Pancreatic Liver Metastases Research Articles

Textural heterogeneity of liver lesions in CT imaging - comparison of colorectal and pancreatic metastases

PurposeTumoral heterogeneity poses a challenge for personalized cancer treatments. Especially in metastasized cancer, it remains a major limitation for successful targeted therapy, often leading to drug resistance due to tumoral escape mechanisms. This work explores a non-invasive radiomics-based approach to capture textural heterogeneity in liver lesions and compare it between colorectal cancer (CRC) and pancreatic cancer (PDAC).Materials and methodsIn this retrospective single-center study 73 subjects (42 CRC, 31 PDAC) with 1291 liver metastases (430 CRC, 861 PDAC) were segmented fully automated on contrast-enhanced CT images by a UNet for medical images. Radiomics features were extracted using the Python package Pyradiomics. The mean coefficient of variation (CV) was calculated patient-wise for each feature to quantify the heterogeneity. An unpaired t-test identified features with significant differences in feature variability between CRC and PDAC metastases.ResultsIn both colorectal and pancreatic liver metastases, interlesional heterogeneity in imaging can be observed using quantitative imaging features. 75 second-order features were extracted to compare the varying textural characteristics. In total, 18 radiomics features showed a significant difference (p < 0.05) in their expression between the two malignancies. Out of these, 16 features showed higher levels of variability within the cohort of pancreatic metastases, which, as illustrated in a radar plot, suggests greater textural heterogeneity for this entity.ConclusionsRadiomics has the potential to identify the interlesional heterogeneity of CT texture among individual liver metastases. In this proof-of-concept study for the quantification and comparison of imaging-related heterogeneity in liver metastases a variation in the extent of heterogeneity levels in CRC and PDAC liver metastases was shown.

Near-infrared Fluorescence Imaging for Detecting Pancreatic Liver Metastasis in an Orthotopic Athymic Mouse Model.

Evidence of metastatic disease precludes oncological resection of pancreatic cancer. Near-infrared (NIR) fluorescent labels, such as indocyanine green (ICG), assist in the intraoperative detection of occult and micrometastatic liver disease. The present study aimed to analyse the role of NIR fluorescence imaging using ICG for pancreatic liver disease as proof of concept in an orthotopic athymic mouse model. Pancreatic ductal adenocarcinoma was induced by injecting L3.6pl human pancreatic tumour cells into the pancreatic tail of seven athymic mice. After four weeks of tumour growth, ICG was injected into the tail vein and NIR fluorescence imaging was performed at harvest to determine tumour-to-liver ratios (TLR) using Quest Spectrum® Fluorescence Imaging Platform. Pancreatic tumour growth and liver metastasis could be visually confirmed for all seven animals. None of the hepatic metastases showed any detectable ICG-uptake. ICG-staining failed to visualize the liver metastases or to increase fluorescence intensity of the rim around the hepatic lesions. ICG-staining fails to visualize liver metastases induced by L3.6pl pancreatic tumour cells in athymic nude mice by NIR fluorescence imaging. Further studies are necessary to delineate the underlying mechanism for insufficient ICG uptake in these pancreatic liver metastases and for the lack of a fluorescent rim around the liver lesions.

Abstract IA16: Immune suppression in cancer and strategies for its reversal

Abstract The microenvironment is involved in multiple aspect of cancer progression. Tumor metastasis is a critical step in the progression of solid tumors that is associated with patient mortality, and the metastatic microenvironment is key regulator of this process. The pre-metastatic niche is the microenvironment important for metastatic initiation that is established at distant sites in response to primary tumor factors during cancer progression. We characterized this microenvironment which involves changes in both stromal and immune populations in the lungs of sarcoma-bearing mice and in the liver in pancreatic- bearing mice by flow cytometry and RNA sequencing approaches. We identified a gene signature in pre-metastatic niche formation that demonstrates upregulation of immune suppression genes that is consistent across different metastatic tissue including lung and liver as well as across species with commonalities in murine and human early metastatic microenvironments. Performing single cell RNA sequencing of the pre-metastatic niche revealed key immune suppressive genes were found in the myeloid cell clusters. In addition to the increase of myeloid cells and immunosuppressive pathways, we discovered that T cell populations are reduced in pre-metastatic lungs. We hypothesized that reversing this immunosuppressive environment would restore T cell function and antitumor immunity. We designed a novel approach in which we generated Genetically-Engineered Myeloid cells (GEMys) to deliver IL-12, a potent antitumor molecule, into the pre-metastatic microenvironment. We evaluated the lungs by flow cytometry and observed that IL12-GEMy-treated mice had increased numbers of T cells and enhanced expression of activation markers, resulting in reduced metastasis and increased survival. This model was effective in an aggressive experimental metastasis model of pancreatic liver metastasis and was not only able to limit metastatic progression but was able to cure a subset of mice compared to rapid metastatic progression in the liver within a month in the untreated pancreatic cancer mice. When combined with chemotherapy pre-conditioning, IL12-GEMys cured mice of established tumors and generated long-lived T cell memory, as these mice were immune to subsequent tumor challenge. These studies demonstrate that IL12-GEMys can functionally modulate the core program of immune suppression in the pre-metastatic niche to successfully rebalance the dysregulated metastatic microenvironment in cancer. Citation Format: Rosandra N. Kaplan. Immune suppression in cancer and strategies for its reversal [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr IA16.

