Study of Bevacizumab + mFOLFOX6 Versus Bevacizumab + FOLFIRI With Biomarker Stratification in Participants With Previously Untreated Metastatic Colorectal Cancer (mCRC)

5-Fluorouracil 400 milligrams per meter-squared (mg/m\^2) by IV bolus and subsequent 2400 mg/m\^2 by IV infusion over 46 hours will be administered every 2 weeks until disease progression or unacceptable toxicity.

Bevacizumab 5 milligrams per kilogram (mg/kg) of body weight via IV infusion will be administered every 2 weeks until disease progression or unacceptable toxicity. If participants are discontinued from oxaliplatin or irinotecan due to unacceptable toxicity, bevacizumab may be given in 3-week cycles with capecitabine.

Irinotecan 180 mg/m\^2 via IV infusion over 2 hours will be administered every 2 weeks until disease progression or unacceptable toxicity.

Leucovorin 400 mg/m\^2 or dose deemed appropriate by Investigator via IV infusion over 2 hours will be administered every 2 weeks until disease progression or unacceptable toxicity.

Oxaliplatin 85 mg/m\^2 via IV infusion over 2 hours will be administered every 2 weeks until disease progression or unacceptable toxicity.

Capecitabine 850 or 1000 mg/m\^2 may be offered in the event of unacceptable toxicity to oxaliplatin or irinotecan, to be given orally twice a day on Days 1 to 14 in 3-week cycles.