The Pancreatic Cancer Early Detection (PRECEDE) Study is a Global Effort to Drive Early Detection: Baseline Imaging Findings in High-Risk Individuals

BACKGROUND

Pancreatic adenocarcinoma (PC) is a highly lethal malignancy with a survival rate of only 12%. Surveillance is recommended for high-risk individuals (HRIs), but it is not widely adopted. To address this unmet clinical need and drive early diagnosis research, we established the Pancreatic Cancer Early Detection (PRECEDE) Consortium.

METHODS

PRECEDE is a multi-institutional international collaboration that has undertaken an observational prospective cohort study. Individuals (aged 18-90 years) are enrolled into 1 of 7 cohorts based on family history and pathogenic germline variant (PGV) status. From April 1, 2020, to November 21, 2022, a total of 3,402 participants were enrolled in 1 of 7 study cohorts, with 1,759 (51.7%) meeting criteria for the highest-risk cohort (Cohort 1). Cohort 1 HRIs underwent germline testing and pancreas imaging by MRI/MR-cholangiopancreatography or endoscopic ultrasound.

RESULTS

A total of 1,400 participants in Cohort 1 (79.6%) had completed baseline imaging and were subclassified into 3 groups based on familial PC (FPC; n=670), a PGV and FPC (PGV+/FPC+; n=115), and a PGV with a pedigree that does not meet FPC criteria (PGV+/FPC-; n=615). One HRI was diagnosed with stage IIB PC on study entry, and 35.1% of HRIs harbored pancreatic cysts. Increasing age (odds ratio, 1.05; P<.001) and FPC group assignment (odds ratio, 1.57; P<.001; relative to PGV+/FPC-) were independent predictors of harboring a pancreatic cyst.

CONCLUSIONS

PRECEDE provides infrastructure support to increase access to clinical surveillance for HRIs worldwide, while aiming to drive early PC detection advancements through longitudinal standardized clinical data, imaging, and biospecimen captures. Increased cyst prevalence in HRIs with FPC suggests that FPC may infer distinct biological processes. To enable the development of PC surveillance approaches better tailored to risk category, we recommend adoption of subclassification of HRIs into FPC, PGV+/FPC+, and PGV+/FPC- risk groups by surveillance protocols.

The PRECEDE consortium: A longitudinal international cohort study of individuals with genetic risk or familial pancreatic cancer

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Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease with lack of effective early detection strategies. There is an incomplete understanding of who is at risk for PDAC development and the contribution of heritability to that risk. Further, efforts at biomarker development for detection of early stage disease have been hampered by small sample sizes, lack of coordination, and inadequate access to high quality clinical data and biospecimens in relevant clinical populations. The PRECEDE Consortium was established to serve as a collaborative international network of PDAC clinical and research centers to accelerate early detection advances by standardizing collection of clinical data and biospecimens from patients at increased risk for PDAC. The consortium goal is to increase the overall survival rate for PDAC to 50% in 10 years by enabling transformative biomarker-driven discoveries in early detection of high-risk premalignant lesions and early stage cancers. Methods: The PRECEDE Consortium (NCT04970056; precedestudy.org) launched in 2019 and began enrollment in May, 2020. Data and biospecimen sharing are required for centers to join the consortium, which is facilitated through use of standardized data and biospecimen collection, and a centralized database (PRECEDELink) managed by a data coordinating center (Arbor Research). Imaging and clinical sequencing data will be stored and analyzed via a PRECEDE solution in the Amazon Web Services cloud. Participants age 18-90 are enrolled into one of seven cohorts based on personal and/or family history of PDAC and carrier status of pathogenic germline variants (PGV) in cancer predisposition genes (CPG). Three-generation pedigrees are collected at enrolment from participants, and standardized clinical germline testing is offered. Blood sample collection for DNA, plasma, and serum is completed at enrollment, and repeated annually for individuals meeting guidelines for annual surveillance. Results: To date, 24 clinical sites have enrolled 2187 participants, with a target of 10,000 participants enrolled from100 sites over the next 5 years. Among enrolled patients, 55% meet criteria for annual surveillance by MRI or endoscopic ultrasound. Demographics of the cohort to date: 56% female; 73% white; 35% CPG PGV carriers; 32% meet criteria for familial pancreatic cancer. Conclusions: The PRECEDE Consortium study is a large international, longitudinal, prospective cohort study designed to accelerate the pace and scale of early diagnosis. Planned projects will address modifiers of risk, penetrance of disease, creating comprehensive risk models for clinical decision-making, and development and validation of biomarker assays. The PRECEDE Consortium provides a unique, innovative platform to bring together key stakeholders (academia, patients, public and private sector) to effect progress.

Patient and Caregiver Considerations and Priorities When Selecting Hospitals for Complex Cancer Care

BACKGROUND

Healthcare policies have focused on centralizing care to high-volume centers in an effort to optimize patient outcomes; however, little is known about patients' and caregivers' considerations and selection process when selecting hospitals for care. We aim to explore how patients and caregivers select hospitals for complex cancer care and to develop a taxonomy for their selection considerations.