Intraoperative detection of colorectal and pancreatic liver metastases using SGM-101, a fluorescent antibody targeting CEA

BackgroundFluorescence-guided surgery can provide surgeons with an imaging tool for real-time intraoperative tumor detection. SGM-101, an anti-CEA antibody labelled with a fluorescent dye, is a tumor-specific imaging agent that can aid in improving detection and complete resection for CEA-positive tumors. In this study, the performance of SGM-101 for the detection of colorectal and pancreatic liver metastases was investigated. MethodsIn this open-label, non-randomized, single-arm pilot study, patients were included with liver metastases from colorectal origin and intraoperatively detected liver metastases from pancreatic origin (during planned pancreatic surgery). SGM-101 was administered two to four days before the scheduled surgery as a single intravenous injection. Intraoperative fluorescence imaging was performed using the Quest Spectrum® imaging system. The performance of SGM-101 was assessed by measuring the intraoperative fluorescence signal and comparing this to histopathology. ResultsA total of 19 lesions were found in 11 patients, which were all suspected as malignant in white light and subsequent fluorescence inspection. Seventeen lesions were malignant with a mean tumor-to-background ratio of 1.7. The remaining two lesions were false-positives as proven by histology. ConclusionCEA-targeted fluorescence-guided intraoperative tumor detection with SGM-101 is feasible for the detection of colorectal and pancreatic liver metastases.

Variation in the surgical management of locally advanced pancreatic cancer.

4122 Background: Recent reports suggest patients with locally advanced pancreatic cancer (LAPC) may become candidates for curative resection following neoadjuvant therapy, with encouraging survival outcomes. Yet the optimal management approach for LAPC remains unclear. We sought to investigate surgeon preferences for the management of patients with LAPC. Methods: An extensive electronic survey was systematically distributed by email to an international cohort of pancreas surgeons. Data collected included surgeon practice characteristics, preferences for staging and management, and 6 clinical vignettes (with detailed videos of post-neoadjuvant arterial and venous imaging) to assess attitudes regarding eligibility for surgical exploration. Results: A total of 150 eligible responses were received from 4 continents. Median duration in practice was 12 years (IQR 6-20) and 75% respondents work in a university setting. Most (84%) are considered high volume, 33% offer a minimally-invasive approach, and 48% offer arterial resection in selected patients. A majority (70%) always recommend neoadjuvant chemotherapy, and 62% prefer FOLFIRINOX. Preferences for duration of neoadjuvant therapy varied widely: 39% prefer ≥2 months, 41% prefer ≥4 months, and 11% prefer 6 months or more. Forty-one percent frequently recommend neoadjuvant radiation, and 51% prefer standard chemoradiotherapy. Age ≥80 years and CA 19-9 of ≥1000 U/mL were commonly considered contraindications to exploration. In 5 clinical vignettes of LAPC, the proportion of respondents that would offer exploration following neoadjuvant varied extensively, from 15% to 54%. In a vignette of oligometastatic pancreatic liver metastases, 32% would offer exploration if a favorable biochemical and imaging response to therapy is observed. Conclusions: In an international cohort of high volume pancreas surgeons, there is substantial variation in attitudes regarding staging preferences and surgical management of LAPC. These results underscore the importance of coordinated multi-disciplinary care, and suggest an evolving concept of “resectability.” Patients and their oncologists should have a low threshold to consider a second opinion for the surgical management of LAPC, if desired.

Imaging mass spectrometry to discriminate breast from pancreatic cancer metastasis in formalin‐fixed paraffin‐embedded tissues

Diagnosis of the origin of metastasis is mandatory for adequate therapy. In the past, classification of tumors was based on histology (morphological expression of a complex protein pattern), while supportive immunohistochemical investigation relied only on few "tumor specific" proteins. At present, histopathological diagnosis is based on clinical information, morphology, immunohistochemistry, and may include molecular methods. This process is complex, expensive, requires an experienced pathologist and may be time consuming. Currently, proteomic methods have been introduced in various clinical disciplines. MALDI imaging MS combines detection of numerous proteins with morphological features, and seems to be the ideal tool for objective and fast histopathological tumor classification. To study a special tumor type and to identify predictive patterns that could discriminate metastatic breast from pancreatic carcinoma MALDI imaging MS was applied to multitissue paraffin blocks. A statistical classification model was created using a training set of primary carcinoma biopsies. This model was validated on two testing sets of different breast and pancreatic carcinoma specimens. We could discern breast from pancreatic primary tumors with an overall accuracy of 83.38%, a sensitivity of 85.95% and a specificity of 76.96%. Furthermore, breast and pancreatic liver metastases were tested and classified correctly.

