Current Pharmaceutical Biotechnology - Volume 14, Issue 7, 2013

Angiogenesis plays crucial roles in tumor growth, progression and metastasis. Non-invasive in vivo imaging of tumor neovasculature is a fundamental prerequisite for effective therapeutic intervention, particularly anti-angiogenic treatment regimens. Emerging molecular imaging techniques now allow recognition of cellular/molecular processes before gross pathological changes, leading to better understanding of fundamental biological processes of tumor angiogenesis. In this review, we will summarize recent progresses on molecular imaging of attractive biochemical epitopes in tumor angiogenesis, especially the endothelial cell targets-based imaging probes.

Cancer is becoming the largest threat to human health. Apart from classical anti-cancer therapies such as surgery, chemotherapies, and radiotherapy, many new therapies are being developed or translated into clinical use. These therapies include various neoadjuvant chemotherapies, minimally invasive treatments, and molecular-targeted therapies. However, none of these methods benefit all patients because treatment should be personalized according to the response of each patient. A futile therapy makes a patient miss the optimum time for treatment and increases the medical burden to the society. Thus, a great challenge is encountered in monitoring such therapies. Classical methods based on anatomical changes such as computed tomography (CT) and magnetic resonance imaging (MRI) have well-known limitations in early response evaluation. Positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) as tracer is a promising method especially when integrated with CT or MRI in one system. This article reviews the current status of monitoring anti-cancer therapies, including the evolution of evaluation criteria from the World Health Organization to the Response Evaluation Criteria in Solid Tumor and the PET Response Criteria in Solid Tumor. The advantages of 18F-FDG PET/CT for response evaluation are analyzed in various malignant tumors, and the pertinent weaknesses are discussed. Finally, several future directions in monitoring anti-cancer therapies are prospected.

Improved knowledge and understanding of key aspects of cancer has led to the development of novel cancer therapeutics acting through complex pathways and mode of actions. The success of these novel cancer therapeutics is often difficult to predict using standard response criteria based on anatomic changes. Monitoring response to cancer therapy at molecular level using Positron Emission Tomography (PET) has gained popularity in recent years. PET allows longitudinal assessment of specific biological processes rather than just changes in anatomic changes in tumor size. In this review, we provide an overview on application for PET imaging to monitor cancer therapy with emphases on PET of tumor metabolism, cell proliferation, angiogenesis, hypoxia and receptor dynamics.

The past few decades have brought on a dramatic change in the treatment of cancer; however, routine treatments fail to specifically clear tumorigenic cells and may be followed by cancer recurrence. Recent advances in developing multifunctional nanoparticles provide exciting new possibilities for drug delivery used in tumor-targeted therapy. Moreover, molecular imaging is an invaluable tool in evaluating new molecular targets, cancer diagnosis, predicting of tumor response to available therapies and monitoring response to therapy as well as developing new drugs prior to clinical translation. Combining of targeted cancer therapy and molecular imaging, termed as image-guided drug delivery, can achieve objectives of noninvasive assessment of drug biodistribution and real-time monitoring of therapeutic responses. Image-guided drug delivery has become an upcoming field with extensive prospect in cancer therapy and may provide an effective platform for personalized cancer care. This review will focus on the significance and recent advances in targeted and traceable therapeutic strategy for cancer therapy.

Cancer is a lethal disease, and its therapy should be tailed to individual patients by functional imaging to optimize therapy strategies. Single-photon emission computed tomography (SPECT) is a quantitative functional imaging modality used by oncologists to monitor tumor response. SPECT can track therapy-induced biological and metabolic changes in tumors; such changes usually precede anatomical alterations. Assessment of treatment response using SPECT tracers may result in modifications in treatment planning and predicting the long-term outcome. These SPECT tracers can be classified into metabolism, cell surface receptor, intracellular receptor, microenvironment, and apoptosis tracers. The most widely used SPECT tracers include 201Tl-thallium chloride, 67Ga-gallium citrate, 123I/131I-sodium iodide, 99mmTc-MIBI, 99mTc-MDP, and 123I/131I –MIBG. Apoptosis tracers, which can directly monitor early tumor response in cancer patients and can predict the outcome, have attracted increasing attention in the field of oncology. Annexin V-based SPECT tracers, including 99mTc-BTAP-annexin V, 99mTc-HYNIC-annexin-V, 99mTc-EC-annexin-V, 99mTc-i-annexin V, and 123I-annexin V, have been evaluated in clinical trials. Novel SPECT tracers, such as radiolabeled small molecules, aptamers, peptides, and proteins, need to be explored in the future to further improve the outcome of cancer therapy. In this review, SPECT tracers used to predict and monitor cancer therapy in both preclinical and clinical settings are summarized. Some tracers may contribute to the improvement of cancer therapy management.

Glycoarrays are very useful tools to investigate the carbohydrate-protein interactions in high-throughput manner. Carbohydrates can be immobilized on the support surface by covalent or noncovalent binding. The biological and medical uses of glycoarrays were summarized herein.