MRI-LINAC: A transformative technology in radiation oncology.

Advances in radiotherapy technologies have enabled more precise target guidance, improved treatment verification, and greater control and versatility in radiation delivery. Amongst the recent novel technologies, Magnetic Resonance Imaging (MRI) guided radiotherapy (MRgRT) may hold the greatest potential to improve the therapeutic gains of image-guided delivery of radiation dose. The ability of the MRI linear accelerator (LINAC) to image tumors and organs with on-table MRI, to manage organ motion and dose delivery in real-time, and to adapt the radiotherapy plan on the day of treatment while the patient is on the table are major advances relative to current conventional radiation treatments.

Radiation Therapy and the In Situ Vaccination Approach.

During the past century, from the advent of preclinical modeling to the establishment of clinical trials, the hypothesis that host defenses regulate tumor growth (posited and refined by leaders in the field of cancer immunity) has become accepted as a scientific pillar in oncology. Since the turn of the millennium, a search has been under way for the best therapeutic approach to reprogram the immune system to recognize tumor cells that have undergone "immune escape." This quest has led some to question conventional scientific views of tumor cell kill, including the role of host immunity in patients treated with radiation therapy.

Results of a phase I-II study of adjuvant concurrent carboplatin and accelerated radiotherapy for triple negative breast cancer.

: To determine feasibility and explore the clinical efficacy of concurrent radiotherapy and carboplatin as adjuvant treatment of triple negative breast cancer (TNBC). : Women with Stage I-II TNBC were treated after surgery in a phase I-II prospective trial [NCT01289353]. Weekly carboplatin (AUC = 2.

Use, complications, and costs of stereotactic body radiotherapy for localized prostate cancer.

Background: Stereotactic body radiotherapy (SBRT) for localized prostate cancer has potential advantages over traditional radiotherapies. Herein, the authors compared national trends in use, complications, and costs of SBRT with those of traditional radiotherapies.

Methods: The authors identified men who underwent SBRT, intensity-modulated radiotherapy (IMRT), brachytherapy, and proton beam therapy as primary treatment of prostate cancer between 2004 and 2011 from Surveillance, Epidemiology, and End Results Program (SEER)-Medicare linked data.

Role of Local Radiation Therapy in Cancer Immunotherapy.

The recent success of cancer immunotherapy has demonstrated the power of the immune system to clear tumors, generating renewed enthusiasm for identifying ways to induce antitumor immune responses in patients. Natural antitumor immune responses are detectable in a fraction of patients across multiple malignant neoplasms and can be reactivated by targeting rate-limiting immunosuppressive mechanisms. In most patients, however, interventions to induce a de novo antitumor immune response are necessary.

Local radiotherapy and granulocyte-macrophage colony-stimulating factor to generate abscopal responses in patients with metastatic solid tumours: a proof-of-principle trial.

Background: An abscopal response describes radiotherapy-induced immune-mediated tumour regression at sites distant to the irradiated field. Granulocyte-macrophage colony-stimulating factor is a potent stimulator of dendritic cell maturation. We postulated that the exploitation of the pro-immunogenic effects of radiotherapy with granulocyte-macrophage colony-stimulating factor might result in abscopal responses among patients with metastatic cancer.

Effects of convection-enhanced delivery of bevacizumab on survival of glioma-bearing animals.

OBJECT Bevacizumab (Avastin), an antibody to vascular endothelial growth factor (VEGF), alone or in combination with irinotecan (Camptosar [CPT-11]), is a promising treatment for recurrent glioblastoma. However, the intravenous (IV) administration of bevacizumab produces a number of systemic side effects, and the increase in survival it provides for patients with recurrent glioblastoma is still only a few months. Because bevacizumab is an antibody against VEGF, which is secreted into the extracellular milieu by glioma cells, the authors hypothesized that direct chronic intratumoral delivery techniques (i.

Quinoline-based antimalarial drugs: a novel class of autophagy inhibitors.

