Circulating Tumor Cells as a Biomarker of Response to Treatment in Patient-Derived Xenograft Mouse Models of Pancreatic Adenocarcinoma

Circulating tumor cells (CTCs) are cells shed from solid tumors into circulation and have been shown to be prognostic in the setting of metastatic disease. These cells are obtained through a routine blood draw and may serve as an easily accessible marker for monitoring treatment effectiveness. Because of the rapid progression of pancreatic ductal adenocarcinoma (PDAC), early insight into treatment effectiveness may allow for necessary and timely changes in treatment regimens. The objective of this study was to evaluate CTC burden as a biomarker of response to treatment with a oral phosphatidylinositol-3-kinase inhibitor, BKM120, in patient-derived xenograft (PDX) mouse models of PDAC. PDX mice were randomized to receive vehicle or BKM120 treatment for 28 days and CTCs were enumerated from whole blood before and after treatment using a microfluidic chip that selected for EpCAM (epithelial cell adhesion molecule) positive cells. This microfluidic device allowed for the release of captured CTCs and enumeration of these cells via their electrical impedance signatures. Median CTC counts significantly decreased in the BKM120 group from pre- to post-treatment (26.61 to 2.21 CTCs/250 µL, p = 0.0207) while no significant change was observed in the vehicle group (23.26 to 11.89 CTCs/250 µL, p = 0.8081). This reduction in CTC burden in the treatment group correlated with tumor growth inhibition indicating CTC burden is a promising biomarker of response to treatment in preclinical models. Mutant enriched sequencing of isolated CTCs confirmed that they harbored KRAS G12V mutations, identical to the matched tumors. In the long-term, PDX mice are a useful preclinical model for furthering our understanding of CTCs. Clinically, mutational analysis of CTCs and serial monitoring of CTC burden may be used as a minimally invasive approach to predict and monitor treatment response to guide therapeutic regimens

UV activation of polymeric high aspect ratio microstructures: Ramifications in antibody surface loading for circulating tumor cell selection

The need to activate thermoplastic surfaces using robust and efficient methods has been driven by the fact that replication techniques can be used to produce microfluidic devices in a high production mode and at low cost, making polymer microfluidics invaluable for in vitro diagnostics, such as circulating tumor cell (CTC) analysis, where device disposability is critical to mitigate artifacts associated with sample carryover. Modifying the surface chemistry of thermoplastic devices through activation techniques can be used to increase the wettability of the surface or to produce functional scaffolds to allow for the covalent attachment of biologics, such as antibodies for CTC recognition. Extensive surface characterization tools were used to investigate UV activation of various surfaces to produce uniform and high surface coverage of functional groups, such as carboxylic acids in microchannels of different aspect ratios. We found that the efficiency of the UV activation process is highly dependent on the microchannel aspect ratio and the identity of the thermoplastic substrate. Colorimetric assays and fluorescence imaging of UV-activated microchannels following EDC/NHS coupling of Cy3-labeled oligonucleotides indicated that UV-activation of a PMMA microchannel with an aspect ratio of ???3 was significantly less efficient toward the bottom of the channel compared to the upper sections. This effect was a consequence of the bulk polymer's damping of the modifying UV radiation due to absorption artifacts. In contrast, this effect was less pronounced for COC. Moreover, we observed that after thermal fusion bonding of the device's cover plate to the substrate, many of the generated functional groups buried into the bulk rendering them inaccessible. The propensity of this surface reorganization was found to be higher for PMMA compared to COC. As an example of the effects of material and microchannel aspect ratios on device functionality, thermoplastic devices for the selection of CTCs from whole blood were evaluated, which required the immobilization of monoclonal antibodies to channel walls. From our results, we concluded the CTC yield and purity of isolated CTCs were dependent on the substrate material with COC producing the highest clinical yields for CTCs as well as better purities compared to PMMA.close9

