First-line FOLFOX plus panitumumab (Pan) followed by 5FU/LV plus Pan or single-agent Pan as maintenance therapy in patients with RAS wild-type metastatic colorectal cancer (mCRC): The VALENTINO study.

3505Background: Since doublets plus anti-EGFRs were continued until progressive disease (PD) in mCRC first-line registration trials, there is scarce evidence if de-escalating treatment intensity after an anti-EGFR-based induction might be not inferior in terms of disease control, while reducing toxicity burden and improving quality of life. In MACRO-2, maintenance with cetuximab alone achieved a 9-month progression-free survival (PFS) rate non inferior than continued mFOLFOX + cetuximab in KRAS ex. 2 wt patients. Methods: RAS wt unresectable mCRC patients, stratified for prior adjuvant therapy and metastatic sites (1 vs ≥2), were randomized and received FOLFOX + Pan induction (8 cycles) followed by maintenance with Pan (arm B) or 5FU/LV + Pan (arm A) until PD/unacceptable toxicity/death. The primary endpoint was non-inferiority of PFS of arm B vs A. An overall sample size of 224 subjects (112 per arm) achieved 90% power to detect a 50% 10-month PFS rate in arm A and a maximum 15% difference in arm B, with...