Induced Electric Fields Inhibit Breast Cancer Growth and Metastasis and Modulate the Immune Tumor Microenvironment

Introduction: Metastatic triple-negative breast cancer (TNBC) remains highly challenging to treat despite advances in oncology. This study investigated whether non-invasive alternating, low-intensity induced electric fields (iEFs) could suppress tumor growth and metastasis while modulating anti-tumor immunity in TNBC. Methods: Orthotopic TNBC mouse models were treated with alternating (100 kHz) and low-intensity (2.7 mV/cm peak), induced electric fields (iEFs), which were delivered non-invasively via a solenoid coil system. Tumor growth and lung metastasis were assessed following treatment. Immune profiling was performed to evaluate changes in T cell states and myeloid cell populations within both primary tumors and metastatic lung tissue. Results: iEF treatment significantly reduced primary tumor growth (n=9) and lung metastases (n=5). Within the tumor microenvironment, iEFs decreased infiltration of immunosuppressive myeloid cells (n=8). In the lung metastatic niche, iEF therapy increased CD8+ T cell abundance while reducing immunosuppressive myeloid populations (n=8). We also observed that iEFs reduced the metastatic potential of cancer cells by inhibiting epithelial-to-mesenchymal transition (n=3). Conclusion: Induced electric field therapy enhances anti-tumor immunity and suppresses metastatic progression in TNBC by enhancing T cell activity and remodeling immunosuppressive myeloid environments. These findings support iEFs as a promising non-invasive immunomodulatory strategy for metastatic TNBC.