Vascular endothelial-targeted therapy combined with cytotoxic chemotherapy induces inflammatory intratumoral infiltrates and inhibits tumor relapses after surgery

Enhanced Efficacy of Combination of Gemcitabine and Phosphatidylserine-Targeted Nanovesicles against Pancreatic Cancer

Phosphatidylserine (PS) is often externalized in viable pancreatic cancer cells and is therapeutically targetable using PS-selective drugs. One of the first-line treatments for advanced pancreatic cancer disease, gemcitabine (GEM), provides only marginal benefit to patients. We therefore investigated the therapeutic benefits of combining GEM and the PS-targeting drug, saposin C-dioleoylphosphatidylserine (SapC-DOPS), for treating pancreatic ductal adenocarcinoma (PDAC). Using cell-cycle analyses and a cell surface PS-based sorting method in vitro, we observed an increase in surface PS as cells progress through the cell cycle from G1 to G2/M. We also observed that GEM treatment preferentially targets G1 phase cells that have low surface PS, resulting in an increased median surface PS level of PDAC cells. Inversely, SapC-DOPS preferentially targets high surface PS cells that are predominantly in the G2/M phase. Finally, combination therapy in subcutaneous and orthotopic PDAC tumors in vivo with SapC-DOPS and GEM or Abraxane (Abr)/GEM (one of the current standards of care) significantly inhibits tumor growth and increases survival compared with individual treatments. Our studies confirm a surface PS and cell cycle-based enhancement of cancer cytotoxicity following SapC-DOPS treatment in combination with GEM or Abr/GEM. Thus, PDAC patients treated with Abr/GEM may benefit from concurrent administration of SapC-DOPS.

Standardization and Optimization of Intraoperative Molecular Imaging for Identifying Primary Pulmonary Adenocarcinomas

PURPOSE

Intraoperative molecular imaging (IMI) is an emerging technology used to locate pulmonary adenocarcinomas and identify positive margins during surgery. Background noise and tissue autofluorescence have been major obstacles. The goal of this study is to optimize the image quality of folate receptor alpha (FRα) targeted IMI for pulmonary adenocarcinomas by modifying emission data.

PROCEDURES

A total of 15 lung cancer patients were enrolled in a pilot study. In the first cohort, FRα upregulation within pulmonary adenocarcinoma tumors was confirmed by analyzing specimens from five pulmonary adenocarcinoma patients with flow cytometry and immunohistochemistry. Next, in a cohort of five additional patients, autofluorescence of intrathoracic structures and tissues was quantified. Lastly, five patients with tumors at various depths from the pleural surface were enrolled and received the FRα-targeted optical contrast agent, EC17. In this final cohort, resected pulmonary adenocarcinomas were imaged at a wide range of fluorescence exposure times (0 to 200 ms), various laser powers, and with unique filter configurations. Tumor-to-noise ratio (TNR) for images was generated using region of interest software.

RESULTS

Pulmonary adenocarcinomas highly express FRα. Significant autofluorescence from native thoracic tissues was found with the highest fluorescent signals at the bronchial stump (547 ± 98, range 423-699), the pulmonary artery (267 ± 64, range 200-374), and cortical bone (266 ± 17, range 243-287). High levels of autofluorescence were appreciated after systemic administration of EC17; however, TNR was improved by altering exposure settings at the time of the imaging. Optimal fluorescent exposure time occurs at 40 ms (25 frames/s).

CONCLUSIONS

Exposure properties can be manipulated to maximize TNR thus allowing for successful intraoperative detection of pulmonary adenocarcinomas during surgery. Optimization of the conditions for intraoperative molecular imaging sets the stage for future clinical trials utilizing targeted IMI techniques which can aid the surgeon at the time of cancer resection.

