The present invention relates to methods for treating TTK positive breast cancers or soft-tissue sarcomas in a mammalian subject by administering a therapeutically effective amount of a TTK antagonist. The invention also provides compositions comprising a TTK antagonist and a HER-2 antagonist, as well as methods of diagnosing a basal-like breast cancer and methods of determining the prognosis of a subject having a cancer by assessing expression of TTK in a tumor sample from a subject.
