Flare Phenomenon in Advanced Colorectal Cancer: Cessation of evacizumab after Predefined Cycles of Therapy may not Affect Outcome

Abstract

Limited number of experimental and clinical studies showed rapid tumor regrowth after bevacizumab cessation in advanced colorectal cancer. We retrospectively evaluated rapid regrowth phenomenon in 105 patients those who were treated with the predefined number of chemotherapy cycles and grouped according to whether the chemotherapy regimen in the first line setting included bevacizumab (CT-Bev arm) or not (CT arm). Median age was 55 years old. Median overall and progression free survival times were 27 and 11 months, respectively. Rapid progression rates were 42\% and 40\% in CT arm and CT -Bev arm without no statistically significant difference (p= 0.84). In CT arm, significantly more patients with stable disease (SD) progressed rapidly compared to patients with complete (CR) or partial response (PR) (53\% vs. 27\%, p= 0.04). This result was also similar in CT-Bev arm (48\% vs. 30\%, p= 0.27) but could not reach to the significant p-value. Overall survival 2, the time from the end of last dose of chemotherapy +/- bevacizumab to death, was significantly shorter in both CT and CT -Bev arms for patients who showed SD compared to CR or PR (15 vs 38 months) (p< 0.001).Current study supports that withdrawal of bevacizumab after predefined treatment cycles may not have any adverse effect on patients' outcome of advanced CRC. This result is particularly acceptable for the patients who show CR or PR to the treatment.