Tumor treating fields suppress tumor cell growth and induce immunogenic cell death biomarkers in biliary tract cancer cell lines

Tumor Treating Fields (TTFields) are low-intensity, intermediate-frequency alternating electric fields that exert antimitotic effects on cancer cells. This study is the first to evaluate the in vitro efficacy of TTFields on biliary tract cancer (BTC) cell lines HCCC-9810 and RBE, investigating their sensitivity to TTFields across varying frequencies and electric field intensities (100-200 kHz, 1.3-2.1 V/cm). The results demonstrated that a frequency of 150 kHz induced the most pronounced cytotoxic effects, significantly impairing clonogenicity and migratory capacity while inducing multipolar spindles and microtubule disorganization. Furthermore, TTFields treatment triggered a marked upregulation of immunogenic cell death (ICD) biomarkers, including enhanced surface exposure of calreticulin (CRT) and increased extracellular release of high mobility group box 1 (HMGB1) and Adenosine triphosphate (ATP). These findings suggest that TTFields hold great promise as a therapeutic strategy for BTC. They not only suppress tumor cell proliferation but also promote the release of ICD-associated biomarkers. Nevertheless, this study is limited to preliminary in vitro experiments. To provide insights for the ongoing clinical trial (NCT06611345), further in vivo studies and mechanistic explorations are essential to investigate the potential of combining TTFields with immune checkpoint inhibitor (ICI) therapy in the treatment of BTC.