Pancreatic ductal adenocarcinoma (PDAC) remains a lethal malignancy with a 5-year survival rate of only 3 % in cases of metastatic disease. Metastatic cancer cells exhibit dynamic adaptations in their metabolic profiles, and previous studies have indicated a unique vulnerability specifically in the mitochondria of metastatic cells. Therefore, we hypothesize that the metastatic potential of pancreatic cancer is determined by intratumoral heterogeneity, with subclones exhibiting distinct metabolic dependencies exerting a considerable impact on disease outcome.

Our previously published multiplexed small-molecule screening platform enables the investigation of metastatic seeding of cancer cells in a rapid, unbiased, and quantitative high-throughput manner. Utilizing this methodology, a library of mitochondria-affecting agents acting on diverse mitochondrial pathways was screened to identify those that were crucial for metastatic seeding. The most suitable candidates were individually validated in an in vivo treatment model of the entire metastatic cascade and resulting primary tumors as well as metastasis examined. Furthermore, RNA-sequencing was performed and a variety of other assays were employed to evaluate the effects of the compounds on specific steps of the metastatic cascade, as well as the cellular metabolism.

The initial screening platform and additional in vivo treatment studies identified IACS-010759, an inhibitor of OXPHOS complex I in the electron transport chain, to significantly reduce PDAC metastasis. While the growth of primary tumors remained unaffected, the tumors of treated mice exhibited a lower incidence of necrotic areas, reduced proliferation and higher levels of senescence. Subsequent analyses of in vivo material and several cell lines in vitro revealed alterations in hypoxia-related pathways and cell cycle. Further metabolic assays confirmed the reduction of oxygen consumption, a shift towards glycolysis and demonstrated the induction of reactive oxygen species (ROS) upon treatment.

We identified an inhibitor of OXPHOS complex I to profoundly reduce the metastatic potential of PDAC cells in vivo. Further examination of the metabolically distinct cell subpopulation(s) that drive metastasis and the impact of mitochondria targeting therapy on metastatic progression should provide valuable knowledge on targetable vulnerabilities.

KFO 337 "PhenoTImE" Phenotypic Therapy and Immune Escape in Cancer, funded by the DFG (German Research Foundation)