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One of the most encouraging developments in oncology has been the success of BRAF inhibitors in BRAF-mutant melanoma. However, in contrast to its striking efficacy in BRAF-mutant melanomas, BRAF inhibitor monotherapy is ineffective in BRAF-mutant colorectal cancer. Although many studies on BRAF inhibitor resistance in colorectal cancer have focused on mechanisms underlying the reactivation of the EGFR/RAS/RAF/MEK/ERK pathway, the current study focuses on identifying novel adaptive signaling mechanisms, a fresh angle on colorectal cancer resistance to BRAF inhibition. We found that treatment with BRAF inhibitors (both current and next-generation BRAF inhibitors) upregulated the Wnt/β-catenin pathway in BRAFV600E-mutant colorectal cancer cell lines through activating the cytoplasmic tyrosine kinase focal adhesion kinase (FAK). The results showed that FAK activation upon BRAF inhibitor treatment did not require EGFR or ERK1/2 activation, implying that BRAF inhibitor treatment-induced hyperactivation of Wnt signaling is “pathway reactivation”-independent. BRAF inhibition–induced Wnt pathway activation was further validated in preclinical models of BRAFV600E-mutant colorectal cancer, including cell line xenograft model and a patient-derived xenograft model. Combined inhibition of BRAF/Wnt pathways or BRAF/FAK pathways exerted strong synergistic antitumor effects in cell culture model and mouse xenograft model. Overall, the current study has identified activation of the Wnt/β-catenin pathway as a novel fundamental cause of colon cancer resistance to BRAF inhibition. Our results suggest that although complete vertical pathway blockade is pivotal for effective and durable control of BRAF-mutant colorectal cancer, cotargeting parallel adaptive signaling—the Wnt/β-catenin pathway—is also essential. Mol Cancer Ther; 17(4); 806–13. ©2017 AACR.

Figure legends

Supplementary Figure 1: BRAF inhibitor increase nuclear β-catenin in BRAF-mutant CRC cells; Supplementary Figure 2: Wnt/β-catenin pathway activation induced by BRAF inhibitor is dependent on FAK; Supplementary Figure 3: FAK inhibitor synergizes with BRAF inhibitor in the treatment of BRAF-mutant CRC; Supplementary Figure 4: BRAF inhibitor activates FAK and Wnt/β-catenin pathway in patient-derived xenografts (PDX) model; Supplementary Figure 5: Cyclin D1 is induced by BRAF inhibitor through FAK/β-catenin axis; Supplementary Figure 6: BRAF inhibitor combined with FAK inhibitor or β-catenin inhibitor strongly inhibited colony formation; Supplementary Figure 7: Next generation BRAF inhibitors activate FAK and increase cellular level of β-catenin

Background and study aims The role of the digital single-operator pancreatoscopy (D-SOP) with electrohydraulic (EHL) or laser lithotripsy (LL) in treating pancreatic ductal stones is unclear. We investigated the safety and efficacy of D-SOP with EHL or LL in patients with obstructing pancreatic duct stones. Patients and methods Retrospective analysis of 109 patients who underwent D-SOP for pancreatic stones at 17 tertiary centers in the United States and Europe from February 2015 to September 2017. Logistic regression was performed to identify factors associated with the need for more than one D-SOP with EHL/LL. Results Most patients were males (70.6 %),mean age 54.7 years. Fifty-nine (54.1 %) underwent EHL and 50 (45.9 %) underwent LL. Mean procedure time was longer in the EHL group (74.4 min vs 53.8 min; P Conclusion D-SOP with EHL or LL is effective and safe in patients with pancreatic ductal stones.

