Planned granulocyte-colony stimulating factor adversely impacts survival after allogeneic hematopoietic cell transplantation performed with Thymoglobulin for myeloid malignancy

STRUCTURED ABSTRACT Background The in vivo depletion of recipient and donor T-lymphocytes using anti-thymocyte globulin (ATG) is widely adopted in allogeneic hematopoietic stem cell transplantation (HCT) to reduce the incidence of both graft failure and graft versus host disease (GVHD). However excess toxicity to donor lymphocytes may hamper immune reconstitution, compromising anti-tumour effects and increasing infection. Granulocyte-colony stimulating factor (G-CSF) administered early after HCT may increase ATG-mediated lympho-toxicity. Objective Our study objective was to investigate the effect of an interaction between ATG and post-transplant G-CSF on allogeneic transplant outcomes, using the Center for International Blood and Marrow Transplant Research (CIBMTR) registry. Study Design We studied patients aged ≥18 years with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) who received thymoglobulin-containing preparative regimens for HLA-matched sibling/unrelated or mismatched unrelated donor HCT from 2010-2018. The effect of planned G-CSF that was started between pre-transplant day 3 and post-transplant day 12 was studied in comparison to transplantations that did not include G-CSF. Cox regression models were built to identify risk factors associated with outcomes 1 year after transplantation. Results 874 patients met study eligibility criteria; 459 (53%) received planned G-CSF. HCTs with planned G-CSF significantly increased risk for non-relapse mortality (HR 2•03, p Conclusion In allogeneic peripheral blood HCT performed with Thymoglobulin for AML and MDS, G-CSF administered early post-transplant results in a two-fold increase in non-relapse mortality and a 10% absolute decrement in survival. The use of planned G-CSF in the early post-transplant period should be carefully considered on an individual patient basis, weighing any perceived benefits against these risks.