Maybe the emphasis on radioprotection has something to do with the scope of the article.
Amifostine and RRx-001 both originate from military radioprotective research. GC4419, a superoxide dismutase, has direct radioprotective properties by snubbing (not a scientific term, yet. I am working on it) superoxide radicals produced by radiation. Palifermin is not an actual radioprotective, but it is the only FDA approved drug for oral mucositis and probably serves as reference for the others. Excluded drugs, Dusquetide, Brilacidin, Validive, Epicatechin (EC-18) and AGO13 are more active in damage repair than in direct radioprotection.