The sequencing of biologic agents used in metastatic colorectal cancer can affect the outcomes. We analyzed a multicenter registry to address a question that could not be answered using current clinical trial data. We found that whether or not patients had received previous bevacizumab, the effect of epidermal growth factor receptor antibodies in later lines of therapy was maintained.Background:
The FIRE-3 [5-fluorouracil, folinic acid, and irinotecan (FOLFIRI) plus cetuximab versus FOLFIRI plus bevacizumab in first line treatment colorectal cancer (CRC)] study reported that first-line FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab resulted in similar progression-free survival (PFS) but improved overall survival (OS). A potential explanation is that the initial biologic agent administered in metastatic CRC (mCRC) affects later line efficacy of the other treatments. We sought to test this hypothesis.Materials and Methods:
We interrogated our mCRC registry (Treatment of Recurrent and Advanced Colorectal Cancer) regarding treatment and outcome data for RAS wild-type patients receiving epidermal growth factor receptor inhibitors (EGFRIs) in second and subsequent lines. Survival outcomes from the beginning of EGFRI use were determined as a function of previous bevacizumab use and the interval between ceasing bevacizumab and beginning EGFRI use.Results:
Of 2061 patients, 222 eligible patients were identified, of whom 170 (77%) had received previous bevacizumab and 52 (23%) had not. PFS and OS from the start of EGFRIs did not differ by previous bevacizumab use (3.8 vs. 4.2 months; hazard ratio [HR], 1.12; P = .81; 9.0 vs. 9.2 months; HR, 1.19; P = .48, respectively) for the whole cohort or when analyzed by the primary tumor side (HR for left side, 1.07; P = .57; HR for right side, 1.2; P = .52). PFS was significantly shorter with right-sided primary tumors when the interval between bevacizumab and EGFRI use was < 6 versus > 6 months (median, 2.2 vs. 6 months; HR, 2.23; P = .01) but not with left-sided tumors (median, 4.2 vs. 5.5 months; HR, 1.12; P = .26).Conclusion:
Previous bevacizumab use had no effect on the activity of subsequent EGFRIs. The apparent effect of time between biologic agents in right-sided tumors might reflect patient selection.