New research in mice reveals that an inhibitor of the Janus kinase 2 (JAK2) protein can shrink triple-negative breast cancer, which lacks expression of the estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (Balko JM et al. Sci Transl Med. 2016;8[334]:334ra53). This cancer is the most lethal form of breast cancer and the only type of breast tumor still lacking a targeted treatment.

JAK2 is part of a signaling pathway that plays a role in stem cell functionality and self-renewal and is deregulated in a variety of cancer types. The pathway is thought to drive malignancy through a variety of processes, including tumorigenesis, invasion, metastasis, proliferation, survival, angiogenesis, antiapoptosis, and immune evasion.