LAUSR

3541 Background: FIRE-3 compared 1st-line therapy with FOLFIRI plus either cetuximab or bevacizumab in 592 KRAS exon 2 wt mCRC patients. The subgroup of extended RASwt patients consisted of 400 patients. The median age of patients treated in FIRE-3 was 64 years. Analyses of efficacy of doublet-chemotherapy in patients >70 years have shown inconsistent results. Methods: In this exploratory analysis, patients were grouped into cohorts with 65 years and 70 years as a cut-off for age-related analysis of the FIRE-3 study population. ORR was compared using Fisher´s exact test, Survival analyses were done using Kaplan-Meier estimation and median survival times were compared using log-rank testing. Results: Within the RAS wt population, patients older than 70 years had a significantly shorter OS when compared to patients ≤70 years of age in both arms (p= 0.02 for cetuximab arm, p= 0.02 for bevacizumab arm). Patients ≤65 years and ≤70 years had a significantly longer OS when treated with FOLFIRI plus cetuximab compared to FOLFIRI plus bevacizumab (p= 0.01 and 0.02 respectively). The OS benefit of cetuximab treated patients compared to bevacizumab treated patients was consistent for patients ≤65 years (p=0.005) and patients ≤70 years (p= 0.009) of age. In patients older than 70 years, however, comparable efficacy of bevacizumab and cetuximab was observed. This effect of age on outcome appears to be affected by sidedness. RAS wt population (n=400). Conclusions: In the overall RAS wt population, younger patients have a significant OS benefit when treated with FOLFIRI plus cetuximab compared to FOLFIRI plus bevacizumab, while this was not the case in patients older than 70 years.[Table: see text]