Long‐term follow‐up of patients receiving allogeneic stem cell transplant for chronic lymphocytic leukaemia: mixed T‐cell chimerism is associated with high relapse risk and inferior survival

Summary There is limited information regarding the immunological predictors of post‐allogeneic stem cell transplant (alloSCT) outcome in chronic lymphocytic leukaemia (CLL), such as mixed T‐cell chimerism. We analysed 143 consecutive patients with relapsed/refractory CLL, transplanted between 2000 and 2012, to determine the prognostic relevance of mixed chimerism post‐alloSCT and the ability of post‐transplant immunomodulation to treat relapse. Mixed T‐cell chimerism occurred in 50% of patients at 3 months and 43% at 6 months post‐alloSCT; upon 3‐ and 6‐month landmark analysis, this was associated with inferior progression‐free survival (PFS) [Hazard ratio (HR) 1·93, P = 0·003 and HR 2·58, P