EGFR and non-small cell lung carcinoma: Preclinical activity of other HSP90 inhibitors has been shown in combination with next-generation EGFR TKIs, such as osimertinib, that have more activity against EGFRex20ins NSCLC than erlotinib.31,32 With next-generation EGFRex20ins inhibitors in clinical development, both TKIs and monoclonal antibodies, the addition of HSP90 inhibition may provide enhanced clinical activity, although the tolerability of these combinations may also be limited by gastrointestinal side effects such as diarrhea and other overlapping toxicities.7