Introduction/Background Although the prognostic value of immune infiltrate has been extensively explored in HGSOC, very few studies explored it according to platinum-sensitivity/resistance status, an important factor for stratifying subsequent therapy.

Methodology Here, we questioned the prognostic value of 5 immune cell subsets (CD3+ and CD8+ T cells, FoxP3+ regulatory T cells, CD68+ and CD163+ tumor-associated macrophages) identified by immunohistochemistry in high-grade serous ovarian carcinoma using a clinically annotated tissue-microarray of 134 tumor samples.

Results We found that high intra-epithelial CD3+ T cell in tumor core was significantly associated with prolonged OS in all patients (HR=0.53; 95% CI [0.3–0.88]; p=0.03), and those who had platinum-sensitive disease (HR=0.51; 95% CI [0.27–0.94]; p=0.03). Similarly, a high density of CD68+ TAMs in tumor core was significantly associated with better OS in all patients (HR=0.49; 95% CI [0.27–0.91]; p=0.02), and those who had platinum-sensitive disease (HR=0.46; 95% CI [0.24–0.89]; p=0.02). Unexpectedly, there was a trend toward better survival in platinum-resistant patients who had stromal accumulation of FoxP3+ Treg (HR=0.27; 95% CI [0.06–1.15]; p=0.08).

Conclusion A deeper spatial and phenotypical characterization of tumor immune microenvironment in HGSOC according to platinum-sensitivity/resistance status is warranted for tailoring precision immunotherapy in this deadly disease.

Disclosures Together, our findings suggest that the prognostic value of immune infiltrate in HGSOC differs according to platinum-sensitivity/resistance status.