Background & Aims: Identification and validation of new functionally relevant and pharmacologically actionable targets for pancreatic ductal adenocarcinoma (PDAC) remains a great challenge. Premalignant acinar cell reprogramming (acinar-to-ductal metaplasia [ADM]) is a precursor of pancreatic intraepithelial neoplasia (PanIN) lesions that can progress to PDAC. This study investigated the role of proline-rich tyrosine kinase 2 (PYK2) in mutant Kras-induced and pancreatitis-associated ADM and PanIN formation, as well as in PDAC maintenance. Methods: Genetically engineered mouse models of mutant Kras (glycine 12 to aspartic acid) and Pyk2 deletion were used for investigating the role of PYK2 in PDAC genesis in mice. In vitro ADM assays were conducted using primary pancreatic acinar cells isolated from mice. Immunohistochemistry, immunofluorescence, and a series of biochemical experiments were used to investigate upstream regulators/downstream targets of PYK2 in pancreatic carcinogenesis. PDAC cell line xenograft experiments were performed to study the role of PYK2 and its downstream target in PDAC maintenance. Results: PYK2 was increased substantially in ADM lesions induced by mutant Kras or inflammatory injury. Pyk2 deletion remarkably suppressed ADM and PanIN formation in a mutant Kras-driven and pancreatitis-associated PDAC model, whereas PYK2 knockdown substantially inhibited PDAC cell growth in vitro and in nude mice. This study uncovered a novel yes-associated protein 1/transcriptional co-activator with PDZ binding motif/signal transducer and activator of transcription 3/PYK2/β-catenin regulation axis in PDAC. Our results suggest that PYK2 contributes to PDAC genesis and maintenance by activating the Wnt/β-catenin pathway through directly phosphorylating β-cateninY654. Conclusions: The current study uncovers PYK2 as a novel downstream effector of mutant KRAS signaling, a previously unrecognized mediator of pancreatitis-induced ADM and a novel intervention target for PDAC. Keywords: Acinar-to-Ductal Metaplasia, Inflammation, KRAS, Wnt/β-Catenin Signaling

One of the most encouraging developments in oncology has been the success of BRAF inhibitors in BRAF-mutant melanoma. However, in contrast to its striking efficacy in BRAF-mutant melanomas, BRAF inhibitor monotherapy is ineffective in BRAF-mutant colorectal cancer. Although many studies on BRAF inhibitor resistance in colorectal cancer have focused on mechanisms underlying the reactivation of the EGFR/RAS/RAF/MEK/ERK pathway, the current study focuses on identifying novel adaptive signaling mechanisms, a fresh angle on colorectal cancer resistance to BRAF inhibition. We found that treatment with BRAF inhibitors (both current and next-generation BRAF inhibitors) upregulated the Wnt/β-catenin pathway in BRAFV600E-mutant colorectal cancer cell lines through activating the cytoplasmic tyrosine kinase focal adhesion kinase (FAK). The results showed that FAK activation upon BRAF inhibitor treatment did not require EGFR or ERK1/2 activation, implying that BRAF inhibitor treatment-induced hyperactivation of Wnt signaling is “pathway reactivation”-independent. BRAF inhibition–induced Wnt pathway activation was further validated in preclinical models of BRAFV600E-mutant colorectal cancer, including cell line xenograft model and a patient-derived xenograft model. Combined inhibition of BRAF/Wnt pathways or BRAF/FAK pathways exerted strong synergistic antitumor effects in cell culture model and mouse xenograft model. Overall, the current study has identified activation of the Wnt/β-catenin pathway as a novel fundamental cause of colon cancer resistance to BRAF inhibition. Our results suggest that although complete vertical pathway blockade is pivotal for effective and durable control of BRAF-mutant colorectal cancer, cotargeting parallel adaptive signaling—the Wnt/β-catenin pathway—is also essential. Mol Cancer Ther; 17(4); 806–13. ©2017 AACR.

