This is a Phase 3, randomized, open-label, global, multicenter, interventional trial to evaluate the efficacy and safety of petosemtamab in combination with investigator's choice (IC) chemotherapy (fluorouracil + leucovorin \[calcium folinate\] + irinotecan \[FOLFIRI\] or 5-FU, leucovorin \[calcium folinate\], and oxaliplatin \[mFOLFOX6\]; Arm A) versus IC cetuximab or bevacizumab in combination with IC chemotherapy (FOLFIRI or mFOLFOX6; Arm B) as second line (2L) treatment for participants with KRAS, NRAS, and BRAF wild type (wt), recurrent, unresectable or metastatic colorectal cancer (CRC).