Radioprotective Agents for Radiation Therapy: Future Trends

Abstract

Only two radioprotective compounds, amifostine and palifermin, currently have the US FDA approval for use in radiation therapy. However, several agents have been reported that show therapeutic promise. Many of these agents are free radical scavengers/antioxidants. Superoxide dismutase and superoxide dismutase mimetics, nitroxides and dietary antioxidants are all being investigated. Recently, alternative strategies of drug development have been evolving, which focus on targeting the series of cellular insult recognition/repair responses initiated following radiation. These agents, which include cytokines/growth factors, angiotensin-converting enzyme inhibitors and apoptotic modulators, show promise of having significant impact on the mitigation of radiation injury. Herein, we review current literature on the development of radioprotectors with emphasis on compounds with proven or potential usefulness in radiation therapy.

L-carnitine has a protective effect on the colonic mucosa during abdominopelvic radiotherapy in rats

“…However, several agents such as free radical scavengers have been reported to show therapeutic promise 34 . A search of the PubMed database revealed no study published in English on the effect of systemic L-carnitine administration on the colonic mucosa during abdominopelvic irradiation.…”

Research and Development of Radioprotective Agents: A Mini-Review

“…This leads to more toxic effect on the surrounding normal tissues [66] that could affect a patient's quality of life. Consequently, this will bring radiation dose reductions or treatment delays that can lead to poor therapeutic outcome [67] . Cancer radiotherapy focuses on three strategies to increase the therapeutic ratio: modification of the intrinsic radiosensitivity via such as molecular targeting, manipulation of microenvironmental factors to enhance the tumor radiosusceptibility, and improvement of radiation delivery to critical tumor locations while sparing normal tissues.…”

Addressing the Symptoms or Fixing the Problem? Developing Countermeasures against Normal Tissue Radiation Injury

“…This necessity likely explains the limited number of agents developed with this mode of action after more than 50 years of investigation. Indeed, despite the herculean efforts made in the 1950s–1980s, the free radical scavenger, amifostine (ethyol/WR-2721), remains one of only two radioprotection agents that have made it into clinical practice, and then in only limited practice (57, 58). However, when considering protection measures for the general population, where there is no definitive need for a differential tumor/normal tissue response, a broader range of agents has been assessed.…”