Combining radiation, immunotherapy, and antiangiogenesis agents in the management of cancer: the Three Musketeers or just another quixotic combination?

Potential synergistic implications for stromal-targeted radiopharmaceuticals in bone-metastatic prostate cancer

Genetic heterogeneity and chemotherapy-resistant 'stem cells' represent two of the most pressing issues in devising new strategies for the treatment of advanced prostate cancer. Though curative strategies have long been present for men with localized disease, metastatic prostate cancer is currently incurable. Though substantial improvements in outcomes are now possible through the utilization of newly approved therapies, novel combinations are clearly needed. Herein we describe potentially synergistic interactions between bone stromal-targeted radiopharmaceuticals and other therapies for treatment of bone-metastatic prostate cancer. Radiation has long been known to synergize with cytotoxic chemotherapies and recent data also suggest the possibility of synergy when combining radiation and immune-based strategies. Combination therapies will be required to substantially improve survival for men with castrate-resistant metastatic prostate cancer and we hypothesize that bone-targeted radiopharmaceuticals will play an important role in this process.

Vaccines based on whole recombinant Saccharomyces cerevisiae cells

The ultimate goal of therapeutic vaccines is to activate and exploit the patient's own immune system to vigorously and dynamically seek and eradicate established malignant or virally infected cells. Therapeutic vaccines also offer the potential for preventing disease recurrence. Saccharomyces cerevisiae-based vaccines, where the yeast is engineered to express viral or tumor antigens, represent an ideal therapeutic approach due to their ability to stimulate tumor- or viral-specific CD4(+) and CD8(+) T-cell responses that are capable of reducing disease burden. This review describes preclinical and clinical studies supporting the development of S. cerevisiae-based therapeutic vaccines for the treatment of cancer and viral diseases, as well as multimodal strategies in which therapeutic vaccines are combined with cytotoxic drugs to achieve a greater clinical response.

A novel combination treatment of armed oncolytic adenovirus expressing IL-12 and GM-CSF with radiotherapy in murine hepatocarcinoma

In this study, a novel combination treatment of armed oncolytic adenovirus expressing interleukin 12 (IL-12) and granulocyte-macrophage colony-stimulating factor (GM-CSF) with radiation was investigated for antitumor and antimetastatic effect in a murine hepatic cancer (HCa-I) model. Tumor bearing syngeneic mice were treated with radiation, armed oncolytic virus Ad-ΔE1Bmt7 (dB7) expressing both IL-12 and GM-CSF (armed dB7), or a combination of both. The adenovirus was administered by intratumoral injection 1 × 10(8) PFU per tumor in 50 µl of PBS four times every other day. Tumor response to treatment was determined by a tumor growth delay assay. Metastatic potential was evaluated by a lung metastasis model. To understand the underlying mechanism, the level of apoptosis was examined as well as the change in microvessel density and expression of immunological markers: CD4+, CD8+ and Cd11c. The combination of armed dB7 and radiation resulted in significant growth delay of murine hepatic cancer, HCa-1, with an enhancement factor of 4.3. The combination treatment also resulted in significant suppression of lung metastasis. Increase of apoptosis level as well as decrease of microvessel density was shown in the combination treatment, suggesting an underlying mechanism for the enhancement of antitumor effect. Expression of immunological markers: CD4+, CD8+ and Cd11c also increased in the combination treatment. This study showed that a novel combination treatment of radiotherapy with armed oncolytic adenovirus expressing IL-12 and GM-CSF was effective in suppressing primary tumor growth.

Can inhibition of angiogenesis and stimulation of immune response be combined into a more effective antitumor therapy?

Cancer initiation and progression is strongly influenced by the tumor microenvironment consisting of various types of host cells (inflammatory cells, vascular cells and fibroblasts), extracellular matrix and non-matrix molecules. Host cells play a defining role in two major processes crucial for tumor growth: angiogenesis and escape from immune surveillance. The interdependence of these processes resemble the principles of Yin and Yang, as the stimulation of tumor angiogenesis inhibits effective immune responses, while angiogenesis inhibition may have the opposite effect. These considerations may be useful in developing anticancer strategies based on the potentially synergistic combinations of antiangiogenic and immunostimulatory drugs.

Vascular endothelial growth factor as an anti-angiogenic target for cancer therapy

New blood vessel formation (angiogenesis) is fundamental to tumor growth, invasion, and metastatic dissemination. The vascular endothelial growth factor (VEGF) signaling pathway plays pivotal roles in regulating tumor angiogenesis. VEGF as a therapeutic target has been validated in various types of human cancers. Different agents including antibodies, aptamers, peptides, and small molecules have been extensively investigated to block VEGF and its pro-angiogenic functions. Some of these agents have been approved by FDA and some are currently in clinical trials. Combination therapies are also being pursued for better tumor control. By providing comprehensive real-time information, molecular imaging of VEGF pathway may accelerate the drug development process. Moreover, the imaging will be of great help for patient stratification and therapeutic effect monitoring, which will promote effective personalized molecular cancer therapy. This review summarizes the current status of tumor therapeutic agents targeting to VEGF and the applications of VEGF related molecular imaging.

Targeted Therapy of Cancer Using Photodynamic Therapy in Combination with Multi-faceted Anti-Tumor Modalities

Photodynamic therapy (PDT) has emerged as one of the important therapeutic options in the management of cancer and other diseases. PDT involves a tumor-localized photosensitizer (PS), which when appropriately illuminated by visible light converts oxygen into cytotoxic reactive oxygen species (ROS), that attack key structural entities within the targeted cells, ultimately resulting in necrosis or apoptosis. Though PDT is a selective modality, it can be further enhanced by combining other targeted therapeutic strategies that include the use of synthetic peptides and nanoparticles for selective delivery of photosensitizers. Another potentially promising strategy is the application of targeted therapeutics that exploit a myriad of critical pathways involved in tumorigenesis and metastasis. Vascular disrupting agents that eradicate tumor vasculature during PDT and anti-angiogenic agents that targets specific molecular pathways and prevent the formation of new blood vessels are novel therapeutic approaches that have been shown to improve treatment outcome. In addition to the well-documented mechanisms of direct cell killing and damage to the tumor vasculature, PDT can also activate the body's immune response against tumors. Numerous pre-clinical studies and clinical observations have demonstrated the immuno-stimulatory capability of PDT. Herein, we aim to integrate the most important findings with regard to the combination of PDT and other novel targeted therapy approaches, detailing its potential in cancer photomedicine.