HSP90 inhibitors have shown modest clinical activity in EGFR-mutant lung cancer, including in combination with erlotinib, and modest activity as a single agent in EGFRex20ins NSCLC.14,24 In this study, the addition of onalespib to erlotinib in EGFR-mutant NSCLC among 10 of 11 patients harboring EGFRex20ins yielded no objective responses in the first 11 patients treated, including eight patients dosed at the RP2D (onalespib at 120 mg/m2 IV on days 1, 8, and 15 and erlotinib at 150 mg PO every day on a 28-day cycle). Here, EGFR is linked to non-small cell lung carcinoma.