Common features with our case include LBCL treated with axi‐cel to CMR, exposure to multiple prior lines of therapy (median 4, range 3–4; prior autologous stem cell transplantation (SCT) in Cases 1 and 2), persistent CD4+ lymphopenia (<200 cells/μl), and hypogammaglobulinaemia (<4 g/L). The gene discussed is CD4; the disease is lymphopenia.