METHODS

This was a qualitative study in which data were gathered from in-depth interviews conducted from March to November 2019 among patients with hepatopancreatobiliary cancers who were scheduled to undergo a pancreatectomy (n = 20) at a metropolitan, urban regional, or suburban medical center and their caregivers (n = 10).

RESULTS

The interviews revealed six broad domains that characterized hospital selection considerations: hospital factors, team characteristics, travel distance to hospital, referral or recommendation, continuity of care, and insurance considerations. The identified domains were similar between participants seen at the metropolitan center and urban/suburban medical centers, with the following exceptions: participants receiving care specifically at the metropolitan center noted operative volume and access to specific services such as clinical trials in their hospital selection; participants receiving care at urban/suburban centers noted health insurance considerations and having access to existing medical records in their hospital selection.

CONCLUSIONS

This study delineates the many considerations of patients and caregivers when selecting hospitals for complex cancer care. These identified domains should be incorporated into the development and implementation of centralization policies to help increase patient access to high-quality cancer care that is consistent with their priorities and needs.

Abstract C19: The role of resident liver macrophages in suppressing the progression of hepatic micrometastases from pancreatic ductal adenocarcinoma

Background: The majority of patients with localized pancreatic ductal adenocarcinoma (PDAC) die from metastatic disease, typically of the liver, despite a margin-negative (R0) resection. Therefore, these patients likely harbor occult metastatic disease in the liver at the time of surgery. In this study, we evaluated the role of resident liver macrophages in suppressing the progression of hepatic micrometastases using a murine model of micrometastatic PDAC with patient-derived xenografts (PDXs).

Methods and Results: Low-passage, patient-derived KRAS-mutant tumor cells expressing firefly luciferase were injected into the spleens of athymic nude mice resulting in liver metastases, followed by splenectomy to remove the primary tumor. Hepatic tumor burden and metastatic growth kinetics were evaluated by bioluminescent imaging on post-injection days 1, 2, 3, 7, and weekly thereafter. Each of the PDX tumors exhibited a decline in tumor burden over the initial days after injection followed by a period of quiescence with a reproducible, PDX-specific time to proliferative outgrowth ranging from 15 days to greater than 200 days. To assess the role of apoptosis in initial tumor cell clearance and suppression of outgrowth, mouse liver preparations were analyzed for expression of cleaved caspase-3 and cleaved PARP in tumor cells using flow cytometry. There was low expression of both apoptosis markers, suggesting that apoptosis is not a major cell-clearance mechanism. Athymic nude mice lack cell-mediated immunity but have functioning innate immunity. Because there is a large population of resident macrophages in the liver, we hypothesized that macrophages play an important role in the clearance and suppression of hepatic PDAC metastases. To test this, hepatic metastasis outgrowth was assessed following macrophage ablation with liposomal clodronate treatment of mice 48 hours prior to tumor cell injection. Following macrophage ablation, there was a trend toward less robust initial tumor cell clearance and a significantly decreased time to proliferative outgrowth compared with control (13 days vs 26 days, p=0.039). H&E sections demonstrated an abundance of hepatic macrophages surrounding tumor cells in the control group while this response was absent in the clodronate group. Splenic tumor cell injections were repeated using athymic nude mice vs NOD scid gamma (NSG) mice which lack both cell-mediated immunity as well as functional macrophages, dendritic cells, and NK cells. Initial tumor cell clearance was significantly reduced in the NSG mice vs nude mice (PDX 608: 35.6% vs 90.1% clearance at seven days, p&lt;0.001; PDX 366: 40.4% vs 76.3% clearance at seven days, p=0.024). Average relative hepatic bioluminescence at 21 days was significantly increased for PDX 608 in the NSG mice (14.7 vs 0.355, p=0.014) and there was a trend toward increase for PDX 366 (3.07 vs 0.025, p=0.065).

Conclusions: In a preclinical model of hepatic micrometastatic PDAC, resident liver macrophages are implicated in the initial clearance and the suppression of proliferation of tumor cells. Further investigation of the interaction of resident hepatic macrophages and micrometastatic PDAC cells may lead to novel strategies for therapy.

Citation Format: Alex D. Michaels, Timothy E. Newhook, James M. Lindberg, Sara J. Adair, Sarbajeet Nagdas, Matthew G. Mullen, Edward B. Stelow, J. Thomas Parsons, Todd W. Bauer. The role of resident liver macrophages in suppressing the progression of hepatic micrometastases from pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr C19.

Adjuvant Trametinib Delays the Outgrowth of Occult Pancreatic Cancer in a Mouse Model of Patient-Derived Liver Metastasis

PURPOSE

Most patients with pancreatic ductal adenocarcinoma (PDAC) die within 5 years following resection plus adjuvant gemcitabine (Gem) from outgrowth of occult metastases. We hypothesized that inhibition of the KRAS pathway with the MEK inhibitor trametinib would inhibit the outgrowth of occult liver metastases in a preclinical model.

