Final results from a randomized phase 3 study of FOLFIRI ± panitumumab for second-line treatment of metastatic colorectal cancer

Background: The study 20050181 demonstrated significant improvements in progression-free survival (PFS), objective response, and a nonsignificant trend toward increased overall survival (OS) with panitumumab-FOLFIRI versus FOLFIRI alone for second-line wild-type (WT) KRAS metastatic colorectal cancer (mCRC). Updated long-term data from a prespecified descriptive analysis are reported. Patients and methods: Patients receiving one prior mCRC treatment were randomly assigned (1:1) to panitumumab (6.0mg/kg)-FOLFIRI versus FOLFIRI every 2 weeks. Co-primary end points (PFS and OS) were prospectively analyzed by tumor KRAS status. Results: One thousand one hundred and eighty-six patients were randomly assigned. In patients with WT KRAS tumors, panitumumab-FOLFIRI significantly improved PFS versus FOLFIRI [median 6.7 versus 4.9 months; hazard ratio (HR) 0.82 [95% confidence interval (CI) 0.69, 0.97]; P = 0.023]. A trend toward longer OS was observed (median 14.5 versus 12.5 months; HR 0.92 [95% CI 0.78, 1.10]; P = 0.37). Response rates improved from 10% to 36% (P <0.0001). From post hoc analyses in patients receiving prior oxaliplatin-bevacizumab, panitumumab-FOLFIRI improved PFS (median 6.4 versus 3.7 months; HR 0.58 [95% CI 0.37, 0.90]; P = 0.014). PFS and OS appeared longer for worst-grade skin toxicity of 2-4, versus 0-1 or FOLFIRI. Safety results were as previously reported and consistent with the known toxicities with anti-epidermal growth factor receptor therapy. Conclusions: These data confirm the primary efficacy and safety findings of this trial and support panitumumab- FOLFIRI as a second-line treatment of WT KRAS mCRC.