New perspectives on zoledronic acid in breast cancer: potential augmentation of anticancer immune response.

A small subset of T cells (gamma-delta T cells) is able to recognize phosphoantigens that are overexpressed in some cancer cells and may selectively target and kill cancer cells with high levels of phosphoantigen. Moreover, nitrogen-containing bisphosphonates, such as zoledronic acid, are able to induce accumulation of specific phosphoantigens in some cancer cells. A recent preclinical study showed that gamma-delta T cells effectively targeted and killed zoledronic acid-treated estrogen-receptor-positive breast cancer cells. These new data provide growing insight into a potential mechanism of action for some of the anticancer activity demonstrated by zoledronic acid in breast cancer clinical trials.