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

198 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 PR9: Granulocyte macrophage colony stimulating factor (GM-CSF) pancreas tumor vaccine in combination with blockade of PD-1 in a preclinical model of pancreatic cancer.

Abstract Introduction: Our phase I/II human clinical trials utilizing a GM-CSF secreting allogeneic pancreas tumor vaccine (GVAX) have been shown to be safe and effective in inducing anti-tumor immune response in pancreatic adenocarcinoma patients. GVAX treated patients have demonstrated infiltration of PD-1+ T cells which is a major immunosuppressive mechanism in the tumor microenvironment. We hypothesized that the use of a PD-1 blocking antibody and GVAX will improve vaccine therapy and pancreatic cancer survival. Methods: Mice were orthotopically transplanted with 2 x 106 Panc02 pancreatic tumor cells to form liver metastases by a hemisplenectomy technique on day 0. Following tumor transplantation, wild-type or PD-1 knockout mice were treated subcutaneously with a mouse GM-CSF secreting pancreatic tumor vaccine (mouse GVAX) in combination with anti-PD-1 antibodies or IgG isotype control. GVAX was given subcutaneously to mice on days 4, 7, 14, and 21 following tumor transplantation, together with a single low-dose of Cytoxan on day 3. Anti-PD-1 antibodies or IgG were administered twice weekly starting post-operative day 3. Results: PD-1 knockout mice challenged with pancreatic liver metastases had a significant survival advantage over wild-type mice (p=0.0002). Wild-type mice showed improved survival both with anti-PD-1 antibody alone (p=0.008) or in combination with vaccine (p&amp;lt;0.0001) versus IgG controls. GVAX in combination with anti-PD-1 antibodies versus anti-PD-1 antibodies alone shows a statistically significant improved survival (p&amp;lt;0.05). Memory T cell analysis demonstrated a strong trend toward increased tumor infiltration of CD8+ effector memory T cells in the combinatorial treatment group versus vaccine alone (66.67% vs 26.47%, p= 0.1). Tumor antigen (mesothelin)-specific cytotoxic CD8+ tumor infiltrating lymphocytes were increased in the combination treatment group (GVAX and anti-PD1 therapy) versus GVAX alone (13.4% vs 5.29%). Conclusions: PD-1 blockade through monoclonal antibodies or genetic knockout in combination with vaccine result in a synergistic anti-tumor effect in a preclinical model of pancreatic cancer versus treatment with anti-PD1 alone. Additionally, anti-PD1 treatment facilitates tumor infiltration of functionally activated mesothelin specific CD8+ T cells. Anti-PD-1 blockade antibody is currently being tested in phase II clinical trials for treating chemotherapy-refractory solid tumor patients. Our study provides a strong rationale for combining PD-1 antibody with GVAX therapy for pancreatic cancer treatment. This abstract is also presented as Poster B28. Citation Format: Kevin C. Soares, Kelly Olino, Barish Edil, Donger Zhou, Anthony Wamwea, Ashley Leubner, Richard Schulick, Drew Pardoll, Elizabeth Jaffee, Lei Zheng. Granulocyte macrophage colony stimulating factor (GM-CSF) pancreas tumor vaccine in combination with blockade of PD-1 in a preclinical model of pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr PR9.

Abstract B145: The novel Hedgehog pathway inhibitor IPI-926 delays metastatic spread and provides a survival benefit in an experimental model of pancreatic liver metastasis.

