Association of C-MYC, MYC Target Gene, and Unfolded Protein Response (UPR) Expression with Clinical Benefit from the Oral Aurora Kinase A (AURKA) Inhibitor, Alisertib (A), in Combination with Paclitaxel (P) Compared with P Alone in Patients (pts) with HER2-negative Metastatic Breast Cancer (MBC)