Six-month stability of bevacizumab (avastin) binding to vascular endothelial growth factor after withdrawal into a syringe and refrigeration or freezing

Purpose: To determine the change in anti-vascular endothelial growth factor (VEGF) activity of bevacizumab (Avastin, Genentech, Inc., San Francisco, CA) after refrigeration or freezing. Methods: Samples of bevacizumab were drawn up from new vials into plastic tuberculin syringes and refrigerated at 4 degrees C for 1 week, 3 weeks, 1 month, 3 months, and 6 months. The vials and syringes were stored at 4 degrees C, and the syringes were capped with a needle. One syringe was frozen at -10 degrees C. The bevacizumab concentration was measured, via its binding to VEGF-165. Results: The percentage of degradation of bevacizumab in the previously pierced vials stored at 4 degrees C compared with that in the unpierced vial was 9.6% at 3 months and 12.7% at 6 months. The bevacizumab drawn into the syringe and stored at 4 degrees C was degraded by 1.6% at 1 week, 0% at 3 weeks, 8.8% at 3 months, and 15.9% at 6 months. The bevacizumab frozen in a syringe at -10 degrees C was degraded by 12.0% at 6 months. Conclusion: The anti-VEGF activity of bevacizumab may degrade minimally over time, with storage.