This study looks at how well a combination of treatments works for a type of colon or rectal cancer called metastatic colorectal cancer, which has spread to other parts of the body. The treatments include chemotherapy (drugs like fluorouracil, oxaliplatin, and leucovorin calcium), bevacizumab (a drug that stops new blood vessels from growing to feed the cancer), and atezolizumab (a drug that helps your immune system attack cancer cells). The goal is to see if these treatments together work better than just atezolizumab alone. Patients will be randomly assigned to one of three groups to receive different treatments. After the treatments, patients will have check-ups every few months for up to five years to monitor their health.

• Study Length: Treatment lasts up to 48 cycles, with follow-up for 5 years.
• Visits Needed: Regular visits every two weeks during treatment and follow-ups every 8 to 12 weeks.
• Risks: Possible side effects from the drugs, such as low blood counts or immune reactions.