A Novel Therapeutic Strategy for Cancer Using Phosphatidylserine Targeting Stearylamine-Bearing Cationic Liposomes

There is a pressing need for a ubiquitously expressed antigen or receptor on the tumor surface for successful mitigation of the deleterious side effects of chemotherapy. Phosphatidylserine (PS), normally constrained to the intracellular surface, is exposed on the external surface of tumors and most tumorigenic cell lines. Here we report that a novel PS-targeting liposome, phosphatidylcholine-stearylamine (PC-SA), induced apoptosis and showed potent anticancer effects as a single agent against a majority of cancer cell lines. We experimentally proved that this was due to a strong affinity for and direct interaction of these liposomes with PS. Complexation of the chemotherapeutic drugs doxorubicin and camptothecin in these vesicles demonstrated a manyfold enhancement in the efficacies of the drugs both in vitro and across three advanced tumor models without any signs of toxicity. Both free and drug-loaded liposomes were maximally confined to the tumor site with low tissue concentration. These data indicate that PC-SA is a unique and promising liposome that, alone and as a combination therapy, has anticancer potential across a wide range of cancer types.

Catch and Release of Cytokines Mediated by Tumor Phosphatidylserine Converts Transient Exposure into Long-Lived Inflammation

Immune cells constantly survey the host for pathogens or tumors and secrete cytokines to alert surrounding cells of these threats. In vivo, activated immune cells secrete cytokines for several hours, yet an acute immune reaction occurs over days. Given these divergent timescales, we addressed how cytokine-responsive cells translate brief cytokine exposure into phenotypic changes that persist over long timescales. We studied melanoma cell responses to transient exposure to the cytokine interferon γ (IFNγ) by combining a systems-scale analysis of gene expression dynamics with computational modeling and experiments. We discovered that IFNγ is captured by phosphatidylserine (PS) on the surface of viable cells both in vitro and in vivo then slowly released to drive long-term transcription of cytokine-response genes. This mechanism introduces an additional function for PS in dynamically regulating inflammation across diverse cancer and primary cell types and has potential to usher in new immunotherapies targeting PS and inflammatory pathways.

Intraoperative Molecular Imaging of Lung Adenocarcinoma Can Identify Residual Tumor Cells at the Surgical Margins

PURPOSE

During lung surgery, identification of surgical margins is challenging. We hypothesized that molecular imaging with a fluorescent probe to pulmonary adenocarcinomas could enhance residual tumor during resection.

PROCEDURES

Mice with flank tumors received a contrast agent targeting folate receptor alpha. Optimal dose and time of injection was established. Margin detection was compared using traditional methods versus molecular imaging. A pilot study was then performed in three humans with lung adenocarcinoma.

RESULTS

The peak tumor-to-background ratio (TBR) of murine tumors was 3.9. Fluorescence peaked at 2 h and was not improved beyond 0.1 mg/kg. Traditional inspection identified 30% of mice with positive margins. Molecular imaging identified an additional 50% of residual tumor deposits (p < 0.05). The fluorescent probe visually enhanced all human tumors with a mean TBR of 3.5.

CONCLUSIONS

Molecular imaging is an important adjunct to traditional inspection to identify surgical margins after tumor resection.

Phosphatidylserine (PS) Is Exposed in Choroidal Neovascular Endothelium: PS-Targeting Antibodies Inhibit Choroidal Angiogenesis In Vivo and Ex Vivo

PURPOSE

Choroidal neovascularization (CNV) accounts for 90% of cases of severe vision loss in patients with advanced age-related macular degeneration. Identifying new therapeutic targets for CNV may lead to novel combination therapies to improve outcomes and reduce treatment burden. Our goal was to test whether phosphatidylserine (PS) becomes exposed in the outer membrane of choroidal neovascular endothelium, and whether this could provide a new therapeutic target for CNV.

METHODS

Choroidal neovascularization was induced in C57BL/6J mice using laser photocoagulation. Choroidal neovascularization lesions costained for exposed PS and for intercellular adhesion molecule 2 (or isolectin B4) were imaged in flat mounts and in cross sections. The laser CNV model and a choroidal sprouting assay were used to test the effect of PS-targeting antibodies on choroidal angiogenesis. Choroidal neovascularization lesion size was determined by intercellular adhesion molecule 2 (ICAM-2) staining of flat mounts.

