Seems to me it does not prevent damage, just allows the cells to repair themselves vice "committing suicide".
"It turns out that radiation doesn't kill healthy cells in the same way that it kills cancer cells. Instead, bone marrow and GI cells overreact to what should be reparable damage and commit suicide, through a well-known process called apoptosis, explained Andrei Gudkov of the Roswell Park Cancer Institute, who led development of the drug code-named CBLB502.
Learning that was the "eureka" moment, Gudkov said. Apoptosis is the body's way of stopping defective cells, with damaged genes, from spreading. Tumors grow because cancer cells block apoptosis in various ways, including by activating a normally dormant cell-signaling pathway called "nuclear factor-KappaB" or NFKB.
The team knew that flagellin, a protein from normal gut bacteria, can wake up NFKB. So they created a drug based on that natural protein."
