Basophil Activation Test: Bridging Allergy and Oncology for Diagnostic, Therapeutic and Prognostic Applications in AllergoOncology: An EAACI Position Paper.

The basophil activation test (BAT) is gaining increasing relevance as an ex vivo functional assay in allergy to evaluate IgE-mediated hypersensitivity reactions to food allergens, venoms, and drugs and to monitor tolerance induction. Establishing universal standard operating protocols has been difficult, due to several challenges including variable activation markers, positive control selection, the need for processing fresh blood samples, and the existence of non-releasing individuals. In oncology, BAT is also an emerging promising diagnostic and management tool to assess hypersensitivity reactions to biologics and chemotherapy agents, monitor drug tolerance in desensitisation, and predict and address the safety of novel anti-cancer IgE-based therapeutics. This position paper highlights the emerging significance of BAT in AllergoOncology, in facilitating therapy monitoring, biomarker discovery, and risk stratification. Capitalising on long-acquired expertise in the development of BAT for allergy, we propose research directions and routes to clinical applications of this highly promising tool in AllergoOncology. We advocate the need for enhanced focus on addressing standardisation challenges and leveraging outputs for precision medicine. By linking allergy and oncology, the key remaining limitations can be addressed, with the aim of realising the significant promise of BAT as a robust tool to enhance personalised care in allergy and AllergoOncology.