Stand-alone Agents Research Articles

Boron neutron capture therapy of EGFR or EGFRvIII positive gliomas using either boronated monoclonal antibodies or epidermal growth factor as molecular targeting agents

In the present report we have summarized studies carried out over the past five years on molecular targeting of the epidermal growth factor receptor (EGFR) and its mutant isoform, EFGRvIII, for BNCT of genetically engineered F98 rat gliomas, expressing either wildtype (F98 EGFR) or mutant receptors (F98 npEGFRvIII). EGF or the monoclonal antibodies (mAbs), cetuximab (IMC-C225) and L8A4, which recognize wildtype EGFR and EGFRvIII, respectively, were heavily boronated using polyamidoamine (PAMAM) dendrimers (BD) linked to the targeting vehicles by means of heterobifunctional reagents. Boronated EGF or mAbs, alone or in combination with i.v. boronophenylalanine (BPA), were administered intracerebrally (i.c.) by either intratumoral (i.t.) injection or convection enhanced delivery (CED) to rats bearing F98 gliomas following which BNCT was initiated. The best survival data were obtained in rats bearing F98 npEGFRvIII gliomas that had received CED of BD-L8A4 either alone or in combination with i.v. boronophenylalanine (BPA). Studies carried out in rats bearing composite tumors (F98 EGFR/F98 npEGFRvIII) demonstrated that it was essential to target both tumor cell populations in order to obtain an optimal therapeutic effect. Based on these observations, we have concluded that EGFR targeting vehicles are useful, but not stand-alone boron delivery agents due to the heterogeneity of receptor expression in brain tumors. They could, however, be quite useful in combination with the two drugs that currently are being used clinically, BPA and sodium borocaptate (BSH) for BNCT of either brain tumors or head and neck cancers.

CpG oligodeoxynucleotides up-regulate antibacterial systems and induce protection against bacterial challenge in rainbow trout ( Oncorhynchus mykiss)

The effects of unmethylated CpG oligodeoxynucleotides (ODN) on the mammalian immune system are relatively well studied but much less is known of their effects on the immune systems of different fish species. Here we show that CpG ODNs significantly enhance the survival of rainbow trout ( Oncorhynchus mykiss) following bacterial challenge when used both as stand-alone prophylactic agents, or as adjuvants to a commercially available vaccine. They are also capable of increasing serum lysozyme activity in vivo and stimulating the production of chemoattractant factors for rainbow trout head kidney (HK) leucocytes in vitro.

A HUMANIZED PEGYLATED SINGLE CHAIN FRAGMENT VARIABLE (SCFV) TARGETING CARCINOEMBRYONIC ANTIGEN CELL ADHESION MOLECULE 6 REDUCES TUMOR BURDEN IN A SCID MOUSE MODEL BOTH ALONE AND IN COMBINATION WITH GEMCITABINE BY INCREASING APOPTOSIS AND DECREASING PROLIFERATION.

Pancreatic ductal adenocarcinoma is the fourth leading cause of cancer and death in North America. In the year 2002, adenocarcinoma of the exocrine pancreas accounted for ≈30,300 new ases and 29,700 deaths. The current treatment strategy for localized pancreatic cancer is multimodality therapy combining pancreaticoduodenectomy with postoperative adjuvant chemotherapy and external beam radiation therapy, which results in a median overall survival of 12 to 24 months. For locally advanced and metastatic pancreatic cancer, the median survival is 6 to 12 months with currently available palliative chemotherapy. CEACAM6 (carcinoembryonic antigen cell adhesion molecule 6 [CD66c]) is an oncogene expressed on the cell surface as a GPI-linked glycoprotein comprised of 3 Ig-like domains capable of homophilic and heterophilic (CEACAM 5 and 8) interactions. It is highly expressed in > 90% of patients with pancreatic ductal adenocarcinoma. Deregulated expression of CEACAM6 inhibits differentiation and apoptosis of cells deprived of their anchorage to the extracellular matrix. We have previously demonstrated that CEACAM6-expressing pancreatic cancer cell lines treated with a murine monoclonal antibody (13-1) display reduced cellular viability by MTS assay, an indication of cytotoxicity. A murine scFv based on mAb (13-1) as well as a humanized form of the murine scFv also showed in vitro activity in CEACAM6-expressing cancer cell lines. In vivo studies using an SCID mouse model xenograft with BXPC-3 cells indicated a significant decrease in tumor burden as a result of treatment with a PEGylated form of the previously mentioned humanized scFv. The humanized scFv drug reduced the tumor burden as a stand-alone agent and in combination with gemcitabine compared with the control animal groups. Immunohistochemical analysis of tumors excised from animals treated with the humanized scFv and untreated animals indicated a marked increase in apoptosis (H&E) as well as a marked decrease in proliferation (Ki67) in the treated group relative to the untreated group. This observed in vivo effect on proliferation and apoptosis is currently being confirmed in vitro using CEACAM6-expressing cancer cell lines.

