Abstract P3-02-04: Combined aurora kinase A and mTORC 1/2 inhibition results in disruption of tumor cell energetics in triple negative breast cancer

Background: We have previously demonstrated the efficacy of pharmacologic targeting of Aurora Kinase A (AurA) in cell line and patient-derived xenograft (PDX) models of triple-negative breast cancer (TNBC). We observed that inherent or acquired resistance to AurA inhibitors was associated with a senescence phenotype and up-regulation of the PI3K/Akt/mTOR pathway. This provided the rationale to assess whether this resistance could be overcome with the combination of the AurA inhibitor alisertib with the TORC1/2 inhibitor TAK-228. In select TNBC PDX models, we found that there were highly significant anti-tumor effects of the combination compared to single agents. The purpose of the current study was to evaluate the potential role for alterations in tumor metabolic profiles in anti-tumor activity after dual inhibition of AurA and TORC1/2, as both pathways are known to mediate cellular metabolism and energy utilization in normal and cancer cells. Methods: Three TNBC PDX models were used for these studies. Tumor sections were implanted subcutaneously on bilateral flanks of athymic nude mice. When tumors reached ~150 mm3 mice were randomized into four treatment arms: vehicle; alisertib (30 mg/kg); TAK-228 (0.75 mg/kg); or the combination and dosed daily by oral gavage for 30 days (n=10 tumors per arm). At end of study, tumors were harvested and polar metabolites extracted for global ultra-high pressure liquid chromatography-mass spectrometry (UHPLC-MS)-based metabolomics with a focus on central carbon and nitrogen metabolism. Metabolites were separated using a high throughput gradient-based C18 method and identified and validated manually against an in-house library of 800+ compounds. Results: Global metabolomics analysis of PDX tumors revealed a significant impact of TAK-228 treatment on fatty acid oxidation, resulting in increased levels of saturated fatty acids (C8, C10, C12) and palmitoleic acid, an increase in arginine, proline, metabolism and a decrease in glutamine metabolism. Alisertib treatment impacted tryptophan metabolism; initial results suggest a disruption of metabolite balance downstream of tryptophan. These disruptions in nitrogen and carbon metabolism occurred in the combination treatment arm as well. Of note, glucose utilization via glycolysis and the pentose phosphate pathway (PPP) were decreased with treatments, with the most profound decrease in the combination arm. Conclusions: In addition to increased anti-tumor growth activity, TNBC PDX tumor metabolic profiles were altered in mice treated alisertib, TAK-228 and the combination. Global metabolomics analysis revealed that several key metabolic pathways, including fatty acid oxidation, amino acid metabolism, glycolysis and PPP activity were significantly dysregulated, likely contributing to the observed tumor growth inhibition. Importantly, the effects on several pathways by the single agents persisted in the combination, while others, including the decrease in glycolysis and PPP activity, were more pronounced in the combination arm. These results support the hypothesis that dual targeting of AurA and TORC1/2 may exert potent anti-tumor activity in TNBC through several mechanisms, including the disruption of tumor cell energetics. This combination is currently being evaluated in a Phase I clinical trial with planned expansion cohorts with serial tumor biopsies (NCT02719691). These clinical samples may provide a means for validation of these preclinical observations and allow continued elucidation of the potential antitumor metabolic reprogramming resulting from this dual targeting strategy and the clinical setting most likely to benefit from this combination. Citation Format: John J Tentler, Angelo D9Allesandro, Julie A Reisz, Kyrie L Dailey, Anna Capasso, Anastasia Ionkina, Stacey M Bagby, Todd M Pitts, Jennifer R Diamond. Combined aurora kinase A and mTORC 1/2 inhibition results in disruption of tumor cell energetics in triple negative breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-02-04.