[Prophylactic G-CSF mobilized donor lymphocytes infusion after non-myeloablative stem cell transplantation prevents relapse in patients with high-risk leukemia].

Objective: To evaluate the anti-leukemia effects of prophylactic G-CSF mobilized donor lymphocytes infusion (pG-DLI) and its relationship with the incidence of graft-versus-host disease (GVHD) in high-risk leukemia patients with non-myeloablative stem cell transplantation (NST).

Methods: 12 patients with high-risk leukemia were analyzed, including Ph⁺ acute lymphocytic leukemia (n=1), acute leukemia (AL) with persistent non-complete remission (n=2), acute myeloid leukemia (AML) with central nervous system (CNS) relapse (n=3), hybrid AL (n=1), secondary AML evolving from myelodysplastic syndrome (MDS/AML) (n=2), chronic myeloid leukemia in accelerated phase (CML-AP) (n=1), CML in blastic phase (CML-BP) (n=2). All patients received non-myeloablative conditioning and pG-DLIs were administered 30-40 days post transplantation if no signs of GVHD were present. The percentage of donor cell chimera was analyzed by short tandem repeat-polymerase chain reaction (STR-PCR) just before and after pG-DLI. The incidence of leukemia relapse and GVHD were observed.

Results: 12 high-risk leukemia patients with a median age of 38 (range: 29-52) years received G-DLI at a median interval of 35 (32-40) days. The median numbers of infused mononuclear cells (MNCs), CD34⁺, and CD3⁺ cells/kg recipient body weight was 2.3×10⁸/kg, 1.7×10⁶/kg, and 0.6×10⁸/kg, respectively. 10 of 12 patients had full donor chimera before pG-DLIs and conversion from mixed to full donor chimera occurred in the other 2 patients shortly after pG-DLI. Grade II acute GVHD (aGVHD) was observed in only 2 patients and chronic GVHD (cGVHD) developed in 6 patients, including involvement of skin (n=3), skin and intestine (n=2), liver (n=1). 1 patient died of cGVHD. With a median follow-up of 40 (24-64) months, 7 patients are alive in remission, with 3-year actuarial overall survival (OS) and disease-free survival (DFS) rates of the same 58.3%.

Conclusion: Our findings indicate that pG-DLI after NST does not increase the risk of aGVHD, but could enhance the capacity graft-vs-leukemia and prevent relapse in high-risk leukemia patients.