Innovative therapies for pediatric brain tumors

Anti-angiogenic Therapy in Pediatric Neuro-oncology

In order to grow, tissues require additional nutrients and oxygen as well as removal of waste products. Tumors achieve this by up-regulating angiogenic cytokines and/or down-regulating natural inhibitory proteins that allow neovascularization to proceed. Brain tumors continue to account for significant morbidity and mortality, in spite of significant advances in neurosurgical and radiation techniques and new chemotherapy combinations. As such, there is a real and immediate need for novel biologic therapies that can target these tumors. A number of new drugs that target different aspects of the angiogenic cascade have been identified and are now in clinical trials in children with primary brain tumors. In many of these pre-clinical and clinical studies, anti-angiogenic therapy has been well tolerated, has lacked many of the traditional toxicities of radiation and chemotherapy, does not require blood-brain barrier penetration, and targets a critical pathway in central nervous system tumor development. This review will discuss what angiogenesis is, how pediatric brain tumors regulate angiogenesis to obtain a vascular supply, what types of inhibitors are available, how different classes of inhibitors work, the types of resistance possible, how rapidly these inhibitors may work, and what surrogate markers of activity are available to follow response.

Anti-angiogenic chemotherapy in central nervous system tumors

Primary central nervous system tumors are infrequent lesions observed in both pediatric and adult patients that account for a disproportionate amount of cancer related morbidity and mortality. A significant number of advances in neurosurgical and radiation therapy techniques have occurred over the last few decades and yet only small improvements in long-term outcome have resulted. The major reason for this is the ability of these advances to minimize surgical or radiation morbidity on surrounding normal tissue rather than eradicating the microscopic infiltrating disease that remains after up-front standard therapy. As such, a great deal of effort has gone into adjuvant chemotherapy that might complement the standard surgical and radiation approaches. This paper will review the literature on anti-angiogenic therapies in central nervous system (CNS) tumor models and clinical disease, with a focus on anti-angiogenic chemotherapy (also referred to as metronomic or low-dose chemotherapy) and the utilization of this approach in conjunction with standard radiation and surgery. A number of excellent reviews covering related aspects of this topic are also available (1-13).

Antiangiogenesis therapy. Current and future agents

Approaches to cancer therapy for most tumors in adults and children have changed little in 50 years: surgery, radiation, and chemotherapy are standard for many solid tumors. When the concept of angiogenesis in cancer biology was introduced in the 1970s, there was little recognition of the therapeutic potential of attacking a tumor's blood supply. Advances in understanding the molecular processes that regulate tumor blood supply and novel agents that can interfere with them have generated a great deal of scientific interest and excitement. This article reviews the current understanding of angiogenesis and its role in cancer then discusses new therapeutic options in animals and humans, with a focus on pediatric tumors and the potential for treating them.

Advances in pediatric neuro-oncology

A number of exciting advances have been reported over the past few years in the understanding and treatment of children with brain tumors. The present review highlights many of the publications from this period, focusing on their relevance within the major diagnostic and treatment domains of pediatric oncology (surgery, radiation therapy, chemotherapy, neuropathology, and neuroradiology). Although many of the publications cited provide confirmation of previously reported work, when taken together they form a good framework of the state of the field from the past few years.