Elena Ioana Braicu

Background: Antibody-drug conjugates (ADCs) represent a promising therapeutic approach for high-grade serous ovarian carcinoma (HGSOC). Patient selection for ADC therapy depends on tumour target expression, making it essential to characterize molecular, spatial, and temporal heterogeneity. Methods: We analyzed two HGSOC tissue microarray cohorts: 100 genomically profiled cases (1565 cores) and 64 matched cases with paired adnexal (A), locally advanced (LA), and recurrent (R) samples (2395 cores). Associations between ADC target expression and molecular characteristics, sampling site, and survival were investigated. Results: ADC targets showed no significant associations with homologous recombination deficiency (HRD) or TP53 mutation status; TROP2 was modestly lower in BRCA1/2 -mutated tumours. Folate receptor-alpha (FolR1) showed notable spatial heterogeneity: 20.2% switched therapeutic-indication groups between centre and margin at A; 21.7% were reclassified between A and LA. Temporally, all markers showed ≥ 20% switching, reaching 38.4% for FolR1 between A and R. High FolR1 expression in A correlated with poorer survival, a pattern not observed in LA or R samples. Conclusions: ADC targets in HGSOC display limited molecular but significant spatial and temporal heterogeneity, with expression classifications varying by site and time. FolR1 expression in adnexal tumours associates with aggressive disease.

Background: Antibody-drug conjugates (ADCs) represent a promising therapeutic approach for high-grade serous ovarian carcinoma (HGSOC). Patient selection for ADC therapy depends on tumor target expression, making it essential to characterize molecular, spatial, and temporal heterogeneity. Methods: We analyzed two HGSOC tissue microarray cohorts: 100 genomically profiled primaries (1,565 cores) and 64 matched cases with paired primary (P), primary disseminated (PD), and recurrent (R) samples (2,395 cores). Associations between ADC target expression and molecular characteristics, sampling site, and survival were investigated. Results: ADC targets showed no significant associations with homologous recombination deficiency (HRD) or TP53 mutation status; TROP2 was modestly lower in BRCA1/2 -mutated tumors. Folate receptor-alpha (FolR1) showed notable spatial heterogeneity: 25% switched therapeutic-indication groups between center and margin at P; 21.7% were reclassified between P and PD. Temporally, all markers showed ≥20% switching, reaching 38.4% for FolR1 between P and R. High FolR1 expression in P correlated with poorer survival, a pattern not observed in PD or R samples. Conclusions: ADC targets in HGSOC display limited molecular but significant spatial and temporal heterogeneity, with expression classifications varying by site and time. FolR1 expression in primary tumors associates with aggressive disease.

Figure S2 displays the Proportions of Molecular subtypes of LTS and STS in the Charité cohort and n the TCGA cohort.

Figure S5 shows Candidate Genes in the Charité Cohort and Correlations among candidate genes and Literature research results for candidate genes.

The Table S1 shows the Patient ID, Cancer Stage and the Residual _Tumor status of the TCGA paired cohort grouped by the Survival Group.

Table S4 displays the characteristics and subtypes of the Charité cohort.

Purpose:The late-stage diagnosis and the aggressiveness of high-grade serous tubo-ovarian carcinoma (HGSC) often result in poor survival outcomes, yet some patients exhibit an exceptionally long survival rate. This study aimed to identify molecular profiles associated with long-/short-term survival in HGSC, with the goal of better understanding protective factors and developing new treatments.Experimental Design:To discover molecular drivers causing the aggressiveness of HGSC, tumor samples from 12 long-term HGSC survivors (>7 years overall survival) and 12 short-term survivors (<1 year overall survival) were analyzed using targeted RNA sequencing followed by computational analysis. We investigated differentially expressed genes and their functional relevance, inferred differences in cell type composition and signaling pathways, as well as mutation status. To validate our findings, we simulated our study design by using HGSC The Cancer Genome Atlas dataset samples. We evaluated differential patterns of gene expression between these two groups and developed molecular profiles of HGSC that correlate with survival phenotypes.Results:Besides known molecular cancer drivers and indicators of poor prognosis, we identified specific transcriptional changes between short- and long-term survivors of HGSC, which indicate that immune processes play a fundamental role in long-term survivors. Our computational analysis reveals an important role for the ensemble of IFN-γ signaling and the RFX transcription factors, as well as the immune cell composition of the tumor microenvironment.Conclusions:Specific immunologic requirements involving IFN-γ signaling and affected pathways seem to be relevant for long-term survival in the generally considered nonimmunogenic HGSC, necessitating further research to improve diagnostic strategies and targeted therapies.

Figure S10 displays differences in celltypes between the cohorts A) for LTS and B) for STS based on CIBERSORT results.