Autologous NK cells as consolidation therapy following stem cell transplantation in multiple myeloma

Summary Few approaches have been made toward exploring autologous NK cells in settings of cancer immunotherapy. Here, we demonstrate the feasibility of infusing multiple doses of ex vivo activated and expanded autologous NK cells in patients with multiple myeloma (MM) post-autologous stem cell transplantation. Infused NK cells were detected in circulation up to 4 weeks after the last infusion. Elevations in plasma granzyme B levels were observed following each consecutive NK cell infusion. Moreover, increased granzyme B levels were detected in bone marrow 4 weeks after the last infusion. All measurable patients had objective, detectable responses after NK cell infusions in terms of reduction in M-component and/or minimal residual disease. The present study demonstrates that autologous NK cell-based immunotherapy is feasible in a setting of MM consolidation therapy. It opens up the possibility for usage of autologous NK cells in clinical settings where patients are not readily eligible for allogeneic NK cell-based immunotherapies. Graphical abstract Highlights • Infusing activated and expanded autologous NK cells in patients with MM is possible • Infused NK cells are detected in circulation for up to 4 weeks • Elevated granzyme B levels are observed following each consecutive NK cell infusion • Objective, detectable responses after NK cell infusions are seen in patients Activated and expanded autologous NK cells were repeatedly infused in patients with multiple myeloma following autologous HSCT. The study by Nahi et al. shows safety and demonstrates efficacy parameters. It opens up the possibility to use autologous NK cells in clinical settings, either alone or as parts of combination therapies.