Dual-inhibition of NAMPT and PAK4 induces anti-tumor effects in 3D-spheroids model of platinum-resistant ovarian cancer

Ovarian cancer typically progresses by forming multiple tumor masses rich in cancer stem cells (CSCs) within the abdomen. Unfortunately, most patients develop resistance to standard platinum-based therapies, highlighting the urgent need for improved treatment strategies. One promising approach involves targeting CSCs by inhibiting NAD+ synthesis. Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the NAD+ salvage pathway, emerges as a compelling drug target in this context. KPT-9274 is an innovative drug that targets both NAMPT and p21-activated kinase 4 (PAK4), but its efficacy against ovarian cancer has not been fully explored. In this study, we demonstrate the effectiveness and underlying mechanisms of KPT-9274 in treating 3D-cultured spheroids resistant to platinum-based drugs. KPT-9274 not only inhibited NAD+ production in NAMPT-dependent cell lines within these spheroids but also reduced NADPH and ATP levels, suggesting impaired mitochondrial function. Additionally, ATG-019 downregulated genes related to inflammation and DNA repair. The drug also decreased PAK4 activity by altering its primarily cytoplasmic localization, leading to NAD+-dependent reductions in the phosphorylation of S6 Ribosomal protein, AKT, and β-Catenin in the cytoplasm. These findings indicate that KPT-9274 could be a promising therapy for ovarian cancer patients resistant to platinum drugs, underscoring the importance of precision medicine in identifying the specific NAD+ production pathway a tumor relies on before treatment.