CD19 and mantle cell lymphoma: While CD19‐targeting chimeric antigen receptor T‐cell (CD19CAR‐T) therapy with axicabtagene ciloleucel (Axi‐cel) [1] and brexucabtagene autoleucel (Brexu‐cel) for relapsed/refractory (r/r) large‐B‐cell‐lymphoma (LBCL), and mantle cell lymphoma (MCL), respectively [2] is highly effective, cardiac decompensation during cytokine release syndrome (CRS) is a life‐threatening complication [3, 4].