Higher-Dose Donor Derived Ex Vivo Expanded Natural Killer Cell Infusion Prior to Haploidentical Stem Cell Transplantation on Acute Myeloid Leukemia: Efficacy and Safety

Adoptive immunotherapy with donor-derived natural killer (NK) cell was deemed as a promising therapeutic in hematological malignancies with anti-cancer, anti-graft-versus-host disease (GvHD), and anti-viral potential. However, the clinical usage was limited by lacking evidence on optimal dosage and timing. Here, we conducted a retrospective cohort study of compassionate use of higher dose (1x10^9/kg) NK cell infusion prior to haploidentical stem cell transplantation on acute myeloid leukemia. NK cells were obtained by 50ml donor peripheral blood through purifying, and ex vivo expanding with interleukin (IL)-2 and IL-15. Twelve patients enrolled in this cohort receiving an average dose of 1 x 10⁹/kg (0.8 - 1.8 x 10⁹/kg) NK cell infusion 12 hours prior to day 0. All patients achieved hematologic reconstitution. I° acute GVHD (aGVHD) appeared in three patients (25%). No chronic GVHD (cGVHD) occurred. With a median follow-up of 12.5 months (range 9-62 months), eight patients are still alive and in disease free survival status. Minimal residual disease (MRD) in alive patient was sustaining negative on day +60, +180 +360 and +720. Three patients relapsed six months posttransplant and one patient died from late bone marrow failure. Our small cohort study implied that infusion of high doses ex vivo expanded donor-derived NK cell infusion prior to haploidentical stem cell transplantation was safe and could potentially have a role to decrease relapse of patients with high-risk AML.

No relevant conflicts of interest to declare.