A Study of DS9051b in Participants With Advanced or Metastatic Adrenocortical Carcinoma and Metastatic Castration-resistant Prostate Cancer

This study is testing a new drug called DS9051b for two types of cancer: adrenocortical carcinoma (a rare cancer of the adrenal glands) and prostate cancer that has spread despite hormone therapy (called metastatic castration-resistant prostate cancer). **You may be eligible if...** - You are 18 or older - You have confirmed adrenocortical carcinoma or prostate cancer that has spread and stopped responding to hormone therapy - For prostate cancer: you have received at least one hormone-blocking drug and at least one round of chemotherapy (or are not able to have chemotherapy) - Your disease is progressing based on PSA levels, imaging, or bone scans - You are well enough to participate (ECOG 0 or 1; ECOG 2 acceptable if pain is the reason) **You may NOT be eligible if...** - You have a history of pituitary gland problems - You have an active autoimmune disease requiring treatment - You require high-dose steroids for a non-cancer condition Talk to your doctor to see if this trial is right for you.