The use of epidermal growth factor receptor monoclonal antibodies in squamous cell carcinoma of the head and neck

Expression and Evaluation of HuscFv Antibody -PE40 Immunotoxin for Target Therapy of EGFR-Overexpressing Cancers

Background

Epidermal growth factor receptor (EGFR) plays an important role in the progression and tumorigenesis of the various cancers. In this regards, anti-EGFR antibodies are valuable approved therapeutics for the EGFR over-expressing cancers. However, the occurrence of mutations in the EGFR and/or KRAS genes; a common phenomenon which is seen in many cancers, lead to the resistance to the EGFR-directed antibodies. EGFR based immunotoxins are capable of overcoming this limitation by directing the toxin moieties to the cancer cells resulting in cell death.

Objectives

In the present study, a novel immunotoxin consisting of the truncated Pseudomonas exotoxin A (PE-40) and anti-EGFR huscFv was developed and evaluated for the induction of cell death in EGFR positive A431tumoral cells.

Materials and Methods

PE-40 fragment of the exotoxin A was amplified by using PCR and ligated to pET22b-huscFv. The reaction was confirmed by PCR and restriction digestion. The immunotoxin was expressed in E. coli BL21 (plysS) and then was purified by Ni-NTA affinity column. Subsequently, the toxicity of the purified immunotoxin was evaluated on EGFR over-expressing epidermoid carcinoma of skin, A431 cell line.

Results

PCR and restriction digestion experiments have verified the integrity of the immunotoxin construct. Purification by affinity column resulted in a highly purified recombinant immunotoxin. MTT assay revealed the growth inhibitory effect of the huscFv-PE40 immunotoxin on EGFR-over-expressing A431 cells with an IC50 value of 250 ng.mL^-1.

Conclusion

In conclusion, the results indicated that the immunotoxin developed in this study has a high toxicity on the EGFR-over-expressing tumor cells and could be considered as a promising candidate for the treatment of the EGFR positive cancers.

The immune system and head and neck squamous cell carcinoma: from carcinogenesis to new therapeutic opportunities

Head and neck squamous cell carcinomas (HNSCCs) exhibit complex interactions with the host immune system that may simultaneously explain resistance to various therapeutic modalities and that may also provide opportunities for therapeutic intervention. Discoveries in immunologic research over the last decade have led to an increased understanding of these interactions as well as the development of a multitude of investigational immunotherapies. Here, we describe the interaction between HNSCC and the immune system, including a discussion of immune cells involved with tumor carcinogenesis and the role of immune-modulating factors derived from tumors. We also describe the current immunotherapeutic approaches being investigated for HNSCC, including a discussion of the successes and limitations. With this review, we hope to present HNSCC as a model to guide future research in cancer immunology.

Real-world cost-effectiveness of cetuximab in locally advanced squamous cell carcinoma of the head and neck

Clinical trial EMR 62202-006 demonstrates prolonged median locoregional control (24.4 vs. 14.9 months), progression-free survival (17.1 vs. 12.4 months) and overall survival (49.0 vs. 29.3 months) for patients who receive cetuximab added to the comparator radiotherapy for locally advanced squamous cell carcinoma of the head and neck (LA SCCHN). In the Netherlands, hospitals receive reimbursement for cetuximab conditional on cost-effectiveness in daily practice. To estimate the real-world incremental cost per quality adjusted life-year (QALY) gained for radiotherapy + cetuximab over radiotherapy alone in first line treatment of LA SCCHN, a Markov model is constructed with health states "alive without progression", "alive following progression" and "death". Transition probabilities per month are estimated from clinical trial data and retrospectively collected real-world data from two Dutch head and neck cancer treatment centres (2007-2010, n = 141). 5-year, 10-year and lifetime horizons are used, without and with discounting (4 % costs, 1.5 % effects) to calculate incremental cost-effectiveness ratios. Two scenarios explore different assumptions on prognosis of real-world versus trial patients. Adding cetuximab to radiotherapy results in increased costs and health gains in both scenarios and across each of the time horizons. Incremental costs per QALY gained range between <euro>14,624 and <euro>38,543 in the base-case. For a willingness to pay of <euro>80,000 per QALY, the acceptability curves for the different scenarios show probabilities between 0.76 and 0.87 of radiotherapy + cetuximab being cost-effective compared to radiotherapy alone. Current results show the combined treatment of radiotherapy + cetuximab to be a cost-effective treatment option for patients with LA SCCHN.

