Compositions and methods are disclosed for treating Triple Negative Breast Cancers (TNBCs). The methods involve administering to a subject with TNBC a composition containing an Ack1 kinase inhibitor. In some embodiments, the method involves first assaying a sample from the subject for Tyr176-phosphorylated-AKT and/or Tyr284-phosphorylated-Ack1. In these embodiments, detection of the phosphorylated AKT and/or Ack1 is an indication that the subject is a suitable candidate for treatment with the Ack1 kinase inhibitor.
