reductase subunit 1 (RRM1) expression in advanced cholangiocarcinoma patients treated with adjuvant gemcitabine-based chemotherapy (AGC).

METHODS

Intratumoural hENT1 and RRM1 expression levels were investigated immunohistochemically in 127 patients with advanced cholangiocarcinoma who underwent surgical resection (68 with AGC and 59 without AGC). The impacts of hENT1 and RRM1 expression on survival were evaluated.

RESULTS

High intratumoural hENT1 and RRM1 expression levels were observed in 86 (68%) and 67 (53%) patients, respectively. In a multivariate analysis of 68 patients who received AGC, high hENT1 (P=0.044) and low RRM1 expression (P=0.009) were independently associated with prolonged disease-free survival (DFS), whereas low RRM1 expression (P=0.024) was independently associated with prolonged overall survival (OS). Moreover, concurrent high hENT1 and low RRM1 expression was a powerful independent predictor of prolonged DFS (P<0.001) and OS (P=0.001) when the combined classification of hENT1 and RRM1 was introduced.

CONCLUSIONS

Concurrent analysis of hENT1 and RRM1 expression may increase the predictive value of these biomarkers for survival of advanced cholangiocarcinoma patients treated with AGC.

hENT1 expression is predictive of gemcitabine outcome in pancreatic cancer: a systematic review

High human equilibrative nucleoside transporter 1 (hENT1)-expression has shown a survival benefit in pancreatic cancer patients treated with gemcitabine in several studies. The aim of this systematic review was to summarize the results and try to assess the predictive value of hENT1 for determining gemcitabine outcome in pancreatic cancer. Relevant articles were obtained from PubMed, Embase and Cochrane databases. Studies evaluating hENT1-expression in pancreatic tumor cells from patients treated with gemcitabine were selected. Outcome measures were overall survival, disease-free survival (DFS), toxicity and response rate. The database searches identified 10 studies that met the eligibility criteria, and a total of 855 patients were included. Nine of 10 studies showed a statistically significant longer overall survival in univariate analyses in patients with high hENT1-expression compared to those with low expression. In the 7 studies that reported DFS as an outcome measure, 6 had statistically longer DFS in the high hENT1 groups. Both toxicity and response rate were reported in only 2 articles and it was therefore hard to draw any major conclusions. This review provides evidence that hENT1 is a predictive marker for pancreatic cancer patients treated with gemcitabine. Some limitations of the review have to be taken into consideration, the majority of the included studies had a retrospective design, and there was no standardized scoring protocol for hENT1-expression.

Elevated perioperative serum CA 19-9 levels are independent predictors of poor survival in patients with resectable cholangiocarcinoma

BACKGROUND AND OBJECTIVES

Identification of prognostic markers is important to establish a perioperative therapeutic strategy for resectable cholangiocarcinoma (CC). The aim of this study was to investigate whether perioperative serum carbohydrate antigen 19-9 (CA19-9) levels can predict survival of patients who underwent surgical resection for CC.

METHODS

The study included 106 patients who underwent surgical resection for CC. Serum CA19-9 levels were measured preoperatively after biliary drainage and postoperatively about 4 weeks after surgery. The association of clinicopathological factors (including perioperative serum CA19-9 levels) with overall survival (OS) was analyzed with univariate and multivariate analyses.

RESULTS

Differences in OS were significant between groups divided on the basis of two preoperative CA19-9 cutoff values (in U/ml) of 37 and 200 and three postoperative CA19-9 cutoff values (in U/ml) of 37, 100, and 200. In multivariate analysis, absence of postoperative adjuvant chemotherapy (P = 0.002), lymph node metastasis (P = 0.0002), preoperative CA19-9 (≥ 200 IU/ml) (P = 0.03), and postoperative CA19-9 (≥ 37 IU/ml) (P < 0.0001) were identified as independent predictors of poor OS.

CONCLUSION

Both pre- and postoperative serum CA19-9 levels predict the survival of patients with resectable CC, and may contribute to the establishment of a new therapeutic strategy.