RESULTS

We found that PS was exposed in CNV lesions and colocalized with vascular endothelial staining. Treatment with PS-targeting antibodies led to a 40% to 80% reduction in CNV lesion area when compared to treatment with a control antibody. The effect was the same as that seen using an equal dose of an anti-VEGF antibody. Results were confirmed using the choroid sprouting assay, an ex vivo model of choroidal angiogenesis.

CONCLUSIONS

We demonstrated that PS is exposed in choroidal neovascular endothelium. Furthermore, targeting this exposed PS with antibodies may be of therapeutic value in CNV.

The phospholipid code: a key component of dying cell recognition, tumor progression and host-microbe interactions

A significant effort is made by the cell to maintain certain phospholipids at specific sites. It is well described that proteins involved in intracellular signaling can be targeted to the plasma membrane and organelles through phospholipid-binding domains. Thus, the accumulation of a specific combination of phospholipids, denoted here as the 'phospholipid code', is key in initiating cellular processes. Interestingly, a variety of extracellular proteins and pathogen-derived proteins can also recognize or modify phospholipids to facilitate the recognition of dying cells, tumorigenesis and host-microbe interactions. In this article, we discuss the importance of the phospholipid code in a range of physiological and pathological processes.

Comparison of Folate Receptor Targeted Optical Contrast Agents for Intraoperative Molecular Imaging

Background. Intraoperative imaging can identify cancer cells in order to improve resection; thus fluorescent contrast agents have emerged. Our objective was to do a preclinical comparison of two fluorescent dyes, EC17 and OTL38, which both target folate receptor but have different fluorochromes. Materials. HeLa and KB cells lines were used for in vitro and in vivo comparisons of EC17 and OTL38 brightness, sensitivity, pharmacokinetics, and biodistribution. In vivo experiments were then performed in mice. Results. The peak excitation and emission wavelengths of EC17 and OTL38 were 470/520 nm and 774/794 nm, respectively. In vitro, OTL38 required increased incubation time compared to EC17 for maximum fluorescence; however, peak signal-to-background ratio (SBR) was 1.4-fold higher compared to EC17 within 60 minutes (p < 0.001). Additionally, the SBR for detecting smaller quantity of cells was improved with OTL38. In vivo, the mean improvement in SBR of tumors visualized using OTL38 compared to EC17 was 3.3 fold (range 1.48–5.43). Neither dye caused noticeable toxicity in animal studies. Conclusions. In preclinical testing, OTL38 appears to have superior sensitivity and brightness compared to EC17. This coincides with the accepted belief that near infrared (NIR) dyes tend to have less autofluorescence and scattering issues than visible wavelength fluorochromes.

Endothelial hypoxic metabolism in carcinogenesis and dissemination: HIF-A isoforms are a NO metastatic phenomenon

Tumor biology is a broad and encompassing field of research, particularly given recent demonstrations of the multicellular nature of solid tumors, which have led to studies of molecular and metabolic intercellular interactions that regulate cancer progression. Hypoxia is a broad stimulus that results in activation of hypoxia inducible factors (HIFs). Downstream HIF targets include angiogenic factors (e.g. vascular endothelial growth factor, VEGF) and highly reactive molecules (e.g. nitric oxide, NO) that act as cell-specific switches with unique spatial and temporal effects on cancer progression. The effect of cell-specific responses to hypoxia on tumour progression and spread, as well as potential therapeutic strategies to target metastatic disease, are currently under active investigation. Vascular endothelial remodelling events at tumour and metastatic sites are responsive to hypoxia, HIF activation, and NO signalling. Here, we describe the interactions between endothelial HIF and NO during tumor growth and spread, and outline the effects of endothelial HIF/NO signalling on cancer progression. In doing so, we attempt to identify areas of metastasis research that require attention, in order to ultimately facilitate the development of novel treatments that reduce or prevent tumour dissemination.

Cancer subclonal genetic architecture as a key to personalized medicine

The future of personalized oncological therapy will likely rely on evidence-based medicine to integrate all of the available evidence to delineate the most efficacious treatment option for the patient. To undertake evidence-based medicine through use of targeted therapy regimens, identification of the specific underlying causative mutation(s) driving growth and progression of a patient's tumor is imperative. Although molecular subtyping is important for planning and treatment, intraclonal genetic diversity has been recently highlighted as having significant implications for biopsy-based prognosis. Overall, delineation of the clonal architecture of a patient's cancer and how this will impact on the selection of the most efficacious therapy remain a topic of intense interest.

