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Bevacizumab or Avastin™ is a genetically engineered chimeric murine/human monoclonal antibody, which specifically binds to the receptor of vascular endothelial cell growth factor (VEGF-R).

Mechanism of action

Its mechanism of action is based on the necessary binding of VEGF to its receptors (Flt-1 et KDR), which are found on the surface of vascular endothelial cells. Under this stimulation, the endothelial cells proliferate and new vessels appear to sustain tumour growth. The administration of Bevacizumab to human colic carcinoma transplanted into nude mice showed a significantly reduced growth of (mouse) micro-vessels and consequently the inhibition of the progression of metastases.

To-day indications

The current indication is the first-line treatment of metastatic rectocolic carcinoma in association with chemotherapy comprising 5-FU. A significantly increased total survival and disease free survival have been observed.

The usual dosage is 5 mg/kg every 14 days intravenously until disease progression.

Many other localisations are currently being tested and further indications will very probably develop in the near future.

Acute complications

Complications can be explained by the mechanism of action.

Gastro-intestinal perforations are rare but may be lethal (in 2% of patients), since they can induce massive haemorrhage or even intraabdominal abscesses. Their symptoms are major abdominal pain with vomiting like peritonitis.

Scar splitting and poor cicatrisation are due to a poor vascularisation. They rarely occur, however we do not know exactly what interval should be respected between surgery and the beginning of Bevacizumab treatment, or worst between the stopping of Bevacizumab and surgery (which may lead to very dangerous situations in the case of perforations).

Haemorrhages may also occur. They can be benign (light epistaxis) and observed relatively often, or they can be severe (major haemorrhages due to lung tumour necrosis, observed in phase II trials).

Hypertension (possibly severe) is relatively frequent (up to 40% of patients), and should be treated in order to avoid cerebral haemorrhage during hypertension crisis.

Other effects have been observed: proteinuria (with no clinical signification in around 15% of patients), rare nephrotic syndromes (1% of patients) or congestive cardiac failure (2% of patients).

A possible allergic reaction during perfusion should be prevented in the same manner as for other antibodies.