49P Correlation of cell counts, tumor mass, and histopathologic phenotype in serous ovarian carcinoma: Implications for TILs therapy development as an ATMP

Background: Tumor-infiltrating lymphocyte (TIL) therapies are a promising strategy for ovarian cancer as advanced therapy medicinal products (ATMPs).Their efficacy depends on the quantity and quality of cells in the starting material.Automated quantitative assessment enables objective, reproducible measurements.Results were cross-validated by flow cytometry (gold standard) on the MaxQuant Miltenyi platform, ensuring reliability.Methods: Cell suspensions from ovarian and fallopian tube tumors were analyzed for cell counts per mL and tumor mass post-resection.Histopathology classified samples as low-grade (LGSC), high-grade (HGSC), or recurrent HGSC.Correlations between cell counts, tumor mass, histopathologic phenotype, and suitability for TIL therapy were assessed.Immunohistochemistry (ER, Ki-67, p53, WT1, PAX8) and surgical outcomes were recorded.Results: Low-grade: moderate cell counts and tumor mass, consistent with lower proliferation.High-grade, partial cytoreduction: elevated cell counts with tumor mass similar to low-grade.High-grade post-chemotherapy: very high cell counts and largest tumor mass, reflecting aggressive phenotype and potential TIL populations.Recurrent HGSC: lowest cell counts and smallest tumor mass, indicating residual disease post-treatment.ADAM measurements correlated highly with flow cytometry, validating quantitative assessment for TIL therapy development. Conclusions:Quantitative cell counts, validated by flow cytometry, correlate with tumor mass and histopathology, supporting patient selection and preparation of material for TIL therapy as an ATMP.Standardized cell quantification enables translational development and optimization of therapeutic processes.