Tumor-treating fields and concurrent cisplatin: an in vitro demonstration of efficacy in triple-negative breast cancer

Chemotherapy is commonly used to treat patients with triple-negative breast cancer. Combinations of platinum-based chemotherapies have demonstrated higher rates of pathologic complete responses of triple-negative breast cancer compared to combinations without platinum-based chemotherapies. However, there is a significant increase in general toxicity with the addition of platinum-based regimens. Some groups have investigated using tumor-treating fields as an alternative treatment method for triple-negative breast cancer, and chemosensitization by tumor-treating fields has been observed in vitro. With the goal of minimizing the toxicities associated with platinum-based chemotherapy, we investigated anti-mitotic effects of concurrent tumor-treating fields and cisplatin treatment to show that the addition of tumor-treating fields further inhibited cell growth in triple-negative breast cancer. We show that combining cisplatin with tumor-treating fields induces higher levels of apoptosis within triple-negative breast cancer cells as opposed to normal epithelial cells and the combination has a more immediate mechanism of cell death than either monotherapy. We also demonstrate that, when combined with tumor-treating fields, a lower dose of chemotherapy can be used to achieve the same efficacy of triple-negative breast cancer cell death as higher doses of individual therapy.