Lioznov et al.54reported that administering LEN after aHSCT for relapsed multiple myeloma induces an increase of activated NK (NKp44+) cells and T (HLA‐DR+) cells and shows clinical responses. Conversely, Dauguet et al.55reported that LEN downregulates IFN‐γ production and cytotoxicity receptor NKp46 expression. Although the absolute number of NK cells was considerably low because we used purified donor T cells as effector cells for GVHD induction, NK cells expanded due to high‐dose LEN administration in the present study. The gene discussed is IFNG; the disease is AL amyloidosis.