Newly Emerging Immune Checkpoints: Promises for Future Cancer Therapy

Cancer immunotherapy has been a great breakthrough, with immune checkpoint inhibitors leading the way. Despite the clinical effectiveness of certain immune checkpoint inhibitors, the overall response rate remains low, and the effectiveness of immunotherapies for many tumors has been disappointing. There is substantial interest in looking for additional immune checkpoint molecules that may act as therapeutic targets for cancer. Recent advances during the last decade have identified several novel immune checkpoint targets, including lymphocyte activation gene-3 (LAG-3), B and T lymphocyte attenuator (BTLA), programmed death-1 homolog (PD-1H), T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIM-3)/carcinoembryonic antigen cell adhesion molecule 1 (CEACAM1), and the poliovirus receptor (PVR)-like receptors. The investigations into these molecules have generated promising results in preclinical studies. Herein, we will summarize our current progress and understanding of these newly-characterized immune checkpoints and their potential application in cancer immunotherapy

Anaplastic Pancreatic Carcinoma Arising Within a Mucinous Cystic Neoplasm of the Pancreas: A Case Report and a Brief Review of the Literature

Background: Anaplastic pancreatic carcinomas (APCs) are among the least frequently encountered pancreatic malignancies, ranging from 0.5% to 7% of all nonendocrine pancreatic malignancies. Furthermore, few cases of APCs have been described arising within a pancreatic mucinous cystic neoplasm (MCN). Case Presentation: A 36-year-old female presented with left upper quadrant pain and a 10 × 8 cm complex cystic mass in the pancreatic tail. Fine needle aspiration of the cyst showed papillary clusters of cells with mild cytological atypia, cyst fluid carcinoembryonic antigen >4000 ng/mL, and amylase of 25 U/L. After an open distal pancreatectomy and splenectomy, the specimen revealed an MCN with multifocal microscopic foci of invasive well-differentiated adenocarcinoma. After additional sampling, foci of undifferentiated malignancy—morphologically resembling sarcomas but with immunohistochemical staining consistent with anaplastic carcinoma—were identified. The patient had an uneventful recovery and is currently undergoing a regimen of gemcitabine-based adjuvant chemotherapy; she remains disease-free at 5 months after initial diagnosis. Conclusions: In this study, we describe a rare case of APC originating from a large pancreatic MCN lesion. This case underlines the importance of scrupulous pathological evaluation of the entire MCN epithelium and adds to the limited world literature of APC originating from pancreatic MCN lesions

Anaplastic Pancreatic Carcinoma Arising Within a Mucinous Cystic Neoplasm of the Pancreas: A Case Report and a Brief Review of the Literature

Background: Anaplastic pancreatic carcinomas (APCs) are among the least frequently encountered pancreatic malignancies, ranging from 0.5% to 7% of all nonendocrine pancreatic malignancies. Furthermore, few cases of APCs have been described arising within a pancreatic mucinous cystic neoplasm (MCN). Case Presentation: A 36-year-old female presented with left upper quadrant pain and a 10 × 8 cm complex cystic mass in the pancreatic tail. Fine needle aspiration of the cyst showed papillary clusters of cells with mild cytological atypia, cyst fluid carcinoembryonic antigen >4000 ng/mL, and amylase of 25 U/L. After an open distal pancreatectomy and splenectomy, the specimen revealed an MCN with multifocal microscopic foci of invasive well-differentiated adenocarcinoma. After additional sampling, foci of undifferentiated malignancy—morphologically resembling sarcomas but with immunohistochemical staining consistent with anaplastic carcinoma—were identified. The patient had an uneventful recovery and is currently undergoing a regimen of gemcitabine-based adjuvant chemotherapy; she remains disease-free at 5 months after initial diagnosis. Conclusions: In this study, we describe a rare case of APC originating from a large pancreatic MCN lesion. This case underlines the importance of scrupulous pathological evaluation of the entire MCN epithelium and adds to the limited world literature of APC originating from pancreatic MCN lesions