Darolutamide Added to Docetaxel Augments Antitumor Effect in Models of Prostate Cancer through Cell Cycle Arrest at the G1–S Transition

Resistance to taxane chemotherapy is frequently observed in metastatic prostate cancer. The androgen receptor (AR) is a major driver of prostate cancer and a key regulator of the G1-S cell-cycle checkpoint, promoting cancer cell proliferation by irreversible passage to the S-phase. We hypothesized that AR signaling inhibitor (ARSi) darolutamide in combination with docetaxel could augment antitumor effect by impeding the proliferation of taxane-resistant cancer cells. We monitored cell viability in organoids, tumor volume, and PSA secretion in patient-derived xenografts (PDX) and analyzed cell cycle and signaling pathway alterations. Combination treatment increased antitumor effect in androgen-sensitive, AR-positive prostate cancer organoids and PDXs. Equally beneficial effects of darolutamide added to docetaxel were observed in a castration-resistant model, progressive on docetaxel, enzalutamide, and cabazitaxel. In vitro studies showed that docetaxel treatment with simultaneous darolutamide resulted in a reduction of cells entering the S-phase in contrast to only docetaxel. Molecular analysis in the prostate cancer cell line LNCaP revealed an upregulation of cyclin-dependent kinase inhibitor p21, supporting blockade of S-phase entry and cell proliferation. Our results provide a preclinical support for combining taxanes and darolutamide as a multimodal treatment strategy in patients with metastatic prostate cancer progressive on ARSi and taxane chemotherapy.