Uptake carriers and oncology drug safety

Members of the solute carrier (SLC) family of transporters are responsible for the cellular influx of a broad range of endogenous compounds and xenobiotics in multiple tissues. Many of these transporters are highly expressed in the gastrointestinal tract, liver, and kidney and are considered to be of particular importance in governing drug absorption, elimination, and cellular sensitivity of specific organs to a wide variety of oncology drugs. Although the majority of studies on the interaction of oncology drugs with SLC have been restricted to the use of exploratory in vitro model systems, emerging evidence suggests that several SLCs, including OCT2 and OATP1B1, contribute to clinically important phenotypes associated with those agents. Recent literature has indicated that modulation of SLC activity may result in drug-drug interactions, and genetic polymorphisms in SLC genes have been described that can affect the handling of substrates. Alteration of SLC function by either of these mechanisms has been demonstrated to contribute to interindividual variability in the pharmacokinetics and toxicity associated with several oncology drugs. In this report, we provide an update on this rapidly emerging field.

Do hENT1 and RRM1 predict the clinical benefit of gemcitabine in pancreatic cancer?

Gemcitabine is a nucleoside analog that is indicated in the treatment of pancreatic cancer. In order to provide a better use of this drug, the search for immunohistological markers is a hot topic in the field of pancreatic cancer. In particular, the use of nucleoside transporter hENT1 and the intracellular target of gemcitabine RRM1 are current subjects for discussion. We have analyzed the majority of studies of hENT1 and RRM1 on pancreatic cancer, and will discuss the further directions that might be followed in order to integrate these proteins in routine clinical practice. The data that is currently available would benefit from the completion of well-designed randomized trials in order to confirm the clinical value of hENT1 and RRM1 as biomarkers in pancreatic cancer patients.

Genomic polymorphisms of SLC29A3 associated with overall survival in advanced non-small-cell lung cancer treated with gemcitabine

Several polymorphisms in the genes involved in drug metabolism or elimination are known to be associated with pharmacokinetic or pharmacodynamic variability, but their correlations with overall survival (OS) and response rate (RR) in lung cancer have been unknown. This prospective study was to investigate whether genetic polymorphisms could influence OS and RR in advanced or metastatic non-small-cell lung cancer (NSCLC) patients treated with third-generation cytotoxic chemotherapy. Three hundred and sixty-four patients with chemotherapy naïve stage IIIB or IV NSCLC, receiving standard first-line chemotherapy, were eligible for this study. The DNA samples were extracted from peripheral blood mononuclear cells before treatment and single nucleotide polymorphisms of solute carrier family 29 member 3 SLC29A3 (rs10999776), SULT1E1 (rs4149525), and TBXAS1 (rs2267703), a category of drug-metabolizing enzymes or transporters were analyzed. Statistical analyses were performed by the log-rank test and Cox proportional hazards model. Patients with SLC29A3 C/T+T/T genotype had longer overall survival (median OS 12.3 months, 95 % CI 11.0-13.6 months) than those with C/C genotype (median OS 11.0 months, 95 % CI 9.9-12.1 months, P = 0.030 for log-rank test). More evidently significant association was found between the SLC29A3 polymorphism and overall survival in patients treated with gemcitabine-based chemotherapy (C/T+T/T versus C/C: median OS 12.0 months, 95 % CI 10.5-13.5 months versus median OS 10.0 months, 95 % CI 9.0-11.0 months, P = 0.027 for log-rank test). No association between the other two genetic polymorphisms and OS was observed. Genes involved in the drug metabolism or elimination (SLC29A3) may be new prognostic biomarkers for patients with advanced NSCLC who receive gemcitabine as the first-line chemotherapy and may unveil an unexplored molecular pathway correlated with the drug response and further may be predictive biomarkers for these patients.

