Current status of radiation countermeasures for acute radiation syndrome under advanced development

Abstract

The availability of safe and effective radiation countermeasures for the military and civilian population represents a significant unmet medical need. To expedite the development of countermeasures for life-threating situations, the United States Food and Drug Administration (US FDA) has implemented the “Animal Rule” which applies to the development and evaluation of drugs and biologics to reduce or prevent life-threatening conditions caused by exposure to lethal or permanently disabling agents where human efficacy trials are neither feasible nor ethical. In addition, the FDA has introduced several incentives (fast track, orphan drug status, and emergency use authorization [EUA]) to attract drug sponsors to develop such agents for human use. Repurposing is vital to make drugs available for life-threatening conditions. Drugs are commonly repurposed for new indications not originally envisioned. By repurposing a drug, it can be made available for human use much quicker, but this pathway also involves issues such as intellectual property rights as corporations are reluctant to expose their blockbuster pharmaceuticals to additional scientific scrutiny. Two radiomitigators for hematopoietic acute radiation syndrome (H-ARS) (Neupogen and Neulasta) have been approved by the FDA through repurposing. The EUA is a legal means for the FDA to approve new drugs or new indications for the previously approved drugs for use during a declared emergency and is a valid way to expedite drug development. Several promising agents with and without FDA investigational new drug (IND) status for ARS are under advanced development. In the next few years, we expect that the FDA will approve a few radioprotectors for H-ARS as well as gastrointestinal ARS via Animal Rule.

Keywords

• Animal Rule
• emergency use authorization
• nonhuman primates
• radiation
• repurposing