Smoot, Rory L.

The Hippo pathway and its effector protein YAP (a transcriptional coactivator) have been identified as important in the biology of both hepatocellular carcinoma and cholangiocarcinoma. First identified as a tumor suppressor pathway in Drosophila , the understanding of the mammalian YAP signaling and its regulation continues to expand. In its “on” function, the canonical regulatory Hippo pathway, a well-described serine/threonine kinase module, regulates YAP function by restricting its subcellular localization to the cytoplasm. In contrast, when the Hippo pathway is “off,” YAP translocates to the nucleus and drives cotranscriptional activity. Given the role of Hippo/YAP signaling in hepatic malignancies, investigators have sought to target these molecules; however, standard approaches have not been successful based on the pathways’ negative regulatory role. More recently, additional regulatory mechanisms, such as tyrosine phosphorylation, of YAP have been described. These represent positive regulatory events that may be targetable. Additionally, several groups have identified potentiating feed-forward signaling for YAP in multiple contexts, suggesting other experimental therapeutic approaches to interrupt these signaling loops. Herein we explore the current data supporting alternative YAP regulatory pathways, review the described feed-forward signaling cascades that are YAP dependent, and explore targeting strategies that have been employed in preclinical models of hepatic malignancies.

Hepatocellular adenomas (HCAs) often pursue an innocuous clinical course. Recent work has elucidated important subtypes of HCA and biomarkers to identify them, including HCA at an increased risk for malignant transformation. Another key complication of HCAs is the risk of spontaneous tumoral hemorrhage, which may be life-threatening. Identification of a predictive biomarker for this clinical complication would therefore be of clinical value. It has been suggested that Argininosuccinate Synthase 1 (ASS1) immunohistochemistry (IHC) identifies HCA with a high propensity for hemorrhage. The aim of our study was to validate ASS1 IHC as a predictive marker of hemorrhage. Eighty-nine HCAs were collected for ASS1 IHC and subtyped according to published criteria. Clinical records were examined for evidence of tumoral hemorrhage. Twenty-one (23.6%) HCAs were complicated by clinically detected hemorrhage and were more likely to be resected (P=0.0002). Hemorrhage complicated all WHO subtypes of HCA. There was no association between hemorrhage and HCA subtype (P=0.92). Neither the distribution of ASS1 expression nor the intensity of ASS1 expression compared to normal liver showed a significant association with hemorrhage (P=0.051 and 0.34). Interlaboratory comparison of 8 cases showed good agreement regarding the intensity (6/8 and 7/8) and distribution of staining (7/8 and 7/8) across 3 laboratories performing ASS1 IHC. In conclusion, all subtypes of HCA may be complicated by hemorrhage. ASS1 IHC expression did not correlate with hemorrhagic complications. Caution is prudent before routine implementation of ASS1 IHC in clinical practice.

e15703 Background: The aim of this study is to identify prognostic factors and effects of adjuvant therapy for patients with ampullary adenocarcinoma who had pancreatoduodenectomy. Methods: A cohort of 123 consecutive patients underwent pancreatoduodenectomy for ampullary adenocarcinoma from January 1, 2006, through August 31, 2016 at Mayo Clinic in Rochester, MN. Only patients with ampullary carcinoma by pathology review were included and were histologically classified as pancreaticobiliary or intestinal subtypes. Median follow-up duration was 41.0 months. Patient survival and its correlation with patient and tumor variables were tested by univariate and multivariate analysis. Results: Pancreatoduodenectomy was curative-intent in 120 out of 123 patients. All 123 patients underwent radical surgery, 32 patients (26.0%) had laparoscopic pancreatoduodenectomy. Among 123 patients, there were 76 men (61.8%).Median age at diagnosis was 67.2 years. 54 patients (45%) without metastatic disease upon surgery had adjuvant therapy (35 patients had chemotherapy only while 19 patient also had radiation). Median overall survival (OS) was 91.8 months. Poor performance status at disease diagnosis (ECOG > = 1), old age ( > = 70 years), primary tumor infiltration (T), lymph node metastasis (N), and advanced disease stage (TNM) had a significant negative impact on survival (p < 0.05 by univariate analysis). Gender, diabetes at disease diagnosis, laparoscopic surgery approach, number of lymph nodes removed, number of positive lymph nodes, and tumor size did not influence survival. In multivariate analysis, ECOG score > = 1, adjuvant treatment, primary tumor infiltration (T) and lymph node metastasis (N) remained statistically significant. Adjuvant therapy was independently associated with improved disease free survival (P = 0.0388) and overall survival (p = 0.030) for patients with advanced disease (stage IIB and above). Conclusions: Poor performance status and advanced disease stage are associated with decreased survival in patients with ampullary adenocarcinoma. Patients with advanced disease should be considered for adjuvant chemotherapy.

