– MS 39 is a highly effective, highly affinity and selective depressant of mutant epidermal growth factor receptor (EGFR) with high efficiency, high affinity and selectivity. MS 39, conjured by gefitinib to VHL ligand via a linker, effectively induced the degradation of mutant EGFR (DC50 values in HCC827(exon 19 del) and H3255 (L858R mutation) lung cancer cell lines were 5 nM and 3.3 nM, respectively). However, there was no significant effect in wild-type EGFR cell lines with concentrations up to 10 μM. MS 39 inhibited the proliferation of H3255 lung cancer cells in vitro and was bioavailable in mice after administration.