When conjugated to MMAE,a potent anticancer small-molecule drug, MS2 T71K/G73R and MS2 T71R/G73Kcan deliver MMAE to glioblastoma cells and produce cytotoxic responseswith low-nanomolar efficacies that are comparable to those of MMAE-ADCs.This demonstrates that MS2 variants with positively charged surfaceresidues can be effective small-molecule delivery vehicles. Here, ADAM8 is linked to glioblastoma.