Synthesis and surface engineering of iron oxide nanoparticles for biomedical applications

Solid tumors require blood vessels for growth, and many new cancer therapies are directed against the tumor vasculature. The widely held view is that these antiangiogenic therapies should destroy the tumor vasculature, thereby depriving the tumor of oxygen and nutrients. Here, I review emerging evidence supporting an alternative hypothesis-that certain antiangiogenic agents can also transiently "normalize" the abnormal structure and function of tumor vasculature to make it more efficient for oxygen and drug delivery. Drugs that induce vascular normalization can alleviate hypoxia and increase the efficacy of conventional therapies if both are carefully scheduled. A better understanding of the molecular and cellular underpinnings of vascular normalization may ultimately lead to more effective therapies not only for cancer but also for diseases with abnormal vasculature, as well as regenerative medicine, in which the goal is to create and maintain a functionally normal vasculature.

http://science.sciencemag.org/content/sci/307/5706/58.full.pdf

Normalization of Tumor Vasculature: An Emerging Concept in Antiangiogenic Therapy

Bevacizumab plus Irinotecan,Fluorouracil,and Leucovorin for Metastatic Colorectal Cancer

Inhibiting angiogenesis is a promising strategy for treatment of cancer and several other disorders, including age-related macular degeneration. Major progress towards a treatment has been achieved over the past few years, and the first antiangiogenic agents have been recently approved for use in several countries. Therapeutic angiogenesis (promoting new vessel growth to treat ischaemic disorders) is an exciting frontier of cardiovascular medicine, but further understanding of the mechanisms of vascular morphogenesis is needed first.

http://dipbsf.uninsubria.it/monti/BFPN%202009/VEGF1.pdf

Angiogenesis as a therapeutic target

Malignant astrocytic gliomas such as glioblastoma are the most common and lethal intracranial tumors. These cancers exhibit a relentless malignant progression characterized by widespread invasion throughout the brain, resistance to traditional and newer targeted therapeutic approaches, destruction of normal brain tissue, and certain death. The recent confluence of advances in stem cell biology, cell signaling, genome and computational science and genetic model systems have revolutionized our understanding of the mechanisms underlying the genetics, biology and clinical behavior of glioblastoma. This progress is fueling new opportunities for understanding the fundamental basis for development of this devastating disease and also novel therapies that, for the first time, portend meaningful clinical responses.

/pdf/malignant-astrocytic-glioma-genetics-biology-and-paths-to-689wwbep62.pdf

Malignant astrocytic glioma: genetics, biology, and paths to treatment.

Vascular and angiogenic processes provide an important target for novel cancer therapeutics. Dynamic contrast-enhanced magnetic resonance imaging is being used increasingly to noninvasively monitor the action of these therapeutics in early-stage clinical trials. This publication reports the outcome of a workshop that considered the methodology and design of magnetic resonance studies, recommending how this new tool might best be used.

/pdf/the-assessment-of-antiangiogenic-and-antivascular-therapies-4c0jsr6z43.pdf

The assessment of antiangiogenic and antivascular therapies in early-stage clinical trials using magnetic resonance imaging: issues and recommendations

Reduced oxygen levels (hypoxia) is one of the most important factors influencing clinical outcome after radiotherapy. This is primarily because hypoxic cells are resistant to radiation treatment; hence, the greater the number of clonogenic cancer stem cells that exist under hypoxia, the lower the local tumour control. Reduced local control will influence overall survival, as may the hypoxic conditions by increasing malignant progression; however, to fight hypoxia, we should first be able to see it. We need noninvasive approaches that can accurately and reliably image hypoxia in tumours, especially using techniques that are routinely available in the clinic, such as PET, MRI and CT. All these imaging methods are already under clinical evaluation in this context. Such data should allow us to identify those patients on an individual basis who have hypoxic tumours and, thus, at the very least should receive some form of hypoxic modifier in conjunction with radiotherapy. Alternatively, the radiation dose could be either increased to the whole tumour or, if the imaging is accurate enough, only to the hypoxic subvolumes. The aim of this Review is to critically assess the potential use of imaging to help improve clinical outcome to radiotherapy.

Imaging hypoxia to improve radiotherapy outcome

Modification of Hypoxia-Induced Radioresistance in Tumors by the Use of Oxygen and Sensitizers.

Hyperthermia: a potent enhancer of radiotherapy.

BACKGROUND
Tumor endothelium represents a valuable target for cancer therapy. The vasculature plays a critical role in the survival and continued growth of solid tumor masses; in addition, the inherent differences between tumor blood vessels and blood vessels associated with normal tissue make the tumor vasculature a unique target on which to base the design of novel therapeutics, which may allow highly selective treatment of malignant disease. Therapeutic strategies that target and disrupt the already formed vessel networks of growing tumors are actively being pursued. The goal of these approaches is to induce a rapid and catastrophic shutdown of the vascular function of the tumor so that blood flow is arrested and tumor cell death due to the resulting oxygen and nutrient deprivation and buildup of waste products occurs.

METHODS
Biologic approaches and small-molecule drugs that can be used to damage tumor vasculature have been identified. Physiologic, histologic/morphologic, and immunohistochemical assessments have demonstrated that profound disruption of the tumor vessel network can be observed minutes to hours after treatment. The small-molecule agents that have made the greatest advances in the clinical setting (5,6-dimethylxanthenone-4-acetic acid [DMXAA], combretastatin A4 disodium phosphate [CA4DP], and ZD6126) are the focus of the current review.

RESULTS
Loss of patent blood vessels, decreased tumor blood flow, extensive necrosis, and secondary ischemia-induced tumor cell death have been well documented in a variety of preclinical tumor models treated with agents such as DMXAA, CA4DP, and ZD6126. The use of such agents in conjunction with irradiation and other chemotherapeutic agents has led to improved treatment outcomes.

CONCLUSIONS
The targeting of tumors' supportive blood vessel networks could lead to improvements in cancer cure rates. It is likely that this approach will prove to be most efficacious when used in concert with conventional treatment strategies. Cancer 2004. © 2004 American Cancer Society.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/cncr.20299

Michael R. Horsman

Papers

The assessment of antiangiogenic and antivascular therapies in early-stage clinical trials using magnetic resonance imaging: issues and recommendations

Imaging hypoxia to improve radiotherapy outcome

Modification of Hypoxia-Induced Radioresistance in Tumors by the Use of Oxygen and Sensitizers.

Hyperthermia: a potent enhancer of radiotherapy.

Vascular‐targeting therapies for treatment of malignant disease