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bioRxiv · 10.1101/2025.08.10.669554

Using targeted therapy to promote a pro-inflammatory tumour microenvironment and anti-tumour immune response in high grade serous ovarian cancer

Zeng, Z.·Gandini, A.·Bhatt, R.·Proctor, M.·Goh, N.·Vora, S.·Walsh, T. P.·Wu, S.·Ferguson, K.·Coward, J.·Kumari, S.·Haass, N. K.·Wells, J.·Hardy, J.·Perrin, L.·Hooper, J.·Ho, G.-Y.·Gonzalez Cruz, J.·Gabrielli, B.
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Abstract

BACKGROUNDHigh-grade serous ovarian cancer (HGSOC) is characterized by elevated replication stress and an immunosuppressive microenvironment. A synergistic combination of checkpoint kinase 1 inhibitor (CHK1i) with low-dose hydroxyurea (LDHU) promotes a unique ATR-independent moderate replication stress response with potent anti-tumour effects. The ability of this approach to reprogram the tumour immune microenvironment (TIME) to overcome the immunosuppression and promote an anti-tumour immune response in HGSOC is the focus of this study. METHODSWe investigated the therapeutic potential of CHK1i+LDHU in established HGSOC cell cultures, fresh tumour cell explants from HGSOC patient ascites, and syngeneic mouse models, assessing tumour cell killing, immunogenic cell death, pro-inflammatory cytokine/chemokine expression, and anti-tumour immune responses. RESULTSCHK1i+LDHU effectively killed ovarian cancer cells regardless of chemotherapy resistance, BRCA2 mutation and homologous recombination repair status in vitro. In vivo, treatment significantly reduced tumour burden and ascites accumulation. CHK1i+LDHU enhanced expression of pro-inflammatory cytokines/chemokines and triggered immunogenic cell death in tumour. In syngeneic models, treatment promoted CD8+ cytotoxic T cell-dependent anti-tumour responses and reduced immunosuppressive signalling within the TIME. CONCLUSIONSCHK1i+LDHU is a promising therapy for chemotherapy-resistant HGSOC, combining direct cytotoxic effects with reprogramming the TIME to reduce immunosuppression and activate a CD8+ T cell-dependent anti-tumour response.

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Zeng, Z., Gandini, A., Bhatt, R., Proctor, M., Goh, N., Vora, S., Walsh, T. P., Wu, S., Ferguson, K., Coward, J., Kumari, S., Haass, N. K., Wells, J., Hardy, J., Perrin, L., Hooper, J., Ho, G.-Y., Gonzalez Cruz, J., Gabrielli, B.. 2025-08-12. Using targeted therapy to promote a pro-inflammatory tumour microenvironment and anti-tumour immune response in high grade serous ovarian cancer. https://doi.org/10.1101/2025.08.10.669554

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