Nationwide pharmacovigilance data for cetuximab-induced anaphylaxis and predictive model validation using prospective specific IgE detection

Background: Cetuximab (chimeric monoclonal antibody to human epidermal growth factor receptor) is used to treat colorectal and head and neck cancers. Due to cross-reactivity with galactose-α-1,3-galactose (alpha-gal), it can induce hypersensitivity even at first administration. We aimed to determine the incidence and clinical manifestation of cetuximab-induced anaphylaxis, and to establish a means of predicting its incidence in patients ahead of treatment. Methods: Nationwide and single-center pharmacovigilance data from 2010 to 2017 were collected from the Korea Institute of Drug Safety-Korea Adverse Event Reporting System and Severance Regional Pharmacovigilance Center. Patients scheduled for cetuximab administration were enrolled prospectively. A skin prick test was carried out and serum IgE specific to cetuximab and cross-reactive allergens were measured. Reactions were monitored after cetuximab infusion. Results: Over 8 years, there were 23 reports of anaphylaxis nationwide. In a single-center study, incidence of cetuximab-induced anaphylaxis was 1.1%. Most anaphylaxis occurred at first injection (93.3%), even under pretreatment with anti-allergic drugs. Four of 64 patients (6.3%) experienced severe anaphylaxis. The median cetuximab-specific IgE titer was 6.9 kU_A/L in patients experiencing anaphylaxis and 0 kU_A/L in those who did not (P < 0.001). The results of alpha-gal, beef sIgE, and cetuximab skin prick testing were similar to those of cetuximab sIgE. Patients who did not experience hypersensitivity were negative in all 4 allergy tests. Its positive and negative predictive values were 100%. Conclusions: Specific IgE detection of cetuximab or alpha-gal can accurately predict cetuximab-induced anaphylaxis prior to first administration.