Autologous Natural Killer Cell Therapy for Human Recurrent Malignant Glioma

Abstract

Background: Natural killer (NK) cells are highly efficient in the cellular immune response against malignant tumors without restriction of major histocompatibility complex. However, clinical studies using autologous NK cells have been reported in only a very limited number of cases, due to the fact that selective NK expansion is difficult to achieve in this patient population. Here, we report the results of adoptive immunotherapy in patients with recurrent malignant gliomas using autologous NK cells that were expanded ex vivo by a novel method. Patients and Methods: Peripheral blood mononuclear cells (PBMCs) were prepared from patients with malignant gliomas, and were co-cultured with an irradiated human feeder cell line (HFWT) in RHAM-alpha medium supplemented with 5% autologous plasma and interleukin-2. The resulting NK cell-rich effector cells were injected into 9 patients (16 courses) with recurrent malignant glioma (6 cases of WHO grade-3 glioma and 3 cases of grade-4 glioma). Results: The mean frequency of NK cells among lymphocytes was 82.2±10.5%. A combination of focal and intravenous injections was performed in 10 courses. Intravenous injection alone was performed in 6 courses. Further, intravenous injection of low-dose interferon beta (6×10⁶ IU/week) was performed as an adjuvant therapy in all courses to achieve maximum benefit for enrolled patients. Clinical evaluation demonstrated 3 PR, 2 MR, 4 NC and 7 PD in a total of 16 courses of treatment. Severe neurological toxicity was not observed in any of the patients. Conclusion: It was demonstrated that NK cell-rich effector cells were expanded ex vivo from PBMCs in all nine cases of recurrent malignant glioma and that NK cell therapy was safe and partially effective in patients with recurrent malignant gliomas.