A brief report of toxicity end points of HER2 vaccines for the treatment of patients with HER2(+) breast cancer

Human epidermal growth factor receptor 2 (HER2)-targeted vaccines are under development, but have so far demonstrated only modest clinical efficacy. Additionally, there has been a lack of adequate safety assessment in large-scale prospective clinical trials. Therefore, we performed a meta-analysis of available clinical trial data to summarize the toxicity profiles of these treatments. Literature search was conducted in February 2018. The trials analyzed had at least one study arm consisting of HER2 vaccine monotherapy. Heterogeneity across studies was analyzed using I(2) statistics. Data were analyzed using random-effects meta-analysis for absolute risk (AR). Eight trials and 248 patients were included. There was no evidence of heterogeneity between studies for grades 3/4 adverse events (AEs) or for death. The AR for treatment-related serious AEs was 5% with no treatment-related deaths. The AR of all-grade fatigue, injection site reaction, and fever/chills/rigors was 33%, 23%, and 31%, respectively. Asymptomatic drop in left ventricle ejection fraction was rare (8%). HER2 vaccines are well tolerated with increased AR of fatigue, injection site reactions, and fever/chills/rigors.