Tumor-treating fields increase cytotoxic degranulation of natural killer cells against cancer cells

Tumor-treating fields (TTFs) are a non-invasive treatment for glioblastoma (GBM) that applies low-intensity, intermediate-frequency, alternating electric fields. Given a 5-year survival of less than 7% for GBM patients, multi-modal treatments are required to improve survival. Natural killer (NK) cells are innate lymphocytes that kill cancer cells and are thus a major target for new immunotherapy approaches. There is potential to combine TTFs with an NK cell-based therapy for GBM treatment. Here, we investigate the impact of TTFs on NK cell viability and functions. Exposure to TTFs does not affect NK cell viability or interferon (IFN)-γ production, a key NK cell function. Of significance, exposure to TTFs increases NK cell degranulation, a proxy of cell killing. These data suggest that the combination of TTFs and NK cell-based therapy may boost tumor cell killing. This provides a basis to further explore this combination, with the end goal of enhancing NK cell immunotherapy potential for patients with GBM.