Ex Vivo IL-15-Stimulated NK Cells as Adoptive Cell Therapy in Haploidentical Transplantation for Pediatric Leukemia

A Phase I/II clinical trial was conducted in pediatric patients with high-risk malignancies to assess the safety and efficacy of NK cell infusion post-haplo-HSCT. Patients received either alloreactive NK cells from KIR/HLA-mismatched donors or IL-15-stimulated NK cells from KIR/HLA-matched donors, across three dose-escalating cohorts. The IL15-NK cell infusion product demonstrated enhanced activating receptor expression and functional capacity. Increased NKG2D expression was observed in NK cells from patients receiving IL15-NK cells. One-year follow-up showed accelerated immune reconstitution in both the allo-NK and IL15-NK cell arms. IL15-NK recipients exhibited a pro-inflammatory cytokine profile (IL-2, IL-4, IL-6, IFN-γ). Elevated CD69 expression was associated with a higher risk of transplant-related complications.