Intermittent or Continuous Panitumumab Plus FOLFIRI for Left Sided RAS/B-RAF Wild-type Metastatic Colorectal Cancer

The investigators hypothesize that intermittent first-line Panitumumab plus FOLFIRI is effective in first line as the same regimen given continuously, resulting in a Time to Treatment Failure (TTF) not inferior to that obtained with standard continuous regimen of Panitumumab plus FOLFIRI, in the treatment of metastatic left sided RAS/B-RAF wild-type colorectal cancer patients. Correlative mechanistic studies on tissue and blood samples, liquid biopsies, could identify potential biomarkers of efficacy and help understanding the evolutionary dynamics of tumors in response to therapy thus optimizing the treatment approach with a personalized anti-EGFR treatment strategy.