“…The basophil activation test (BAT) [ 8 , 9 , 10 ] is widely used to study and predict type 1 hypersensitivity reactions to food [ 11 , 12 , 13 , 14 , 15 ], venom [ 16 , 17 , 18 ] and drugs [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ] in the allergy field. To date, however, its application to study basophils ex vivo in the context of cancer has been limited to case reports or small studies focused on the detection of allergic reactions to chemotherapeutic agents [ 5 , 6 , 26 , 27 , 28 , 29 ]. Here, we conduct the first evaluation of basophils in a cohort of 53 ovarian cancer patients with diverse tumor histologies and treatment histories (treatment-naïve, chemotherapy, debulking surgery, targeted monoclonal antibodies (mAbs), small molecule inhibitors).…”