Characteristics of patients with development of large granular lymphocyte expansion among dasatinib-treated patients with relapsed Philadelphia chromosome-positive acute lymphoblastic leukemia after allogeneic stem cell transplantation

Introduction Widespread use of tyrosine kinase inhibitors (TKIs) in combination with chemotherapy and allogeneic hematopoietic stem cell transplantation (allo-SCT) has totally changed the existing treatment strategies for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph⁺ALL). However, the prognosis after relapse after allo-SCT is still dismal. Patients and Methods We analyzed the clinical outcome of therapy using dasatinib, a second-generation TKI, in 9 patients with relapsed Ph⁺ALL after allo-SCT. Dasatinib was initiated at a median time of 168 days after allo-SCT at dosages ranging from 20 mg to 100 mg daily. Results Six of 9 patients manifested a marked increase in large granular lymphocytes (LGLs), but all 6 patients discontinued dasatinib because of adverse events (AEs) such as pleural effusion. Four of 6 patients resumed dasatinib, and 3 of them have been alive with molecular complete remission and a persistent increase of LGLs. Conclusion Our results demonstrated that dasatinib therapy can induce LGL expansion accompanied by AEs, but this phenomenon can be associated with long-term survival benefit in a proportion of relapsed Ph⁺ALL patients after allo-SCT.