Combination therapy with low molecular weight heparin and Adriamycin results in decreased breast cancer cell metastasis in C3H mice

The aim of this study was to investigate the effect of low molecular weight heparin (LMWH) against breast cancer cell invasion and metastasis in C₃H mice and the underlying mechanism. The C₃H mouse breast cancer model was established, and the mice were then randomly divided into four groups: normal saline group, LMWH group, Adriamycin positive control group and the combination group (LMWH combined with Adriamycin). Twelve days after inoculation, drug treatment was initiated. During the one-month period of drug administration, tumor growth curves were recorded. At the end of the treatment period, the mice were sacrificed and the solid tumor tissue and lung were removed. Hematoxylin and eosin (H&E) staining was used to observe the overall changes in tumor cell morphology and lung metastasis following the treatment. A terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay was used for detection of apoptosis in tumor cells, and immunohistochemical (IHC) analysis was used to determine the expression of vascular endothelial growth factor (VEGF). The tumor growth curves demonstrated that the overall growth of the combination group was less compared with that of the other three groups, indicating that LMWH inhibited the growth of the tumors. H&E staining showed that the area of tumor cell necrosis in the combination group was significantly greater compared with that in the other groups, and less metastasis was observed in the lung. The results from the TUNEL staining demonstrated that there was an increase in the number of blue-black apoptotic cells, and the expression of VEGF was significantly reduced in the combination group compared with the other three groups. Therefore, this indicates that LMWH, combined with Adriamycin significantly reduced the growth of breast cancer cells in C₃H mice. The results suggest that the mechanism may be associated with breast cancer cell apoptosis and inhibition of VEGF expression.

Intraoperative near-infrared imaging can distinguish cancer from normal tissue but not inflammation

Introduction

Defining tumor from non-tumor tissue is one of the major challenges of cancer surgery. Surgeons depend on visual and tactile clues to select which tissues should be removed from a patient. Recently, we and others have hypothesized near-infrared (NIR) imaging can be used during surgery to differentiate tumors from normal tissue.

Methods

We enrolled 8 canines and 5 humans undergoing cancer surgery for NIR imaging. The patients were injected with indocyanine green (ICG), an FDA approved non-receptor specific NIR dye that accumulates in hyperpermeable tissues, 16–24 hours prior to surgery. During surgery, NIR imaging was used to discriminate the tumor from non-tumor tissue.

Results

NIR imaging identified all tumors with a mean signal-to-background ratio of 6.7. Optical images were useful during surgery in discriminating normal tissue from cancer. In 3 canine cases and 1 human case, the tissue surrounding the tumor was inflamed due to obstruction of the vascular supply due to mass effect. In these instances, NIR imaging could not distinguish tumor tissue from tissue that was congested, edematous and did not contain cancer.

Conclusions

This study shows that NIR imaging can identify tumors from normal tissues, provides excellent tissue contrast, and it facilitates the resection of tumors. However, in situations where there is significant peritumoral inflammation, NIR imaging with ICG is not helpful. This suggests that non-targeted NIR dyes that accumulate in hyperpermeable tissues will have significant limitations in the future, and receptor-specific NIR dyes may be necessary to overcome this problem.

Metronomic chemotherapy: possible clinical application in advanced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a hypervascular highly angiogenic tumor usually associated with liver cirrhosis. Vascular endothelial growth factor plays a critical role in vascular development in HCC. In contrast to the treatment of early-stage HCC, the treatment options for advanced HCC are limited and prognosis is often poor, which contributes to this tumor type being the third leading cause of cancer-related deaths worldwide. Metronomic chemotherapy, which was originally designed to inhibit angiogenesis, involves low-dose chemotherapeutic agents administered in a frequent regular schedule with no prolonged breaks and minimizes severe toxicities. We reviewed the potential effects and impact of metronomic chemotherapy in preclinical studies with HCC models and in patients with advanced HCC, especially when combined with a molecular targeted agent. Metronomic chemotherapy involves multiple mechanisms that include antiangiogenesis and antivasculogenesis, immune stimulation by reducing regulatory T cells and inducing dendritic cell maturation, and possibly some direct tumor cell targeting effects, including the cancer stem cell subpopulation. The total number of preclinical studies with HCC models shows impressive results using metronomic chemotherapy-based protocols, especially in conjunction with molecular targeted agents. Four clinical trials and two case reports evaluating metronomic chemotherapy for HCC indicate it to be a safe and potentially useful treatment for HCC. Several preclinical and clinical HCC studies suggest that metronomic chemotherapy may become an alternative type of chemotherapy for advanced unresectable HCC and postsurgical adjuvant treatment of HCC.

