Photo Credit: Evgen_Prozhyrko

The following is a summary of “Non-Allergic Urticarial Skin Reactions Associated With MOv18 IgE, a First-In-Class IgE Antibody Recognising Folate Receptor Alpha,” published in the March 2025 issue of European Journal of Allergy and Clinical immunology by Stavraka et al. 

IgE antibodies targeting cancer antigens showed strong anti-tumor effects. MOv18 IgE, recognizing folate receptor alpha (FRα), showed early efficacy with mild urticarial reactions. 

Researchers conducted a retrospective study on immunological and allergic responses linked to urticarial reactions in patients treated with MOv18 IgE. 

They analyzed FRα expression and MOv18 IgE reactivity in human skin using immunohistochemistry, immunofluorescence, and immuno-mass spectrometry. They conducted transcriptomic analyses on paired lesional and non-lesional biopsies from 1 patient. They assessed systemic markers, including cytokines, β-tryptase, and basophil activation, throughout the trial and during the reaction. 

The results showed that 62.5% of 24 patients treated with IgE developed transient urticarial reactions during the first infusion, decreasing with subsequent doses, with no β-tryptase elevation or allergic signs. No FRα expression or MOv18 IgE binding was found in human skin. In the highest-dose patient, lesional biopsies showed scattered eosinophils, neutrophils, and mast cell degranulation without increased immune infiltration. Transcriptomic analysis indicated pro-inflammatory but not allergic pathway activation, with no systemic allergic mediators or basophil activation detected. 

Investigators found that urticarial reactions after MOv18 IgE treatment were unlikely due to allergic mechanisms or skin antigen recognition. They concluded that the reactions resembled infusion-related effects seen with monoclonal antibodies. 

Source: onlinelibrary.wiley.com/doi/full/10.1111/all.16514