e15045 Background: BRAF V600E mutations are present in 7% of mCRC patients (pts) and portend a poor prognosis. Data guiding initial treatment decisions are limited. This study investigates the management approach and clinical impact of utilizing metastasectomy for pts with BRAF V600E mCRC. Methods: By using prospective clinical and molecular data from Mayo Clinic, pts with BRAF V600E mCRC were analyzed for clinical characteristics, treatment and survival outcomes. Statistical analyses utilized Kaplan-Meier method, Log-rank test, and Cox proportional hazards models. Results: 164 pts with BRAF V600E mCRC were identified between 6/1999-8/2015. Complete follow up data were available for 52 pts. Median age of 65 years, 61% female, ECOG PS ≤ 1, 71% of pts had right sided tumors and 28% presented with liver limited metastasis. Only 7% (4/52) received FOLFOXIRI/BEV (average of 8 cycles). Peripheral neuropathy, pending BRAF status , and prior progression on FOLFOX, were the most common reasons documented for avoiding FOLFOXIRI/BEV. FOLFOX/BEV was the most common 1st line regimen used (32% of pts). Median overall survival (mOS) for all 52 pts was 25 months (mo) with median progression free survival (PFS) of 9.3 mo, reflecting worse survival when compared to BRAF wild-type control patients treated at Mayo Clinic (249 pts, mOS: 43 mo). With median follow up of 18.3 mo, 21 pts who underwent metastasectomy had improved OS (29.1mo vs. 22.7mo, HR = 0.33; CI: 0.12-0.78; p = 0.01) and PFS (13.6mo vs. 6.2mo, HR = 0.53, CI: 0.28-0.97; p = 0.03) when compared to the non-metastasectomy cohort, respectively. In multivariate analysis, metastasectomy remained statistically significant for improved survival outcomes (HR 0.52; 95% CI 0.07-1.02; p = 0.02). Median relapse-free survival after metastasectomy was 9.7 mo (95% CI, 5.5 mo-19.5 mo). Only 2 pts remain disease free at the time of last follow up, with 1 pt without recurrent disease for greater than 2 years (28.9 mo). Conclusions: The use of multimodality therapy incorporating metastasectomy for BRAF V600E mCRC is a critical component for enhanced survival outcomes.

3556 Background: To define and update survival rates and relapse patterns in patients (pts) with isolated advanced abdominal nodal metastasis secondary to colorectal cancer (CRC), treated with curative intent using aggressive trimodality therapy. Methods: Fifty-seven pts with isolated advanced abdominal lymph node metastasis (retroperitoneal and mesenteric) secondary to colorectal cancer received trimodality therapy defined as chemotherapy delivered in conjunction with external beam radiotherapy (EBRT) followed by lymphadenectomy and intraoperative radiotherapy (IORT). Infusional 5-FU was the most common radiosensitizer used (66%, 38 pts). The median dose of EBRT was 50 Gy & the median dose of intraoperative radiotherapy was 12.5 Gy. End points included distant metastasis, toxicities, local failure within EBRT field, recurrence within the intraoperative radiotherapy field, and survival. Results: 49% of pts were male, median age 50.5 yrs. All patients had ECOG ≤ 1. 27 pts had primary right sided colon cancer, 16 left sided colon cancer and 14 rectal primaries. Median time from initial CRC diagnosis to development of abdominal lymph node metastatic disease was 24 months (95% CI, 23.5-45.1 months). 84% (48 pts) had paraaortic nodal metastases, 12% (7 pts) had mesenteric nodal metastases, and 3% (2 pts) had both. With a median follow up of 89.4 months, the median overall survival and 5-year estimated survival rate were 53.2 months (95% CI, 46.4-78.8 months) and 42%, respectively. Median progression free survival was 19.3 months (95% CI, 15.6-32.8 months). 21 (37%) pts never developed distant disease. Outcome was not affected by disease sidedness, rectal primary, or mutational profile. Treatment was well tolerated without any grade 3/4 toxicities. Conclusions: The use of trimodality therapy including EBRT with radiosensitizing chemotherapy, lymphadenectomy and IORT produces sustainable long-term survival in selected metastatic CRC pts presenting with isolated retroperitoneal/mesenteric nodal relapse.

