Randomized comparison of FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab as first-line treatment of KRAS wild-type metastatic colorectal cancer German AIO study KRK-0306 (FIRE-3)

SUMMARY: It is common practice to combine anti-EGFR agent ERBITUX® (Cetuximab) or anti-VEGF agent AVASTIN® (Bevacizumab) with chemotherapy, in the initial management of patients with metastatic colorectal cancer. There is however a higher likelihood for patients with tumors expressing wild type KRAS (non-mutated KRAS), to respond to ERBITUX®. In this randomized multicenter study, a CAMPTOSAR® (Irinotecan) based backbone, FOLFIRI (folinic acid, fluorouracil and Irinotecan) given along with ERBITUX® (Group A) was compared with FOLFIRI plus AVASTIN® (Group B), in treatment naïve patients with metastatic ColoRectal Cancer (mCRC). Of the 592 patients with wild type KRAS mCRC, 297 patients were randomized to Group A and 295 patients to Group B. The median age was 64 years. The median duration of treatment was 4.7 months and 5.3 months in Group A and Group B respectively. The primary endpoint was Objective Response Rate (ORR). Even though the ORR was comparable in Groups A and B (62% vs 57%), there was a significant improvement in the overall survival (OS) favoring Group A (28.8 vs 25.0 months, HR= 0.77, P=0.0164). The comparable response rates and surprising improvement in OS in the ERBITUX® group suggests that either ERBITUX® or AVASTIN® can be added to FOLFIRI, in the first-line treatment of wild type KRAS mCRC patients. It is however clear that in wild type KRAS mCRC patients, it may be harmful to combine ERBITUX® with FOLFOX chemotherapy regimen, as was seen in the EPOCH trial and based on MRC COIN trial, NORDIC-VII trial and N0147 trial, ERBITUX® should not be combined with FOLFOX chemotherapy regimen as there is no added benefit. It is now well established that mCRC that harbors KRAS mutations in exon 2 (about 40% of the patients) do not benefit from anti-EGFR therapies. The PRIME study has given us aditional insight and it appears that other activating RAS mutations may also predict lack of response to anti-EGFR therapies. With regards to BRAF mutations, they portend a poor prognosis, regardless of treatment. Heinemann V, Weikersthal LF, Decker T, et al. J Clin Oncol 31, 2013 (suppl; abstr LBA3506)