ERBB2 and Skin rash: In cohort 2 of the ZENITH20 phase II trial, 90 patients with HER2 MUT NSCLC received poziotinib 16 mg once daily and achieved an ORR of 27.8%, disease control rate (DCR) of 70%, and mPFS of 5.5 months; however, significant toxicities were reported, including skin rash 83% (G ≥ 3 47%), diarrhoea 80% (G ≥ 3 20%), and stomatitis 67% (G ≥ 3 10%), which led to a 13.3% discontinuation rate [67].