Therapeutic human monoclonal antibodies against cancer

There are over 30 monoclonal antibodies that are FDA approved for a variety of diseases ranging from malignancies to autoimmune diseases to macular degeneration. These antibodies include murine, fully humanized, and chimeric antibodies. There are a number of monoclonal antibodies used in the treatment of malignancies; in fact, three of the top five grossing antibodies (bevacizumab, trastuzumab, and rituximab) are used in oncology Scolnik (mAbs 1:179-184, 2009).

Magnetic nanoparticles as mediators of ligand-free activation of EGFR signaling

BACKGROUND

Magnetic nanoparticles (NPs) are of particular interest in biomedical research, and have been exploited for molecular separation, gene/drug delivery, magnetic resonance imaging, and hyperthermic cancer therapy. In the case of cultured cells, magnetic manipulation of NPs provides the means for studying processes induced by mechanotransduction or by local clustering of targeted macromolecules, e.g. cell surface receptors. The latter are normally activated by binding of their natural ligands mediating key signaling pathways such as those associated with the epidermal growth factor (EGFR). However, it has been reported that EGFR may be dimerized and activated even in the absence of ligands. The present study assessed whether receptor clustering induced by physical means alone suffices for activating EGFR in quiescent cells.

METHODOLOGY/PRINCIPAL FINDINGS

The EGFR on A431 cells was specifically targeted by superparamagnetic iron oxide NPs (SPIONs) carrying either a ligand-blocking monoclonal anti-EGFR antibody or a streptavidin molecule for targeting a chimeric EGFR incorporating a biotinylated amino-terminal acyl carrier peptide moiety. Application of a magnetic field led to SPION magnetization and clustering, resulting in activation of the EGFR, a process manifested by auto and transphosphorylation and downstream signaling. The magnetically-induced early signaling events were similar to those inherent to the ligand dependent EGFR pathways. Magnetization studies indicated that the NPs exerted magnetic dipolar forces in the sub-piconewton range with clustering dependent on Brownian motion of the receptor-SPION complex and magnetic field strength.

CONCLUSIONS/SIGNIFICANCE

We demonstrate that EGFR on the cell surface that have their ligand binding-pocket blocked by an antibody are still capable of transphosphorylation and initiation of signaling cascades if they are clustered by SPIONs either attached locally or targeted to another site of the receptor ectodomain. The results suggest that activation of growth factor receptors may be triggered by ligand-independent molecular crowding resulting from overexpression and/or sequestration in membrane microdomains.

NADPH oxidase biology and the regulation of tyrosine kinase receptor signaling and cancer drug cytotoxicity

The outdated idea that reactive oxygen species (ROS) are only dangerous products of cellular metabolism, causing toxic and mutagenic effects on cellular components, is being replaced by the view that ROS have several important functions in cell signaling. In aerobic organisms, ROS can be generated from different sources, including the mitochondrial electron transport chain, xanthine oxidase, myeloperoxidase, and lipoxygenase, but the only enzyme family that produces ROS as its main product is the NADPH oxidase family (NOX enzymes). These transfer electrons from NADPH (converting it to NADP-) to oxygen to make O(2)•-. Due to their stability, the products of NADPH oxidase, hydrogen peroxide, and superoxide are considered the most favorable ROS to act as signaling molecules. Transcription factors that regulate gene expression involved in carcinogenesis are modulated by NADPH oxidase, and it has emerged as a promising target for cancer therapies. The present review discusses the mechanisms by which NADPH oxidase regulates signal transduction pathways in view of tyrosine kinase receptors, which are pivotal to regulating the hallmarks of cancer, and how ROS mediate the cytotoxicity of several cancer drugs employed in clinical practice.