Object: Chloroquine (CQ) is a quinoline-based drug widely used for the prevention and treatment of malaria. More recent studies have provided evidence that this drug may also harbor antitumor properties, whereby CQ possesses the ability to accumulate in lysosomes and blocks the cellular process of autophagy. Therefore, the authors of this study set out to investigate whether CQ analogs, in particular clinically established antimalaria drugs, would also be able to exert antitumor properties, with a specific focus on glioma cells.

Radiotherapy and immunogenic cell death.

Advances in understanding the mechanisms that underlie the interplay between radiation-invoked immune responses and tumor regression are underway. Emerging applications of local radiotherapy as an immunologic adjuvant have provided radiation oncologists with a method for converting malignant cells into endogenous anticancer vaccines. The dispersion of radiotherapy-induced immune-stimulating tumor antigens released from dying tumor cells into the surrounding milieu (known as immunogenic cell death, Fig.

Chloroquine enhances temozolomide cytotoxicity in malignant gliomas by blocking autophagy.

Object: In a recent clinical trial, patients with newly diagnosed glioblastoma multiforme benefited from chloroquine (CQ) in combination with conventional therapy (resection, temozolomide [TMZ], and radiation therapy). In the present study, the authors report the mechanism by which CQ enhances the therapeutic efficacy of TMZ to aid future studies aimed at improving this therapeutic regimen.

Methods: Using in vitro and in vivo experiments, the authors determined the mechanism by which CQ enhances TMZ cytotoxicity.

Radiation fosters dose-dependent and chemotherapy-induced immunogenic cell death.

Established tumors are typified by an immunosuppresive microenvironment. Countering this naturally occurring phenomenon, emerging evidence suggests that radiation promotes a proimmunogenic milieu within the tumor capable of stimulating host cancer-specific immune responses. Three cryptic immunogenic components of cytotoxic-agent induced cell death-namely, calreticulin cell surface exposure, the release of high mobility group box 1 (HMGB1) protein, and the liberation of ATP-have been previously shown to be critical for dendritic cell (DC) activation and effector T-cell priming.

The optimal partnership of radiation and immunotherapy: from preclinical studies to clinical translation.

The main role of the immune system is to restore tissue homeostasis when altered by pathogenic processes, including neoplastic transformation. Immune-mediated tumor rejection has been recognized as an extrinsic tumor suppressor mechanism that tumors need to overcome to progress. By the time a tumor becomes clinically apparent it has successfully escaped immune control by establishing an immunosuppressive microenvironment.

Is tumor (R)ejection by the immune system the "5th R" of radiobiology?

Traditional factors of DNA damage and tumor cell kill, described by the "4 R's" of radiobiology (Reassortment, Reoxygenation, Repair, and Repopulation) fall short in explaining the role of immunity in hosts treated with radiotherapy. We propose a "5th R," (immune-mediated) Rejection, which recognizes the contribution of the immune system to the antineoplastic effects of radiotherapy.

An abscopal response to radiation and ipilimumab in a patient with metastatic non-small cell lung cancer.

A posteriori evidence suggests that radiotherapy to a targeted tumor can elicit an immune-mediated abscopal (ab-scopus, away from the target) effect in non-targeted tumors, when combined with an anti-cytotoxic T-lymphocyte antigen-4 monoclonal (CTLA-4) antibody. Concurrent radiotherapy and ipilimumab (a human monoclonal anti-CTLA-4 antibody) induced immune-mediated abscopal effects in poorly immunogenic pre-clinical tumor models and metastatic melanoma patients. However, no such reports exist for patients with metastatic lung adenocarcinoma.

Taxanes as radiosensitizers.

In parallel with the discovery of the taxanes, our understanding of the molecular underpinnings that comprise the classic biologic principles of fractionated radiotherapy has rapidly evolved over the past half century. Early studies have implicated DNA as the primary target for radiation-induced lethality. More recently, however, the molecular biology involved in radiosensitization of tumor cells has been unveiled.

The convergence of radiation and immunogenic cell death signaling pathways.

