Spatial profiling of ovarian clear cell carcinoma (OCCC) and identification of immune-hot features.

Abstract

e17543 Background: OCCC is an ovarian cancer subtype with high incidence in Asia. Despite its frequent occurrence as an early-stage disease, optimal therapeutic options for high-risk patients are limited. Recently, immune-hot features have been proposed as an indicator for poor prognosis for early-stage OCCC. Specific patterns of intra-tumoral heterogeneity (ITH) associated with these immune-hot features have yet to be defined. Methods: Formalin-fixed paraffine embedded (FFPE) tumor sections from 10 early-stage primary OCCC patients were included. Digital Spatial Profiling (DSP) of 18 protein targets from the Human Protein Core Panel was conducted by using the nanoString GeoMx system to profile selected regions of interest (ROIs) based on the reference H&E staining morphology. Areas of illumination (AOIs) were defined according to ROI segmentation by the fluorescence signals of pan-cytokeratin (PanCK), CD45, or DNA. The digital signals were quantified by the nanoString nCounter system. Results: Unsupervised hierarchical clustering of 252 AOIs from 229 ROIs showed 5 distinct clusters. PanCK+ AOIs distributed in 5 clusters were found to express combinations of markers suggestive of immune mimicry: granzyme B (GZMB) high epithelial cells (C1-a), immune signal high epithelial cells (C1-b), immune-like cells (C1-c), fibronectin-high epithelial cells (C2-a), and signal-cold epithelial cells (C2-b). CD45+ AOIs were mostly clustered in C1-c. Tumor cells with C1-c and C2-a features were associated with recurrence while those in C1-a were associated with no recurrence (Chi-square p=2.8E-04). Tumor infiltrating immune cells (TIIs), which were found to be more enriched of the macrophage lineage (stronger CD68 expression, p=4.5E-03), were associated with recurrence (66.7% in recurrence vs 14.3% in no recurrence, Chi-Square p=0.098). TIIs appeared in PanCK segments of C1-b and C1-c with higher frequencies (45% in C1-b, 25% in C1-c, Chi-square p=0.046) and in PanCK segments of C1-a with extremely low frequency (0%). Correlating with morphology, tumors with recurrence showed higher frequency of papillary pattern (54.7%, Chi-Square p=1.01E-04) and lower frequency of tubulocystic pattern (18.9%, Chi-Square p=7.21E-03). Plus, TIIs were found with high frequency in ROIs with papillary pattern (65.2%, Chi-Square p=4.99E-04) and low frequency in ROIs with tubulocystic pattern (8.7%, Chi-Square p=6.43E-03). Papillary ROIs, which showed macrophage lineage immune mimicry, high CD68 intensity and low PanCK intensity, were found to have very low frequency of PanCK segments of C1-a (6.2%, Chi-Square p=1.26E-04), but extremely high frequency (100%) of PanCK segments of C1-c. Conclusions: Spatial profiling of early-stage OCCC tumors revealed immune-hot tumor features associated with recurrence. These features included immune mimicry of tumor cells, the presence of TIIs, and a papillary pattern in morphology.