17α-Ethinyl-androst-5-ene-3β, 17β-diol, a novel potent oral radioprotective agent, confers radioprotection of hematopoietic stem and progenitor cells in a granulocyte colony stimulating factor-independent manner.

Our findings demonstrate the radioprotective efficacy of EAD and reveal that the 17α-Ethinyl group is essential for its oral activity. Given its oral efficacy and low toxicity, EAD has potential as an optimal radioprotector for use by first responders as well as at-risk civilian populations.