Perineural invasion in extrahepatic cholangiocarcinoma: prognostic impact and treatment strategies

BACKGROUND

The significance of perineural invasion in extrahepatic cholangiocarcinoma has not been fully elucidated. This study aims to determine the prognostic impact of and optimal treatment strategy for perineural invasion in patients with extrahepatic cholangiocarcinoma.

METHODS

Medical records of 133 patients with extrahepatic cholangiocarcinoma who underwent curative resection were reviewed retrospectively. Ninety-eight patients had perineural invasion and 35 patients did not. Univariate and multivariate survival analyses were performed to clarify the prognostic impact of and optimal treatment strategy for perineural invasion.

RESULTS

Only tumor differentiation (P=0.024) was independently associated with perineural invasion in the multivariate logistic regression model. Multivariate survival analysis revealed that perineural invasion (P=0.002), resection margin status(P=0.016), and International Union Against Cancer (UICC) pT factor (P=0.015) were independent prognostic factors of overall survival. Overall 5-year survival rates for patients with and without perineural invasion were 28 and 74 %, respectively. Among 98 patients with perineural invasion, the use of adjuvant chemotherapy (P=0.003), lymph node status (P=0.015), resection margin status (P=0.008), and UICC pT factor (P=0.016) were independently associated with overall survival by multivariate analysis. Overall 5-year survival rates for patients with perineural invasion who did and did not receive adjuvant chemotherapy were 33 and 21 %, respectively (P=0.023).

CONCLUSIONS

Perineural invasion is a potent prognostic factor in extrahepatic cholangiocarcinoma. Adjuvant chemotherapy may improve the overall survival of patients with perineural invasion.

Prognostic predictive values of gemcitabine sensitivity-related gene products for unresectable or recurrent biliary tract cancer treated with gemcitabine alone

BACKGROUND

Gemcitabine is a pyrimidine nucleoside analog that is a commonly used chemotherapeutic agent for unresectable or recurrent biliary tract cancer (BTC). Several molecules involved in gemcitabine metabolism, including human equilibrative nucleoside transporter (hENT1), deoxycytidine kinase (dCK), and ribonucleotide reductase subunit M1 (RRM1), have been investigated as predictive biomarkers of gemcitabine efficacy, mostly in pancreatic cancer. The aim of this study is to clarify which biomarker is the most reliable among hENT1, dCK, and RRM1 to predict survival in patients with advanced BTC treated with gemcitabine alone.

METHODS

The analysis was performed on samples from 28 patients with unresectable or recurrent BTC who were treated with gemcitabine alone as first-line therapy. The starting date of overall survival (OS) and progression-free survival (PFS) was defined as the date of first treatment with gemcitabine. Intratumoral hENT1, dCK, and RRM1 expressions were examined by immunohistochemistry.

RESULTS

The expressions of hENT1, dCK, and RRM1 had no significant relationships with age, gender, primary tumor site, recurrence/unresectable, or histological type. Among the three molecules, only hENT1 expression was a significant factor affecting OS and PFS in univariate analysis; OS was 11.4 months for high hENT1 expression versus 5.7 months for low, P = 0.0057; PFS was 7.7 months for high versus 2.5 months for low, P = 0.0065. Multivariate analyses also identified hENT1 expression as an independent predictive factor for OS.

CONCLUSIONS

hENT1 is the most reliable predictive marker of survival in patients with advanced BTC treated with gemcitabine.

Finding novel pharmaceuticals in the systems biology era using multiple effective drug targets, phenotypic screening and knowledge of transporters: where drug discovery went wrong and how to fix it