METHODS

Liver metastases harvested from two patients with PDAC (Tumors 608, 366) were implanted orthotopically in mice. Tumor cell lines were derived and transduced with lentiviruses encoding luciferase and injected into spleens of mice generating microscopic liver metastases. Growth kinetics of liver metastases were measured with bioluminescent imaging and time-to-progression (TTP), progression-free survival (PFS), and overall survival (OS) were determined.

RESULTS

Trametinib (0.3 mg/kg BID) significantly prolonged OS versus control (Tumor 608: 114 vs. 43 days, p < 0.001; Tumor 366: not reached vs. 167 days, p = 0.0488). In vivo target validation demonstrated trametinib significantly reduced phosphorylated-ERK and expression of the ERK-responsive gene DUSP6. In a randomized, preclinical trial, mice were randomized to: (1) control, (2) adjuvant Gem (100 mg/kg IP, Q3 days) × 7 days followed by surveillance, or (3) adjuvant Gem followed by trametinib. Sequential Gem-trametinib significantly decreased metastatic cell outgrowth and increased TTP and PFS.

CONCLUSIONS

Treatment of mice bearing micrometastases with trametinib significantly delayed tumor outgrowth by effectively inhibiting KRAS-MEK-ERK signaling. In a randomized, preclinical, murine trial adjuvant sequential Gem followed by trametinib inhibited occult metastatic cell outgrowth in the liver and increased PFS versus adjuvant Gem alone. An adjuvant trial of sequential Gem-trametinib is being planned in patients with resected PDAC.

Morbidity and mortality of hepatectomy for benign liver tumors

BACKGROUND

This study compared the morbidity and mortality following hepatectomy for benign liver tumors and hepatic metastases.

METHODS

This retrospective cohort study compared patients who underwent hepatectomy for benign liver tumors and metastases reported to National Surgical Quality Improvement Program between 2005 and 2011.

RESULTS

A total of 5,542 patients underwent hepatectomy: 1,164 (21%) for benign and 4,378 (79%) for metastatic diseases. Patients with benign tumors were younger, predominantly female, and were less likely to have preoperative comorbidities (all P < .037). Rates of major complications including infections, embolism, renal failure, stroke, coma, cardiac arrest, reoperation, and ventilator dependence were similar between the 2 groups (all P ≥ .05). Thirty-day mortality was .9% among patients with benign tumors and 1.4% among patients with metastases (P = .128). After adjusting for significant effects of age and major complications (both P ≤ .007), benign vs malignant diagnosis and extent of hepatectomy was not associated with 30-day survival (both P ≥ .083).

CONCLUSIONS

Despite patients with benign disease being younger and healthier, risks of major complications are similar after hepatectomy for benign and metastatic disease. Hepatectomy should be offered selectively for patients with benign liver tumors.

Morbidity and mortality of pancreaticoduodenectomy for benign and premalignant pancreatic neoplasms

OBJECTIVES

Patients with benign neoplasms of the pancreas are selected for pancreaticoduodenectomy if there is concern for malignant transformation. This study compares outcomes after pancreaticoduodenectomy for patients with premalignant and malignant pancreatic neoplasms.

STUDY DESIGN

This retrospective cohort study included all patients who underwent pancreaticoduodenectomy for histologically confirmed benign/premalignant pancreatic neoplasms and primary pancreatic malignancy reported to National Surgical Quality Improvement Program (NSQIP) from 2005 to 2011. Patient characteristics, intraoperative and postoperative morbidity and mortality were compared.

RESULTS

A total of 6085 patients underwent pancreaticoduodenectomy: 744 (12.2 %) for benign/premalignant and 5341 (87.8 %) for malignant pancreatic neoplasms. Patients with benign/premalignant neoplasms were more commonly female, had lower American Society of Anesthesiologists (ASA) class, and were less likely to have major comorbidities (all p ≤ 0.003). After resection, patients with benign/premalignant neoplasms were more likely to develop organ space infection (13.4 vs. 8.5 %, p < 0.001) and sepsis (12.2 vs. 9.2 %, p = 0.009). Cardiovascular, pulmonary, renal, and other organ system complications (p = 0.12) as well as 30-day mortality (3.0 vs. 2.0 %, p = 0.128) did not differ.

CONCLUSIONS

Organ space infection and sepsis are more common after pancreaticoduodenectomy for benign/premalignant neoplasms. Planned improvements in NSQIP data capture should allow for better measurement of this morbidity. A carefully balanced risk and benefit discussion should precede resection in these patients.

