Trastuzumab and paclitaxel in patients (pts) with EGFR mutated non-small-cell lung cancer (NSCLC) that express HER2 after progression on EGFR TKI treatment.

9042Background: HER2 expression as well as amplification has been well recognized in tumor biopsies of pts with an EGFR mutation who developed EGFR TKI resistance. It is unknown whether HER2 targeting in this setting can result in tumor responses. Methods: Single arm open label phase II study to study the safety and efficacy of paclitaxel-trastuzumab treatment in pts with a sensitizing EGFR mutation who show tumor membrane HER2 expression in a tumor biopsy (immunohistochemistry (IHC) ≥1) after progression on EGFR TKI treatment. Paclitaxel (60 mg/m2) and trastuzumab (first dose 4 mg/kg, thereafter 2 mg/kg) were dosed weekly until disease progression or unacceptable toxicity. Primary end-point was tumor response according to RECIST. Sample size of 20 pts was calculated to evaluate the primary objective of ≥30% objective response rate. The study was deemed positive when ≥7 pts would show a partial or complete response. Results: 21 pts were enrolled from 08-2012 to 02-2017. 7 pts were exon 21 L858R positive a...