Hypersensitivity Reactions To Monoclonal Antibodies: Desensitization Approach

Increasing use of monoclonal antibodies (mAbs) in chronic inflammatory and oncologic disorders, leads to increasing incidence of hypersensitivity reactions (HSRs). Desensitization is a useful approach in cases without alternative therapy. Twelve patients were referred to our Allergy Department (May 2008-August 2011) due to immediate HSRs to mAbs. Skin-testing (ST) was performed. Two patients underwent a 12-step desensitization protocol previously described, with a total of 11 desensitizations. Dexchlorpheniramine, acetaminophen and glucocorticoids were used as standard premedication for these drugs. In 1 case of severe reaction acetylsalicylic acid and montelukast were added. mAbs involved were rituximab=6, infliximab=3, cetuximab=1, adalimumab=1, trastuzumab=2, bevacizumab=1, efalizumab=1, etanercept=1 (3 patients reacted to more than 1). HSRs were classified as mild=3, moderate=7 and severe= 2 (Brown 2004). Only one patient showed positive intradermal-test to efalizumab. Two patients were desensitized to rituximab, one of them also to infliximab. Reactions occurred in 5 out of 11 procedures (45%). 4 of them were mild (oropharyngeal pruritus), 1 was moderate (flushing, mild hypotension), finishing infusion in all these cases. The moderate reaction ocurred in a first desensitization to rituximab, in spite of ASA and montelukast premedication. This patient tolerated 4 subsequent desensitizations following the same protocol. Ten desensitizations were successfully completed, and 1 patient rejected to continue due to adverse drug effects during the infusion. We found a low rate of positive ST, suggestive of an IgE-mediated mechanism, in patients with immediate HSRs to mAbs.