EGFR and non-small cell lung carcinoma: For example, the most advanced clinical compound to date, poziotinib, has achieved a 64% objective response rate, a significant improvement upon the previous 8.7% objective response rate for afatinib59 and 17% objective response rate for the Hsp90 inhibitor luminespib.96 Several outstanding challenges lie ahead–for instance, given the significant molecular heterogeneity of the size and location of distinct EGFR exon 20 insertions, it will be important to determine whether all patients within this molecular subtype of NSCLC will universally respond to these inhibitors.