RecruitingDrug trialA Study Evaluating the Safety, Pharmacokinetics, and Preliminary Activity of GDC-1261 in Participants With Advanced or Metastatic Prostate CancerThe purpose of this study is to evaluate the safety, pharmacokinetics (PK), and preliminary activity of GDC-1261 in participants with advanced or metastatic prostate cancer. It's also to identify a recommended dose(s) and regimen for GDC-1261 for subsequent studies.