Overcoming intratumor heterogeneity of polygenic cancer drug resistance with improved biomarker integration

Improvements in technology and resources are helping to advance our understanding of cancer-initiating events as well as factors involved with tumor progression, adaptation, and evasion of therapy. Tumors are well known to contain diverse cell populations and intratumor heterogeneity affords neoplasms with a diverse set of biologic characteristics that can be used to evolve and adapt. Intratumor heterogeneity has emerged as a major hindrance to improving cancer patient care. Polygenic cancer drug resistance necessitates reconsidering drug designs to include polypharmacology in pursuit of novel combinatorial agents having multitarget activity to overcome the diverse and compensatory signaling pathways in which cancer cells use to survive and evade therapy. Advances will require integration of different biomarkers such as genomics and imaging to provide for more adequate elucidation of the spatially varying location, type, and extent of diverse intratumor signaling molecules to provide for a rationale-based personalized cancer medicine strategy.

Changes in the local tumor microenvironment in recurrent cancers may explain the failure of vaccines after surgery

Each year, more than 700,000 people undergo cancer surgery in the United States. However, more than 40% of those patients develop recurrences and have a poor outcome. Traditionally, the medical community has assumed that recurrent tumors arise from selected tumor clones that are refractory to therapy. However, we found that tumor cells have few phenotypical differences after surgery. Thus, we propose an alternative explanation for the resistance of recurrent tumors. Surgery promotes inhibitory factors that allow lingering immunosuppressive cells to repopulate small pockets of residual disease quickly. Recurrent tumors and draining lymph nodes are infiltrated with M2 (CD11b(+)F4/80(hi)CD206(hi) and CD11b(+)F4/80(hi)CD124(hi)) macrophages and CD4(+)Foxp3(+) regulatory T cells. This complex network of immunosuppression in the surrounding tumor microenvironment explains the resistance of tumor recurrences to conventional cancer vaccines despite small tumor size, an intact antitumor immune response, and unaltered cancer cells. Therapeutic strategies coupling antitumor agents with inhibition of immunosuppressive cells potentially could impact the outcomes of more than 250,000 people each year.

Intraoperative near-infrared imaging of surgical wounds after tumor resections can detect residual disease

PURPOSE

Surgical resection remains the most effective therapy for solid tumors worldwide. The most important prognostic indicator for cure following cancer surgery is a complete resection with no residual disease. However, intraoperative detection of retained cancer cells after surgery is challenging, and residual disease continues to be the most common cause of local failure. We hypothesized that visual enhancement of tumors using near-infrared imaging could potentially identify tumor deposits in the wound after resection.

EXPERIMENTAL DESIGN

A small animal model of surgery and retained disease was developed. Residual tumor deposits in the wound were targeted using an U.S. Food and Drug Administration-approved imaging agent, indocyanine green, by the enhanced permeability and retention effect. A novel handheld spectrometer was used to optically visualize retained disease after surgery.

RESULTS

We found residual disease using near-infrared imaging during surgery that was not visible to the naked eye or micro-CT. Furthermore, examination of tumor nodules was remarkably precise in delineating margins from normal surrounding tissues. This approach was most successful for tumors with increased neovasculature.

CONCLUSIONS

The results suggest that near-infrared examination of the surgical wound after curative resection can potentially enable the surgeon to locate residual disease. The data in this study is the basis of an ongoing Phase I/II clinical trial in patients who undergo resection for lung and breast cancer.