Trial Targeting Gut Bacterial Androgen Production to Reverse Therapeutic Resistance to Abiraterone in Patients With Metastatic Prostate Cancer

To determine if dexamethasone or dexamethasone plus metronidazole restore sensitivity to abiraterone for the treatment of metastatic prostate cancer.

To test whether giving dexamethasone with or without metronidazole in combination with abiraterone could help reverse resistance to abiraterone for patients with metastatic castration-resistant prostate cancer (mCRPC). Abiraterone and prednisone (AA/P) is a second-line therapy for mCRPC given when first-line androgen deprivation therapy fails. However, resistance to AA/P can develop. The investigators do not know exactly how cancer becomes resistant, but there is evidence that suggests it could be due to androgen production by the bacteria in your gut (gut microbiome). This study is focused on the gut microbiome as a source of androgen production that could cause AA/P resistance in mCRPC.