Our stability data (Figure 1D) indicates that the enzymatic digestion of Val-Cit-PABC-R848 leads to a rapid release of the R848 payload, which can be mediated in vivo by Cathepsin B and other tumor-associated proteases for which the Val-Cit linker is a substrate (Miller et al., 2021). This evidence concerns the gene CTSB and neoplasm.