Background and study aims Little is known about the learning curve for image interpretation in volumetric laser endomicroscopy (VLE) in Barrett’s esophagus (BE). The goal of this study was to calculate the learning curve, competence of image interpretation, sensitivity, specificity, and accuracy of VLE among novice users. Methods 31 novice users viewed 96 VLE images electronically at three academic institutions after a brief training session. There were 24 images of each histologic type: normal gastric cardia, normal esophageal squamous epithelium, non-neoplastic BE, and neoplastic BE. The users were asked to identify the correct tissue type and level of confidence. The cumulative summation (CUSUM) technique was used to construct a learning curve. Results 22 (71 %) of the physicians achieved VLE interpretation competency during their 96-slide review. Half of the physicians achieved competency at 65 images (95 % confidence interval [CI] 45 – 85). There was a statistically significant association between confidence in diagnosis and selecting the correct histologic tissue type (P Conclusion The majority of novice users achieved competence in image interpretation of VLE for BE, using a pre-selected image set, with a favorable learning curve after a brief training session. An electronic review of VLE images, prior to real-time use of VLE, is encouraged.

About 76% of patients with lung adenocarcinoma harbor activating mutations in the receptor tyrosine kinase (RTK)/RAS/RAF pathways, leading to aberrant activation of the mitogen‐activated protein kinase (MAPK) pathways particularly the MAPK/ERK pathway. However, many lung adenocarcinomas lacking these genomic mutations also display significant MAPK pathway activation, suggesting that additional MAPK pathway alterations remain undetected. This study has identified serine/threonine kinase mitogen‐activated protein 4 kinase 4 (MAP4K4) as a novel positive regulator of MAPK/ERK signaling in lung adenocarcinoma. The results showed that MAP4K4 was drastically elevated in lung adenocarcinoma independently of KRAS or EGFR mutation status. Knockdown of MAP4K4 inhibited proliferation, anchorage‐independent growth and migration of lung adenocarcinoma cells, and also inhibited human lung adenocarcinoma xenograft growth and metastasis. Mechanistically, we found that MAP4K4 activated ERK through inhibiting protein phosphatase 2 activity. Our results further showed that downregulation of MAP4K4 prevented ERK reactivation in EGFR inhibitor erlotinib‐treated lung adenocarcinoma cells. Together, our findings identify MAP4K4 as a novel MAPK/ERK pathway regulator in lung adenocarcinoma that is required for lung adenocarcinoma maintenance.

Introduction Little is known about the additive yield of wide-area transepithelial sampling with computer-assisted three-dimensional analysis (WATS-3D) after a thorough examination with advanced imaging. The aim was to evaluate the adjunctive yield of WATS-3D after advanced imaging. Methods This is an observational cohort study from January 2017 to December 2018 for consecutive patients who underwent an examination that consists of high-definition white light endoscopy (HDWLE), narrow-band imaging (NBI), volumetric laser endomicroscopy (VLE), and Seattle protocol (SP) biopsies (collectively termed HDWLE-NBI-VLE-SP examination). Raised lesions were removed by endoscopic resection. Areas suspicious for dysplasia on NBI and VLE were biopsied. This was followed by random biopsies and WATS-3D brush biopsies. Results One hundred thirty-eight cases were included in this study. Thirty-five cases (25% of the total) were identified as some degree of dysplasia on the HDWLE-NBI-VLE-SP examination. Adjunctive use of WATS-3D yielded an additional 12 new cases of dysplasia (9 with crypt dysplasia and 3 with low-grade dysplasia [LGD]), for added yield of 34.3% (=12/35, 95% confidence interval 14.6%-62.2%). When restricting the analysis to LGD and higher, 21 dysplastic cases (15% of the total cases) were identified by HDWLE-NBI-VLE-SP, while WATS-3D found 4 additional new cases (3 with LGD and 1 with high-grade dysplasia) for an added yield of 19% (=4/21, 95% confidence interval 0.6%-45.7%). Discussion The addition of WATS-3D to an already thorough examination with HDWLE-NBI-VLE-SP may increase the yield of dysplasia detection.

