Low Rate of Cetuximab Hypersensitivity Reactions in Northeast Tennessee: An Appalachian Effect?

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Purpose: Cetuximab is a monoclonal antibody with a known risk of hypersensitivity reactions. Early studies showed hypersensitivity reaction rates of 3%, but there appears to be a higher incidence in the southeastern United States. To confirm the findings from nearby institutions that cetuximab-associated hypersensitivity reactions occur in approximately 20% of patients in the southeastern United States.

Methods: A retrospective chart review was conducted at Johnson City Medical Center in Johnson City, Tennessee. Each patient’s first infusion was analyzed for hypersensitivity reaction, as well as for demographic information such as allergy and smoking history, pre-medications, and malignancy type.

Results: Data from the first infusion of cetuximab were collected for a total of 71 patients with various malignancies. The overall rate of grade 3 or higher hypersensitivity reaction was 1.4%, and total rate of hypersensitivity reaction was 8.5%. These findings more closely correlate to the early clinical trials and package insert. Both severe (p = 0.001) and any-grade (p = 0.002) hypersensitivity reaction occurred less frequently in one Southeastern Appalachian medical center compared to academic medical centers directly to the east and west.

Conclusions: Patients in southern Appalachia may be less likely to develop cetuximab hypersensitivity reactions compared to surrounding areas in the Southeastern U.S. These results lend support to the theory that exposure to lonestar ticks (Amblyomma americanum) may be responsible for the development of IgE antibodies to cetuximab that cause hypersensitivity reactions. The development of quick and reliable bedside predictors of cetuximab hypersensitivity reactions may aid clinicians considering the use of cetuximab.