Project 1: Targeting Metabolic Dependencies in PDAC

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Abstract - Project 1 (Targeting Metabolic Dependencies in PDAC) Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer death in the United States with a median survival of less than 6 months and a dismal 5-year survival rate of 7%. The highly malignant nature of PDAC is largely the result of driving oncogenic Kras mutations (Kras*) in >90% of tumors, as well as the heterogeneous nature of the disease at both the genomic and cellular levels. To date, no drug directly targeting Kras* has reached the clinic, and inhibitors of Kras* effector pathways in clinical trials have achieved only minimal responses followed by relapse of aggressive disease. Furthermore, immune targeting of PDAC has so far been unsuccessful. Thus, a critical need remains to identify new therapeutic vulnerabilities in PDAC. In our previous grant cycle, Project 1 and our P01 team established a role for Kras* in tumor maintenance in vivo wherein it controlled key metabolism enzymes supporting cancer-relevant anabolic processes that, in turn, are required for Kras*-driven PDAC maintenance. Using our inducible Kras* PDAC model, we also identified a subset of tumor cells with tumor-initiating cell (TIC) properties that can survive Kras* extinction and may lead to tumor recurrence following oncogene ablation. One of the hallmarks of these Kras* extinction-resistant cells (KRCs) is the shift from aerobic glycolysis to mitochondrial oxidative metabolism to sustain cell viability. Our P01 team further demonstrated that, while PDAC exhibits high basal autophagy, autophagic flux in KRCs was further enhanced to supply substrate for mitochondrial oxidative phosphorylation (OXPHOS), and targeting autophagy or OXPHOS effectively eliminated KRCs to prevent tumor relapse. Therefore, the collaborative work from our P01 team strongly suggests that effective therapeutics for PDAC should target not only players essential for Kras*-dependent tumor maintenance, but also pathways required to maintain KRCs. These data are the basis for an initiative begun during the last grant cycle to develop a novel OXPHOS inhibitor compound in PDAC, IACS-10759, at the Institute for Applied Cancer Science. In this next cycle, Project 1 will continue our efforts to better define the metabolism programs that sustain Kras*-dependent tumors as well as KRCs and to explore the translational potential of targeting metabolic processes, including targeting OXPHOS with IACS- 10759. Project 1 will work closely with the Cores, which have extensive expertise in pathology, preclinical therapeutics, and computational biology, and will be highly integrated with Project 2 to characterize the role of autophagy-regulating pathways. Our studies will also integrate with Project 3, using our inducible Kras* mouse model to explore the effects of Kras*-dependent and –independent metabolism programs on tumor immunity and response to immune checkpoint therapy. The knowledge gained from these highly integrated studies aims to inform future clinical trials opportunities.