ERBB2 and neoplasm: Based on pre-clinical data showing mutant versus WT selectivity across 48 allosteric HER2 mutant variants and EGFR or HER2 exon 20 insertion mutants, as well as tumor growth inhibition in vivo, a phase I/II trial, MasterKey-01 (NCT04209465), is ongoing to determine the dosing regimen and recommended phase II dose (RP2D) of BDTX-189 monotherapy [61].