Despite the sequencing of the human genome, the rate of innovative and successful drug discovery in the pharmaceutical industry has continued to decrease. Leaving aside regulatory matters, the fundamental and interlinked intellectual issues proposed to be largely responsible for this are: (a) the move from 'function-first' to 'target-first' methods of screening and drug discovery; (b) the belief that successful drugs should and do interact solely with single, individual targets, despite natural evolution's selection for biochemical networks that are robust to individual parameter changes; (c) an over-reliance on the rule-of-5 to constrain biophysical and chemical properties of drug libraries; (d) the general abandoning of natural products that do not obey the rule-of-5; (e) an incorrect belief that drugs diffuse passively into (and presumably out of) cells across the bilayers portions of membranes, according to their lipophilicity; (f) a widespread failure to recognize the overwhelmingly important role of proteinaceous transporters, as well as their expression profiles, in determining drug distribution in and between different tissues and individual patients; and (g) the general failure to use engineering principles to model biology in parallel with performing 'wet' experiments, such that 'what if?' experiments can be performed in silico to assess the likely success of any strategy. These facts/ideas are illustrated with a reasonably extensive literature review. Success in turning round drug discovery consequently requires: (a) decent systems biology models of human biochemical networks; (b) the use of these (iteratively with experiments) to model how drugs need to interact with multiple targets to have substantive effects on the phenotype; (c) the adoption of polypharmacology and/or cocktails of drugs as a desirable goal in itself; (d) the incorporation of drug transporters into systems biology models, en route to full and multiscale systems biology models that incorporate drug absorption, distribution, metabolism and excretion; (e) a return to 'function-first' or phenotypic screening; and (f) novel methods for inferring modes of action by measuring the properties on system variables at all levels of the 'omes. Such a strategy offers the opportunity of achieving a state where we can hope to predict biological processes and the effect of pharmaceutical agents upon them. Consequently, this should both lower attrition rates and raise the rates of discovery of effective drugs substantially.

The promiscuous binding of pharmaceutical drugs and their transporter-mediated uptake into cells: what we (need to) know and how we can do so

A recent paper in this journal sought to counter evidence for the role of transport proteins in effecting drug uptake into cells, and questions that transporters can recognize drug molecules in addition to their endogenous substrates. However, there is abundant evidence that both drugs and proteins are highly promiscuous. Most proteins bind to many drugs and most drugs bind to multiple proteins (on average more than six), including transporters (mutations in these can determine resistance); most drugs are known to recognise at least one transporter. In this response, we alert readers to the relevant evidence that exists or is required. This needs to be acquired in cells that contain the relevant proteins, and we highlight an experimental system for simultaneous genome-wide assessment of carrier-mediated uptake in a eukaryotic cell (yeast).

Perihilar cholangiocarcinoma: a surgeon's viewpoint on current topics

Perihilar cholangiocarcinomas are defined anatomically as "tumors that are located in the extrahepatic biliary tree proximal to the origin of the cystic duct". However, as the boundary between the extrahepatic and intrahepatic bile ducts is not well defined, perihilar cholangiocarcinomas potentially include two types of tumors: one is the "extrahepatic" type, which arises from the large hilar bile duct, and the other is the "intrahepatic" type, which has an intrahepatic component with the invasion of the hepatic hilus. The new TNM staging system published by the International Union Against Cancer (UICC) has been well revised with regard to perihilar cholangiocarcinoma, but it still lacks stratification of patient prognosis and has little applicability for assessing the feasibility of surgical treatment; therefore, further refinement is essential. Most patients with perihilar cholangiocarcinomas present with jaundice, and preoperative biliary drainage is mandatory. Previously, percutaneous transhepatic biliary drainage was used in many centers; however, it is accepted that endoscopic naso-biliary drainage is the most suitable method of preoperative drainage. Portal vein embolization is now widely used as a presurgical treatment for patients undergoing an extended hepatectomy to minimize postoperative liver dysfunction. The surgical resection of a perihilar cholangiocarcinoma is technically demanding and continues to be the most difficult challenge for hepatobiliary surgeons. Because of advances in diagnostic and surgical techniques, surgical outcomes and survival rates after resection have steadily improved. However, survival, especially for patients with lymph node metastasis, is still unsatisfactory, and the establishment of adjuvant chemotherapy is necessary. Further synergy of endoscopists, radiologists, oncologists, and surgeons is required to conquer this intractable disease.