Ibrutinib has recently been shown to counteract IgE‐dependent activation of human BAs.26, 27 To examine whether ibrutinib exerts inhibitory effects on IgE‐dependent histamine release in canine neoplastic MCs, we performed experiments using NI‐1 cells, known to express a functional IgE receptor30, 34 and primary mastocytoma cells. The gene discussed is IGHE; the disease is mastocytoma.