High grade serous ovarian cancer (HGSOC) is a lethal gynaecological malignancy, most often detected at the late stages of disease, and at which point, response to therapy is only seen in a minority of patients. As new treatments are introduced, there is a growing need to better understand how the tumour microenvironment (TME) is predictive of therapeutic benefit. Here, we spatially analysed tumour samples from 55 HGSOC patients using high-plex spatial proteomics to characterise the TME and define the contributions to patient survival in cisplatin resistance. Using a custom-developed 48-plex cyclic immunofluorescent protein panel, we analysed tumour and immune cell interactions and their functional and metabolic profiles. We found that a higher number of CD66+ cells in a 50 µm radius of tumour cells (p = 0.025) and a higher number of cytotoxic CD8 T -Cells within a 10 µm radius of the tumour boundary were associated with improved overall survival (p = 0.03). We found that in areas of metabolically active tumour cells, the proximity of T-Reg Cells was associated with better overall survival when the activity of the tumour was increased in either citrate synthase activity (p = 0.0064) or high nitric oxide (p = 0.017). However, with metabolically less active tumours, there was an association with worse overall survival (p = 0.033). Taken together, our data suggest that a comprehensive functional understanding of the TME is needed to quantify the therapeutic benefits of immunotherapy in HGSOC.

Arutha Kulasinghe is on the Scientific Advisory Board for Omapix Solutions, Predxbio, Molecular Instruments and Visiopharm. All other authors declare no financial or non-financial competing interests.

The authors would like to acknowledge the support from the Wesley Research Institute, Frazer Institute (University of Queensland), and the Translational Research Institute.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

This study profiled formalin-fixed paraffin-embedded (FFPE) tissue microarray (TMA) consisting of single 1mm diameter tissue cores from 55 women with HGSOC (TA4359, SKU: 69574359, Tristar Technologies, USA). The tissues consisted of samples collected between 2009 and 2017 with informed written consent provided by the collaborating hospital sites. This study has the approval of the University of Queensland Human Research Ethics (2021/HE001936).

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Yes

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All data produced in the present study are available upon reasonable request to the authors