Co-treatment with panitumumab and trastuzumab augments response to the MEK inhibitor trametinib in a patient-derived xenograft model of pancreatic cancer

Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations and epidermal growth factor receptor (EGFR) family signaling are drivers of tumorigenesis in pancreatic ductal adenocarcinoma (PDAC). Previous studies have demonstrated that combinatorial treatment of PDAC xenografts with the mitogen-activated protein kinase–extracellular-signal-regulated kinase (ERK) kinase1/2 (MEK1/2) inhibitor trametinib and the dual EGFR/human epidermal growth factor receptor 2 (HER2) inhibitor lapatinib provided more effective inhibition than either treatment alone. In this study, we have used the therapeutic antibodies, panitumumab (specific for EGFR) and trastuzumab (specific for HER2), to probe the role of EGFR and HER2 signaling in the proliferation of patient-derived xenograft (PDX) tumors. We show that dual anti-EGFR and anti-HER2 therapy significantly augmented the growth inhibitory effects of the MEK1/2 inhibitor trametinib in three different PDX tumors. While significant growth inhibition was observed in both KRAS mutant xenograft groups receiving trametinib and dual antibody therapy (tumors 366 and 608), tumor regression was observed in the KRAS wild-type xenografts (tumor 738) treated in the same manner. Dual antibody therapy in conjunction with trametinib was equally or more effective at inhibiting tumor growth and with lower apparent toxicity than trametinib plus lapatinib. Together, these studies provide further support for a role for EGFR and HER2 in pancreatic cancer proliferation and underscore the importance of therapeutic intervention in both the KRAS–rapidly accelerated fibrosarcoma kinase (RAF)–MEK–ERK and EGFR-HER2 pathways to achieve maximal therapeutic efficacy in patients.

Abstract 4040: The MEK inhibitor trametinib delays tumor outgrowth and prolongs survival in a patient-derived mouse model of occult hepatic metastatic pancreatic cancer

Background: Survival for patients with pancreatic ductal adenocarcinoma (PDAC) remains dismal and the majority of patients succumb to metastatic disease. Even for those with localized PDAC, most will die from metastatic disease despite margin-negative resection and adjuvant therapy. Therefore, these patients must harbor occult metastatic PDAC at presentation. We have developed a PDAC model of occult liver metastases using patient-derived xenografts (PDXs) to study the growth of PDAC within the metastatic microenvironment of the liver and evaluated the role of KRAS-MEK-ERK signaling on tumor progression.

Methods and Results: Extensively characterized low passage, patient-derived KRAS-mutant (Tumors 608, 366, and 654) and wild-type (Tumors 738 and 215) PDAC cells expressing luciferase were injected into the spleens of athymic, nude mice and allowed to circulate for 10 minutes, after which a splenectomy was performed. To evaluate metastatic cell growth kinetics in the liver, tumor burden was monitored by sequential bioluminescent imaging. Each of the PDX tumors exhibited a characteristic and reproducible time to proliferative outgrowth ranging from 20 days (Tumor 608) to greater than 100 days (Tumor 654). To evaluate the role of KRAS signaling in maintaining dormant cell survival and proliferative outgrowth, tumor 608 cells were injected and mice were treated with the MEK inhibitor trametinib (0.3 mg/kg, daily) or control beginning 48 hours post-injection. Trametinib significantly reduced metastatic tumor burden, delayed time to proliferative outgrowth, and greatly prolonged survival as compared to control (med. survival: 114 vs. 43 days, p&lt;0.001). In contrast, in an orthotopic model with 250-500 mm3 tumors trametinib led to limited inhibition in tumor growth for Tumor 608. To characterize these PDAC cells, we isolated Tumor 608 cells from the liver 48 and 72 hours, 10 and 28 days after splenic injection using magnetic column separation with human EpCAM (CD326)-targeted magnetically labeled microbeads. Flow cytometric analyses of retrieved cells revealed that decreased cellular markers of proliferation and increased PARP cleavage correlated with decreased tumor burden observed at these timepoints in mice treated with trametinib.

Conclusions: Using a model of occult liver metastatic PDAC, patient-derived tumors exhibited characteristic, albeit different growth kinetics in the liver microenvironment. Further, inhibition of KRAS-MEK-ERK signaling with the MEK inhibitor trametinib decreased metastatic cellular proliferation, increased apoptosis, prolonged metastatic tumor outgrowth, and significantly increased survival. Further investigation into factors promoting PDAC cell survival within the hepatic microenvironment will lead to development of rational therapeutic strategies for patients with occult metastatic PDAC.

Citation Format: Timothy Eric Newhook, James M. Lindberg, Sara J. Adair, J. Thomas Parsons, Todd W. Bauer. The MEK inhibitor trametinib delays tumor outgrowth and prolongs survival in a patient-derived mouse model of occult hepatic metastatic pancreatic cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4040. doi:10.1158/1538-7445.AM2014-4040

A thirteen-gene expression signature predicts survival of patients with pancreatic cancer and identifies new genes of interest

BACKGROUND

Currently, prognostication for pancreatic ductal adenocarcinoma (PDAC) is based upon a coarse clinical staging system. Thus, more accurate prognostic tests are needed for PDAC patients to aid treatment decisions.

METHODS AND FINDINGS

Affymetrix gene expression profiling was carried out on 15 human PDAC tumors and from the data we identified a 13-gene expression signature (risk score) that correlated with patient survival. The gene expression risk score was then independently validated using published gene expression data and survival data for an additional 101 patients with pancreatic cancer. Patients with high-risk scores had significantly higher risk of death compared to patients with low-risk scores (HR 2.27, p = 0.002). When the 13-gene score was combined with lymph node status the risk-score further discriminated the length of patient survival time (p<0.001). Patients with a high-risk score had poor survival independent of nodal status; however, nodal status increased predictability for survival in patients with a low-risk gene signature score (low-risk N1 vs. low-risk N0: HR = 2.0, p = 0.002). While AJCC stage correlated with patient survival (p = 0.03), the 13-gene score was superior at predicting survival. Of the 13 genes comprising the predictive model, four have been shown to be important in PDAC, six are unreported in PDAC but important in other cancers, and three are unreported in any cancer.

