Preselecting Tumour-Infiltrating Lymphocyte Subsets To Implement Adoptive Immunotherapy In Ovarian Cancer

Background Adoptive cell therapy (ACT) of expanded in-vitro tumour specific T-cells isolated from fresh tumour infiltrates has shown promising results in melanoma patients, and in ovarian cancer (OC). The use of pre-enriched tumor-specific T cells may simplify the TIL production method and enhances the tumour-reactivity of the final cellular product. We have investigated the role of PD-1 as a biomarker for the isolation and expansion of tumour-specific CD8 TILs in OC. Methods Samples from ten OC patients were analyzed. We used flow cytometry FACs Aria sorter for phenotyping and separate T-cells. For reactivity assay we performed co-cultures of TILs with autologous tumour and non-related tumor cell line, and measured INFγ released by ELISPOT. For immunofluorescence multiplex we used a Vectra® microscope and inForm® software to analyzed data. Tumour DNA sequencing was done using a TrueShight™ 170 gene panel. Results Both CD8+PD-1+and CD8+PD-1- TIL subsets expanded efficiently and no difference in fold expansion was found. Tumor-reactive TILs were detected in 5/10 patients and this tumor-reactivity was exclusively present in the cells derived from the PD-1+-enriched fraction. There were a higher frequency of CD8+PD-1+CD137+ by FC (p = 0,0079) in reactive group in fresh biopsy. Total CD8+and CD8+PD-1+were more frequent in reactive patients (p = 0,0079, p = 0,0317). CD8+PD-1+CD137+were more frequent (p = 0,0437) by IF in the tumoral epithelium of reactive patients. There were more total CD4+ and CD4+PD-1+by FC in reactive group (p = 0,0079, p = 0,0159). By IF we observed more CD4+PD-1+in both epithelium and stroma of reactive group (p = 0,0437). Patients with reactive TILs exhibited significantly high number of missense mutactions (p = 0,0198). Conclusions CD8+PD-1+ T-cell subset include tumour-specific T-cell in OC. CD8+PD-1+CD137+ cells in epithelium may work as a biomarker for reactivity. Higher mutation load is related with tumour-reactive TILs in OC. Legal entity responsible for the study The authors. Funding ISCIII Spanish grant (PI15/02027). Disclosure All authors have declared no conflicts of interest.