Purpose: To evaluate the safety and efficacy of dexamethasone intravitreal implant (Ozurdex, DEX implant) 0.7 and 0.35 mg in the treatment of patients with diabetic macular edema (DME).Design: Two randomized, multicenter, masked, sham-controlled, phase III clinical trials with identical protocols were conducted. Data were pooled for analysis.Participants: Patients (n = 1048) with DME, best-corrected visual acuity (BCVA) of 20/50 to 20/200 Snellen equivalent, and central retinal thickness (CRT) of ≥300 μm by optical coherence tomography.Methods: Patients were randomized in a 1:1:1 ratio to study treatment with DEX implant 0.7 mg, DEX implant 0.35 mg, or sham procedure and followed for 3 years (or 39 months for patients treated at month 36) at ≤40 scheduled visits. Patients who met retreatment eligibility criteria could be retreated no more often than every 6 months.Main Outcome Measures: The predefined primary efficacy endpoint for the United States Food and Drug Administration was achievement of ≥15-letter improvement in BCVA from baseline at study end. Safety measures included adverse events and intraocular pressure (IOP).Results: Mean number of treatments received over 3 years was 4.1, 4.4, and 3.3 with DEX implant 0.7 mg, DEX implant 0.35 mg, and sham, respectively. The percentage of patients with ≥15-letter improvement in BCVA from baseline at study end was greater with DEX implant 0.7 mg (22.2%) and DEX implant 0.35 mg (18.4%) than sham (12.0%; P ≤ 0.018). Mean average reduction in CRT from baseline was greater with DEX implant 0.7 mg (−111.6 μm) and DEX implant 0.35 mg (−107.9 μm) than sham (−41.9 μm; P < 0.001). Rates of cataract-related adverse events in phakic eyes were 67.9%, 64.1%, and 20.4% in the DEX implant 0.7 mg, DEX implant 0.35 mg, and sham groups, respectively. Increases in IOP were usually controlled with medication or no therapy; only 2 patients (0.6%) in the DEX implant 0.7 mg group and 1 (0.3%) in the DEX implant 0.35 mg group required trabeculectomy.Conclusions: The DEX implant 0.7 mg and 0.35 mg met the primary efficacy endpoint for improvement in BCVA. The safety profile was acceptable and consistent with previous reports.

BACKGROUND AND AIMS Endoscopic ultrasound-guided transmural drainage using lumen apposing metal stents (LAMSs) is becoming a popular and promising therapeutic approach for drainage of intra-abdominal fluid collections. There has been an increasing number of studies evaluating LAMS for drainage of pancreatic pseudocysts (PP), walled-off pancreatic necrosis (WOPN), and gallbladder (GB) drainage. The aim of this meta-analysis is to analyze the literature to date regarding the clinical success, technical success, and adverse events of LAMS in treatment of pancreatic fluid collections and GB drainage. METHODS A comprehensive search of multiple literature databases through November 2016 was performed. Human studies with at least 10 subjects that examined the clinical success, technical success, and adverse events of LAMS in treating PP, WOPN, and GB drainage were included. RESULTS A total of 993 patients (608-WOPN; 204-PP; 181-GB drainage) underwent drainage from 20 trials. For drainage of WOPN, the pooled technical success was 98.9% [95% confidence interval (CI): 98.2% to 99.7%] and clinical success was 90% (95% CI: 87% to 93%) (τ=0.001). For drainage of PP, the pooled technical success was 97% (95% CI: 95% to 99%) and clinical success was 98% (95% CI: 96% to 100%), (τ=0.001). For GB drainage, the pooled technical success was 95% (95% CI: 91% to 99%) and clinical success was 93% (95% CI: 90% to 97%), (τ=0.001). Total adverse events occurred in 11% of patients with higher complication rates observed in GB drainage. There was no evidence of publication bias in this meta-analysis. CONCLUSIONS Endoscopic ultrasound-guided transmural drainage using LAMS is becoming a widely accepted therapeutic approach for the treatment of PP, WOPN, and GB drainage with high clinical and technical success rates and acceptable adverse events. Further prospective randomized trials reporting long-term clinical efficacy and cost-effectiveness are needed to validate LAMS as a therapeutic modality for pancreatic and GB collections.