Abstract Metastasis, or the spread of disseminated tumor cells to and colonization of distal sites, is a major cause of cancer mortality. The Hedgehog (Hh) signaling pathway is normally involved in embryogenesis; however recent evidence suggests a role for this pathway in cancer and metastasis. Thus, inhibitors of Hh signaling may have potential utility as novel targeted anti-tumor therapies. IPI-926 is a novel, selective, small molecule that antagonizes the Hh pathway by binding to the Smoothened receptor, the major upstream facilitator of Hh signal transduction, and is currently in phase 2 clinical trials for pancreatic cancer, chondrosarcoma and primary myelofibrosis. Administration of IPI-926 in combination with gemcitabine inhibits incidence of metastases in a KRAS/p53 transgenic model of pancreatic cancer (Olive et al., 2009), supporting an integral role for the Hh pathway in this process. To further explore the activity of IPI-926 in the setting of metastasis, we developed an experimental model of pancreatic cancer liver metastasis where luciferase-tagged tumor cells were implanted in the liver via an intra-splenic injection, followed by splenectomy, resulting in liver metastases. Tumor burden, as assessed by bioluminescence and survival were employed to evaluate IPI-926 activity utilizing different dosing regimens. While treatment of tumor-bearing animals with established disease provided no survival benefit, IPI-926 administered on the day of cell implant provided modest but reproducible increase in survival. However, prophylactic administration of IPI-926 beginning 14 days (d) prior to cell implant resulted in a significant decrease in disease burden and enhanced survival. The activity was dependent on the schedule of IPI-926 administration. Treatment initiated 14d prior to cell implant was more effective than 7d before cell implant, and treatment started only 2d prior to cell implantation showed no difference compared to treatment initiated on the day of cell implant. Histological analysis of pre-treated vs control livers confirmed decreased metastatic nodule formation. In addition, analysis of serum harvested from IPI-926 14d pre-treated vs control animals showed down-regulation of components of the VEGF, PDGF and MMP pathways, suggesting that IPI-926 modulation of these pathways may be involved in the observed effects on metastatic spread. The activity of IPI-926 was also evaluated in the setting of sunitinib enhancement of metastases (Ebos et al., 2010) in the above model. As has been shown previously, short, high-dose sunitinib administration resulted in striking increases in disease burden and shortening of survival compared to control animals. However, when IPI-926 was administered 14d prior to cell implant and sunitinib treatment, disease burden and survival were returned to the levels observed in the control group. In summary, IPI-926 administration delays metastasis in an experimental model of pancreatic liver metastasis and in response to high-dose anti-angiogenic therapy. These results provide rationale for the evaluation of IPI-926 as adjuvant/neoadjuvant therapy to help control metastatic spread post surgical resection in pancreatic cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B145.

Subcutaneous needle-tract seeding after fine needle aspiration biopsy of pancreatic liver metastasis

A case of subcutaneous neoplastic seeding after fine needle aspiration biopsy of a pancreatic liver metastasis is reported. Neoplastic seeding is a rare complication after fine needle biopsy (FNB). The seeding appeared 3 months after the biopsy with a subcutaneous hypoechoic nodule; diagnosis was confirmed by fine needle aspiration of the nodule. The neoplastic seeding did not change the outcome of the patient.

Human pancreatic adenocarcinomas express parathyroid hormone-related protein.

PTH-related protein (PTHrP) is expressed in many common malignancies such as breast and prostate cancer and can regulate their growth. Little is known, however, about the role of PTHrP in pancreatic adenocarcinoma. To study PTHrP in pancreatic exocrine cancer, we studied its expression in pancreatic cancer cell lines and surgical specimens. Eight human pancreatic adenocarcinoma cell lines were evaluated: AsPC-1, BxPC-3, Capan-1, CFPAC-1, MIA PaCa-2, PANC-1, PANC-28, and PANC-48. Murine monoclonal antibodies to the amino-terminal (1-34), mid-region (38-64), and carboxyl-terminal peptides (109-141) of PTHrP were used to identify cellular PTHrP and secreted PTHrP, including Western blotting and immunocytochemical staining for PTHrP from each cell line. Cellular PTHrP was detected in all cell line extracts by both Western blotting and immunoassay. CFPAC-1, derived from a pancreatic liver metastasis, had the highest concentration of PTHrP, and MIA PaCa-2, derived from primary pancreatic adenocarcinoma, had the lowest. PTHrP was localized by immunocytochemical staining in the cytoplasm in all but one cell line, and both nuclear and cytoplasmic immunostaining were observed in the MIA PaCa-2 and PANC-1 cells. Secretion of PTHrP into cell medium was also observed for each cell line and paralleled intracellular PTHrP levels. Evidence for differential processing of PTHrP expression was provided by studies demonstrating different patterns of PTHrP among the cell lines when assessed by PTHrP immunoassays directed against different PTHrP peptides. In specific, PTHrP secretion measured by a PTHrP-(38-64) assay was highest for BxPC-3, whereas the highest levels of secreted PTHrP-(109-141) occurred in CFPAC-1 and PANC-1. Growth of AsPC-1 cells was stimulated in a dose-dependent manner by PTHrP-(1-34). Immunostaining from archival tissue of patients with pancreatic adenocarcinoma revealed strong PTHrP expression in all 14 specimens. All patients were eucalcemic preoperatively. These results demonstrate that PTHrP is commonly expressed in pancreatic cancer. Our data suggest that PTHrP may have growth-regulating properties in pancreatic adenocarcinoma cells, but further studies are required.