ABSTRACT
Summary: Introduction. The main mechanism involved in hypersensitivity reactions (HSR) to Taxanes (primarily Paclitaxel and Docetaxel) seems to be a complement activation by their excipients: polyoxyethylated castor oil (Paclitaxel) and Polysorbate 80 (Docetaxel). SARS-CoV-2 vaccines contains Polysorbate 80 or polyethylene glycol (PEG) as excipients, which are structurally correlated to polyoxyethylated castor oil. The aim of this study was to verify the presence of a higher risk of HSR to SARS-CoV-2 vaccines in patients with history of HSR to taxanes. Methods. Patients with history of HSR to taxanes were evaluated before the vaccination in our center and underwent skin tests for PEG and Polysorbate 80 (P and P). Some patients completed the vaccination course in other centers without prior P and P skin tests because they had not manifested taxanes hypersensitivity before vaccination, or because those tests were not available. Results. A total of 50 patients were evaluated. 100% of patients with history of hypersensitivity to taxanes completed the vaccine course with no cases of anaphylaxis. 33 patients underwent skin tests for P and P before the vaccination and no correlation was found between P and P skin tests positivity and taxanes skin tests positivity (p = 0.538). 7 patients developed mild symptoms during skin tests and vaccination, similar but weaker than those suffered at the time of the taxane infusion, and independently from the results of skin tests (2/7 positive patients). Conclusions. In our cohort Patients with history of reaction to taxanes were not at higher risk to develop anaphylaxis to SARS-CoV-2 vaccines. However, a common non-IgE mediated mechanism behind those HSRs cannot be completely excluded. This can only account for mild and harmless symptoms in case of SARS-CoV-2 vaccines. Antihistamine premedication and longer observation after the vaccination are still prudent in these patients.