M. Pascal M. Pascal Jitesh Chauhan Jitesh Chauhan Edward Knol Edward Knol Rodolfo Bianchini Rodolfo Bianchini Mariana C. Castells Mariana C. Castells Leticia de las Vecillas Sanchez Leticia de las Vecillas Sanchez Karin Hartmann Karin Hartmann Elena Izquierdo Elena Izquierdo Uta Jappe Uta Jappe Teodorikez-Wilfox Jimenez-Rodriguez Teodorikez-Wilfox Jimenez-Rodriguez Francesca Levi-Schaffer Francesca Levi-Schaffer Lina Mayorga Lina Mayorga Aurélie Poli Aurélie Poli Frank. A Redegeld Frank. A Redegeld Alexandra F. Santos Alexandra F. Santos Erika Jensen-Jarolim Erika Jensen-Jarolim Christoph Bergmann Christoph Bergmann Sophia Karagiannis Sophia Karagiannis Heather J. Bax Heather J. Bax Wiley 2025 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. PDFDocument eng 2025-11-14T10:47:02.242331Z 2025 AllergoOncology Allergy Basophil Activation Test (BAT) Cancer Immunotherapy Hypersensitivity Reactions Precision Medicine 1223817 b application/pdf http://creativecommons.org/licenses/by-nc-nd/4.0/