YM155 Inhibition of Survivin Enhances Carboplatin Efficacy in Metastatic Castration-Resistant Prostate Cancer

Background/Objectives: Metastatic castration-resistant prostate cancer (mCRPC) remains a major clinical challenge due to its aggressive behavior and resistance to therapy. Survivin, a member of the inhibitor of apoptosis protein family, is overexpressed in various cancers and associated with poor prognosis. YM155 (Sepantronium bromide) suppresses survivin expression and has demonstrated antitumor activity in preclinical models. We investigated the association between survivin expression and clinical outcomes in mCRPC patients and evaluated the antitumor activity of YM155, alone and in combination with carboplatin, in mCRPC cell lines. Methods: Analysis of publicly available RNA-seq datasets from mCRPC patients was performed to assess correlations between survivin expression and clinical outcomes. Radiographic progression-free survival (rPFS) and overall survival (OS) were estimated using the Kaplan-Meier method and compared via log-rank or Fisher's exact tests. In vitro assays were conducted on mCRPC cell lines treated with YM155, carboplatin, or both, to evaluate cell viability, clonogenicity, and apoptosis. Results: Survivin was significantly overexpressed in mCRPC compared with localized prostate cancer and was even higher in castration-resistant neuroendocrine disease. High survivin levels were associated with shorter OS (p = 0.006). In patients treated with platinum-based therapies, high survivin was also linked to shorter rPFS (p = 0.01), reduced OS (p = 0.006), and a smaller PSA decline (p = 0.006). In vitro, YM155 reduced survivin expression, impaired cell viability and colony formation, induced apoptosis, and synergistically enhanced the cytotoxicity of carboplatin. Conclusions: Our findings suggest that survivin may serve as a prognostic biomarker and potential therapeutic target in platinum-treated, AR-independent mCRPC. The integration of clinical and functional data provides translational support for combining the survivin inhibitor YM155 with platinum-based therapy. These results warrant further validation in larger patient cohorts and in vivo models.