Can bevacizumab be used a second time to treat metastatic colorectal cancer?

The authors investigated the efficacy and safety of continuing or reintroducing bevacizumab (Avastin) in patients with metastatic colorectal cancer that has progressed.

Metastatic colorectal cancer indicates that the cancer has spread from the colon or rectum to distant sites in the body. Bevacizumab is an anti-cancer drug that blocks the formation of new blood vessels needed for the cancer to grow and spread. Combined with chemotherapy it is a standard first treatment option for patients with metastatic colorectal cancer.

Cancer can continue to progress despite this first treatment strategy and a change of treatment is often required. It is not known whether it is safe and effective for patients to continue taking or reintroduce bevacizumab as part of a second treatment strategy. 

This study included 184 patients with metastatic colorectal cancer. All patients had previously been treated with chemotherapy plus bevacizumab. Patients were divided into 2 groups, group 1 switched chemotherapy drug and group 2 switched chemotherapy and took bevacizumab. The chemotherapy used was either mFOLFOX6 (5-fluorouracil [Efudex], leucovorin, oxaliplatin [Eloxatin]) or FOLFIRI (5-fluorouracil, leucovorin, irinotecan [Camptosar]), depending on which option patients had used first. 66% of patients took FOLFOX and 34% of patients took FOLFIRI In both groups.

After 18 months the cancer had progressed for 99% of patients. The average time till it progressed was 5 months for group 1 and 6.8 month for group 2. Patients in group 1 had a 30% higher risk of earlier progression than patients in group 2. Patients in group 2 tended to have longer overall survival times (time from treatment until death from any cause). Patients in group 1 had a 23% increased risk of a shorter overall survival than group 2.

50% of patients in group 2 had stopped taking bevacizumab for at least 3 months before reintroducing it. There was no difference in timing of progression for patients who had continued bevacizumab, compared to patients who had a break in treatment.

There were slightly more minor adverse event in the bevacizumab group. Adverse events included high blood pressure, bleeding and excess protein in urine samples. There were no differences in the numbers of moderate to severe adverse events.

This study concluded that continuation or reintroduction of bevacizumab with a second chemotherapy drug improves patient outcome. They suggest that the results support its use for treatment of metastatic colorectal cancer in future.