Ionizing radiation (IR) triggers programmed cell death in tumor cells through a variety of highly regulated processes. Radiation-induced tumor cell death has been studied extensively in vitro and is widely attributed to multiple distinct mechanisms, including apoptosis, necrosis, mitotic catastrophe (MC), autophagy, and senescence, which may occur concurrently. When considering tumor cell death in the context of an organism, an emerging body of evidence suggests there is a reciprocal relationship in which radiation stimulates the immune system, which in turn contributes to tumor cell kill.

Inhibition of autophagy and induction of breast cancer cell death by mefloquine, an antimalarial agent.

Autophagy has been recognized as a potential target for cancer therapy. The antimalarial drug chloroquine (CQ) is able to inhibit autophagy and therefore is being considered for cancer therapeutics. However, the relatively low potency of CQ prompted us to investigate whether other lysosomotropic agents might be more effective, and thus potentially more useful.

Preferential killing of triple-negative breast cancer cells in vitro and in vivo when pharmacological aggravators of endoplasmic reticulum stress are combined with autophagy inhibitors.

The cellular processes of autophagy and endoplasmic reticulum stress (ERS) appear to be interconnected, and it has been proposed that autophagy may serve to reduce ERS via removal of terminally misfolded and aggregated proteins. Conversely, there are indications that blockage of autophagy may increase ERS. Based on earlier work demonstrating that pharmacologically aggravated ERS can result in tumor cell killing, we investigated whether blockage of autophagy would enhance this effect in a therapeutically useful manner.

Green tea epigallocatechin gallate enhances therapeutic efficacy of temozolomide in orthotopic mouse glioblastoma models.

The alkylating agent temozolomide, in combination with surgery and radiation, is the current standard of care for patients with glioblastoma. However, despite this extensive therapeutic effort, the inclusion of temozolomide extends survival only by a few short months. Among the factors contributing to chemoresistance is elevated expression of the endoplasmic reticulum (ER) chaperone GRP78 (glucose-regulated protein 78; BiP), a key pro-survival component of the ER stress response system.

Antiangiogenic activities of 2,5-dimethyl-celecoxib on the tumor vasculature.

Our laboratory has previously shown that a novel compound, 2,5-dimethyl-celecoxib (DMC), which is structurally similar to the cyclooxygenase-2 (COX-2) inhibitor celecoxib but lacks the COX-2-inhibitory function, mimics the antitumor effects of celecoxib. Most studies on DMC, however, focused on its effects on tumor cells. Here, we investigated the activities of DMC as an antiangiogenic agent in both in vitro and in vivo systems.

Glioma-associated endothelial cells are chemoresistant to temozolomide.

Temozolomide is considered the standard of care and drug of choice for the treatment of initially diagnosed malignant gliomas. Although well tolerated, temozolomide still has limited clinical efficacy. Following drug treatment, patient prognosis still remains poor; tumor recurrence is almost universal.

Enhanced killing of chemo-resistant breast cancer cells via controlled aggravation of ER stress.

Moderate activity of the endoplasmic reticulum (ER) stress response system exerts anti-apoptotic function and supports tumor cell survival and chemoresistance, whereas its more severe aggravation may exceed the protective capacity of this system and turn on its pro-apoptotic module. In this study, we investigated whether the combination of two pharmacologic agents with known ability to trigger ER stress via different mechanisms would synergize and lead to enhanced tumor cell death. We combined the HIV protease inhibitor nelfinavir (Viracept) and the cyclooxygenase 2 (COX-2) inhibitor celecoxib (Celebrex) and investigated their combined effect on ER stress and on the viability of breast cancer cells.

Green tea polyphenols block the anticancer effects of bortezomib and other boronic acid-based proteasome inhibitors.

The anticancer potency of green tea and its individual components is being intensely investigated, and some cancer patients already self-medicate with this "miracle herb" in hopes of augmenting the anticancer outcome of their chemotherapy. Bortezomib (BZM) is a proteasome inhibitor in clinical use for multiple myeloma. Here, we investigated whether the combination of these compounds would yield increased antitumor efficacy in multiple myeloma and glioblastoma cell lines in vitro and in vivo.