[Successful Continuation of Treatment in Advanced Colorectal Cancer by Switching to a Prior Biologic Agent after Emergence of Bevacizumab Allergy to a Biosimilar Drug-A Case Report].

Biosimilar(BS)drugs have recently been introduced owing to concerns with healthcare economics. In this report, we present a case in which a patient discontinued bevacizumab treatment following an allergic reaction to a BS formulation of bevacizumab but was able to safely continue treatment by switching to an original bevacizumab formulation in the late-line setting. The patient was a 66-year-old man diagnosed with unresectable colorectal cancer with synchronous multiple liver metastases. After primary tumor resection, chemotherapy including the original bevacizumab formulation was initiated. Allergic reactions to the BS formulation of bevacizumab occurred during the second-line treatment; however, in the late-line setting, switching back to the original bevacizumab formulation enabled the safe continuation of therapy. Overall, our case study suggests that switching of biologic agents may contribute to the ongoing management of chemotherapy.