This B-cell activation leads to the secretion of interleukin (IL)-10, IL-35 and transforming growth factor-β, which suppress cytotoxic T-cell activity.9 By inhibiting BTK, tirabrutinib may induce CD8+ T-cell activation, resulting in keratinocyte death and contributing to the development of SJS/TEN. This evidence concerns the gene CD8A and toxic epidermal necrolysis.