Comparative Enzymatic and Stability Assays Reveal GPLG as an Effective Cathepsin B Cleavable Linker for Tumor-Targeting Drug Conjugates

'-dimethylethylenediamine spacer, GPLG exhibited the fastest Cathepsin B cleavage within the first 30 min of the assay, and higher stability at pH 5.4 and in both human and rat plasma samples. These results highlight GPLG as a promising lysosomal-sensitive linker for next-generation SMDCs and ADCs.