Refining epidermal growth factor receptor (EGFR) -inhibition-related rash (EIRR) phenotypes with a cetuximab (C) monotherapy stage of a phase II trial for non-small cell lung cancer (NSCLC)

8089 Background: Papulopustular rash (R) severity by National Cancer Institute Common Terminology Criteria (CTC) across disease settings and EGFR inhibitors correlates with improved tumor response rates. Better characterizing EIRR will advance development of biomarkers for individualizing EGFR-inhibitor therapy. Methods: An EIRR-specific rating scale (ES) (based on a validated rosacea scale: 0 = no R, 1 = isolated lesion¼, 5 = pustules/erythema on face/head/neck + chest/back) and time-to-R were assessed prospectively. 50 patients (pts) with: metastatic/recurrent NSCLC following prior platinum, no prior EGFR inhibitors, and ≤ 2 prior regimens, received C [400mg/m2 then 250mg/m2/week (w)] for 2w and were randomized to combined C and pemetrexed (P) [500mg/m2 q 3 w] or to continue C followed at progression by P. Each pt’s R was rated by CTC and ES scales at baseline, 1, 2, and 3 w and every 3 w until progression. To optimize R phenotypes for future genotype/treatment response studies, we compared grading by C...