Rectal indomethacin is a popular chemopreventive agent to help prevent post-ERCP pancreatitis (PEP). Previous meta-analyses have shown an overall protective effect for PEP in average-risk and high-risk patients. However, these meta-analyses are limited by a small number of studies. Recently, more trials have been published addressing this issue. The aim is to determine whether rectal indomethacin prevents PEP in average-risk and high-risk groups, after incorporating these new data.A comprehensive search of multiple literature databases in April 2016 was performed. Human prospective randomized controlled trials with placebo controls that examined the effect of rectally administered indomethacin on the incidence of PEP were included.A total of 8 trials between 2007 and 2016 (n = 3778) were included. No significant publication bias existed. All studies used similar criteria to detect pancreatitis. Random effects model meta-analysis showed that the rate of PEP was significantly lower using indomethacin compared with placebo (relative risk, 0.43; 95% confidence interval, 0.28-0.65; P .001) in high-risk patients. There was no significant statistical or clinical heterogeneity. Among average-risk patients, the rate of PEP was similar (non-significant) between the indomethacin and placebo groups (relative risk, 0.74; 95% confidence interval, 0.52-1.07; P = .115). The result of the main outcome remained robust in multiple sensitivity analyses.Rectal indomethacin given before or after ERCP is protective against PEP in high-risk patients versus placebo; however, it is not protective in average-risk patients versus placebo.

Since nearly 100% of pancreatic ductal adenocarcinoma (PDAC) carried mutational activation of KRAS, KRAS and its effectors are theoretically ideal candidates for PDAC therapeutic intervention. Unfortunately, attempts to directly inhibit oncogenic KRAS or known RAS effector pathways have been either unsuccessful or proven ineffective. As a result, there is significant interest in identifying novel downstream effectors of oncogenic KRAS signaling that could be amenable to pharmacologic intervention. Our results suggest that PYK2 (proline-rich tyrosine kinase 2, a non-receptor cytoplasmic tyrosine kinase) is a novel downstream mediator of mutant KRAS signaling and a new actionable therapeutic target for PDAC. Specifically, our studies revealed: (1) mutant KRAS activated PYK2 gene transcription in a YAP1 (Yes-associated protein 1)-dependent manner. Hippo pathway effector YAP1 is a transcription cofactor and a powerful downstream effector of mutant KRAS in PDAC. (2) PYK2 levels were drastically elevated in mouse PanINs (pancreatic intraepithelial neoplasia) and human PDAC tissues. (3) Functionally, Whole-body deletion of PYK2, even heterozygous deletion, remarkably suppressed PanIN formation and progression to PDAC in the Pdx1-Cre KRASG12D mice model. Further, knockdown of PYK2 abrogated tumor growth in a PDAC cell line xenograft model, indicating that PYK2 is required for PDAC maintenance. (4) Mechanistically, PYK2 directly phosphorylated β-catenin at tyrosine (Y) 654 to promote the Wnt/β-catenin pathway and increased RelA/p65 phosphorylation at serine (S) 536 to promote the NF-κB pathway in PDAC cells. Because both pathways are essential for PDAC development in mice, we propose that PYK2 contributes to PDAC through upregulating Wnt/β-catenin and NF-κB pathways. Overall, our study has revealed that PYK2 is a new actionable target for treating PDAC. Citation Format: Jing Hu, Chenxi Gao, Guangming Chen, Xuan Gao, Dennis H. Zhang, Shih-Fan Kuan. PYK2 as a therapeutic target for pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-310. doi:10.1158/1538-7445.AM2017-LB-310

