Soluble ST2 is a member of the IL‐1 receptor family,29 with IL‐33 as its only known ligand.30 sST2 level was found to be a useful biomarker of non‐response to GVHD therapy and improved risk stratification according to clinical grade.31 Meanwhile, baseline serum sST2 had good predictive value for heart failure 20 and myocardial infarction 21 of all subtypes and cardiovascular death in a large community‐dwelling population. This evidence concerns the gene IL33 and graft versus host disease.