EGFR and Skin rash: In vitro and in vivo studies demonstrated that Rociletinib irreversibly and selectively inhibits mutant EGFR, including T790M mutation, with minimal activity against wild type EGFR, suggesting that drug tolerability to this agent may be superior to first and second generation EGFR inhibitors, for which major toxicities (diarrhea, skin rash and interstitial lung disease) are attributed to wild type EGFR blockage.