Bevacizumab and its impact on survival for patients receiving subsequent anti-EGFR therapy: Results from the South Australian metastatic colorectal cancer registry.

Abstract

754 Background: Questions over the impact of 1st line bevacizumab on subsequent sensitivity to anti-EGFR therapy have been raised with authors hypothesizing that up-front anti-VEGF agent’s use influences biological changes that increase the risk of acquired resistance to subsequent EGFR inhibitors. Methods: Aretrospective cohort study was performed to compare the characteristics and survival of patients who were treated with an anti-EGFR therapy 2nd line and beyond by two groups defined by the 1st line therapy; 1. chemotherapy (chemo) plus bevacizumab (bev) and 2. chemo alone. Pearson chi test analysis was performed to determine whether receiving 1st line bev was associated with worse OS. Results: 348 mCRC patients who received chemo with or without bev and then an anti-EGFR therapy were studied. Patient characteristics are summarised in table. The significant differences between group 1. Vs. 2. were as follows; median age, lower use of single agent FU, KRAS status not tested, and where BRAF MT status was known (11%); BRAF MT rate. Median OS for the 2 groups was 34.2 mths, and 28.2 mths respectively (p = 0.12). Conclusions: Survival was not significantly different between the two groups, and the trend was towards higher OS with chemo plus bev suggesting that in our registry population, bev administration in first line therapy with chemo did not lead to a worse outcome for those patients subsequently receiving anti-EGFR therapy. [Table: see text]