Background and Importance The increased use of monoclonal antibodies (mAb) for cancer treatment has been associated with a higher incidence of hypersensitivity reactions (HR). Drug desensitisation is a procedure that, by inducing temporary tolerance, allows patients who have developed a drug HR to safely receive it. This technique is performed according to previously published studies and plays a significant role for patients with HR, enabling treatment continuation.

Aim and Objectives To conduct a descriptive analysis of the use of mAb as a desensitisation protocol and to evaluate their effectiveness in a series of cases.

Material and Methods All oncological-haematological patients, who underwent desensitisation using a 3-concentration protocol due to HR to mAb in a University Hospital between 2019 and 2022, were included. Clinical information was retrospectively collected from medical records (SAP®, Genomi®), including oncohaematologic cancer type, mAb desensitised, time and severity of the reaction, allergology study results (skin test and/or Basophil Activation Test (BAT)), suspected underlying mechanism (Inmunoglobulin E (IgE) mediated or non-IgE mediated), breakthrough reactions during any of the desensitisation and final outcome.

Results Thirty-six patients received mAb desensitisation regimens, with a total of 357 desensitisations of eight different drugs [rituximab (123), cetuximab (87), daratumumab (68), trastuzumab (45), brentuximab (13), Obinutuzumab (9), isatuximab (9), trastuzumab entamsine (3)]. Each patient received an average of 10 administrations (1–52) in desensitisation regimen. Twenty-eight patients had haematological pathologies (77%), most of them treated with rituximab. Seventeen out of 36 (47%) patients desensitised experienced a reaction at first contact with the drug. Half of all patients (18) suffered moderate to severe HR; and only five patients had a confirmed IgE-mediated HR, confirmed by skin tests or BAT. 86% of the patients did not experience any reaction (breakthrough reactions) during the desensitisation. The remaining experienced some mild reaction during at least one of the desensitisations, but after adjusting the infusion regimen they tolerated treatment adequately. All (100%) of the desensitisations were successful; patients were able to receive the medication they were being treated without experiencing any adverse reactions that require discontinuation.

Conclusion and Relevance The high success of desensitisations to mAb in our hospital highlights the importance of this technique preventing switching to other treatments that might be more expensive and less effective.

Conflict of Interest No conflict of interest.