1. Background

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has remarkably improved the dismal prognosis of many aggressive hematological malignancies. However, post-transplant relapse remains a major challenge [1]. As there are limited treatment options for the patients relapsed after allo-HSCT, these populations often have poor prognosis. Donor lymphocyte infusions (DLIs) are routinely used as a preemptive measure or therapeutic modality for recurrence. The engraftment of donor T cells is able to eradicate tumor cells and mediate antitumor activity mainly through graft-versus-lymphoma (GVL) effect. However, DLI has met with limited success as these allogeneic lymphocytes can also target normal tissues, thus leads to high risk of clinically significant GVHD [2]. For this reason, new therapeutic interventions are urgently needed for relapsed B-cell malignancies.