Incidence and risk factors of infusion reactions in patients with breast cancer administered trastuzumab plus pertuzumab-based regimen

Purpose Pertuzumab (Per) is a humanized monoclonal antibody used in combination with trastuzumab (Tra) in the treatment of human epidermal growth factor receptor-2 (HER2)-positive breast cancer. The administration of biologics, such as Tra and Per, frequently causes infusion reactions (IRs) with fever and chills. This study aimed to clarify the characteristics of and risk factors for IRs in Tra + Per combination therapy. Methods Between March 2013 and December 2019, 64 patients with breast cancer who started Tra + Per combination therapy were included in the study. The severity of IRs was graded according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Results The incidence of IRs in the Tra + Per combination therapy was 48.4% (31/64). The severity of IRs in the Tra + Per combination therapy was Grade 1 (9 patients) and Grade 2 (22 patients). Lymphocyte counts were significantly different between the IR and non-IR groups in patients receiving Tra + Per combination therapy (univariate analysis, p = 0.006; multivariate analysis, p = 0.050). ROC curve analysis found the cutoff value of lymphocyte counts were 1.60 (× 10 3 /µL). The incidence of IRs in the lymphocyte counts ≥ 1.60 group was significantly higher than that in the lymphocyte counts < 1.60 group ( p < 0.001). Conclusion Our study indicates that the severity of IRs in most patients is moderate or less and the risk of IRs is higher in patients with higher lymphocyte counts (≥ 1.60 × 10 3 /µL).