Bevacizumab (Avastin) can have serious side effects, including infusion-related reactions, blood clots, and damage to the gut:
Infusion-related reactions

These can be life-threatening and require immediate medical attention. Symptoms include fever, chills, shaking, dizziness, trouble breathing, itching or rash, lightheadedness, or fainting.

Blood clots
Bevacizumab can increase the risk of blood clots, which can be life-threatening. Signs include pain, swelling, and redness where the clot is.

Gut damage
Bevacizumab can damage the gut or bowel, such as causing a blockage or hole. This is especially a concern if there is a lot of cancer in the abdominal cavity.

Other serious side effects include:
Posterior reversible encephalopathy syndrome (PRES), a brain condition

Nosebleeds or bleeding from the gums
Coughing up or vomiting blood or material that looks like coffee grounds

Unusual bleeding or bruising
Increased menstrual flow or vaginal bleeding
Pink, red, or dark brown urine
Red or tarry black bowel movements
Heart failure
Kidney problems
Severe stroke or heart problems
Nervous system and vision problems
___________

My goodness.
LL can't trial quick enough.