CONCLUSIONS

We identified a 13-gene expression signature that predicts survival of PDAC patients and could prove useful for making treatment decisions. This risk score should be evaluated prospectively in clinical trials for prognostication and for predicting response to chemotherapy. Investigation of new genes identified in our model may lead to novel therapeutic targets.

Genomic profiling of intrahepatic cholangiocarcinoma: refining prognosis and identifying therapeutic targets

BACKGROUND

The molecular alterations that drive tumorigenesis in intrahepatic cholangiocarcinoma (ICC) remain poorly defined. We sought to determine the incidence and prognostic significance of mutations associated with ICC among patients undergoing surgical resection.

METHODS

Multiplexed mutational profiling was performed using nucleic acids that were extracted from 200 resected ICC tumor specimens from 7 centers. The frequency of mutations was ascertained and the effect on outcome was determined.

RESULTS

The majority of patients (61.5 %) had no genetic mutation identified. Among the 77 patients (38.5 %) with a genetic mutation, only a small number of gene mutations were identified with a frequency of >5 %: IDH1 (15.5 %) and KRAS (8.6 %). Other genetic mutations were identified in very low frequency: BRAF (4.9 %), IDH2 (4.5 %), PIK3CA (4.3 %), NRAS (3.1 %), TP53 (2.5 %), MAP2K1 (1.9 %), CTNNB1 (0.6 %), and PTEN (0.6 %). Among patients with an IDH1-mutant tumor, approximately 7 % were associated with a concurrent PIK3CA gene mutation or a mutation in MAP2K1 (4 %). No concurrent mutations in IDH1 and KRAS were noted. Compared with ICC tumors that had no identified mutation, IDH1-mutant tumors were more often bilateral (odds ratio 2.75), while KRAS-mutant tumors were more likely to be associated with R1 margin (odds ratio 6.51) (both P < 0.05). Although clinicopathological features such as tumor number and nodal status were associated with survival, no specific mutation was associated with prognosis.

CONCLUSIONS

Most somatic mutations in resected ICC tissue are found at low frequency, supporting a need for broad-based mutational profiling in these patients. IDH1 and KRAS were the most common mutations noted. Although certain mutations were associated with ICC clinicopathological features, mutational status did not seemingly affect long-term prognosis.

Genomic profiling of intrahepatic cholangiocarcinoma: Refining prognostic determinants and identifying therapeutic targets

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Background: The molecular alterations that drive tumorigenesis in intrahepatic cholangiocarcinoma (ICC) remain poorly defined. We sought to define the incidence and prognostic significance of mutations associated with ICC among patients undergoing surgical resection. Methods: 138 patients who underwent resection at 6 centers in the United States and Europe were included in the cohort. Mutational profiling was performed using nucleic acids that were extracted from resected ICC tumor specimens; mutations were identified using a multiplexed mutational profiling platform. The frequency of mutations was ascertained and the impact on outcome determined. Results: Most patients had a solitary tumor (82%) and median tumor size was 6.0cm. Most patients had R0 resection (89%); 19% patients had N1 disease, while 15% had microscopic vascular invasion. A minority received adjuvant therapy (30%). The majority (55%) of patients had no genetic mutation identified. Among the 62 (45%) patients with a genetic mutation, only a small number of gene mutations were identified with a frequency of >5%: IDH1 (17.4%), KRAS (8.7%), BRAF (5.8%), PIK3CA (5.1%). In contrast, other genetic mutations were identified in very low frequency: IDH2 (3.6%), NRAS (3.6%), TP53 (2.2%), MAP2K1 (1.5%), CTNNB1 (0.7%), and PTEN (0.7%). Approximately 7% of IDH1-mutant tumors were associated with a concurrent PIK3CA gene mutation, and to a much lower extent, a mutation in MAP2K1 (2%). No concurrent mutations in IDH1 and KRAS were noted. Compared with ICC tumors that had no identified mutation, IDH1-mutant tumors were more often bilateral (OR 3.46), while KRAS-mutant tumors were more likely to be associated with perineural invasion (OR 5.72)(both P<0.05). While clinicopathological features such as tumor number and nodal status were associated with survival, no specific mutation was associated with prognosis. Conclusions: Most patients with resected ICC had no somatic mutation identified on multiplexed mutational profiling. IDH1 and KRAS were the most common mutations noted. While certain mutations were associated with ICC clinicopathological features, mutational status did not seemingly impact long-term prognosis.

