Topotecan Syndergizes with SP141 in the Management of Uveal Melanoma

Purpose: Uveal melanoma (UM) is a rare but aggressive intraocular malignancy originating in the uvea (choroid, iris, and ciliary body). Despite primary treatment, 50% of UM patients develop metastases to the liver, lungs, bones, and skin. Topotecan, a topoisomerase I inhibitor, and SP141, an MDM2 inhibitor, have been studied in cancers, including retinoblastoma. This study explores a combined approach with these drugs in the 92-1 UM cell line. Methods: Primary choroidal melanoma-derived 92-1 cells were treated with topotecan and SP141 individually to determine IC50 values. Cell viability and proliferation were assessed using the MTT assay and the xCELLigence real-time monitoring system. The synergistic effects were analyzed quantitatively using the Loewe Additivity and Highest Single-Agent (HSA) models. Flow cytometry was employed to analyze cell cycle distribution, while cell death and apoptosis were monitored via high-throughput, real-time quantitative analysis using the IncuCyte live-cell kinetic imaging system. Results: Both Topotecan and SP141 induced significant cell death in 92-1 cells. xCELLigence showed dose- and time-dependent inhibition of proliferation. Combining sub-IC50 concentrations of topotecan and SP141 exhibited significant synergistic effects, markedly reducing growth. Cell cycle analysis revealed that topotecan causes a dose-dependent biphasic arrest in G2 and S phases, while SP141 causes G2/M arrest, leading to cell death. Cytotoxicity assays corroborated increased cell death following combination therapy, and the Caspase 3/7 assay indicated that apoptosis is the mechanism underlying cell death. Conclusions: The multi-targeted approach combining topotecan and SP141 drugs demonstrated synergistic therapeutic effects in 92-1 cells, suggesting a potential treatment strategy for managing UM.