Immunotherapies that repolarize macrophages and regulatory T cells enhance the effect of chemotherapy in high-grade serous ovarian cancer (Mouse)

We conducted single-cell RNA sequencing (scRNAseq) of tumor-infiltrating immune cells in high-grade serous ovarian cancer (HGSOC) omental biopsies to identify potential targets that could enhance response to neo-adjuvant chemotherapy (NACT). Analysis of 64,097 cells identified NACT-induced overexpression of stabilin-1 (clever-1) on macrophages and FOXP3 in Tregs and these were validated at the protein level. STAB1 inhibition in vitro induced anti-tumor macrophages. FOXP3 anti-sense oligonucleotide (FOXP3-ASO), repolarised Tregs to an effector T cell phenotype. ScRNAseq on 69,781 cells from an HGSOC syngeneic mouse model recapitulated the patients’ data. Combining chemotherapy with anti-stabilin1 antibody and/or Foxp3-ASO significantly increased survival of mice with established peritoneal disease in two HGSOC syngeneic models and progression-free survival in a third model. Long-term survivors (300 days+) were resistant to tumor rechallenge. Anti-stabilin1 antibody enriched the tumors with CXCL9+ macrophages and Foxp3-ASO increased TBET cell infiltration. Our results suggest targeting these molecules may improve chemotherapy response in patients. Single cell RNA sequencing on whole omental tumours from HGS2 mouse model. Tumours were harvested from three control mice and 3 mice one week after the third dose of carboplatin and paclitaxel.