Ovarian cancer cell lines overexpressing Cyclin E1 protein (Cyclin E1high) were more sensitive to azenosertib than ovarian cancer cell lines with lower levels of Cyclin E1 protein (Cyclin E1low) inducing significant cytotoxic effects (GRmax < -0.5)…. In vivo, the synergy between azenosertib and paclitaxel was stronger in Cyclin E1high OVCAR3 model (46% reduction of initial tumor volume/104% TGI) than Cyclin E1low A2780 model (85% TGI).