Abstract The Hippo pathway effector, Yes-associated protein (YAP), is a transcriptional coactivator implicated in cholangiocarcinoma (CCA) pathogenesis. YAP is known to be regulated by a serine/threonine kinase relay module (MST1/2–LATS1/2) culminating in phosphorylation of YAP at Serine 127 and cytoplasmic sequestration. However, YAP also undergoes tyrosine phosphorylation, and the role of tyrosine phosphorylation in YAP regulation remains unclear. Herein, YAP regulation by tyrosine phosphorylation was examined in human and mouse CCA cells, as well as patient-derived xenograft (PDX) models. YAP was phosphorylated on tyrosine 357 (Y357) in CCA cell lines and PDX models. SRC family kinase (SFK) inhibition with dasatinib resulted in loss of YAPY357 phosphorylation, promoted its translocation from the nucleus to the cytoplasm, and reduced YAP target gene expression, including cell lines expressing a LATS1/2-resistant YAP mutant in which all serine residues were mutated to alanine. Consistent with these observations, precluding YAPY357 phosphorylation by site-directed mutagenesis (YAPY357F) excluded YAP from the nucleus. Targeted siRNA experiments identified LCK as the SFK that most potently mediated YAPY357 phosphorylation. Likewise, inducible CRISPR/Cas9-targeted LCK deletion decreased YAPY357 phosphorylation and its nuclear localization. The importance of LCK in CCA biology was demonstrated by clinical observations suggesting LCK expression levels were associated with early tumor recurrence following resection of CCA. Finally, dasatinib displayed therapeutic efficacy in PDX models. Mol Cancer Res; 16(10); 1556–67. ©2018 AACR.

Abstract Background The purpose of this study was to define survival rates in patients with isolated advanced abdominal nodal metastases secondary to colorectal cancer (CRC), treated with curative-intent trimodality therapy. Materials and Methods Sixty-five patients received trimodality therapy, defined as chemotherapy delivered with external beam radiotherapy (EBRT) followed by lymphadenectomy and intraoperative radiotherapy (IORT). Infusional 5-fluorouracil was the most common radiosensitizer used (63%, 41 patients). The median dose of EBRT was 50 Gy, and the median dose of IORT was 12.5 Gy. We evaluated time to distant metastasis, toxicities, local failure within the EBRT field, recurrence within the IORT field, and survival. Results Fifty-two percent of patients were male; patients’ median age was 50.5 years. All patients had an Eastern Cooperative Oncology Group score ≤1. Twenty-nine patients had right-sided colon cancer, 22 had left-sided colon cancer, and 14 had rectal primaries. The median time from initial CRC diagnosis to development of abdominal nodal metastatic disease was 20.6 months (95% confidence interval [CI], 21.2–40.8 months). Seventy-eight percent (51 patients) had para-aortic nodal metastases, 15% (10 patients) had mesenteric nodal metastases, and 6% (4 patients) had both. With a median follow-up of 77.6 months, the median overall survival and 5-year estimated survival rate were 55.4 months (95% CI, 47.2–80.9 months) and 45%, respectively. The median progression-free survival was 19.3 months (95% CI, 16.5–32.8 months). Twenty-six (40%) patients never developed distant disease. The outcome was not affected by disease sidedness or rectal primary. Treatment was well tolerated without grade 3 or 4 toxicities. Conclusion Trimodality therapy produces sustainable long-term survival in selected patients with metastatic CRC presenting with isolated retroperitoneal or mesenteric nodal relapse. Implications for Practice This article reports a unique trimodality approach incorporating external beam radiotherapy with radiosensitizing chemotherapy, surgical resection, and intraoperative radiotherapy provides durable survival benefit with significant curative potential for patients with metastatic colorectal cancer who present with isolated abdominal nodal (mesenteric and/or retroperitoneal) recurrence.

