The range of new therapies that are currently under development for HER2-positive MBC include (i) new TKIs targeting ERBB receptors and inhibitors of their down-stream signaling, (ii) inhibitors of cell cycle, HSP90, and angiogenesis, (iii) HER2-targeted drug delivery, and (iv) new antibodies and immunotherapy aimed at HER2-positive BC. The gene discussed is ERBB2; the disease is breast cancer.