Abstract 935: Inhibition of pancreatic cancer growth via MEK-targeted therapy is significantly enhanced by concomitant inhibition of EGFR and Her2

Introduction: MAPK and EGFR family signaling promote tumor proliferation in pancreatic ductal adenocarcinoma (PDAC). Previously we have shown that lapatinib (EGFR/Her2 inhibitor) significantly improved the ability of trametinib (MEK1/2 inhibitor) to inhibit PDAC tumor growth. Here, we investigated whether combined panitumumab (EGFR inhibitor), trastuzumab (Her2 inhibitor) and trametinib treatment would more effectively inhibit tumor growth than trametinib monotherapy in a patient-derived (PD), orthotopic, xenograft model of PDAC.

Methods: In vitro proliferation assays were performed with PD-PDAC cell line MAD09-366 exposed to trametinib, panitumumab, trastuzumab, and combination therapies. Western blot analysis was performed on treated cell lysates. Athymic, nude mice were orthotopically implanted with 3 different PD-PDAC xenografts (MAD09-366, 08-608, and 08-738). Established murine tumors were treated with control, trametinib (0.3mg/kg,PO, qDay), panitumumab (500ug, IP, BIW), trastuzumab (200ug, IP, BIW) or combination for 2-4 weeks. Interval volumetric MRI was used to measure tumor growth. Phospho-RTK and MAPK arrays were used to assess tumor molecular response.

Results: In vitro studies demonstrated improved growth inhibition of MAD09-366 (Kras mut.) cells exposed to combination therapy with all 3 inhibitors relative to control or each inhibitor alone. Western blot analysis revealed that EGF stimulation increased Ras pathway signaling in this Kras mutant cell line. Under conditions of EGF stimulation, the greatest inhibition of Ras pathway signaling was seen in cells exposed to all 3 inhibitors. In vivo studies in all PD-PDAC xenografts revealed that triple inhibitor therapy significantly decreased the rate of tumor growth relative to control, trametinib alone, panitumumab alone, or panitumumab plus trastuzumab. In two of three PD-PDACs assessed, triple therapy was superior to trametinib plus panitumumab. The greatest response was seen in MAD08-738 (Kras wt) triple-therapy-treated mice whose tumor size decreased by 9.3%. Phospho-array analysis demonstrated increased activity of Akt and its downstream effectors in trametinib treated tumors. Relative Akt phosphorylation returned to levels seen in control treated tumors with the addition of panitumumab and trastuzumab under triple therapy.

Conclusions: Combination therapy with trametinib, panitumumab, and trastuzumab produced the most complete in vitro Ras signaling blockade and most effective in vivo growth inhibition. Phospho-array data suggests that a compensatory increase in pro-survival PI3K/Akt signaling in response to Ras pathway blockade alone is mitigated by the concomitant inhibition of EGFR/Her2 signaling. This combination treatment strategy should be considered for a future clinical trial in pancreatic cancer patients.

Citation Format: James M. Lindberg, Timothy E. Newhook, Sara J. Adair, Clifford A. Cutchins, Alison Kim, J. Thomas Parsons, Todd W. Bauer. Inhibition of pancreatic cancer growth via MEK-targeted therapy is significantly enhanced by concomitant inhibition of EGFR and Her2. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 935. doi:10.1158/1538-7445.AM2013-935

Effect of trametinib in combination with panitumumab and trastuzumab on tumor growth in an orthotopic xenograft model of human pancreatic cancer

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Background: Aberrant MAPK and EGFR family signaling are key drivers of pancreatic ductal adenocarcinoma(PDAC). We hypothesized that combination trametinib(MEK1/2 inhibitor), panitumumab(EGFR inhibitor) and trastuzumab(Her2 inhibitor) would more effectively suppress tumor growth than any of these monotherapies. Methods: Patient-derived PDAC cell line MAD09-366 was exposed to trametinib, panitumumab, trastuzumab, and combination therapies in vitro. Western blot analysis was performed on treated cell lysates. Athymic, nude mice were orthotopically implanted with patient-derived PDAC xenografts(MAD09-366, 08-608, and 08-738). Established murine tumors were treated with control, trametinib (0.3mg/kg, qDay), panitumumab (500ug, BIW), trastuzumab (200ug, BIW) or in combination. MRI was used to assess tumor response. Results: Two of 3 PDACs were Kras mutant, 2 of 3 demonstrated increased Her2 activity, and all 3 showed increased EGFR activity. In vitro studies showed increased growth inhibition of triple-therapy-treated cells relative to control or each inhibitor alone. Western blot analysis revealed that EGF stimulation increased Ras pathway signaling in this Kras-mutant cell line. With EGF stimulation, the greatest Ras pathway signaling inhibition was seen in triple-therapy-treated cells. In vivo studies in all PDAC xenografts revealed that triple therapy significantly decreased tumor growth rate relative to control, trametinib alone, panitumumab alone, or panitumumab plus trastuzumab. In 2 of 3 PDACs assessed, triple therapy was superior to trametinib plus panitumumab. Average tumor size in MAD08-738 triple-therapy-treated mice decreased by 9.3%. Conclusions: Triple therapy with trametinib, panitumumab, and trastuzumab demonstrated the greatest in vitro Ras signaling blockade. In vivo, this combination produced significant tumor growth inhibition or regression in all PDAC tumors studied. This regimen should be considered for a future clinical trial in pancreatic cancer patients.

