Introduction: High-grade serous carcinoma (HGSC) is the most common and lethal subtype of ovarian cancer, with five-year survival rates below 50%. Immunotherapy has not been effective for HGSC, whose metabolic microenvironment is known to interfere with successful anti-tumor immunity. Because NK cells respond to a diversity of activation signals, we expect they could be leveraged to target HGSC, but their activity can be limited by immunosuppressive metabolites, including adenosine. We hypothesize that adenosine is an important regulator of NK cell metabolism in the HGSC TME.

Methods: We conducted metabolomics mass spectrometry-based analysis on HGSC cell lines treated with adenosine to identify significant changes to individual metabolites, as well as metabolic pathways using MetaboAnalyst Pathway Analysis. To validate mass spectrometry findings, we co-cultured peripheral blood mononuclear cells (PBMCs) with HGSC cell lines and measured phenotypic changes by flow cytometry. We measured NK functional output via CD107a (degranulation) and CD69 (activation). Ongoing studies are using pathway inhibitors to sequentially target pathways of interest and observe the effects in the NK population.

Results: Preliminary analysis revealed that treating tumour cells with adenosine induces metabolic changes that interrupt NK activity. When adenosine is added to NK:HGSC co-cultures, subsets of NK cells exhibit decreased responsiveness to HGSC. Adenosine-treated HGSC cell lines show significant changes to metabolites that can be mapped to specific metabolic pathways, including arginine and proline metabolism, glycerophospholipid metabolism, and sphingolipid metabolism.

Conclusions: The presence of extracellular adenosine alters HGSC metabolism with putative impacts on NK cell function. Ongoing studies aim to understand how to restore and maintain NK cell function in the context of the adenosine-rich HGSC microenvironment.