Safety and Efficacy Study of MEHD7945A + FOLFIRI Versus Cetuximab + FOLFIRI as Second Line Therapy in Participants With KRAS Wild-Type Metastatic Colorectal Cancer (mCRC)

Inclusion Criteria:

- Histologically or cytologically confirmed adenocarcinoma of the colon and/or rectum,
with KRAS wild-type status

- Progressive disease on or after first-line oxaliplatin-containing regimen for mCRC;
participants must have received oxaliplatin-containing chemotherapy for greater than
or equal to (>/=) 3 months; no more than one prior chemotherapy regimen for
metastatic disease is allowed

- Measurable disease per modified Response Evaluation Criteria in Solid Tumors Version
1.1 (RECIST v1.1)

- Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

- Adequate hematologic and end-organ function

Exclusion Criteria:

- Prior treatment with irinotecan

- Prior treatment with an investigational or approved human epidermal growth factor
receptor (HER)-targeted agent

- Last anti-tumor therapy within 4 weeks prior to Cycle 1, Day 1

- Leptomeningeal disease as the only manifestation of the current malignancy

- Active infection requiring intravenous antibiotics

- Active autoimmune disease that is not controlled by nonsteroidal anti-inflammatory
drugs

- Current severe, uncontrolled systemic disease

- Known human immunodeficiency virus (HIV) infection

- Untreated/active central nervous system metastases (progressing or requiring
anticonvulsants or corticosteroids for symptomatic control)

- Pregnant or lactating women

- Malignancies other than colorectal cancer within 5 years prior to randomization,
except for adequately treated basal or squamous cell skin cancer and carcinoma in
situ of the cervix