Preoperative bowel preparation for pancreaticoduodenectomy: Is it necessary?

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Background: Preoperative bowel preparation (PBP) before pancreaticoduodenectomy (PD) is commonly performed; however, the effect of PBP on intraoperative fluid requirements and acute renal failure (ARF) after PD has not been reported. The goal of this study was to determine the effect of PBP on postoperative complications, intraoperative fluid requirements, and ARF after PD. Methods: In this retrospective sequential analysis, all patients undergoing PD consecutively from September 2005 to July 2012 by a single surgeon were identified. Clinical data from patients who received PBP from September 2005 to November 2008 was compared to those without PBP from December 2008 to July 2012. Results: In all, 140 consecutive patients were identified with 49 (35%) having received PBP. There was no significant difference in the frequency of chronic renal failure between groups. The PBP group received a larger total intraoperative fluid volume (9.33 vs 6.54 L, p<0.001) and had a higher incidence of postoperative ARF (22.4% vs. 5.4%, p = 0.003) compared to those without PBP. There was no significant difference in the rates of superficial, deep, or organ space surgical site infections between the two groups. Additionally, there was no significant difference in the rates of pancreatic leak, other GI tract leak, or postoperative ileus between the groups. Conclusions: Surgical site infections are not significantly reduced with PBP prior to PD. In contrast, PBP is associated with a 2.8 L increase in intraoperative fluid administration and a 17% increase in the incidence of postoperative ARF. Thus, PBP should not be offered routinely prior to pancreaticoduodenectomy. [Table: see text]

Targeting occult metastatic disease: A hematogenously derived xenograft model of human pancreatic tumor growth in the murine liver

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Background: Most pancreatic cancer patients will die following surgery due to recurrent metastatic disease. Thus, better systemic therapies are needed to treat occult metastases to improve survival. We have developed a model of occult liver metastasis from pancreatic cancer in order to evaluate novel treatment strategies. Methods: Pancreatic cancer cells (MAD 09-366, 08-608, MPanc96) transduced with green fluorescent protein (GFP) and luciferase were injected into the spleens of athymic, nude mice to generate hepatic metastases. Ninety-six hours after injection, tumor-bearing mice were treated with MEK1/2 inhibitor (trametinib, 0.3mg/kg, daily), gemcitabine (100mg/kg, twice weekly), or vehicle control. Sequential bioluminescence imaging, flow cytometry, and histologic evaluation were used to assess hepatic tumor growth and behavior. Results: All injected cell lines generated hepatic metastases. Different cell lines exhibited different growth kinetics. MPanc96 injected mice demonstrated a 64% decrease in average luminescence from 6 to 72 hrs after injection followed by a 146-fold increase from 72hrs until sacrifice at 21 days. Extensive liver metastases were noted at necropsy. Flow cytometry analysis of digested mouse livers following MPanc96 injection revealed rapid clearance followed by sharp outgrowth of tumor cells that mirror the bioluminescent imaging data. MPanc96 injected mice treated with trametinib exhibited significant hepatic tumor growth inhibition relative to gemcitabine and control treated mice. At 21 days, trametinib treated mice demonstrated a 14.9-fold increase in average luminescence while on treatment compared to an 82.5-fold increased for gemcitabine treated mice (p = 0.028) and a 195.5-fold increase for control mice (p = 0.027). Conclusions: This in vivo model of pancreatic liver metastases has proven effective in assessing treatment effects on pancreatic metastatic growth. Trametinib appears to be a superior agent to gemcitabine at inhibiting metastatic pancreatic tumor growth and its effectiveness will be evaluated using this model with additional patient-derived tumor cell lines.

Abstract 5600: Acquired resistance of pancreatic cancers to combination therapy with lapatinib plus the MEK 1/2 inhibitor GSK1120212: Using a murine orthotopic xenograft model to identify resistance pathways

Background: The high incidence of KRAS mutations in human pancreatic cancers has driven the testing of MEK1/2 inhibitors (e.g. GSK1120212) in clinical trials for pancreatic cancer. We have recently shown that human patient-derived tumors expressing activated epidermal growth factor (EGF)/HER2 receptors exhibit enhanced response to combination therapy with GSK1120212 and lapatinib, using a mouse xenograft model. A phase I clinical trial of GSK1120212 plus lapatinib is now underway. We report here the analysis of tumors that have acquired resistance to this therapy in the setting of the mouse xenograft model with the goal of identifying additional effective combination therapies and improved strategies for treatment of patients with resistant disease. Methods: Three patient-derived pancreatic cancer xenografts expressing either mutant or wild type KRAS and activated EGF/HER2 receptors were implanted orthotopically in nude mice and treated with combination lapatinib (EGFR/HER2 inhibitor) and GSK1120212 (MEK1/2 inhibitor). Tumor volume was assessed by sequential MRI. Following treatment, tumors were reimplanted in second and third generation mice and retreated to generate therapy-resistant tumors. Drug-resistant and drug-naïve tumors were compared using gene expression profiling, protein kinase arrays and Western blotting analysis. Results: Acquired resistance developed in all three tumor xenografts. Gene expression profiling identified multiple genes whose expression changed in response to drug treatment. Western blot analysis of tumor lysates from resistant and naive tumors revealed examples of select resistant tumors with either sustained activation of ERK1/2 or inactivation of ERK1/2 in the presence of inhibitor. Individual resistant tumors exhibiting inactivation of ERK1/2 exhibited increased activity of alternate survival signaling pathways including increased pAkt, pp38, pJNK, and pGSK3β levels relative to drug naïve control tumors. Phospho-RTK array analysis revealed increased pFGFR1 and pVEGFR1 levels in select resistant tumors suggesting a possible role for up-regulated RTK signaling in acquired resistance. Conclusions: Using an orthotopic murine model bearing patient-derived pancreatic cancer xenografts, we have developed a model of acquired resistance to lapatinib plus GSK1120212. Interrogation of comparative gene expression and phospho-protein studies revealed alterations in signaling pathways that may contribute to drug resistance. Current studies aim to exploit these pathways to 1) derive strategies for treatment of drug-resistant tumors, and 2) develop additional rational combinatorial therapies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5600. doi:1538-7445.AM2012-5600

