Table 3.

Other promising radiation countermeasures at advanced stages of development requiring US FDA IND status.

Countermeasures	Mode of action	Efficacy in animal model of radiation injury	Safety/side effects	Remarks	Ref.
Amifostine/Ethyol, 2-(3-aminopropyl) aminoethylphosphorothioate	Protects against radiation and chemotherapy induced DNA damage, anti-mutagenic and anti-carcinogenic, scavenges free radicals	Highly efficacious cytoprotectant in vivo at high doses	Sides effects at higher doses	FDA approved for the reduction of xerostomia in radiotherapy patients with head and neck cancers	[87–91]
γ-tocotrienol (GT3)	Antioxidant, free-radical scavenger, stimulates G-CSF, HMG-CoA reductase inhibitor	Protect mice against hematopoietic and GI injury when administered prior to irradiation, efficacious in NHP (unpublished observation)	Safe (200 –1000 mg/kg)	Additional NHP efficacy studies being initiated at AFRRI	[93,96–98,102]
Myeloid progenitor cells	Bridging therapy, stimulates myeloid, erythroid and dendritic cell development	Effective against supralethal doses of radiation in murine model when administered as late as 7 d post-irradiation	Cells of human origin appear to be safe	CLT-008, human myeloid progenitors in Phase-I trial in patients undergoing umbilical cord blood transplant for hematological malignancies	[115–117]

GI: Gastrointestinal; GRAS: Generally regarded as safe by the US FDA; HMG-CoA: 3-hydroxy-3-methylglutaryl-coenzyme A; IND: Investigational new drug.