LAUSR

The purpose of this study was to explore the Fabʹ fragment of anti-FSHR (Follicle Stimulating Hormone Receptor) antibody as a targeting ligand to graft on the surface of paclitaxel (PTX) liposomes (PLs) for site-specific drug delivery in ovarian cancer (OC) cells. Anti-FSHR antibody Fab’ fragment conjugated PTX encapsulated immunoliposomes (ILs) were prepared, characterized, and evaluated to determine their in vitro efficacy in FSHR receptor positive (Caov3) and negative (SKOV3) OC cells. FSHR expression was determined by confocal microscopy and flow cytometry. The results confirmed that FSHR expression levels of Caov3 were higher and no expression was detected in SKOV3. ILs were prepared by covalent conjugation of Fab’ fragments to functionalized PLs via thioether linkage which was confirmed by SDS-PAGE analysis. Immunoreactivity of the prepared ILs was determined against Fabʹ in Caov3 cells using flow cytometry and it was observed that after conjugation, Fabʹ remained intact and also maintained the binding characteristic to the receptor. In MTT assay at the end of 48 h, the IC50 value for ILs was found to be 10.8 and 3.5 folds lower than Taxol® and PLs respectively in Caov3. However, being receptor negative, there was no significant difference noticed for IC50 when PLs and ILs were compared for SKOV3. To prove, whether immune tagging improves cell-specific uptake of ILs in FSHR-expressing cells, cell uptake studies were carried out using confocal microscopy and flow cytometry which showed higher uptake of ILs in Caov3 but not in SKOV3. For assessment of anti-angiogenic activity, a wound scratch assay was performed on Caov3 cells. At an equimolar concentration of treatment given to the cells by PLs and ILs, the % recovery of the wound was 1.3 and 2.3 times lower than Taxol® respectively indicating the superior performance of ILs in inhibiting cell proliferation. The quantitation of cell death after treatment was carried out by flow cytometry after staining with propidium iodide and the highest amount of cell death was seen in ILs group for Caov3 cells. Evaluation of cell cycle in the Caov3 indicated superior results of arrest of cells in G2/M phase. Further, an increase in cell death was observed as indicated by the increase in % of cells in subG1 stage. Performance of PLs was similar in Caov3 and SKOV3 leading to almost around 22% of arrest in G2/M stage, however, for ILs, the number of cells in G2/M was 28% for Caov3 cells at the end of 24 h indicating that the targeted formulation was able to better get internalized in the cells due to receptor-mediated uptake. The results highlight the importance of FSHR as a prominent target for OC therapy and the potential of anti-FSHR Antibody Fab' conjugated nanocarriers as a site-specific delivery system to reduce the limitations associated with OC chemotherapy. Citation Format: Priyanka Bhatt. FSHR-mediated targeted delivery of paclitaxel immunoliposomes in receptor overexpressing ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2005.