Tweaking Innate Immunity: The Promise of Innate Immunologicals as Anti‐Infectives

New and exciting insights into the importance of the innate immune system are revolutionizing our understanding of immune defense against infections, pathogenesis, and the treatment and prevention of infectious diseases. The innate immune system uses multiple families of germline-encoded pattern recognition receptors (PRRs) to detect infection and trigger a variety of antimicrobial defense mechanisms. PRRs are evolutionarily highly conserved and serve to detect infection by recognizing pathogen-associated molecular patterns that are unique to microorganisms and essential for their survival. Toll-like receptors (TLRs) are transmembrane signalling receptors that activate gene expression programs that result in the production of proinflammatory cytokines and chemokines, type I interferons and antimicrobial factors. Furthermore, TLR activation facilitates and guides activation of adaptive immune responses through the activation of dendritic cells. TLRs are localized on the cell surface and in endosomal/lysosomal compartments, where they detect bacterial and viral infections. In contrast, nucleotide-binding oligomerization domain proteins and RNA helicases are located in the cell cytoplasm, where they serve as intracellular PRRs to detect cytoplasmic infections, particularly viruses. Due to their ability to enhance innate immune responses, novel strategies to use ligands, synthetic agonists or antagonists of PRRs (also known as 'innate immunologicals') can be used as stand-alone agents to provide immediate protection or treatment against bacterial, viral or parasitic infections. Furthermore, the newly appreciated importance of innate immunity in initiating and shaping adaptive immune responses is contributing to our understanding of vaccine adjuvants and promises to lead to improved next-generation vaccines.

Discodermolide analogues as the chemical component of combination bacteriolytic therapy

The marine natural product (+)-discodermolide ( 1) and several simplified analogues of this microtubule-stabilizing agent have proven to be potent in vitro cell growth inhibitory agents in several human cancer cell lines. Here, we demonstrate the in vivo efficacy of discodermolide and several simplified congeners, both as stand-alone anti-tumor agents and, in the case of (+)-2,3-anhydrodiscodermolide ( 3), as a chemical component of the combination bacteriolytic therapy. A single intravenous injection of (+)- 3 plus genetically modified Clostridium novyi-NT spores caused rapid and complete regressions of tumors in mice bearing HCT116 colorectal cancer xenografts.

Piroxicam promotes apoptosis and has a twofold effect on colon tumorigenesis in Mlh1/Apc mouse

1026 Background: Increase amount of cyclooxygenase 2 (COX-2) is commonly found in malignant and premalignant lesions and overexpression of COX-2 is associated with both human and animal colon cancer. It has recently become evident that nonsteroidal anti-inflammatory drugs (NSAIDs) such as piroxicam, which inhibits the constitutive (COX-1) and inducible (COX-2) isoforms, represent a potential class of cancer chemopreventive agents. The mechanism of action of piroxicam on gastrointestinal cancer has not been determined. The present study examines the effect of piroxicam on Mlh1/APC 1638N mice, a preclinical model of intestinal cancer. Methods: Mice were fed orally once daily for 9 weeks with either AIN-76 diet or the same diet supplemented with piroxicam (60 ppm). Upon completion of treatment, the number and location of intestinal tumors was determined. Additional variables examined were the mean number of apoptotic cells in each crypt in the cecum and in the small intestine. Results: Administration of piroxicam to Mlh1/Apc mice produced an 82% decrease of the mean number of tumor per mouse in the small intestine (0.09 vs 0.5 respectively, p<0.05) and an increase in the cecum (1.18 vs 0.1, p<0.01) compared to vehicle-treated mice. The number of apoptotic positive cells/crypt was increased in the small intestine (0.21 versus 0.87, p<0.05) but also in the cecum (0.35 versus 0.84, p < 0.001). In small intestine, however, apoptosis was mostly triggered at the base of the crypt, the area considered to harbour the stem cells, whilst a whole length crypt apoptotic activation was found in the cecum. Conclusions: Piroxicam was able to induce apoptosis in intestinal mucosa, to reduce tumor number in the small intestine, and to increase tumorigenesis in the cecum when administered to Mlh1/Apc mice. Differences in the intramucosa distribution of the piroxicam-induced apoptosis between the two locations could be responsible for differences in tumor response. The findings in the present study call in to question the utility of piroxicam as a stand-alone chemopreventive agent. No significant financial relationships to disclose.

Human-centred integration of a stand-alone manufacturing facility in a networked product development environment

Recent advances in Internet technology have led to the concept of networked product development. This includes geographically separated teams, co-located over wide area networks for the design, manufacture and marketing of products. Such a distributed environment consists of humans, software and manufacturing machines. Previous research in networked product development assumed that all manufacturing facilities were already networked and remotely accessible, and excluded the non-networked machines. This paper presents a human-centred methodology for virtual integration of stand-alone facilities into a networked environment. The methodology is based on a modified Open Systems Interconnection (OSI) model and has been realised through a hybrid architecture which includes stand-alone machines, humans and software agents. A laboratory-based experiment was carried out to validate the integration methodology for a stand-alone injection moulding machine. The role of humans in the integration process at different stages of the experiment has been analysed. Results suggest that virtual integration of stand-alone facilities into a networked environment is both feasible and practical. However, the effectiveness of the integration methodology to solve real world industry problems will need further investigation. The main implication of this research is that humans will continue to play an indispensable role in the evolution towards a global manufacturing environment in terms of flexibility and reusability of legacy based and modern manufacturing facilities.

Design and implementation of an X.400 stand-alone user agent

The CCITT X.400 Series of Recommendations on Message Handling Systems (MHS) define a distributed message exchange model aiming towards the development of an international mail network by interconnecting public and private networks worldwide. The essential functional components of the MHS Model are the User Agents (UAs) and the Message Transfer Agents (MTAs). Users of the MHS — originators and recipients of messages — request its services through a UA which in turn interacts with the Message Transfer System (MTS). QK-MHS/VM, is an electronic mail system developed at Queen's University under the IBM VM/SP operating system, and is based on the CCITT Recommendations. Design and implementation issues in the development of a remote UA model on a personal computer to be connected to QK-MHS/VM are surveyed in this paper.