Exploring Predictive Risk Factors of Infusion Reactions with First Pertuzumab Administration in HER2-positive Breast Cancer Patients: A Single Institution Experience.

Introduction: Pertuzumab and trastuzumab are monoclonal antibodies used for treating HER2-positive breast cancer. These anti-HER2 antibodies may induce infusion reactions (IR), mainly upon first administration. We investigated factors predicting IR in the initial pertuzumab treatment for HER2-positive breast cancer. Methods: We retrospectively reviewed the medical records of 57 patients who first received pertuzumab-containing treatment in our hospital from January 2014 to February 2021. The frequency of IR during or immediately after pertuzumab administration was examined. We also analyzed patient characteristics that may represent possible risk factors for IR. Results: The incidence rate of IR was 44% (25/57). Red blood cell count (P < 0.001), hemoglobin (Hb) concentration (P = 0.0011), and hematocrit (P < 0.001) immediately before pertuzumab administration were significantly lower in patients with IR than in those without. In patients with IR, erythrocyte levels immediately before pertuzumab treatment were significantly lower than baseline when having received anthracycline-containing chemotherapy within three months. Logistic regression analysis showed that a decrease in Hb levels was a significant risk factor for IR (log odds ratio = -17). According to the receiver-operating characteristic analysis, a 10% decrease in Hb after anthracycline-containing treatment was the best cut-off value for predicting IR (sensitivity: 88%; specificity: 77%; area under the curve: 0.87). Conclusions: Our study showed a higher incidence of IR after pertuzumab treatment than in clinical trials. There was a strong association between IR occurrence and erythrocyte levels lower than baseline in the group that received anthracycline-containing chemotherapy immediately before.