Acquired resistance to combination therapy with lapatinib and MEK 1/2 inhibitor GSK1120212 in an in vivo murine model of pancreatic cancer

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Background: Mutations of the oncogene KRAS and activation of cell-surface receptor tyrosine kinases are important and preserved mechanisms of tumorgenicity in pancreatic cancer. Dual inhibition of the downstream KRAS effector MEK 1/2 and tyrosine kinases EGFR and Her2 results in effective inhibition of patient-derived tumor growth in a murine orthotopic transplantation model. Because combinatorial therapies are moving rapidly into clinical trials, we sought to develop a model of acquired tumor resistance to this combination therapy.

Methods: Patient-derived pancreatic tumor xenografts MAD 09-366 (KRAS mut), MAD 08-608 (KRAS mut) and MAD 08-738 (KRAS wt) were implanted orthotopically in nude mice and treated with combination lapatinib (EGFR/Her2 inhibitor) and GSK1120212 (MEK1/2 inhibitor) and tumor volume was measured by MRI. Following 4-6wks of treatment, tumors were reimplanted in second and third generation mice and retreated. Tumors were evaluated by phospho-RTK and phospho-MAPKinase array.

Results: Acquired resistance developed in all three tumor xenografts. Treated tumors demonstrated a relative volume decrease in the original (F0) generation. All second re-implantation (F2) tumors, demonstrated relative tumor volume increases despite treatment. A comparison of pre-treatment mean tumor volumes showed a significant decrease in tumor size from the F0 to F2 generations suggesting selection for slower growing tumors. Array data demonstrated increased activation of FGFR1, VEGFR1/3, GSK-3β, p38, and Akt in resistant tumors as compared to their pre-treatment controls. These may represent mechanisms of tumor resistance and warrant further investigation.

Conclusions: Repeated tumor exposure in vivo to combination treatment with GSK1120212 and lapatinib was used to develop a preclinical, orthotopic murine model of acquired drug resistance in patient-derived pancreatic cancers. This model provides the opportunity to define the mechanism of resistance in an appropriate tumor microenvironment and to develop alternative strategies for treating tumors resistant to this and other emerging therapies.

The incidence and preoperative detection of nodal metastases in resected pancreatic neuroendocrine tumors

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Background: Pancreatic neuroendocrine tumors (pNETs) are a heterogeneous group of rare malignancies in which surgical resection remains the only curative therapy. The optimal surgical approach (enucleation vs. pancreatectomy) is controversial. This study aims to determine the 1) incidence, 2) predictors, and 3) preoperative detection of lymph node (LN) metastases in resected pNETs to help guide surgical management.

Methods: A retrospective review of prospectively collected data was performed for all patients with pancreatic neuroendocrine tumors who underwent surgical resection at the University of Virginia between 1991 and 2010. The electronic medical record, radiology reports and pathology reports were used to identify patient demographics, surgical procedure, tumor functional status, type, size, location, and LN status.

Results: In all, 76 patients were identified. Most tumors were non-functioning (71%) with insulinomas (13%) and gastrinomas (5%) representing the largest groups of functioning pNETs. Nineteen tumors (25%) had LN metastases at the time of resection. LN-positive tumors were significantly larger than LN-negative tumors (4.0 ± 0.4 cm vs. 2.8 ± 0.2 cm, p=0.01). Five (11%) of 46 tumors ≤ 3 cm and one (14%) of 7 tumors ≤ 1 cm had LN metastases. There were no significant relationships between LN status and either tumor type or location (head/uncinate vs. body/tail). Of patients with LN-positive tumors, preoperative CT or MRI detected the LN metastases in only 19%.

Conclusions: Twenty-five percent of pNETs are associated with LN metastasis. The only predictor of LN metastasis was tumor size, but even smaller tumors were associated with LN metastasis. The sensitivity of preoperative CT and MRI is quite poor in detecting LN metastasis. Thus, formal resection with lymphadenectomy should be considered the standard of care for pNETs.

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