Nelfinavir, a protease inhibitor used in the treatment of human immunodeficiency virus (HIV), has been found to inhibit the growth of human epidermal growth factor receptor 2 (HER2)-positive tumors in mice.

Noting in Journal of the National Cancer Institute (2012;104[20]:1576-1590) that new drug targets specific for HER2-positive breast cancer, a highly aggressive form of the disease, are needed, Joong Sup Shim, PhD, and fellow investigators screened the Johns Hopkins Drug Library to identify a number of inhibitors of breast cancer cells. Shim, of the Department of Pharmacology and Molecular Sciences at Johns Hopkins School of Medicine in Baltimore, Maryland, and the rest of the research team then performed a pharmacologic profile of seven genotypically individual breast cancer cell lines using a subset of those inhibitor agents.

The profiling revealed that nelfinavir selectively inhibited the growth of HER2-positive breast cancer cells in mice, and also inhibited the growth of trastuzumab-resistant and/or lapatinib-resistant HER2-positive breast cancer cells in vitro at concentrations consistent with dosage regimens used for HIV patients. 

“With a relatively low toxicity profile and much available information on its drug-drug interactions and on pharmacokinetics, nelfinavir is ready for clinical testing in HER2 breast cancer patients,” the researchers concluded.