Objective The objective of this study was to assess the accuracy of gadoxetic acid hepatic enhancement indices in predicting posthepatectomy liver failure (PHLF) and other major complications (OMCs). Methods Sixty-five patients underwent prehepatectomy gadoxetic acid–enhanced magnetic resonance imaging. Enhancement indices were calculated by obtaining regions of interest on magnetic resonance images and segmented volumes of the liver and spleen. Multivariate regression analysis was performed to predict PHLF and OMC as a function of the indices, and areas under the receiver operator characteristic (AUROC) curves were calculated. Results Areas under the receiver operator characteristic values varied from 0.412 to 0.681 and 0.462 to 0.738 in predicting PHLF and OMC, respectively. The most accurate indices in predicting PHLF were the region of interest–based, fat-normalized relative liver enhancement and liver enhancement index (AUROC, 0.681). The most accurate index in predicting OMC was the volumetric least-squares regression slope of a pharmacokinetic model (K hep_V, AUROC, 0.738). Conclusions Indices of gadoxetic acid liver enhancement demonstrate variable performance in predicting PHLF and OMC.

Abstract Background BRAF V600E mutations are present in 8%–10% of patients with metastatic colorectal cancer (mCRC) and portend poor prognosis. This study investigated the impact of metastasectomy for patients with BRAF V600E mCRC. Subjects, Materials, and Methods Using prospective clinical and molecular data, patients with BRAF V600E mCRC were analyzed for clinical characteristics and survival. Statistical analyses utilized the Kaplan-Meier method, log-rank test, and Cox proportional hazard models. Results Fifty-two patients were identified between July 1, 2008, and January 4, 2016. Patient characteristics included median age 65 years, 61% female, Eastern Cooperative Oncology Group performance status ≤1, 71% with right-sided tumors, and 28% with liver-limited metastasis. In the first-line setting, 7% (4/52) received fluorouracil, leucovorin, oxaliplatin, and irinotecan (FOLFOXIRI)/bevacizumab (BEV) and 81% were treated with doublet chemotherapy consisting of fluoropyrimidine, oxaliplatin, and BEV. Median overall survival (OS) for all 52 patients was 25 months with median progression-free survival (PFS) of 9.3 months. With median follow-up of 18.3 months, 21 patients underwent metastasectomy with longer OS (29.1 months vs. 22.7 months, hazard ratio [HR] = 0.33; confidence interval [CI], 0.12–0.78; p = .01) and PFS (13.6 months vs. 6.2 months, HR = 0.53, CI, 0.28–0.97; p = .03) compared with the non-metastasectomy cohort. In multivariate analysis, metastasectomy remained significant for improved survival outcomes (HR = 0.52; 95% CI, 0.07–1.02; p = .02). Median disease-free survival after metastasectomy was 9.7 months (95% CI, 5.5–19.5). Two patients remain disease-free at the time of last follow-up, with one patient without relapse for greater than 2 years (28.9 months). Conclusion Multimodality therapy incorporating metastasectomy for BRAF V600E mCRC should be considered and might be associated with improved overall survival in select patients. Implications for Practice BRAF V600E metastatic colorectal cancer (mCRC) represents an extremely difficult molecular subset of colorectal cancer to treat. To date, this subset remains refractory to standard chemotherapies, prompting extensive clinical investigation regarding novel treatment approaches and targeted modalities. While the use of metastasectomy for expanded RAS wild-type and RAS mutated mCRC has resulted in improved overall survival for select patients, utilization of metastasectomy in patients with BRAF V600E mCRC remains controversial. This article explores the authors' experience with BRAF V600E mCRC to ascertain whether a multidisciplinary approach incorporating metastasectomy for well-selected patients improves overall survival.