FOLFOXIRI Plus Bevacizumab With or Without Atezolizumab as 1st Line Treatment of pMMR and IS IC-High Metastatic Colorectal Cancer Patients.

This is a prospective, open-label, multicenter phase III randomized trial in which patients with initially unresectable, previously untreated pMMR and Immunoscore IC-high mCRC will be randomized in a 1:1 ratio to receive induction treatment with FOLFOXIRI plus bevacizumab up to 8 cycles followed by maintenance with 5-FU/LV plus bevacizumab until disease progression, unacceptable toxicity or patient's refusal (arm A) or FOLFOXIRI plus bevacizumab plus atezolizumab up to 8 cycles followed by maintenance with 5-FU/LV plus bevacizumab plus atezolizumab until disease progression, unacceptable toxicity or patient's refusal (arm B). Stratification factors will be ECOG Performance Status (0 versus 1, 2), primary tumour location (right versus left/rectum) and liver metastases (yes versus no). The second- and subsequent lines of treatment will be at investigators' choice.