Primary hepatocytes undergo phenotypic dedifferentiation upon isolation from liver that typically includes down regulation of uptake transporters and up regulation of efflux transporters. Culturing cells between layers of collagen in a three‐dimensional (3D) “sandwich” is reported to restore hepatic phenotype. This report examines how 3D culturing affects accumulation of fluorophores, the cytotoxic response to bile acids and drugs, and whether cell to cell differences in fluorescent anion accumulation correlate with differences in cytotoxicity. Hepatocytes were found to accumulate fluorescent bile acid (FBA) at significantly higher levels than the related fluorophores, carboxyfluorescein diacetate, (4.4‐fold), carboxyfluorescein succinimidyl ester (4.8‐fold), and fluorescein (30‐fold). In 2D culture, FBA accumulation decreased to background levels by 32 h, Hoechst nuclear accumulation strongly decreased, and nuclear diameter increased, indicative of an efflux phenotype. In 3D culture, FBA accumulation was maintained through 168 h but at 1/3 the original intensity. Cell to cell differences in accumulated FBA did not correlate with levels of liver zonal markers L‐FBAP (zone 1) or glutamine synthetase (zone 3). Cytotoxic response to hydrophobic bile acids, acetaminophen, and phalloidin was maintained in 3D culture, and cells with higher FBA accumulation showed 12–18% higher toxicity than the total population toward hydrophobic bile acids (P < 0.05). Long‐term imaging showed oscillations in the accumulation of FBA over periods of hours. Overall, the studies suggest that high accumulation of FBA can indicate the sensitivity of cultured hepatocytes to hydrophobic bile acids and other toxins., These studies use automated image analysis and fluorescent dye accumulation to demonstrate that 3D culturing enhances organic anion accumulation and cytotoxic response in long‐term hepatocyte cultures. The level of anion accumulation was found to vary through days in culture and also between single cells, and higher fluorescent bile acid accumulation correlated with higher toxic response to hydrophobic bile acids.

Aberrant activation of Wnt/β-catenin signaling plays an unequivocal role in colorectal cancer (CRC), but identification of effective Wnt inhibitors for use in cancer remains a tremendous challenge. New insights into the regulation of this pathway could reveal new therapeutic point of intervention, therefore are greatly needed. Glycogen synthase kinase 3β(GSK3β) is a major component of the Wnt/β-catenin pathway, how GSK3β is regulated in Wnt signaling and tumorigenesis remains largely unknown. This study investigated the function and regulation of GSK3β phosphorylation in Wnt/β-catenin signaling and Wnt-driven intestinal tumorigenesis. The function of GSK3β phosphorylation at tyrosine 216 (Y216) in Wnt/-catenin signaling and CRC cells was analyzed by a series of biochemistry experiments and anchorage independent growth assays. Phosphorylation of GSK3βY216 by focal adhesion kinas (FAK) was studied in in vitro reconstitution system and in cells. The role of FAK-mediated phosphorylation of GSK3βY216 was tested by examining adenoma formation and associated molecular changes in control and FAK inhibitor-treated APCmin/+ mice. Immunohistochemistry was used to evaluate the expression levels of FAK, p-GSK3βY216 and β-catenin in CRC patients. Our results showed that GSK3βY216 phosphorylation was required for the activation of the Wnt/β-catenin pathway. Pharmacological inhibition of FAK suppressed adenoma formation in APCmin/+ mice accompanied by reduced intestinal levels of p-GSK3βY216 and β-catenin. FAK, p-GSK3βY216 and β-catenin were elevated and positively correlated in human CRC tissues. Together, our findings indicate that FAK/GSK3βY216 axis is critical for the activation of Wnt/β-catenin signaling in APC-driven intestinal tumorigenesis, thus providing a compelling mechanistic justification for clinical exploration of FAK inhibitors in colorectal cancer patients carrying APC mutations. Citation Format: Chenxi Gao, Guangming Chen, Shih-Fan Kuan, Dennis H. Zhang, Jing Hu. FAK promotes the Wnt/β-catenin pathway and intestinal tumorigenesis by phosphorylating GSK3ββ. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-033. doi:10.1158/1538-7445.AM2015-LB-033